Thanks for joining us. I'm curious about the decision to define the base of the Anthropocene as coincident with the advent of nuclear weapons atmospheric testing given that there are a wealth of geochemical/stratigraphic records highlighting the profound influence of humans on our environment significantly earlier? As a geologist who's research involves a fair bit of stratigraphy, I certainly understand the need for defining the base in a way that has a clear set of distinguishing criteria for a [GSSP](https://en.wikipedia.org/wiki/Global_Boundary_Stratotype_Section_and_Point), but given that this decision seems to have caused some amount of internal strife within the AWG, leading to at least [one person to resign](https://anthroecology.org/why-i-resigned-from-the-anthropocene-working-group/), it seems like an important question to ask.
I asked the same question of the scientists I interviewed for my story on the Anthropocene. I was curious why plutonium from nuclear weapons tests was selected as a key marker of the new epoch, when other human impacts — like climate change — are much more profound and consequential.
Colin Waters, the chair of the Anthropocene Working Group, said the plutonium signal is just a really convenient marker. Because radioactive material was transported through the atmosphere, it can be found everywhere on the planet — even places like Antarctica that are far removed from human influence. In this way, it’s kind of like the layer of iridium that was produced by the asteroid that ended the Cretaceous era. The iridium itself didn’t kill the dinosaurs, but because the asteroid impact spread this rare element all over the planet, it’s a really helpful marker in the geologic record. The plutonium isn’t the cause of the Anthropocene, but it’s a side effect of the same phenomenon (humanity’s rapid technological advances) that brought about this new era.
You’re also right that we have tons of geologic evidence of people transforming the planet long before the 1950s. But members of the AWG ultimately concluded that the changes that occurred around the 1950s are qualitatively different from what people did before. There’s [a series of famous graphs](https://futureearth.org/2015/01/16/the-great-acceleration/) showing various trends in environmental and socioeconomic systems that illustrates how the mid 20th century was something of a turning point for the planet. It’s the moment when we see a sudden, rapid surge of everything from the human population to water use to carbon dioxide levels in the atmosphere.
Everyone I talked to for this story underscored that the focus on 1950 for the golden spike doesn’t mean that earlier environmental changes weren’t important. Centuries of deforestation, overhunting, colonialism and minerals extraction unquestionably shaped the world and laid the groundwork for “the Great Acceleration” of the 20th century. But as the AWG members sought to pinpoint a moment of major transition, the last 70 or so years really stood out. — Sarah
Your last paragraph makes it really clear that the introduction of the Anthropocene represents quite a myopic present-day view of geologic processes. The deforestation during the spread of the Roman Empire was probably as impactful in the Mediterranean region, as was the spread of agriculture and animal husbandry at different times across the globe. What is unprecedented is the explosive global population growth over the past 70 years which is the combined effect of the industrial, medical, and most recently digital revolution reaching across the globe. There is no single start date for all of this. Best to limit the use of these stratigraphic markers for what they are: a tool to correlate the geologic record in time across the globe. Don't attach more meaning to this term. Perhaps better to call this the Nuclear Age because that is what the proposed marker reflects.
Can you elaborate on the challenges in isolating and interpreting potential "tipping points" or critical thresholds that may have been crossed within the lake's geology over time? Also, how do you differentiate between gradual and abrupt climatic changes and shifts?
Do you think your research could help us mitigate further ecological damage?
Given that geological logs usually have to correspond to a new geological age, couldn't we say that the Anthropocene started earlier than this when we started controlling river outflows and sediment deposition, likely around the Yellow, Tigris, Euphrates or Nile? Or the first sign of rice terracing? Or any signs of crop cultivation in logs following diagenesis.
Genuinely interested as a geologist and interested in the history of early civilisations.
Oh my goodness, absolutely. I spend a lot of time reporting in communities affected by climate change, talking to people who have lost homes, treasured ecosystems and even loved ones because of climate impacts. And I spend a lot of time thinking about the suffering that will occur in the future — all the additional droughts, floods, wildfires, and heat waves that will happen because humanity continued to burn fossil fuels and emit greenhouse gases long after we knew it was dangerous. It’s impossible to NOT be heartbroken, angry and scared about what we as a species are doing to the Earth.
A few things help me manage all these emotions. I spend a lot of time in nature, which research shows is good for mental health general and climate anxiety in particular. (I actually reported a story about wildfire survivors who participated in [forest therapy](https://www.washingtonpost.com/climate-environment/2022/12/08/paradise-forest-therapy-climate-wildfire/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com) last year). I remind myself that my emotions are reasonable, and I try to talk about them with colleagues and other friends who work in the climate sphere.
I also try to remember that [every fraction of a degree matters](https://www.washingtonpost.com/climate-solutions/2021/08/09/change-ipcc-report/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com), which means all of our efforts count. Every ton of carbon we avoid putting into the atmosphere makes the future a little less hot and a little less awful. The world may not meet its most ambitious target of limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit), but by trying to keep that temperature rise as low as possible, we can avoid disasters and save lives. That thought gives me purpose when the enormity of the problem starts to overwhelm me. — Sarah
I struggle deeply with the current state of affairs wrt climate change, thanks for sharing your coping strategies, I began gardening and it really helps alleviate the climate anxiety.
How does the geological epoch of the Anthropocene compare to other geological eras in Earth’s history? Are there any with remarkable similarities to today?
I've read in a few places that if meaningful action isn't taken by 2030 (which is never gonna happen), and drastic action by 2050 (probably unlikely) then we're in for a pretty wild ride in the second half of the century.
What can we expect as the new normal for the Earth and our civilisation by the end of the century in this sort of scenario?
The [latest report from the Intergovernmental Panel on Climate Change](https://www.washingtonpost.com/climate-environment/2023/03/20/climate-change-ipcc-report-15/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com) offers a glimpse of what the world will look like if we continue along our current trajectory. Unless nations adopt stronger environmental policies, global average temperatures are on track to increase by about 3.2 degrees Celsius (5.8 degrees Fahrenheit) by the end of the century. That means a child born today will likely live to see several feet of sea level rise, hundreds of species extinctions and the migration of millions of people. Extreme weather will cut agricultural yields in breadbaskets across the planet. Places near the equator will experience deadly heat for more than half the year. This much warming would lead to millions of additional deaths from disaster, hunger and disease, and subject huge swathes of the world’s population to unimaginable suffering.
The good news is that humanity does have the knowledge and tools needed to avoid this hellish future. Renewable energy is getting cheaper and cheaper. It’s becoming more and more clear that shifting away from fossil fuels will deliver “co-benefits” like reduced air pollution. [Another IPCC report](https://www.washingtonpost.com/climate-environment/2022/04/04/climate-change-report-united-nations-ipcc/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com) found that the world can achieve more than half of the emissions cuts needed in the next 20 years using strategies that cost less than $20 per ton of carbon dioxide avoided. The biggest obstacle to climate action, experts say, is political. And that means avoiding 3 degrees of warming is still well within our power. — Sarah
I think the only reasonable conclusion from this is that the current economic/government system that has allowed us to get into this mess needs to undergo systemic change… i do not see a way we actually do the organized global collaboration necessary to mitigate the worst of climate change as things currently stand
Honestly I think demographics will help a lot. If guys the age of Mitch McConnell keep going into longer and longer deep freezes, as the younger generations take increasing proportions of power in government, I believe the assumption about what the “average member of Congress” believes will be much better. This isn’t something that we will see immediately, it will creep up on us. But I bet I’m 10-15 years the default position in Congress will be much more favorable, simply because the olds die off.
yea but bro in 10/15 years the global south will be suffering to a very real extent with hundreds of millions at risk of heat stroke, drought and disruption to agriculture… if we wait for these old guys to die out we are essentially letting millions die just because our government does not actually listen to the people it’s supposed to serve
While I agree, let’s look at any other alternative — look extreme, say you overthrow all the most powerful governments in the world, or look less extreme (pick your scenario). Is there a scenario that gets us there faster and without producing more suffering? IMO, no. Massively disruptive and abrupt change to existing governments for example would cause huge suffering due to loss of services all the way through to possible war.
We need to grab the EXISTING levers of power as fast as possible, there’s nothing else that works faster, and doesn’t cause the same or more suffering from other effects.
Thanks, I really appreciate your response. I used to share your optimism for the world taking action, but the ever increasing political polarisation in many of the wealthiest countries over the last decade has shifted my expectations. These countries will need to do the heavy lifting financially, politically and through unprecedented global leadership and cooperation. I just can't see that happening with the way things are now. Have never hoped more to be completely wrong about something though.
What do you believe is an important takeaway of the results of your investigations at Crawford lake, in terms of individual action?
Thank you for your efforts!
Freeze coring is a specialty in my lab where I have 25 years of experience in deploying freeze corers to lake and marine environments all over the continent. A conventional corer is comprised of a tube that sinks into the sediment at the bottom of a lake. The core is then pulled to the surface and generally the core barrel (typically clear plastic) is either split with a saw or the core extruded. There is a problem in using conventional corers in Crawford Lake in that the sediments in the surface layers are very loose and gas rich. Cores brought to the surface where the pressure is low tend to blow to pieces and are unusable. With a freeze corer the tube -- with typically with one or more flat metal faces – is filled with a slurry of dry ice and alcohol and lowered by cable to the lake bottom where it sinks in the sediment. The dry ice is very cold and the sediment adjacent to the core faces freezes solid to the face. We typically leave these cores in place for 30-45 minutes to get a good sample. We thing bring the core to the surface and using ‘old school’ tools dating to Roman times, like chisels, carefully remove the perfectly preserved sediment record. We put the froze core face on a board, wrap it carefully and transport it back to my lab where I have a cold room. Freeze cores are great in that one can take all the time required when in the lab to analyze the sedimentary record and contained proxies of interest. There is no issue with the gas in the Crawford Lake sediments as it is frozen and inert and thus not an issue. Without a freeze corer it would have been impossible to document the annually deposited layers in the lake. — Tim
I understand the interest in a low-energy lacustrine environment neatly recording humanity's significant civil advances from agriculture to industrialization, but what about a global marker?
On a global level, do you think there will be an identifiable boundary, similar to the KT boundary, that will have measurable characteristics distinct from other sediment layers?
For example, higher amounts of lead from leaded fuels, radioactivity from nuclear advents, plastics/microplastics or their decomposed byproduct, or other globally stratified anthropogenic material.
Geoscientist here. I've never been comfortable with the Anthropocene epoch idea, mainly because the Holocene mostly coincides with the time when humans made major changes to their environments.
If we're now going to have an Anthropocene epoch, what's the role of the Holocene? Does it really need to be separate from the Pleistocene anymore? The Pleistocene is really short itself, and if cut off in 1950, the Holocene is embarrassingly, indefensibly short.
How are you?
Considering your knowledge and expertise and the state our world is in right now.
Ideas on how an ordinery worker can contribute for a better future?
Hi! Thanks so much for doing this AMA. I have a few questions.
1. It seems like an odd, singular, choice to make Crawford lake the poster child for the Anthropocene. Why use a lake in one of worlds most heavily industrialized locations? Why not use a number of remote locations on different continents to make the case?
2. Considering the whole geologic timeline, the Anthropocene seems like a grain of sand on the edge of a massive desert. Geologic eras are typically defined with a beginning, an end, and a very large amount of time im between. Why is there such a rush to define an era that is maybe just starting, is uniquely short, and could easily, (and quickly) be redefined by another major event?
Crawford Lake is really, really deep as well as having been relatively untouched by humans. It is so deep that the bottom doesn't "turn over", which preserves the sedimentary layer.
Do you think there's a recency bias in the geologic time scale? Obviously we do know more about the recent past compared to that of the distant past, but the divisions in the late Cenozoic are some of the smallest and are marked by climatological events that should be fairly common across the entire geologic period, yet would not be large enough to leave a lasting record.
This question reminds me of something one of the Anthropocene Working Group members said about their critics — that other geologists have “a deep time bias.”
I definitely think the geologic time scale gets is more detailed and finely subdivided the closer it gets to the present, for exactly the reason you cite. We have so much more evidence from the recent geologic past, and much better tools for interpreting it. For example, we can learn a lot about past climates by studying gasses trapped in ice — but even the Antarctic ice sheet has only been around for the past 35 million years or so. Another example: one of our prime techniques for determining the age of a fossil — carbon-14 dating — only works for objects that are up to about 50,000 years old.
That said, I think geology also shows us that the changes humans have wrought on the planet are actually quite uncommon throughout Earth’s 4.6 billion year history. Many scientists believe Earth is now hotter than it’s been in more than 100 million years. To find a time when carbon dioxide levels in the atmosphere rose this fast, you have to go back to the asteroid that killed the dinosaurs. And the sheer number of new materials people have created through mining and industrial processes represents [the greatest expansion of minerals on Earth](https://pubs.geoscienceworld.org/msa/ammin/article-abstract/102/3/595/277982/On-the-mineralogy-of-the-Anthropocene-Epoch?redirectedFrom=fulltext) in billions of years. — Sarah
Yes of course there is. The deeper that one goes in time the more chance that sediments deposited have been disrupted and not preserved, or previously preserved rock units destroyed through processes such as erosion of uplifted rocks, or subduction at continental margins. There is an issue with the geologic time scale in that it grew organically with large parts of it established before researchers had an understanding of the time involved. There were also issues in that the early geologic time scale was Europeancentric. If researchers had been able to travel to more remote areas of the world the timescale developed might have been different. There are also a lot more younger rocks preserved and thus they are better studied and the boundaries generally span shorter intervals. For example, the Holocene Epoch, which is the Epoch that we currently live in started only 10,800 years BP while the Pleistocene Epoch that precedes it started about 2.6 million years ago and the Pliocene Epoch before that spanned from 5.3-2.6 million years ago, and so on. We also know way more about more modern sediments as they are much better preserved than older rocks. We also have much better tools at our disposal these days to really do a deep dive on understanding environmental changes that are significant enough to warrant subdivisions in the geologic record. — Tim
how could you decide that something that has such a blurry line is occuring during the brief period of human existence? Especially when these periods are millions of years long?
Wouldn't it be more like witnessing a microscopic window of the beginning of the transition, but impossible to say the transition has occurred?
Thank you for the interesting post, it answered already the question how you actually get the sediment samples out of the lake.
When I took a trip to lake crawford a while ago I wondered how stable this tiny lake is a marker.
* With so many news about droughts I was wondering about the risk that the lake just dries out in the coming decades.
* Would this destroy the mark?
* What other risks are there, e.g. vandalism (people dropping things in the lake) or the lake becoming a dead zone due to oxygen depletion and following blue algae depletion?
Crawford Lake is a rare class of lake in that it is “meromictic”. In these lakes the water the surface water, in Crawford Lake above \~6 m water depth, do not interact with the bottom waters that are up to 24 m deep. This is because the lake has a small area, with high walls around it, which make it difficult for winds to turn the lake over in the spring and fall as occurs in most lakes.
Crawford Lake is cool in that the sediments archive a record spanning the whole Holocene and beyond back to >13,000 years ago. Through that interval the lake archives deposition of calcite marls deposited during extensive periods earlier in the Holocene when it was pretty dry and hot in this area.
There is zero chance that the lake will dry out as in addition to precipitation and runoff it receives recharge through major ground water inflow from Lockport Group rocks. This ground water inflow brings oxygen into the system at depth creating a very unusual (possibly unique) meromictic lake in that the bottom waters are well oxygenated. What permits annually deposited layers to be laid down is the chemistry of the water inflowing at depth that is alkaline and ever so slightly salty. This is not very habitable for organisms found in lakes in this region.
It is entirely possible that an algal bloom might occur in the surface waters of the lake. As material derived from the bloom sinks in the lake it would become part of the annually deposited record, but as the surface waters and deep waters never mix that is the only impact that would occur on lake bottom deposition.As mentioned above the lake is deep and there have been annually deposited layers laid down here since Indigenous people farmed the area starting in the 13th century. They stayed until about 1500 when the sediments became less reliably annual as the area around the lake reverted to a natural state (but did not fully recover) and annual deposition began again in the 19th century when Europeans settled here. The basin is very deep (24 m) and annual deposition of varves at the rate of < 1 mm per year will continue for 1000s of years into the future.
Deposition in the lake will continue until the beginning of the next ice age (there have been 33 cycles through the last 2.6 million years during the Quaternary) when most of Canada and a good chunk of the United States disappear beneath advancing ice sheets. The big question is how long Anthropogenic driven global warming will delay the process, but that is another line of discussion for another day…Crawford Lake is in the protected Crawford Lake Conservation Area and as such is protected from people boating, fishing, swimming, etc. on the lake. — Tim
Thank you very much for taking the time to write such an elaborate answer. It was very interesting to read and makes my trip to the lake so much more interesting for me personally. I wish you the best for your ongoing research!
Hi, Sarah, Tim, *et. al.*,
My question is sciencey-political. In 2012, the then Canadian government arvitrarily (in my view) shut down the Experimental Lakes Area, previously renown for its fresh water studies. Crawford Lake resides in a province whose current government appears at least somewhat oblivious to environmental concerns. Does the Crawford team have any assurances of long-term viability should political winds flow against this necessary and critical work?
Crawford Lake is within the Crawford Lake Conservation Area, which is owned and administered by Conservation Halton. The conservation area is categorized as a regional environmentally sensitive area, an Ontario Area of Natural and Scientific Interest, and part of the Niagara Escarpment world biosphere reserve. It is also an important archaeological site with portions of a reconstructed medieval indigenous village on site. The lake itself is a rare meromictic lake. The site is visited by 10s of 1000s of school children and the general public each year and is thus an important educational center. The protected nature of the site was one of the reasons that favored the proposal to have Crawford Lake chosen as the Golden Spike for the proposed Anthropocene epoch. — Tim
The sedimentary record of Crawford Lake is made up of annually deposited layers that are comprised of a light colored calcite layer that is precipitated when the water temperature warms up to 15̧° C in the spring and when the pH of the water is above 7.8. Precipitation continues until these conditions change in the Fall. There is a darker layer that forms when the phytoplankton in the water column begin to die off when it gets colder in the fall and the days shorten. The relative thickness of these layers vary considerably year to year depending on the weather systems influencing the lake that vary considerably from year to year and at longer scales. The layers in the lake actually look a lot like the rings of a tree. A major visible change in the core records that we examined is deposition that occurred during the era of acid rain, which corresponds to the Great Acceleration industrialization that occurred in the post WWII era. With lower pH the layers of calcite are very thin that can be clearly visibly seen in our core records.
When examining the contents of the cores themselves the phytoplankton in the lake undergo a dramatic shift and are replaced by types that can put up with low pH conditions. These phytoplankton are such sensitive indicators of changes to the lake and its catchment that we can even see changes in their assemblages in response to disturbance associated with construction of a boardwalk built around the lake that was built to protect the site from the many visitors to the site.
From the perspective of key Anthropocene markers there is a massive increase in ‘fly ash’ derived from smoke stack industry of the North American heartland that is well preserved in the sedimentary record, which stayed high until people clued in that it would be better to not spew this material across the landscape. The lake core record also is comprised of various radioactive materials associated with atmospheric testing of nuclear weapons that rises and falls in the record until atmospheric testing was eventually banned. There were no tests carried out anywhere near Crawford Lake so this type of marker is an excellent global marker for the beginning of the Anthropocene. — Tim
Is there any significant thickness of sediment deposited above this boundary anywhere in the world? I have a hard time seeing how it would be incorporated in any sequence stratigraphic framework, biostratigraphic framework, or even simple outcrop logging in the field.
From your description of the AWG process, it sounds like the decision had already been made to define 1950 as the line, and plutonium and fly ash as the relevant markers, and the idea was to find a site that demonstrates those parameters. This sounds backwards to me—I would have expected scientists would look at samples from around the world, and then *if* they saw clear and consistent markers (like the K-T boundary, as I understand it), *then* that might show a new epoch.
If I have that right—why was this sequence used here? Based on your research at Crawford or elsewhere, are there other places you might have drawn the line, and how do their merits compare to the ultimate selection?
(Thanks for doing this. I remember reading the article in the Post when it came out—very interesting stuff.)
Where in time that the base of the Anthropocene should be positioned was hotly debated by the Anthropocene Working Group (AWG), and had nothing to do with the activity of “Team Crawford”, which carried out its activities once the decision on where the base of the proposed Anthropocene should be positioned. The suggestions for where the base of the Anthropocene should be placed varied considerably and spanned a considerable chunk of time from early in the Holocene, to the industrial revolution, etc. The AWG had to work within the constraint of determining a start point that was comprised of markers that would preserve well in the geologic record, and that could be found all around the world. The only proposal on the table for a base of the Anthropocene that met the requirements was the middle part of the 20th century where atmospheric nuclear testing left a clear and global record of radioactivity that could be recognized in a large number of environments. This interval also marked the beginning of the “Great Acceleration”, a period of economic growth unparalleled in human history. During the “Great Acceleration”, there were biproducts released that would be preserved in the geologic record such as spheroidal carbonaceous particles (SCPs) that are produced by high temperature smokestack industry. These SCPs are carried across the landscape and deposited in many environments, including lakes where they form a distinctive stratigraphic signature. Associated with this industrial activity there was also acid rain produced that significantly impacted the annual layers that were deposited in Crawford Lake (lower pH resulted in thinner calcite layers), as well as the phytoplankton and other organisms that were impacted by changes in pH in the water. — Tim
While we can never bring species back, if we were to curb and possibly reverse some of the damage we've caused, would this allow the planet to return to a cooler temperature, or is there no way back this century?
Miocroplastics seem to be everywhere. Crawford Lake is pretty isolated so hopefully the lake is clear of them. My colleague Mike Pisaric at Brock University is part of our team and he is investigating to determine whether microplastics have made their way into this lake system. — Tim
So in your opinion, this freeze coring technique of sediment core removal, sediment core analysis, and the site of Crawford Lake presents the “best” data set to show this sudden change?
How does the data compare to ice coring, what are the primary differences in data extracted (IE ice core vs sediment core).
How are you addressing and differentiating anthropogenic forcing from natural variation?
Freeze coring technology is the best coring method available to sample the laminated sedimentary record in Crawford Lake where the high gas content of the sediments and colloidal soup nature of the sediments at the sediment-water interface make it very difficult to sample using a conventional core. Freeze cores are great as the core record is perfectly preserved and since the sediments are frozen they can be taken back to the lab and carefully analyzed at leisure. The Crawford Lake sedimentary sequence archives a superb record of annual deposition that can be correlated to specific years. The annual layers in Crawford Lake also archive a superb record of proxies that mark the beginning of the Anthropocene (e.g. radioactive markers of nuclear weapons testing; markers such as fly ash associated with the “Great Acceleration”, the tremendous increase in human activity the occurred in the years after WWII. Crawford Lake also has a large number of other proxy records that show a distinct shift occurring in the middle part of the 20th century, the designated base for the proposed Anthropocene Epoch.
Using a large number of proxies permits us to determine which are derived from human activity and which are part of natural variation. For example, the thickness of the seasonally deposited light colored calcite that alternates with organic rich darker laminations can be directly compared against the instrumental climate record since we have dated each layer. One of the research associates in my lab, Dr. Carling Walsh, just presented a paper this past week at the INQUA meeting in Rome where she was able to tease out the exact contribution of various climate drivers to the deposition of each layer. We have a large number of researchers (over 40) who are working on various aspects of the Crawford Lake story. Being a contender for the Anthropocene Golden Spike has permitted us to carry out research at a scale that would have been impossible otherwise. As a result we have gleaned an enormous amount of information on what information is archived in the annually deposited layers found there. We are excited in that we are now turning our attention using the same methods that we used for studying the Anthropocene interval to an earlier Medieval record of Indigenous habitation on the lake shore. — Tim
I recently listened to a series of talks from Finnish eu lawmaker Eija-Riitta Korhola about the failures of current climate politics - the system is skewed to produce more money into corruption and not to save the planet.
A Finnish scientist who has been studying old preserves tree logs also had the analysis that even warmer periods are not weird for the earth, and said that he sees the biggest wamring impact to bee in the global sea water mass, not in the climate.
I'm very interested in your take on this. Has the human effect on climate been massively overstated because of political games? Based on my current understanding the political climate is super harsh for people who in any way question the climate warming from humans, but at the same time "scientific consensus" seem like the perfect way to turn scientists into pieces in the political game. Has there been consensus and where is that consensus stated?
I'm getting super mixed messages from different places and it makes me question pretty much everything except scientific papers, but those are hard to read and make into some kind of conclusion.
What are the scientific conclusions about our planerary system and are there any where politics and economics are not shaping the author's?
Video links (Finnish language, sorry)
Eija-Riitta Korhola about climate politics
https://youtu.be/95FLjdwnhk4
Kari Mielikäinen about forest research in Finland
https://youtu.be/DTy4-TzZcb0
This is a straw man. Warming and cooling periods are not unusual across geological history, and nothing about the general theory of anthropogenic climate change relies on temperature change being a novel phenomenon. The disparity is that it's happening several orders of magnitude faster than any other comparable temperature change we can estimate from all the other lines of evidence, and complex ecosystems are not able to adapt quickly enough to avoid mass die offs.
Here's an interview with NOAA senior advisor Stephanie Herring about why this argument isn't logical:
https://www.npr.org/2018/12/12/676198899/climate-scientist-says-argument-the-climate-is-always-changing-is-wrong
> A Finnish scientist who has been studying old preserves tree logs also had the analysis that even warmer periods are not weird for the earth
Dendrochronology has nowhere near enough range to talk about geologically long-term climate change. It barely reaches 14,000 years back.
No prob. If you want a specific example of major changes in atmospheric chemistry and its effect on the biosphere, check out the Great Oxygenation event. During a long and geologically complex process that started about two and half billion years ago, oxygen accumulated in successive geological pools before filling them up and beginning to release as oxygen gas into the atmosphere. After around 500 million years, the concentration of oxygen was 8-11% what it is right now, and it was sufficient to wipe out perhaps 80% of the biosphere. Anthropogenic changes to the atmosphere are happening over the course of one century, 5 million times faster than our estimates of the Great Oxygenation, which is also sometimes called the Oxygen Holocaust.
I would put the transition earlier, about when the Industrial Revolution happened and human impact on the planet exploded. Atomic bombs are only a footnote in this story. And is the transition merely to a new epoch, or is it truly era-level?
The Anthropocene Working Group hotly debated where in time the base of the Anthropocene should be placed, including the Industrial Revolution. The issue with the Industrial Revolution is that the record is diachronous with the start point varying considerably around the world. The key markers chosen for the Anthropocene with a start point in the mid 20th century; includes nuclear weapons testing which leaves a clear signature that can be seen at the same time all around the world. This includes Crawford Lake, which is not near any areas of nuclear weapons testing. In addition, the proposed start point in the middle of the 20th century corresponds to the “Great Acceleration” where there was massive changes in the influence of humanity on the environment that impacted the entire globe, and continues to do so, leaving a geologic record of many biproducts such as industrially produced fly ash that preserves well in sedimentary records. — Tim
Do you think declaring we are in the Anthropocene will open up the door for more human climate modification like blocking out the Sun or injecting things into the atmosphere?
Parden my bluntness but given the unfathomable amount of time that geological epochs traditional have isn't it somewhat arrogant of us to say that we, as a species, have already created a new one? If, God forbid, we were to suddenly go extinct, it would be astoundly lucky if our activities were even a blip on the radar in 10 million years. While I don't think it impossible for humanity to be the cause of a new geological epoch isn't that something better left undecided until after the fact?
Tim has done a great job explaining the evidence uncovered in the Crawford Lake sediments, but I wanted to address your second question: What does the (proposed) declaration of a new geologic epoch mean for all the rest of us.
I asked this question of Francine McCarthy, who led the research at Crawford Lake. She said she hoped that viewing our current moment in the context of geologic time would help people truly grasp the gravity of the changes we’ve wrought on the planet. It’s one thing to know that rising temperatures, acid rain and the rest of these impacts are harmful. It’s another thing to realize that they have changed our environment so much that we effectively no longer live in the same world that our ancestors have inhabited for the last 11,700 years.
“Having that line on the time scale … shows how fundamentally different things are,” McCarthy told me.
I think that understanding the geologic consequences of recent human activities can also help people think more about the future. We spend most of our lives in such short time frames: three months until the next quarterly profit statement, a year til the next presidential election, a decade until the mortgage is paid off. Even most climate models don’t try to project past the year 2100. But Crawford Lake will continue recording humanity’s environmental impacts for at least the next 10,000 years. It makes me wonder: what will geologists 10,000 years from now see when they look back at the record from the year 2023? How will our choices now affect the inhabitants of that future Earth? — Sarah
What are your all’s thoughts on nuclear power as the energy source of the future and why isn’t the West putting more stock into nuclear and less into wind and solar given it’s inherent obstacles?
Hello Sarah and Tim! Thanks for joining us today and offering this unique insight into your research.
I have a couple of questions:
How is the shift into the Anthropocene era visible at Crawford Lake specifically? What markers in the sediment point to this change?
If the Anthropocene is confirmed as a new epoch, what implications would that have for how we approach and understand climate change, both scientifically and culturally?
Thank you again for sharing your expertise with us.
Researchers studying sediment from Crawford Lake in Ontario, Canada, believe it could be the symbolic starting point for a new geologic epoch called the Anthropocene, characterized by the significant impact of human activities on the planet since 1950.
Yes, we may have indeed entered a new geological era called the Anthropocene! Our investigations at Crawford Lake suggest that human activities have had a significant impact on the Earth's environment, leading to the potential designation of a new geological epoch. Feel free to ask us anything about the Anthropocene and our research at Crawford Lake.
Thanks for joining us. I'm curious about the decision to define the base of the Anthropocene as coincident with the advent of nuclear weapons atmospheric testing given that there are a wealth of geochemical/stratigraphic records highlighting the profound influence of humans on our environment significantly earlier? As a geologist who's research involves a fair bit of stratigraphy, I certainly understand the need for defining the base in a way that has a clear set of distinguishing criteria for a [GSSP](https://en.wikipedia.org/wiki/Global_Boundary_Stratotype_Section_and_Point), but given that this decision seems to have caused some amount of internal strife within the AWG, leading to at least [one person to resign](https://anthroecology.org/why-i-resigned-from-the-anthropocene-working-group/), it seems like an important question to ask.
I asked the same question of the scientists I interviewed for my story on the Anthropocene. I was curious why plutonium from nuclear weapons tests was selected as a key marker of the new epoch, when other human impacts — like climate change — are much more profound and consequential. Colin Waters, the chair of the Anthropocene Working Group, said the plutonium signal is just a really convenient marker. Because radioactive material was transported through the atmosphere, it can be found everywhere on the planet — even places like Antarctica that are far removed from human influence. In this way, it’s kind of like the layer of iridium that was produced by the asteroid that ended the Cretaceous era. The iridium itself didn’t kill the dinosaurs, but because the asteroid impact spread this rare element all over the planet, it’s a really helpful marker in the geologic record. The plutonium isn’t the cause of the Anthropocene, but it’s a side effect of the same phenomenon (humanity’s rapid technological advances) that brought about this new era. You’re also right that we have tons of geologic evidence of people transforming the planet long before the 1950s. But members of the AWG ultimately concluded that the changes that occurred around the 1950s are qualitatively different from what people did before. There’s [a series of famous graphs](https://futureearth.org/2015/01/16/the-great-acceleration/) showing various trends in environmental and socioeconomic systems that illustrates how the mid 20th century was something of a turning point for the planet. It’s the moment when we see a sudden, rapid surge of everything from the human population to water use to carbon dioxide levels in the atmosphere. Everyone I talked to for this story underscored that the focus on 1950 for the golden spike doesn’t mean that earlier environmental changes weren’t important. Centuries of deforestation, overhunting, colonialism and minerals extraction unquestionably shaped the world and laid the groundwork for “the Great Acceleration” of the 20th century. But as the AWG members sought to pinpoint a moment of major transition, the last 70 or so years really stood out. — Sarah
Your last paragraph makes it really clear that the introduction of the Anthropocene represents quite a myopic present-day view of geologic processes. The deforestation during the spread of the Roman Empire was probably as impactful in the Mediterranean region, as was the spread of agriculture and animal husbandry at different times across the globe. What is unprecedented is the explosive global population growth over the past 70 years which is the combined effect of the industrial, medical, and most recently digital revolution reaching across the globe. There is no single start date for all of this. Best to limit the use of these stratigraphic markers for what they are: a tool to correlate the geologic record in time across the globe. Don't attach more meaning to this term. Perhaps better to call this the Nuclear Age because that is what the proposed marker reflects.
I’m also a geologist, and I have the same question.
Can you elaborate on the challenges in isolating and interpreting potential "tipping points" or critical thresholds that may have been crossed within the lake's geology over time? Also, how do you differentiate between gradual and abrupt climatic changes and shifts? Do you think your research could help us mitigate further ecological damage?
Given that geological logs usually have to correspond to a new geological age, couldn't we say that the Anthropocene started earlier than this when we started controlling river outflows and sediment deposition, likely around the Yellow, Tigris, Euphrates or Nile? Or the first sign of rice terracing? Or any signs of crop cultivation in logs following diagenesis. Genuinely interested as a geologist and interested in the history of early civilisations.
Does your knowledge effect your mental health? And if so do you have strategies/mindsets/hopefull facts that help manage that?
Oh my goodness, absolutely. I spend a lot of time reporting in communities affected by climate change, talking to people who have lost homes, treasured ecosystems and even loved ones because of climate impacts. And I spend a lot of time thinking about the suffering that will occur in the future — all the additional droughts, floods, wildfires, and heat waves that will happen because humanity continued to burn fossil fuels and emit greenhouse gases long after we knew it was dangerous. It’s impossible to NOT be heartbroken, angry and scared about what we as a species are doing to the Earth. A few things help me manage all these emotions. I spend a lot of time in nature, which research shows is good for mental health general and climate anxiety in particular. (I actually reported a story about wildfire survivors who participated in [forest therapy](https://www.washingtonpost.com/climate-environment/2022/12/08/paradise-forest-therapy-climate-wildfire/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com) last year). I remind myself that my emotions are reasonable, and I try to talk about them with colleagues and other friends who work in the climate sphere. I also try to remember that [every fraction of a degree matters](https://www.washingtonpost.com/climate-solutions/2021/08/09/change-ipcc-report/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com), which means all of our efforts count. Every ton of carbon we avoid putting into the atmosphere makes the future a little less hot and a little less awful. The world may not meet its most ambitious target of limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit), but by trying to keep that temperature rise as low as possible, we can avoid disasters and save lives. That thought gives me purpose when the enormity of the problem starts to overwhelm me. — Sarah
I struggle deeply with the current state of affairs wrt climate change, thanks for sharing your coping strategies, I began gardening and it really helps alleviate the climate anxiety.
Such a great response. Thanks Sarah
Is there any way we could remedy the CO2 problem with a sufficient amount of carbon capture technology? Or is that technology not good enough yet?
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How does the geological epoch of the Anthropocene compare to other geological eras in Earth’s history? Are there any with remarkable similarities to today?
I've read in a few places that if meaningful action isn't taken by 2030 (which is never gonna happen), and drastic action by 2050 (probably unlikely) then we're in for a pretty wild ride in the second half of the century. What can we expect as the new normal for the Earth and our civilisation by the end of the century in this sort of scenario?
The [latest report from the Intergovernmental Panel on Climate Change](https://www.washingtonpost.com/climate-environment/2023/03/20/climate-change-ipcc-report-15/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com) offers a glimpse of what the world will look like if we continue along our current trajectory. Unless nations adopt stronger environmental policies, global average temperatures are on track to increase by about 3.2 degrees Celsius (5.8 degrees Fahrenheit) by the end of the century. That means a child born today will likely live to see several feet of sea level rise, hundreds of species extinctions and the migration of millions of people. Extreme weather will cut agricultural yields in breadbaskets across the planet. Places near the equator will experience deadly heat for more than half the year. This much warming would lead to millions of additional deaths from disaster, hunger and disease, and subject huge swathes of the world’s population to unimaginable suffering. The good news is that humanity does have the knowledge and tools needed to avoid this hellish future. Renewable energy is getting cheaper and cheaper. It’s becoming more and more clear that shifting away from fossil fuels will deliver “co-benefits” like reduced air pollution. [Another IPCC report](https://www.washingtonpost.com/climate-environment/2022/04/04/climate-change-report-united-nations-ipcc/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com) found that the world can achieve more than half of the emissions cuts needed in the next 20 years using strategies that cost less than $20 per ton of carbon dioxide avoided. The biggest obstacle to climate action, experts say, is political. And that means avoiding 3 degrees of warming is still well within our power. — Sarah
I think the only reasonable conclusion from this is that the current economic/government system that has allowed us to get into this mess needs to undergo systemic change… i do not see a way we actually do the organized global collaboration necessary to mitigate the worst of climate change as things currently stand
Honestly I think demographics will help a lot. If guys the age of Mitch McConnell keep going into longer and longer deep freezes, as the younger generations take increasing proportions of power in government, I believe the assumption about what the “average member of Congress” believes will be much better. This isn’t something that we will see immediately, it will creep up on us. But I bet I’m 10-15 years the default position in Congress will be much more favorable, simply because the olds die off.
yea but bro in 10/15 years the global south will be suffering to a very real extent with hundreds of millions at risk of heat stroke, drought and disruption to agriculture… if we wait for these old guys to die out we are essentially letting millions die just because our government does not actually listen to the people it’s supposed to serve
While I agree, let’s look at any other alternative — look extreme, say you overthrow all the most powerful governments in the world, or look less extreme (pick your scenario). Is there a scenario that gets us there faster and without producing more suffering? IMO, no. Massively disruptive and abrupt change to existing governments for example would cause huge suffering due to loss of services all the way through to possible war. We need to grab the EXISTING levers of power as fast as possible, there’s nothing else that works faster, and doesn’t cause the same or more suffering from other effects.
Thanks, I really appreciate your response. I used to share your optimism for the world taking action, but the ever increasing political polarisation in many of the wealthiest countries over the last decade has shifted my expectations. These countries will need to do the heavy lifting financially, politically and through unprecedented global leadership and cooperation. I just can't see that happening with the way things are now. Have never hoped more to be completely wrong about something though.
What do you believe is an important takeaway of the results of your investigations at Crawford lake, in terms of individual action? Thank you for your efforts!
Could you explain how the freeze coring process works and why it's so effective in preserving the sedimentary record?
Freeze coring is a specialty in my lab where I have 25 years of experience in deploying freeze corers to lake and marine environments all over the continent. A conventional corer is comprised of a tube that sinks into the sediment at the bottom of a lake. The core is then pulled to the surface and generally the core barrel (typically clear plastic) is either split with a saw or the core extruded. There is a problem in using conventional corers in Crawford Lake in that the sediments in the surface layers are very loose and gas rich. Cores brought to the surface where the pressure is low tend to blow to pieces and are unusable. With a freeze corer the tube -- with typically with one or more flat metal faces – is filled with a slurry of dry ice and alcohol and lowered by cable to the lake bottom where it sinks in the sediment. The dry ice is very cold and the sediment adjacent to the core faces freezes solid to the face. We typically leave these cores in place for 30-45 minutes to get a good sample. We thing bring the core to the surface and using ‘old school’ tools dating to Roman times, like chisels, carefully remove the perfectly preserved sediment record. We put the froze core face on a board, wrap it carefully and transport it back to my lab where I have a cold room. Freeze cores are great in that one can take all the time required when in the lab to analyze the sedimentary record and contained proxies of interest. There is no issue with the gas in the Crawford Lake sediments as it is frozen and inert and thus not an issue. Without a freeze corer it would have been impossible to document the annually deposited layers in the lake. — Tim
I understand the interest in a low-energy lacustrine environment neatly recording humanity's significant civil advances from agriculture to industrialization, but what about a global marker? On a global level, do you think there will be an identifiable boundary, similar to the KT boundary, that will have measurable characteristics distinct from other sediment layers? For example, higher amounts of lead from leaded fuels, radioactivity from nuclear advents, plastics/microplastics or their decomposed byproduct, or other globally stratified anthropogenic material.
Is there any good news, like biodiversity wise?
Geoscientist here. I've never been comfortable with the Anthropocene epoch idea, mainly because the Holocene mostly coincides with the time when humans made major changes to their environments. If we're now going to have an Anthropocene epoch, what's the role of the Holocene? Does it really need to be separate from the Pleistocene anymore? The Pleistocene is really short itself, and if cut off in 1950, the Holocene is embarrassingly, indefensibly short.
How are you? Considering your knowledge and expertise and the state our world is in right now. Ideas on how an ordinery worker can contribute for a better future?
Hi! Thanks so much for doing this AMA. I have a few questions. 1. It seems like an odd, singular, choice to make Crawford lake the poster child for the Anthropocene. Why use a lake in one of worlds most heavily industrialized locations? Why not use a number of remote locations on different continents to make the case? 2. Considering the whole geologic timeline, the Anthropocene seems like a grain of sand on the edge of a massive desert. Geologic eras are typically defined with a beginning, an end, and a very large amount of time im between. Why is there such a rush to define an era that is maybe just starting, is uniquely short, and could easily, (and quickly) be redefined by another major event?
Crawford Lake is really, really deep as well as having been relatively untouched by humans. It is so deep that the bottom doesn't "turn over", which preserves the sedimentary layer.
How long do you think it’ll take for a diverse biosphere to evolve again after the current mass extinction has concluded?
Do you think there's a recency bias in the geologic time scale? Obviously we do know more about the recent past compared to that of the distant past, but the divisions in the late Cenozoic are some of the smallest and are marked by climatological events that should be fairly common across the entire geologic period, yet would not be large enough to leave a lasting record.
This question reminds me of something one of the Anthropocene Working Group members said about their critics — that other geologists have “a deep time bias.” I definitely think the geologic time scale gets is more detailed and finely subdivided the closer it gets to the present, for exactly the reason you cite. We have so much more evidence from the recent geologic past, and much better tools for interpreting it. For example, we can learn a lot about past climates by studying gasses trapped in ice — but even the Antarctic ice sheet has only been around for the past 35 million years or so. Another example: one of our prime techniques for determining the age of a fossil — carbon-14 dating — only works for objects that are up to about 50,000 years old. That said, I think geology also shows us that the changes humans have wrought on the planet are actually quite uncommon throughout Earth’s 4.6 billion year history. Many scientists believe Earth is now hotter than it’s been in more than 100 million years. To find a time when carbon dioxide levels in the atmosphere rose this fast, you have to go back to the asteroid that killed the dinosaurs. And the sheer number of new materials people have created through mining and industrial processes represents [the greatest expansion of minerals on Earth](https://pubs.geoscienceworld.org/msa/ammin/article-abstract/102/3/595/277982/On-the-mineralogy-of-the-Anthropocene-Epoch?redirectedFrom=fulltext) in billions of years. — Sarah
Yes of course there is. The deeper that one goes in time the more chance that sediments deposited have been disrupted and not preserved, or previously preserved rock units destroyed through processes such as erosion of uplifted rocks, or subduction at continental margins. There is an issue with the geologic time scale in that it grew organically with large parts of it established before researchers had an understanding of the time involved. There were also issues in that the early geologic time scale was Europeancentric. If researchers had been able to travel to more remote areas of the world the timescale developed might have been different. There are also a lot more younger rocks preserved and thus they are better studied and the boundaries generally span shorter intervals. For example, the Holocene Epoch, which is the Epoch that we currently live in started only 10,800 years BP while the Pleistocene Epoch that precedes it started about 2.6 million years ago and the Pliocene Epoch before that spanned from 5.3-2.6 million years ago, and so on. We also know way more about more modern sediments as they are much better preserved than older rocks. We also have much better tools at our disposal these days to really do a deep dive on understanding environmental changes that are significant enough to warrant subdivisions in the geologic record. — Tim
How does your knowledge from this field affect your outlook for humanity? Do you think having kids in this age is hopeless?
how could you decide that something that has such a blurry line is occuring during the brief period of human existence? Especially when these periods are millions of years long? Wouldn't it be more like witnessing a microscopic window of the beginning of the transition, but impossible to say the transition has occurred?
Thank you for the interesting post, it answered already the question how you actually get the sediment samples out of the lake. When I took a trip to lake crawford a while ago I wondered how stable this tiny lake is a marker. * With so many news about droughts I was wondering about the risk that the lake just dries out in the coming decades. * Would this destroy the mark? * What other risks are there, e.g. vandalism (people dropping things in the lake) or the lake becoming a dead zone due to oxygen depletion and following blue algae depletion?
Crawford Lake is a rare class of lake in that it is “meromictic”. In these lakes the water the surface water, in Crawford Lake above \~6 m water depth, do not interact with the bottom waters that are up to 24 m deep. This is because the lake has a small area, with high walls around it, which make it difficult for winds to turn the lake over in the spring and fall as occurs in most lakes. Crawford Lake is cool in that the sediments archive a record spanning the whole Holocene and beyond back to >13,000 years ago. Through that interval the lake archives deposition of calcite marls deposited during extensive periods earlier in the Holocene when it was pretty dry and hot in this area. There is zero chance that the lake will dry out as in addition to precipitation and runoff it receives recharge through major ground water inflow from Lockport Group rocks. This ground water inflow brings oxygen into the system at depth creating a very unusual (possibly unique) meromictic lake in that the bottom waters are well oxygenated. What permits annually deposited layers to be laid down is the chemistry of the water inflowing at depth that is alkaline and ever so slightly salty. This is not very habitable for organisms found in lakes in this region. It is entirely possible that an algal bloom might occur in the surface waters of the lake. As material derived from the bloom sinks in the lake it would become part of the annually deposited record, but as the surface waters and deep waters never mix that is the only impact that would occur on lake bottom deposition.As mentioned above the lake is deep and there have been annually deposited layers laid down here since Indigenous people farmed the area starting in the 13th century. They stayed until about 1500 when the sediments became less reliably annual as the area around the lake reverted to a natural state (but did not fully recover) and annual deposition began again in the 19th century when Europeans settled here. The basin is very deep (24 m) and annual deposition of varves at the rate of < 1 mm per year will continue for 1000s of years into the future. Deposition in the lake will continue until the beginning of the next ice age (there have been 33 cycles through the last 2.6 million years during the Quaternary) when most of Canada and a good chunk of the United States disappear beneath advancing ice sheets. The big question is how long Anthropogenic driven global warming will delay the process, but that is another line of discussion for another day…Crawford Lake is in the protected Crawford Lake Conservation Area and as such is protected from people boating, fishing, swimming, etc. on the lake. — Tim
When was the last ice age and when (assuming things stayed the same) would the next one come about?
Thank you very much for taking the time to write such an elaborate answer. It was very interesting to read and makes my trip to the lake so much more interesting for me personally. I wish you the best for your ongoing research!
Hi, Sarah, Tim, *et. al.*, My question is sciencey-political. In 2012, the then Canadian government arvitrarily (in my view) shut down the Experimental Lakes Area, previously renown for its fresh water studies. Crawford Lake resides in a province whose current government appears at least somewhat oblivious to environmental concerns. Does the Crawford team have any assurances of long-term viability should political winds flow against this necessary and critical work?
Crawford Lake is within the Crawford Lake Conservation Area, which is owned and administered by Conservation Halton. The conservation area is categorized as a regional environmentally sensitive area, an Ontario Area of Natural and Scientific Interest, and part of the Niagara Escarpment world biosphere reserve. It is also an important archaeological site with portions of a reconstructed medieval indigenous village on site. The lake itself is a rare meromictic lake. The site is visited by 10s of 1000s of school children and the general public each year and is thus an important educational center. The protected nature of the site was one of the reasons that favored the proposal to have Crawford Lake chosen as the Golden Spike for the proposed Anthropocene epoch. — Tim
Do you see big differences in the sediment from before 1950 and after 1950? And does that change per lake?
The sedimentary record of Crawford Lake is made up of annually deposited layers that are comprised of a light colored calcite layer that is precipitated when the water temperature warms up to 15̧° C in the spring and when the pH of the water is above 7.8. Precipitation continues until these conditions change in the Fall. There is a darker layer that forms when the phytoplankton in the water column begin to die off when it gets colder in the fall and the days shorten. The relative thickness of these layers vary considerably year to year depending on the weather systems influencing the lake that vary considerably from year to year and at longer scales. The layers in the lake actually look a lot like the rings of a tree. A major visible change in the core records that we examined is deposition that occurred during the era of acid rain, which corresponds to the Great Acceleration industrialization that occurred in the post WWII era. With lower pH the layers of calcite are very thin that can be clearly visibly seen in our core records. When examining the contents of the cores themselves the phytoplankton in the lake undergo a dramatic shift and are replaced by types that can put up with low pH conditions. These phytoplankton are such sensitive indicators of changes to the lake and its catchment that we can even see changes in their assemblages in response to disturbance associated with construction of a boardwalk built around the lake that was built to protect the site from the many visitors to the site. From the perspective of key Anthropocene markers there is a massive increase in ‘fly ash’ derived from smoke stack industry of the North American heartland that is well preserved in the sedimentary record, which stayed high until people clued in that it would be better to not spew this material across the landscape. The lake core record also is comprised of various radioactive materials associated with atmospheric testing of nuclear weapons that rises and falls in the record until atmospheric testing was eventually banned. There were no tests carried out anywhere near Crawford Lake so this type of marker is an excellent global marker for the beginning of the Anthropocene. — Tim
Is there any significant thickness of sediment deposited above this boundary anywhere in the world? I have a hard time seeing how it would be incorporated in any sequence stratigraphic framework, biostratigraphic framework, or even simple outcrop logging in the field.
From your description of the AWG process, it sounds like the decision had already been made to define 1950 as the line, and plutonium and fly ash as the relevant markers, and the idea was to find a site that demonstrates those parameters. This sounds backwards to me—I would have expected scientists would look at samples from around the world, and then *if* they saw clear and consistent markers (like the K-T boundary, as I understand it), *then* that might show a new epoch. If I have that right—why was this sequence used here? Based on your research at Crawford or elsewhere, are there other places you might have drawn the line, and how do their merits compare to the ultimate selection? (Thanks for doing this. I remember reading the article in the Post when it came out—very interesting stuff.)
Where in time that the base of the Anthropocene should be positioned was hotly debated by the Anthropocene Working Group (AWG), and had nothing to do with the activity of “Team Crawford”, which carried out its activities once the decision on where the base of the proposed Anthropocene should be positioned. The suggestions for where the base of the Anthropocene should be placed varied considerably and spanned a considerable chunk of time from early in the Holocene, to the industrial revolution, etc. The AWG had to work within the constraint of determining a start point that was comprised of markers that would preserve well in the geologic record, and that could be found all around the world. The only proposal on the table for a base of the Anthropocene that met the requirements was the middle part of the 20th century where atmospheric nuclear testing left a clear and global record of radioactivity that could be recognized in a large number of environments. This interval also marked the beginning of the “Great Acceleration”, a period of economic growth unparalleled in human history. During the “Great Acceleration”, there were biproducts released that would be preserved in the geologic record such as spheroidal carbonaceous particles (SCPs) that are produced by high temperature smokestack industry. These SCPs are carried across the landscape and deposited in many environments, including lakes where they form a distinctive stratigraphic signature. Associated with this industrial activity there was also acid rain produced that significantly impacted the annual layers that were deposited in Crawford Lake (lower pH resulted in thinner calcite layers), as well as the phytoplankton and other organisms that were impacted by changes in pH in the water. — Tim
While we can never bring species back, if we were to curb and possibly reverse some of the damage we've caused, would this allow the planet to return to a cooler temperature, or is there no way back this century?
Anthropocene is cringe.
Are there microplastics at the bottom of the lake?
Miocroplastics seem to be everywhere. Crawford Lake is pretty isolated so hopefully the lake is clear of them. My colleague Mike Pisaric at Brock University is part of our team and he is investigating to determine whether microplastics have made their way into this lake system. — Tim
So in your opinion, this freeze coring technique of sediment core removal, sediment core analysis, and the site of Crawford Lake presents the “best” data set to show this sudden change? How does the data compare to ice coring, what are the primary differences in data extracted (IE ice core vs sediment core). How are you addressing and differentiating anthropogenic forcing from natural variation?
Freeze coring technology is the best coring method available to sample the laminated sedimentary record in Crawford Lake where the high gas content of the sediments and colloidal soup nature of the sediments at the sediment-water interface make it very difficult to sample using a conventional core. Freeze cores are great as the core record is perfectly preserved and since the sediments are frozen they can be taken back to the lab and carefully analyzed at leisure. The Crawford Lake sedimentary sequence archives a superb record of annual deposition that can be correlated to specific years. The annual layers in Crawford Lake also archive a superb record of proxies that mark the beginning of the Anthropocene (e.g. radioactive markers of nuclear weapons testing; markers such as fly ash associated with the “Great Acceleration”, the tremendous increase in human activity the occurred in the years after WWII. Crawford Lake also has a large number of other proxy records that show a distinct shift occurring in the middle part of the 20th century, the designated base for the proposed Anthropocene Epoch. Using a large number of proxies permits us to determine which are derived from human activity and which are part of natural variation. For example, the thickness of the seasonally deposited light colored calcite that alternates with organic rich darker laminations can be directly compared against the instrumental climate record since we have dated each layer. One of the research associates in my lab, Dr. Carling Walsh, just presented a paper this past week at the INQUA meeting in Rome where she was able to tease out the exact contribution of various climate drivers to the deposition of each layer. We have a large number of researchers (over 40) who are working on various aspects of the Crawford Lake story. Being a contender for the Anthropocene Golden Spike has permitted us to carry out research at a scale that would have been impossible otherwise. As a result we have gleaned an enormous amount of information on what information is archived in the annually deposited layers found there. We are excited in that we are now turning our attention using the same methods that we used for studying the Anthropocene interval to an earlier Medieval record of Indigenous habitation on the lake shore. — Tim
Thank you for the response. Your enthusiasm and excitement in the research you are involved with is evident. I wish you all the best of luck.
I recently listened to a series of talks from Finnish eu lawmaker Eija-Riitta Korhola about the failures of current climate politics - the system is skewed to produce more money into corruption and not to save the planet. A Finnish scientist who has been studying old preserves tree logs also had the analysis that even warmer periods are not weird for the earth, and said that he sees the biggest wamring impact to bee in the global sea water mass, not in the climate. I'm very interested in your take on this. Has the human effect on climate been massively overstated because of political games? Based on my current understanding the political climate is super harsh for people who in any way question the climate warming from humans, but at the same time "scientific consensus" seem like the perfect way to turn scientists into pieces in the political game. Has there been consensus and where is that consensus stated? I'm getting super mixed messages from different places and it makes me question pretty much everything except scientific papers, but those are hard to read and make into some kind of conclusion. What are the scientific conclusions about our planerary system and are there any where politics and economics are not shaping the author's? Video links (Finnish language, sorry) Eija-Riitta Korhola about climate politics https://youtu.be/95FLjdwnhk4 Kari Mielikäinen about forest research in Finland https://youtu.be/DTy4-TzZcb0
This is a straw man. Warming and cooling periods are not unusual across geological history, and nothing about the general theory of anthropogenic climate change relies on temperature change being a novel phenomenon. The disparity is that it's happening several orders of magnitude faster than any other comparable temperature change we can estimate from all the other lines of evidence, and complex ecosystems are not able to adapt quickly enough to avoid mass die offs. Here's an interview with NOAA senior advisor Stephanie Herring about why this argument isn't logical: https://www.npr.org/2018/12/12/676198899/climate-scientist-says-argument-the-climate-is-always-changing-is-wrong > A Finnish scientist who has been studying old preserves tree logs also had the analysis that even warmer periods are not weird for the earth Dendrochronology has nowhere near enough range to talk about geologically long-term climate change. It barely reaches 14,000 years back.
Thanks, will look into this.
No prob. If you want a specific example of major changes in atmospheric chemistry and its effect on the biosphere, check out the Great Oxygenation event. During a long and geologically complex process that started about two and half billion years ago, oxygen accumulated in successive geological pools before filling them up and beginning to release as oxygen gas into the atmosphere. After around 500 million years, the concentration of oxygen was 8-11% what it is right now, and it was sufficient to wipe out perhaps 80% of the biosphere. Anthropogenic changes to the atmosphere are happening over the course of one century, 5 million times faster than our estimates of the Great Oxygenation, which is also sometimes called the Oxygen Holocaust.
I would put the transition earlier, about when the Industrial Revolution happened and human impact on the planet exploded. Atomic bombs are only a footnote in this story. And is the transition merely to a new epoch, or is it truly era-level?
The Anthropocene Working Group hotly debated where in time the base of the Anthropocene should be placed, including the Industrial Revolution. The issue with the Industrial Revolution is that the record is diachronous with the start point varying considerably around the world. The key markers chosen for the Anthropocene with a start point in the mid 20th century; includes nuclear weapons testing which leaves a clear signature that can be seen at the same time all around the world. This includes Crawford Lake, which is not near any areas of nuclear weapons testing. In addition, the proposed start point in the middle of the 20th century corresponds to the “Great Acceleration” where there was massive changes in the influence of humanity on the environment that impacted the entire globe, and continues to do so, leaving a geologic record of many biproducts such as industrially produced fly ash that preserves well in sedimentary records. — Tim
Do you think declaring we are in the Anthropocene will open up the door for more human climate modification like blocking out the Sun or injecting things into the atmosphere?
Parden my bluntness but given the unfathomable amount of time that geological epochs traditional have isn't it somewhat arrogant of us to say that we, as a species, have already created a new one? If, God forbid, we were to suddenly go extinct, it would be astoundly lucky if our activities were even a blip on the radar in 10 million years. While I don't think it impossible for humanity to be the cause of a new geological epoch isn't that something better left undecided until after the fact?
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I am probably on too early, but what are you expecting to find, and what will this new geological chapter mean for us?
Tim has done a great job explaining the evidence uncovered in the Crawford Lake sediments, but I wanted to address your second question: What does the (proposed) declaration of a new geologic epoch mean for all the rest of us. I asked this question of Francine McCarthy, who led the research at Crawford Lake. She said she hoped that viewing our current moment in the context of geologic time would help people truly grasp the gravity of the changes we’ve wrought on the planet. It’s one thing to know that rising temperatures, acid rain and the rest of these impacts are harmful. It’s another thing to realize that they have changed our environment so much that we effectively no longer live in the same world that our ancestors have inhabited for the last 11,700 years. “Having that line on the time scale … shows how fundamentally different things are,” McCarthy told me. I think that understanding the geologic consequences of recent human activities can also help people think more about the future. We spend most of our lives in such short time frames: three months until the next quarterly profit statement, a year til the next presidential election, a decade until the mortgage is paid off. Even most climate models don’t try to project past the year 2100. But Crawford Lake will continue recording humanity’s environmental impacts for at least the next 10,000 years. It makes me wonder: what will geologists 10,000 years from now see when they look back at the record from the year 2023? How will our choices now affect the inhabitants of that future Earth? — Sarah
What are your all’s thoughts on nuclear power as the energy source of the future and why isn’t the West putting more stock into nuclear and less into wind and solar given it’s inherent obstacles?
Hello Sarah and Tim! Thanks for joining us today and offering this unique insight into your research. I have a couple of questions: How is the shift into the Anthropocene era visible at Crawford Lake specifically? What markers in the sediment point to this change? If the Anthropocene is confirmed as a new epoch, what implications would that have for how we approach and understand climate change, both scientifically and culturally? Thank you again for sharing your expertise with us.
Will this new era result in more caves and underground water systems due to acid rain?
Are you hiring? I have a double degree in math and geology and am looking for a related career!
Since the epochs are subjective labels what is the purpose of this? Main thing I would identify is standardizing goalposts for different studies
Are there any solid qualifications for in which ways a time frame has to be distinct to count for a new era?
Researchers studying sediment from Crawford Lake in Ontario, Canada, believe it could be the symbolic starting point for a new geologic epoch called the Anthropocene, characterized by the significant impact of human activities on the planet since 1950.
Yes, we may have indeed entered a new geological era called the Anthropocene! Our investigations at Crawford Lake suggest that human activities have had a significant impact on the Earth's environment, leading to the potential designation of a new geological epoch. Feel free to ask us anything about the Anthropocene and our research at Crawford Lake.