Earth’s Worst Extinction “Inescapably” Tied To Siberian Traps, C02, And Climate Change

Skeptical Science - Howard Lee

The latest batch of rock dates released by the MIT geochronology team "inescapably" nails the link between the end-Permian Siberian Traps eruptions and Earth’s worst mass extinction, pointing to the critical role of greenhouse gasses in the catastrophe.

The link
Seth Burgess and Samuel Bowring confirmed the long-hypothesized link by comparing new, high-precision dates from volcanic rocks with equally precise dates for the mass extinction measured from volcanic ash in sediments spanning the end-Permian boundary in China. By ensuring the same labs and chemical tracers were used in both sets of measurements, they were able to compare the dates at an unprecedented precision of 0.04% or better, even though the rocks sampled were from locations thousands of miles apart.
The Siberian Traps are an example of a rare geological phenomenon called a “Large Igneous Province” (LIP) which has been linked to 4 out of the “big 5” mass extinctions since animals evolved. The new timeline enables science to zoom in to the details of the terrible events 252 million years ago, in which more than 90% of marine, and some 75% of land life went extinct.

Timeline of Earth’s worst mass extinction. Redrawn and simplified from Burgess & Bowring 2015, annotations and photos added.

The timeline
The LIP began with explosive eruptions around 252.3 million years ago, as magma and lava encountered waterlogged, swampy terrain. These eruptions blanketed the region in volcanic ash, in some areas building to a kilometer thick. Then at 252.24 million years ago, lava flows took over: curtains of bright lava gushed from fissures, emitting CO2 and SO2, before flowing through lava tubes to advancing lava fronts. Fully 2/3 of the entire Siberian Traps lava sequence erupted this way over 300,000 years, building to 4 km thick of stacked lava flows that form the “traps” landscape of the Siberian Traps today. That’s some 3 million cubic kilometers of magma – with associated gasses - erupted before and at the onset of the mass extinction.
The end-Permian mass extinction began towards the end of those lava eruptions, at the same time as a huge spike in the carbon isotope balance, indicating that massive amounts of CO2 and/or methane were released into the atmosphere and oceans from an exponentially growing pool rich in carbon-12. The rapidity of this isotope “excursion” strains the limits of even the new dating resolution, with a duration somewhere between 2,100 and 18,800 years. The smaller of those numbers is a mere 2 complete ocean circulations at today’s rates, fewer if circulation was more sluggish in the Permian. This matters because we expect abrupt global warming and ocean acidification if CO2 emissions overwhelm the oceans’ capacity to process them, as explained in this article.
Since life preferentially stores carbon-12 over carbon-13, this suggests that a large reservoir of once-living carbon was rapidly converted to CO2. Alternatively, it might indicate a mantle source unusually rich in carbon-12.
The mass extinction unfolded for about 61,000 years into the early Triassic. The uncertainty on the extinction episode means it might have been as short as 13,000 or as long as 109,000 years – a timespan during which complex life on Earth was nearly wiped out by the deteriorating environment and climate change.
Over the years leading into the mass extinction the oceans gradually became more acidic, resulting in the loss of shelly, carbonate producing animals, and leaving sea beds dominated by sponges. Then at the carbon isotope excursion even the sponges disappeared as the environment became heavily polluted. The terrestrial extinction happened at the same time, as acid rain fell and global temperatures soared some 10°C. As the seas warmed they became starved of oxygen so that even the worms that burrowed in the seabed disappeared. Temperatures remained high well into the Triassic, and it took 10 million years for biodiversity to recover.
As Burgess and Bowring point out, these symptoms:
“…all point to anomalously high atmospheric pCO2 as a critical driver of both terrestrial and marine biotic crises”

The mystery
The mystery is: what triggered the massive carbon release in the final few millennia of the eruptions, rather than any time in the preceding 300,000 years? As Burgess and Bowring say:
“The enormous total volume of LIP magmas might be less important than an aliquot of the total, erupted/emplaced in a very restricted interval.”
It may be that the progressive degradation of the Permian conditions brought the environment to a tipping point, such as the destabilization of methane clathrates in the oceans.  But a recent study suggests that by the end-Permian reserves of marine clathrates were largely tapped-out.
Burgess and Bowring suggest an alternative scenario:
“Early sill intrusion into, and magma transport through an untapped, volatile-rich basin may be this critical aliquot."
They dated the Noril’sk 1 underground igneous intrusion - the oldest found anywhere in the Siberian Traps – as beginning around same time as the carbon isotope excursion.  Noril’sk 1 marks the beginning of a new phase of the eruptions – the injection of many underground sheets of magma (“sills” and “dikes”) into the Tunguska sedimentary basin, a thick sequence of sedimentary rocks containing fossil fuels. Some sills reach 350 meters thick and extend great distances, and cumulatively the intrusions exceed 2 million cubic kilometers of magma.
Svensen et al showed in 2009 that these sills baked coal, oil and natural gas, salt, limestone, and organic-rich shales in the sediments, generating large volumes of methane and CO2, as well as a cocktail of noxious gasses, acids, ozone-eating chemicals and coal fly-ash. These gasses exploded into the atmosphere through thousands of pipe eruptions across Siberia, belching columns of gas and pollutants from vents up to 1.6 km wide, leaving behind mineral-rich pipes that are mined for iron ore today.
Earlier this year Fristad et al published a study of the carbon chemistry of one of those pipes, which showed that the carbon involved in its formation was indeed rich in carbon-12, strongly linking Permian pipe eruptions with the massive release of carbon-12 recorded in the isotope excursion.
Noril’sk 1 was amazingly long-lived, having 3 distinct magma injections over some 267,000 years. But many of the observed Siberian sills and dikes are dated to after the mass extinction, a time when the carbon isotope curve shows only minor variation. It may be that the sediments had limited reserves of carbon to bake-off. Within a few thousand years their fossil fuel reserves may have been exhausted.

Then and now
As I outlined in this earlier article, emission rates matter a lot when it comes to our oceans’ ability to process them. Some LIPs, like the Paraná-Etendeka LIP, erupted slowly without causing environmental destruction and global climate change. These new dates suggest that the initial phase of the Siberian Traps had a relatively modest effect on the global environment, but later on during the eruptions, probably when widespread sill intrusions occurred and greenhouse gasses from baking of sediments were added to the load, this appears to have overwhelmed the already-stressed environment.
The irony is that back in the Permian the combustion of fossil fuels contributed to global warming and an environmental catastrophe so extreme that it came close to extinguishing complex life. Today we are embarking down a similar path, emitting at rates probably faster than in the end-Permian, even though our total emission quantities are smaller.
As new dates keep resolving the timeframes for these epoch-changing events in Earth’s past to ever-briefer intervals, their similarities with modern climate change increase. If Earth responded in a similar manner several times in its past, it is crucial that we focus research on understanding just how similar our modern path is, and how far along it we have already travelled, because the destination isn’t exactly a picnic spot.

References

• Burgess, S. D., & Bowring, S. A. (2015). High-precision geochronology confirms voluminous magmatism before, during, and after Earth’s most severe extinction. Science Advances, 1(7), e1500470.
• Burgess, S. D., Bowring, S., & Shen, S. Z. (2014). High-precision timeline for Earth’s most severe extinction. Proceedings of the National Academy of Sciences, 111(9), 3316-3321.
• Black, B. A., Weiss, B. P., Elkins-Tanton, L. T., Veselovskiy, R. V., & Latyshev, A. (2015). Siberian Traps volcaniclastic rocks and the role of magma-water interactions. Geological Society of America Bulletin, B31108-1.
• Paris, G., Donnadieu, Y., Beaumont, V., Fluteau, F., & Goddéris, Y. (2015). Geochemical consequences of intense pulse-like degassing during the onset of the Central Atlantic Magmatic Province. Palaeogeography, Palaeoclimatology, Palaeoecology.
• Grasby, S. E., Beauchamp, B., Bond, D. P., Wignall, P., Talavera, C., Galloway, J. M., ... & Blomeier, D. (2015). Progressive environmental deterioration in northwestern Pangea leading to the latest Permian extinction.Geological Society of America Bulletin, B31197-1.
• Majorowicz, J., Grasby, S. E., Safanda, J., & Beauchamp, B. (2014). Gas hydrate contribution to Late Permian global warming. Earth and Planetary Science Letters, 393, 243-253.
• Svensen, H., Planke, S., Polozov, A. G., Schmidbauer, N., Corfu, F., Podladchikov, Y. Y., & Jamtveit, B. (2009). Siberian gas venting and the end-Permian environmental crisis. Earth and Planetary Science Letters, 277(3), 490-500.
• Grasby, S. E., Sanei, H., & Beauchamp, B. (2011). Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction. Nature Geoscience, 4(2), 104-107.
• Fristad, K. E., Pedentchouk, N., Roscher, M., Polozov, A., & Svensen, H. (2015). An integrated carbon isotope record of an end-Permian crater lake above a phreatomagmatic pipe of the Siberian Traps. Palaeogeography, Palaeoclimatology, Palaeoecology, 428, 39-49.

Climate Change Is Getting Worse — And U.N. Climate Reports Are Getting Harder To Understand

The Washington Post - Chelsea Harvey

Delegates attend the opening of the Intergovernmental Panel on Climate Change (IPCC) at the Tivoli Congress Center in Copenhagen on Oct. 27, 2014. (Keld Navntoft/AFP/Getty Images)

Let’s face it: Climate science isn’t always the easiest subject to explain to non-scientists. However, the political charge surrounding global conversations about climate change makes it all the more important to communicate the science to the general public as clearly and accurately as possible. Unfortunately, new research suggests that the world’s foremost body dedicated to reviewing and communicating climate science may be falling short in this area.
The U.N.’s Intergovernmental Panel on Climate Change holds some of the greatest responsibility when it comes to communicating climate science, if only because it is so high-profile and regarded as the gold standard of climate science. Every five to seven years or so, the IPCC releases an assessment report reviewing the recent research of thousands of climate scientists around the world. Each assessment report is released in a series of sections devoted to specific topics, and each section is accompanied by a “summary for policymakers” (SPM),which is intended to summarize the findings for a non-scientific audience, particularly government officials who can use the information to help create new climate policies.
The reports also tend to receive extensive coverage in the media, and more so as the years go on and the international focus on climate change continues to sharpen. This means that the IPCC’s assessments are reaching a bigger audience than ever before.
But although the IPCC’s reach has been expanding, its reports have not necessarily become easier for the layperson to understand — in fact, just the opposite, argues a new study, published today in Nature Climate Change. The study uses analysis software to find that the readability of the IPCC’s SPMs has generally deteriorated over time, even as media coverage of it has become increasingly readable.
“We started looking into IPCC communications because we (in line with many other people) had the feeling that IPCC summaries for policymakers are quite simply difficult to read and to understand,” said Ralf Barkemeyer, an associate professor at the KEDGE Business School and the study’s lead author, in an e-mail to The Post. Although the organization does employ a communications staff, the IPCC has been criticized in the past for problems with communication, not only when it comes to the language of the reports, but also when it comes to relaying its internal decision-making processes to the public.
Barkemeyer and his colleagues used two different tools to analyze the texts of the SPMs and their corresponding media coverage: an algorithm which assesses readability and a separate software which assesses how optimistic a text is in tone. They applied these analysis tools to four types of publications: the IPCC reports and related articles in popular science publications (namely, the journals Science and Nature), newspapers and tabloids.
In general, the IPCC reports were the least readable and newspapers and tabloids were the most readable, with popular science publications occupying a middle ground between them. For instance, one of the SPMs from the latest assessment report includes such complex phrasing as, “Mitigation scenarios reaching concentration levels of about 500 ppm CO2eq by 2100 are more likely than not to limit temperature change to less than 2 °C relative to pre-industrial levels, unless they temporarily ‘overshoot’ concentration levels of roughly 530 ppm CO2eq before 2100, in which case they are about as likely as not to achieve that goal.”
Media coverage was also generally more pessimistic in tone than the IPCC reports themselves — perhaps unsurprisingly. As the authors note, “Newspapers need to turn a piece of scientific information into a piece of news, which among other aspects requires bringing future climate change consequences into the sphere of immediate interest of the reader. Using emotive language is one of the journalistic strategies for bringing the future into the immediate.”
What was surprising, according to Barkemeyer, was that there was no improvement in the SPMs’ readability as more reports were released over time. “Given the huge amount of attention that has been paid to this topic in recent years, we would definitely have expected to see some improvements over time,” Barkemeyer said in his e-mail — but in fact, some sections of the reports seemed to become less readable as time went on.
The assessment reports are typically released in different sections, which address specific topics and are published by three designated committees, or “working groups,” each of which also provides its own summary for policymakers. The researchers found that while the readability of working group I’s SPMs remain fairly stable over time, working groups II and III deteriorate over time. In contrast, readability for newspapers and popular science magazines did increase as time went on, peaking in 2007.
The authors also found that political tensions may play a role in an SPM’s readability. Every time an assessment report is released, it goes through a round of edits known as the plenary process. As the authors note, “The plenary process is important to the SPM because its ‘approval’ means that the material has been subjected to detailed line-by-line discussion and agreement between government delegates and authors.” Yet when they compared the SPMs’ readability pre- and post-plenary, they found that the plenary process actually lowered readability in five out of eight cases.
“We found a strong relationship between political mood and SPM readability,” the authors write. They assessed political mood by examining reports on the plenary processes from the Earth Negotiations Bulletin reporting service. When political tensions were running high, the readability went down after the plenary process was complete.
Low readability is a problem if it means that the reports aren’t clear to the policymakers they’re meant to inform, Barkemeyer said. “Hard-to-understand summaries are more likely to be misunderstood – and it will then be necessary that intermediaries ‘translate’ information from these summaries into a language that policymakers can understand,” he wrote in his e-mail. “Thus, the communication process becomes more complicated, with more actors involved, and a higher likelihood of misinterpretations and disagreements along the way.”
“There is no doubt that more needs to be done to make IPCC reports more readable and accessible,” said an IPCC statement on the study e-mailed to The Post. “The newly elected Chair of the IPCC, Hoesung Lee, has made this point and we are determined to tackle it. The challenge is to do it in a way that does not damage the scientific rigor and robustness of the reports, or allow important nuances in them to be lost.”
The IPCC has already made some steps toward improving its communication, the statement noted. “The previous Session of the IPCC, in Nairobi in February this year, took decisions to enhance the usability of IPCC reports, for instance by using digital technology to share and disseminate information, and to draw on specialists (such as science writers and graphical designers) to enhance the readability of IPCC reports. The IPCC is holding an expert meeting in February 2016 to discuss lessons learned from communicating the Fifth Assessment Report, and when the scoping process for the Sixth Assessment Report starts next year the Panel will have an opportunity to tackle this.”
But it may be that the low general readability scores indicated in this study don’t actually pose that much of a problem for the documents’ intended audiences, said Michael Oppenheimer, a professor of geosciences and international affairs at Princeton University who was a lead author in the IPCC’s fourth assessment report and a coordinating lead author on the IPCC’s special SREX report on extreme climate events and disasters.
“This and other reviews of IPCC communication don’t emphasize enough that the target is primarily governments (for example, the staff of EPA or DoE or an environment ministry), not the average newspaper reader (or even a scientifically attuned reader),” Oppenheimer said in an e-mail to The Post. “The main point of the four-day plenaries which produce the SPMs is so that the material drafted by scientists can be converted to a form that is understandable to governments while still accurately reflecting the science.”
He added: “One might ask this: If, as the study finds, newspapers and other intermediaries are doing a progressively better job of communicating IPCC findings to the larger public, and if governments are happy with the SPMs, is there really a problem?”
Still, it remains unclear whether the science in the documents is actually being interpreted correctly by the policymakers and journalists who read them. On this front, Oppenheimer agrees with the authors that improvements could still be made to the IPCC’s writing teams in order to ensure that the documents are likely to be understood correctly by their readers.
One option would be to hire professional science communicators to help write the reports, Barkemeyer said. But, he cautioned, “potential benefits could be outweighed by the addition of yet another set of actors in the process, potentially distorting and politicizing the original voice of the scientific panel.” A simpler course of action could be to simply provide science communication training for the reports’ existing authors. A U.S. based climate communication group has already begun providing such a service for U.S. climate reports. A team of experts from the organization served as communication advisers on the 2014 U.S. National Climate Assessment in order to improve its readability and accessibility to the general public.
In any case, the increasing urgency of international efforts to combat climate change, along with corresponding growth in media coverage and public interest, means the need for effective science communication will only become more relevant as time goes on.
And while the authors note that the IPCC is already aware of the challenges associated with translating climate science to a lay audience, and has taken steps over the years to improve its communication, Barkemeyer concludes: “Our findings illustrate that there is still a lot of room for improvement.”

The Biggest Question About Climate Change Isn’t ‘If’ Or ‘When.’ It’s ‘How Abrupt?’

The Washington Post - Chris Mooney

The 2015 Arctic sea ice summertime minimum — which was 699,000 square miles below the 1981-2010 average. A new study cites Arctic sea ice collapse as a possible ‘abrupt’ consequence of climate change. (NASA’s Goddard Scientific Visualization Studio via Reuters)

It has been quite the week for climate change news: We’ve learned that scientists can now quantify the United States’ expected levels of inundation by rising seas, that droughts in the Amazon could triple, and much more.
But the most troubling research — depending, that is, on how you interpret it — may have appeared in a less-noticed, first-of-its-kind study just published in the influential Proceedings of the National Academy of Sciences. In it, the researchers attempted something that seems never to have been successfully done before. Namely, they mined the data from a large suite of computerized climate change simulations, or models, to determine how often they produced abrupt and disruptive changes in a few decades or even less — surely the most feared impact of climate change.
The result — that out of 37 abrupt changes detected in these climate simulations, fully 18 of them occurred at temperature levels less than 2 degrees Celsius of warming — is simultaneously dramatic and yet also difficult to assess. Models, after all, are mathematically sophisticated simulacra that embed scientists’ best current physical understanding of how the Earth system and its components work, but still should not be confused with reality.
Nonetheless, the authors — led by Sybren Drijfhout, a professor at the Royal Netherlands Meteorological Institute — assert that their results represent a sign of how unstable the future could really be, even before we reach warming levels of 2 degrees Celsius above pre-industrial levels (often thought of as a kind of guardrail in international climate negotiations). “It is likely that the Earth system will experience sharp regional transitions at moderate warming,” they write, “although the prediction of any particular event has a very high uncertainty.”
So what’s going on here — and should we really believe this?
Mining models for major disruptions. The study — which Drijfhout undertook with a large team of researchers at institutes in Britain, the Netherlands, Germany and France — is in effect a massive “big data” inquiry into an urgent mystery about climate change. That mystery is this: When, precisely, can a relatively slow and steady rate of global warming trigger abrupt or sudden shifts in particular regions or Earth systems?
The topic has been much discussed — but also remains very murky. So to examine it in a new way, the researchers looked at the results of no less than 37 separate computerized climate change simulations, or models, which were used in the U.N. Intergovernmental Panel on Climate Change’s 2013 assessment report of the state of climate science. Each model’s results were examined out to the year 2100 — or farther, in cases where that was possible — under different assumptions about levels of greenhouse gas emissions, and resulting planetary warming.
In doing this, the work is entering new territory. “There has been no systematic study of the potential for abrupt shifts in state-of-the-art Earth System Models,” the research noted, calling the paper “a first step toward a robust assessment of abrupt change.”

A high-resolution global atmospheric modeling run on the Discover supercomputer at the NASA Center for Climate Simulation at Goddard Space Flight Center in Greenbelt, Md. (NASA/Goddard)

And sure enough, the models did produce many abrupt changes — but they were also rarely in agreement with one another. Some changes — for instance, a massive oceanic algal bloom in the Indian Ocean in the next century, which only appeared in one model — are dismissed by the researchers as a possible fluke. “That’s the one we are really most unsure about,” says Drijfhout.
On the other hand, other changes that showed up more frequently are precisely the types of things that scientists have long forecast might result from a warming of the climate. For instance, multiple models showed rapid collapses of Arctic sea ice, particularly in extreme global warming scenarios. And multiple models also produced partial or full shutdowns of circulation in the North Atlantic— a change that sometimes occurred for only moderate levels of warming (less than 2 degrees Celsius above pre-industrial levels).
“A striking feature is that the majority of abrupt transitions occur in the ocean-sea ice system, implying that this Earth system component is more prone to abrupt change than other components,” the research added. “These are very nonlinear processes that are reasonably well resolved in the models,” says Drijfhout — suggesting that if they turn up again and again, they may be something that can really happen in the real world.
Other experts react. But here, perhaps, we should pause. Models are not predictions of the future — they’re more about understanding than about forecasting. And when an abrupt change shows up in just one model but not others, that could be simply due to the equations embedded in that particular simulation. Indeed, “no type of abrupt shifts occurs in all models,” the authors say.
Researchers asked to look at the study by The Washington Post offered some criticism, while also noting that the research certainly has consistencies with other evidence about abrupt climate changes. Until now, such work has largely been based on studies of the Earth’s past using so-called “proxy” evidence like ice cores or ocean sediments.
“As the authors note, it’s unclear whether these events are related to specific simplifications or perhaps even bugs in the codes, and without some consistency across models it’s hard to make any useful predictions,” said Gavin Schmidt, director of the Goddard Institute for Space Studies at NASA — which runs one of the models in question — by e-mail. “The places where most of these events occur are not surprising of course — the North Atlantic stands out.”
A similar take came from Richard Alley, a glaciologist at Penn State University who chaired a National Academy of Sciences panel on abrupt climate change. “Many questions exist about the ability of models to simulate ‘tipping points’ or abrupt changes accurately,” Alley said. “But the paleoclimate record shows clearly that such abrupt jumps have occurred, and this new paper shows that they are fairly common and widespread in the modeled climate system.”
The most critical take came from Kevin Trenberth, a climate researcher at the National Center for Atmospheric Research in Boulder, Colo. “I don’t find anything in this paper surprising or very illuminating,” he said by e-mail. “The paper does not validate the models to be able to say that any of them are realistic or likely. It is likely that some of these are more the result of model flaws. But it is a start,” Trenberth added.
Drijfhout said by e-mail that he agrees that climate models have not been validated based on their ability to capture abrupt changes — rather, he argues, they are validated based on their ability to capture the present climate and even “tuned” to be good at this. “There is consensus that climate models tend to be more stable than the real climate,” he said in his e-mail. For this reason, Drijfhout believes that models may underestimate its real instability and capability for abrupt shifts.
“In general there seem to be more missed cases than false alarms,” he said.
It’s also important to note that the simulations were not capable of detecting one possible abrupt shift that worries many climate scientists right now — the potential for a collapse of the West Antarctic ice sheet. “They are clearly correct in noting that some potential abrupt events aren’t possible in this class of models — no ice sheet components, or sub-surface methane hydrate routines,” noted Gavin Schmidt, director of the Goddard Institute for Space Studies at NASA, by e-mail.
In the end, the most striking finding from the study remains how many abrupt shifts occur — at least in the models — with relatively modest levels of warming. Granted, the paper also acknowledges that abrupt changes were most likely to occur at the highest warming scenarios.
“There is of course a certain tendency for the whole climate system to become more unstable when the warming gets larger,” said Drijfhout, “but we cannot say, ‘as long as it’s this and this much, nothing will happen.’ Every .1 or .2 degrees in temperature is as dangerous as any other, I would say. And that’s the main message of this exercise, or this paper.”
It remains to be seen how many other scientists agree with this assessment — and whether through future research, they can alter or improve on our abilities to detect truly abrupt climate change scenarios with modern computer simulations.