Alarming new study makes today’s climate change more comparable to Earth’s worst mass extinction

by howardlee, Skeptical Science, April 2, 2014

The Permian Mass Extinction 251.9 million years ago, otherwise known as “The Great Dying,” was the closest this planet has come to extinguishing all complex life on Earth. Around 90% of all species died out in this single event, a worse toll even than the Cretaceous extinction that wiped out the dinosaurs.

For years the cause of the Permian Mass Extinction has been linked to massive volcanic eruptions in Siberia. Volcanic CO2 and a cocktail of noxious gasses combined withburning coal and geothermally-baked methane emissions to enact a combination of toxic effects and, most importantly, ocean acidification and global warming. It led to a world where equatorial regions and the tropics were too hot for complex life to survive. That’s a fact so astonishing it bears repeating: global warming led to a large portion of planet Earth being lethally hot on land and in the oceans! The cascading extinctions in ecosystems across the planet unfolded over 61,000 years, and it took 10 million years for the planet to recover! For comparison, our distant ancestors separated from apes only 7 million years ago.

Until recently the scale of the Permian Mass Extinction was seen as just too massive, its duration far too long, and dating too imprecise for a sensible comparison to be made with today’s climate change. No longer.

In “High-precision timeline for Earth’s most severe extinction,” published in PNAS on February 10, authors Seth Burgess, Samuel Bowring, and Shu-zhong Shen employed new dating techniques on Permian–Triassic rocks in China, bringing unprecedented precision to our understanding of the event. They have dramatically shortened the time frame for the initial carbon emissions that triggered the mass extinction from roughly 150,000 years to between 2,100 and 18,800 years. This new time frame is crucial because it brings the timescale of the Permian Extinction event’s carbon emissions shorter by two orders of magnitude, into the ballpark of human emission rates for the first time.

How does this relate to today’s global warming?

Climate and CO2 have changed hand-in-hand through most of geological time. Mostly these changes happened slowly enough that the long-term feedbacks of Earth’s climate system had time to process them. This was true during the orbitally-induced glacial-interglacial cycles in the ice ages. In warmer interglacials, more intense insolation in northern hemisphere summers led to warmer oceans which were in equilibrium with slightly more CO2 in the atmosphere by adjusting their carbonate levels. In glacial times with less intense northern hemisphere summer insolation, the cooler oceans dissolved more CO2, and carbonate levels adjusted accordingly. The changes occurred over gentle timescales of tens of thousands to hundreds of thousands of years – plenty slow enough for slow feedbacks like the deep oceans and ice sheets to keep pace.

How oceans processed the slow glacial-interglacial changes in the ice ages. CCD = Carbonate Compensation Depth, CO32- = carbonate. Based on text in Zeebe, Annual Reviews 2012.

Rapid carbon belches, such as in the Permian and today, occur within the time frame of fast feedbacks (surface ocean, water vapor, clouds, dust, biosphere, lapse rate, etc.) but before the vast deep ocean reservoir and rock weathering can cut-in to buffer the changes. The carbon overwhelms the surface ocean and biosphere reservoirs so it has nowhere to go but the atmosphere, where it builds up rapidly, creating strong global warming via the greenhouse effect. The surface oceans turn acidic as they become increasingly saturated in CO2. The oceans warm, so sea levels rise. Those symptoms should sound familiar.

 

How oceans get overwhelmed by rapid large CO2 emissions from Large Igneous Province (LIP) eruptions and human emissions. CCD = Carbonate Compensation Depth, CO32- = carbonate. Based on text in Zeebe, Annual Reviews 2012.

Burgess et al.’s paper brings the Permian into line with many other global-warming extinction events, like the Triassic, the Toarcian, the Cretaceous Ocean Anoxic Events, The PETM, and the Columbia River Basalts, whose time frames have been progressively reduced as more sophisticated dating has been applied to them. They all produced the same symptoms as today’s climate change – rapid global warming, ocean acidification, and sea level rises, together with oxygen-less ocean dead zones and extinctions. They were all (possibly excluding the PETM – see below) triggered by rare volcanic outpourings called “Large Igneous Provinces” (LIPs) that emitted massive volumes of CO2 and methane at rates comparable to today’s emissions. The PETM may also have been triggered by a LIP, although that is still debated. 

Can we seriously expect Earth’s climate to behave differently today than it did at all those times in the past?

Some have pointed out that since we began our modern climate change in an “icehouse” era with ice sheets to melt and low starting CO2 levels, we might not generate a Permian-like hothouse. In addition, since the Permian, calcareous algae have changed the way deep oceans process carbonate, providing more of a buffer. But that buffer only comes into play if the deep oceans come into play, which most estimates consider won’t happen for a few more centuries.

All in all, the parallels between the many mass extinction events in the geological record and today’s climate change offer no comfort about the legacy we’re leaving for our children and our grandchildren. Rather they stand as signposts for an increasingly scary future.

http://www.skepticalscience.com/Lee-commentary-on-Burgess-et-al-PNAS-Permian-Dating.html

"Arctic amplification dominated by temperature feedbacks in contemporary climate models," by F. Pithan & T. Mauritsen, Nature Geosci., (2014); doi: 10.1038/ngeo2071

Nature Geoscience, (2014) ; doi:10.1038/ngeo2071

Arctic amplification dominated by temperature feedbacks in contemporary climate models

Felix Pithan and Thorsten Mauritsen

Abstract

Climate change is amplified in the Arctic region. Arctic amplification has been found in past warm¹ and glacial² periods, as well as in historical observations^3,4 and climate model experiments^5,6. Feedback effects associated with temperature, water vapour and clouds have been suggested to contribute to amplified warming in the Arctic, but the surface albedo feedback—the increase in surface absorption of solar radiation when snow and ice retreat—is often cited as the main contributor^7,8,9,10. However, Arctic amplification is also found in models without changes in snow and ice cover^11,12. Here we analyse climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archive to quantify the contributions of the various feedbacks. We find that in the simulations, the largest contribution to Arctic amplification comes from temperature feedbacks: as the surface warms, more energy is radiated back to space in low latitudes, compared with the Arctic. This effect can be attributed to both the different vertical structure of the warming in high and low latitudes, and a smaller increase in emitted blackbody radiation per unit warming at colder temperatures. We find that the surface albedo feedback is the second main contributor to Arctic amplification and that other contributions are substantially smaller or even oppose Arctic amplification.

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2071.html

"Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade" by J.-P. Vernier et al., Geophys. Res. Lett., 38 (2011); doi: 10.1029/2011GL047563

Geophysical Research Letters, 38 (2011) L12807; doi: 10.1029/2011GL047563

Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade

Key Points

• Minor tropical volcanic eruptions: important source of stratospheric aerosols
• Stratospheric aerosol layer mainly impacted by those events
• Potential impacts on climate and ozone chemistry

J.-P. Vernier (NASA Langley Research Center, Hampton, VA, USA, and LATMOS, CNRS, INSU, Université de Versailles Saint Quentin, Université de Paris 6, Guyancourt, France), L. W. Thomason (NASA Langley Research Center, Hampton, VA, USA), J.-P. Pommereau (LATMOS, CNRS, INSU, Université de Versailles Saint Quentin, Université de Paris 6, Guyancourt, France), A. Bourassa (Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Saskatchewan, Canada), J. Pelon, A. Garnier, and A. Hauchecorne (LATMOS, CNRS, INSU, Université de Versailles Saint Quentin, Université de Paris 6, Guyancourt, France), L. Blanot (LATMOS, CNRS, INSU, Université de Versailles Saint Quentin, Université de Paris 6, Guyancourt, and ACRI-ST, Sophia-Antipolis, France), C. Trepte (NASA Langley Research Center, Hampton, VA, USA), Doug Degenstein (Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Saskatchewan, Canada) and F. Vargas (Institute for Research and Development, Paraíba Valley University, São José dos Campos, Brazil)

Abstract

The variability of stratospheric aerosol loading between 1985 and 2010 is explored with measurements from SAGE II, CALIPSO, GOMOS/ENVISAT, and OSIRIS/Odin space-based instruments. We find that, following the 1991 eruption of Mount Pinatubo, stratospheric aerosol levels increased by as much as two orders of magnitude and only reached “background levels” between 1998 and 2002. From 2002 onwards, a systematic increase has been reported by a number of investigators. Recently, the trend, based on ground-based lidar measurements, has been tentatively attributed to an increase of SO₂ entering the stratosphere associated with coal burning in Southeast Asia. However, we demonstrate with these satellite measurements that the observed trend is mainly driven by a series of moderate but increasingly intense volcanic eruptions primarily at tropical latitudes. These events injected sulfur directly to altitudes between 18 and 20 km. The resulting aerosol particles are slowly lofted into the middle stratosphere by the Brewer-Dobson circulation and are eventually transported to higher latitudes.

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Received 25 March 2011; accepted 30 April 2011; published 30 June 2011.

http://www.agu.org/pubs/crossref/2011/2011GL047563.shtml

A blast from the past: Kerry Emanuel's "Phaeton's Reins" from 2007 still current; "As long as we continue to elect scientific illiterates like James Inhofe, who believes global warming to be a hoax, we will lack the ability to engage in intelligent debate." (Emanuel refers to the debate on how to solve the problem)

"Phaeston's Reins" by Kerry Emanuel

Dr. Kerry Emanuel, MIT

(Kerry Emanuel is a professor of meteorology at MIT and the author of Divine Wind: The History and Science of Hurricanes. In 2006 Time magazine recognized him as one of the world’s 100 most influential people. He is politically conservative -- in the old sense of the word. For those of you who don't know who Phaeton was:  http://en.wikipedia.org/wiki/Pha%C3%ABton)

[I am beginning this post in the middle of the article. Go to the link below to see the figure -- but to make a long story short, the red line goes up and the blue line doesn't much.]

The figure above shows the results of two sets of computer simulations of the global average surface temperature of the 20th century using a particular climate model. In the first set, denoted by blue, only natural, time-varying forcings are applied; these consist of variable solar output and “dimming” owing to aerosols produced by known volcanic eruptions. The second set (in red) adds in the man-made influences on sulfate aerosols and greenhouse gases. In each set, the model is run four times beginning with slightly different initial states, and the range among the four ensemble members is denoted by the shading in the figure, reflecting the free random variability of the climate produced by this model, while the colored curves show the average of the four ensemble members. The observed global average surface temperature is depicted by the black curve. One observes that the two sets of simulations diverge during the 1970s and have no overlap at all today, and that the observed global temperature also starts to fall outside the envelope of the all natural simulations in the 1970s. This exercise has been repeated using many different climate models, with the same qualitative result: one cannot simulate the evolution of the climate over last 30 years without including in the simulations mankind’s influence on sulfate aerosols and greenhouse gases. This, in a nutshell, is why almost all climate scientists today believe that man’s influence on climate has emerged from the background noise of natural variability.

The consequences


Projections based on climate models suggest that the globe will continue to warm another 3-7 °F over the next century. This is similar to the temperature change one could experience by moving, say, from Boston to Philadelphia. Moreover, the warming of already hot regions—the tropics—is expected to be somewhat less, while the warming of cold regions like the arctic is projected to be more, a signal already discernable in global temperature measurements. Nighttime temperatures are increasing more rapidly than daytime warmth. [The latest data through April 2011 show that this is accelerating.]

Is this really so bad? In all the negative publicity about global warming, it is easy to overlook the benefits: It will take less energy to heat buildings, previously infertile lands of high latitudes will start producing crops, and there will be less suffering from debilitating cold waves. Increased CO2 might also make crops grow faster. On the down side, there will be more frequent and more intense heat waves, air conditioning costs will rise, and previously fertile areas in the subtropics may become unarable. Sure, there will be winners and losers, but will the world really suffer in the net? Even if the changes we are bringing about are larger than the globe has experienced in the last few thousand years, they still do not amount to the big natural swings between ice ages and interglacial periods, and the earth and indeed human beings survived these.

But there are consequences of warming that we cannot take so lightly. During the peak of the last ice age, sea level was some 400 feet lower than today’s, since huge quantities of water were locked up in the great continental ice sheets. As polar regions warm, it is possible that portions of the Greenland and Antarctic ice sheets will melt, increasing sea level. Highly detailed and accurate satellite-based measurements of the thickness of the Greenland ice show that it is actually increasing in the interior but thinning around the margins, and while there are also patterns of increase and decrease in Antarctic ice, it appears to be thinning on the whole. Meltwater from the surface of the Greenland ice sheet is making its way to the bottom of the ice, possibly allowing the ice to flow faster toward the sea. Our understanding of the physics of ice under pressure is poor, and it is thus difficult to predict how the ice will respond to warming. Were the entire Greenland ice cap to melt, sea level would increase by around 22 feet—flooding many coastal regions including much of southern Florida and lower Manhattan.

My own work has shown that hurricanes are responding to warming sea surface temperatures faster than we originally expected, especially in the North Atlantic, where the total power output by tropical cyclones has increased by around 60% since the 1970s. The 2005 hurricane season was the most active in the 150 years of records, corresponding to record warmth of the tropical Atlantic. Hurricanes are far and away the worst natural disasters to affect the U.S. in economic terms. Katrina may cost us as much as $200 billion, and it has claimed at least 1,200 lives. Globally, tropical cyclones cause staggering loss of life and misery. Hurricane Mitch of 1998 killed over 10,000 people in Central America, and in 1970 a single storm took the lives of some 300,000 people in Bangladesh. Substantial changes in hurricane activity cannot be written off as mere climate perturbations to which we will easily adjust.

Basic theory and models show another consequential result of a few degrees of warming. The amount of water vapor in the air rises exponentially with temperature: a 7-degree increase in temperature increases water vapor by 25%. [OK, this shocked the hell outta me!  Currently, it is estimated that water vapor has increased by 4% and look at the havoc it has wreaked during the Extreme Spring of 2011.  An additional 21% sounds apocalyptic!] One might at first suppose that since the amount of water ascending into clouds increases, the amount of rain that falls out of them must increase in proportion. But condensing water vapor heats the atmosphere, and in the grand scheme of things, this must be compensated by radiative heat loss. On the other hand, simple calculations show that the amount of radiative heat loss increases only very slowly with temperature, so that the total heating by condensation must increase slowly as well. Models resolve this conundrum by making it rain harder in places that are already wet and at the same time increasing the intensity, duration, or geographical extent of droughts. Thus, the twin perils of flood and drought actually both increase substantially in a warmer world. [We have gotten a big dose of this in in 2010 and 2011 already.]

It is particularly sobering to contemplate such outcomes in light of the evidence that smaller, natural climate swings since the end of the last ice age debilitated and in some cases destroyed entire civilizations in such places as Mesopotamia, Central and South America, and the southwestern region of what is today the United States.

In pushing the climate so hard and so fast, we are also conscious of our own collective ignorance of how the climate system works. Perhaps negative-feedback mechanisms that we have not contemplated or have underestimated will kick in, sparing us from debilitating consequences [So far, all the uncontemplated feedbacks discovered during the years since this article was written have been negative.]. On the other hand, the same could be said of positive feedbacks, and matters might turn out worse than projected. The ice-core record reveals a climate that reacts in complex and surprising ways to smoothly and slowly changing radiative forcing caused by variations in the earth’s orbit. Far from changing smoothly, it remains close to one state for a long time and then suddenly jumps to another state. We do not understand this, and are worried that a sudden climate jump may be part of our future.

Science, politics, and the media

Science proceeds by continually testing and discarding or refining hypotheses, a process greatly aided by the naturally skeptical disposition of scientists. We are, most of us, driven by a passion to understand nature, but that means being dispassionate about pet ideas. Partisanship—whatever its source—is likely to be detected by our colleagues and to yield a loss of credibility, the true stock of the trade. We share a faith—justified by experience—that at the end of the day, there is a truth to be found, and those who cling for emotional reasons to wrong ideas will be judged by history accordingly, whereas those who see it early will be regarded as visionaries.

The evolution of the scientific debate about anthropogenic climate change illustrates both the value of skepticism and the pitfalls of partisanship. Although the notion that fossil-fuel combustion might increase CO2 and alter climate originated in the 19th century, general awareness of the issue dates to a National Academy of Sciences report in 1979 that warned that doubling CO2 content might lead to a 3-8 degree increase in global average temperature. Then, in 1988, James Hansen, the director of NASA’s Goddard Institute for Space Studies, set off a firestorm of controversy by testifying before Congress that he was virtually certain that a global-warming signal had emerged from the background climate variability. At that time, less was known about natural climate variability before the beginning of systematic instrumental records in the nineteenth century, and only a handful of global climate simulations had been performed.

Most scientists were deeply skeptical of Hansen’s claims; I certainly was. It is important to interpret the word “skeptical” literally here: it was not that we were sure of the opposite, merely that we thought the jury was out.

[I strongly disagree with Dr. Emanuel's take on what occurred next, so if you want to read it, you will have to go to the link.  However, I think it very likely that Dr. Emanuel's take on what actually occurred back in the 1980s and 1990s has likely changed as he received better and more accurate information on the machinations of the extremely well-funded right-wing faux think tanks.]

But I found this jewel later:

There are other obstacles to taking a sensible approach to the climate problem. We have preciously few representatives in Congress with a background or interest in science, and some of them display an active contempt for the subject. As long as we continue to elect scientific illiterates like James Inhofe, who believes global warming to be a hoax, we will lack the ability to engage in intelligent debate.

And this:

Like it or not, we have been handed Phaeton’s reins, and we will have to learn how to control climate if we are to avoid his fate.

http://www.cerritos.edu/tstolze/Kerry%20Emanuel_%20Phaeton's%20Reins.pdf

A. H. Goldstein et al., PNAS 106, Biogenic carbon and anthropogenic pollutants combine to form a cooling haze over the southeastern United States

Proceedings of the National Academy of Sciences, (May 18, 2009), Vol. 106, No. 22, pp. 8835-8840. doi: 10.1073/pnas.0904128106

Biogenic carbon and anthropogenic pollutants combine to form a cooling haze over the southeastern United States

Allen H. Goldstein¹, Charles D. Koven², Colette L. Heald and Inez Y. Fung (Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, U.S.A.)

Contributed by Inez Y. Fung April 15, 2009 (received for review July 28, 2008).

Abstract

Remote sensing data over North America document the ubiquity of secondary aerosols resulting from a combination of primary biogenic and anthropogenic emissions. The spatial and temporal distribution of aerosol optical thickness (AOT) over the southeastern United States cannot be explained by anthropogenic aerosols alone, but is consistent with the spatial distribution, seasonal distribution, and temperature dependence of natural biogenic volatile organic compound (BVOC) emissions. These patterns, together with observations of organic aerosol in this region being dominated by modern ¹⁴C and BVOC oxidation products with summer maxima, indicate nonfossil fuel origins and strongly suggest that the dominant summer AOT signal is caused by secondary aerosol formed from BVOC oxidation. A link between anthropogenic and biogenic emissions forming secondary aerosols that dominate the regional AOT is supported by reports of chemicals in aerosols formed by BVOC oxidation in a NO_x- and sulfate-rich environment. Even though ground-based measurements from the IMPROVE network suggest higher sulfate than organic concentrations near the surface in this region, we infer that much of the secondary organic aerosol in the Southeast must occur above the surface layer, consistent with reported observations of the organic fraction of the total aerosol increasing with height and models of the expected vertical distribution of secondary organic aerosols from isoprene oxidation. The observed AOT is large enough in summer to provide regional cooling; thus we conclude that this secondary aerosol source is climatically relevant with significant potential for a regional negative climate feedback as BVOC emissions increase with temperature.

• A.H.G., C.D.K., C.L.H., and I.Y.F. designed research; A.H.G., C.D.K., and C.L.H. performed research; A.H.G., C.D.K., C.L.H., and I.Y.F. analyzed data; and A.H.G., C.D.K., C.L.H., and I.Y.F. wrote the paper. The authors declare no conflict of interest.

• ↵²Present address: Laboratoire des Sciences du Climat et l'Environnement, Gif-sur-Yvette, France.

• ↵³Present address: Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523.

*Correspondence may be addressed to: e-mail: ahg@nature.berkeley.edu or ifung@berkeley.edu

Link to abstract: http://www.pnas.org/content/106/22/8835.abstract