Here is an update of my review of the best papers on climate science in the past year. If you want a broader overview of the literature in the past few years, focusing specifically on how unrestricted emissions of greenhouse gas emissions are projected to impact the United States, try “An introduction to global warming impacts: Hell and High Water.”
I’m adding some of the best figures from those papers, too. For those who like their science delivered through videos, let me suggest the panel I hosted earlier this month, may I suggest Video and PPTs of “The Science of Climate Change” with Dr. Christopher Field and Dr. Michael MacCracken (which is the source of the above figure showing the decadal temperature trend, together with the annual temps).
In 2009, the scientific literature caught up with what top climate scientists have been saying privately for a few years now:
- Many of the predicted impacts of human-caused climate change are occurring much faster than anybody expected — particularly ice melt, everywhere you look on the planet.
- If we stay anywhere near our current emissions path, we are facing incalculable catastrophes by century’s end, including rapid sea level rise, massive wildfires, widespread Dust-Bowlification, large oceanic dead zones, and 9°F warming — much of which could be all but irreversible for centuries. And that’s not the worst-case scenario!
- The consequences for human health and well being would be extreme.
That’s no surprise to anybody who has talked to leading climate scientists in recent years, read my book Hell and High Water (or a number of other books), or followed this blog. Still, it is a scientific reality that I don’t think more than 2 people in 100 fully grasp, so I’m going to review here the past year in climate science. I’ll focus primarily on the peer-reviewed literature, but also look at some major summary reports.
Let’s start with the basics. Heat-trapping greenhouse gases are at unprecedented levels, and the paleoclimate record suggests that even slightly higher levels are untenable:
- World carbon dioxide levels jump 2.3 ppm in 2008 — highest in probably 20 million years
- Science: CO2 levels haven’t been this high for 15 million years, when it was 5° to 10°F warmer and seas were 75 to 120 feet higher “” “We have shown that this dramatic rise in sea level is associated with an increase in CO2 levels of about 100 ppm.”
- Nature Geoscience study: Oceans are acidifying 10 times faster today than 55 million years ago when a mass extinction of marine species occurred
- New study of Greenland under “more realistic forcings” concludes “collapse of the ice-sheet was found to occur between 400 and 560 ppm” of CO2
Since we have record levels of heat-trapping gases, it’s not surprising that we also learned that this was the hottest decade in the temperature record and that the Arctic is the hottest in at least two millenia.
- World Meteorological Organization and NOAA both report: 2000–2009 is the hottest decade on record: “The decade of the 2000s (2000–2009) was warmer than the decade spanning the 1990s (1990–1999), which in turn was warmer than the 1980s (1980–1989).”
- Human-caused Arctic warming overtakes 2,000 years of natural cooling, “seminal” study finds [see figure below]
A Hockey Stick in Melting Ice
In two key papers, we learned that the planet is warming from those GHGs just where climate science said it would “” the oceans, which is where more than 90% of the warming was projected to end up (see “Skeptical Science explains how we know global warming is happening.”). The key findings in the second study are summed up in this figure:
Figure : Time series of global mean heat storage (0–2000 m), measured in 108 Jm-2.
That study makes clear that upper ocean heat content, perhaps not surprisingly, is simply far more variable than deeper ocean heat content, and thus an imperfect indicator of the long-term warming trend.
Unexpectedly, even Antarctica appears to be warming:
This global warming is driving melting at extraordinary rates every where we look, including places nobody expected:
- Satellite data stunner: “Our data suggest that EAST Antarctica is losing mass”¦. Antarctica may soon be contributing significantly more to global sea-level rise.”
- Nature: “Dynamic thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized.”
- Large Antarctic glacier thinning 4 times faster than it was 10 years ago: “Nothing in the natural world is lost at an accelerating exponential rate like this glacier.”
- De-Icer: USGS report details “recent dramatic shrinkage” in U.S. glaciers, matching global decline
- North Pole poised to be largely ice-free by 2020: “It’s like the Arctic is covered with an egg shell and the egg shell is now just cracking completely”
- Another one bites the dust, literally: Bolivia’s 18,000 year-old Chacaltaya glacier is gone
- Another climate impact coming faster than predicted: Glacier National Park to go glacier-free a decade early
- World’s Glaciers Shrink for 18th Year
And given that unexpectedly fast ice melt, it’s no surprise the science now projects much higher and much faster sea level rise than just a few years ago:
- Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100 [see figure]
- High Water: Greenland ice sheet melting faster than expected and could raise East Coast sea levels an extra 20 inches by 2100 “” to more than 6 feet.
- West Antarctic ice sheet collapse even more catastrophic for U.S. coasts
- Nature sea level rise shocker: Coral fossils suggest “catastrophic increase of more than 5 centimetres per year over a 50-year stretch is possible.” Lead author warns, “This could happen again.”
We continued to learn about the dangerous positive carbon-cycle feedbacks that threaten to amplify the impacts of human-caused GHGs.
- Science stunner: “Clouds Appear to Be Big, Bad Player in Global Warming” “” an amplifying feedback (sorry Lindzen and fellow deniers)
- So many amplifying methane feedbacks, so little time to stop them all
- Science: Global warming is killing U.S. trees, a dangerous carbon-cycle feedback
- Study: Water-vapor feedback is “strong and positive,” so we face “warming of several degrees Celsius”
Indeed, the best evidence is that the climate is now being driven by amplifying feedbacks — see, most notably:
- The defrosting of the permafrost [see figure below]
- The drying of the Northern peatlands (bogs, moors, and mires).
- The destruction of the tropical wetlands
- Decelerating growth in tropical forest trees “” thanks to accelerating carbon dioxide
- Wildfires and Climate-Driven forest destruction by pests
- The desertification-global warming feedback
- The saturation of the ocean carbon sink
Using the first “fully interactive climate system model” applied to study permafrost, the researchers found that if we tried to stabilize CO2 concentrations in the air at 550 ppm, permafrost would plummet from over 4 million square miles today to 1.5 million. If concentrations hit 690 ppm, permafrost would shrink to just 800,000 square miles:
High emissions levels + positive feedbacks = climate catastrophe:
- M.I.T. doubles its 2095 warming projection to 10°F “” with 866 ppm and Arctic warming of 20°F
- Our hellish future: Definitive NOAA-led report on U.S. climate impacts warns of scorching 9 to 11°F warming over most of inland U.S. by 2090 with Kansas above 90°F some 120 days a year “” and that isn’t the worst case, it’s business as usual!”
- Ocean dead zones to expand, “remain for thousands of years”
- U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm “¦ the worst-case IPCC scenario trajectories (or even worse) are being realised” “” 1000 ppm
- Climate change expected to sharply increase Western wildfire burn area “” as much as 175% by the 2050
“This graph shows the percentage increase in area burned by wildfires, from the present-day to the 2050s, as calculated by the model of Spracklen et al.  for the May-October fire season. The model follows a scenario of moderately increasing emissions of greenhouse gas emissions and leads to average global warming of 1.6 degrees Celsius (3 degrees Fahrenheit) by 2050. Warmer temperatures can dry out underbrush, leading to more serious conflagrations in the future climate.”
And the plausible worst-case scenario is even worse than this grim “business as usual” emissions case:
- UK Met Office: Catastrophic climate change, 13–18°F over most of U.S. and 27°F in the Arctic, could happen in 50 years, but “we do have time to stop it if we cut greenhouse gas emissions soon.”
- “The Copenhagen Diagnosis” warns “Without significant mitigation, the report says global mean warming could reach as high as 7 degrees Celsius by 2100.”
- NOAA stunner: Climate change “largely irreversible for 1000 years,” with permanent Dust Bowls in Southwest and around the globe
This is the “plausible worst case scenario” for 2060 from the UK Met Office that occurs in 10% of model runs of high emissions with the carbon cycle feedbacks [temperature in degrees Celsius, multiple by 1.8 for Fahrenheit]:
And this is not good news for human health and welfare
- The Lancet medical journal: Cutting greenhouse gas emissions has major direct health benefits
- NRC: Burning fossil fuels costs the U.S. $120 billion a year “” not counting mercury or climate impacts!
- Global Warming Is A Medical Emergency”: Hellish heatwaves to harm health of millions
- Climate change helps spread dengue fever in 28 states
- Half of world’s population could face climate-driven food crisis by 2100
So the time to act is most certainly now.
I’ll end with the best piece of scientific news I wrote about, which suggests it is not too damn late to act — a NOAA-led study, “Observational constraints on recent increases in the atmospheric CH4 burden” (subs. req’d, NOAA online news story here), which found:
Measurements of atmospheric CH4 from air samples collected weekly at 46 remote surface sites show that, after a decade of near-zero growth, globally averaged atmospheric methane increased during 2007 and 2008. During 2007, CH4 increased by 8.3 ± 0.6 ppb. CH4 mole fractions averaged over polar northern latitudes and the Southern Hemisphere increased more than other zonally averaged regions. In 2008, globally averaged CH4 increased by 4.4 ± 0.6 ppb; the largest increase was in the tropics, while polar northern latitudes did not increase. Satellite and in situ CO observations suggest only a minor contribution to increased CH4 from biomass burning. The most likely drivers of the CH4 anomalies observed during 2007 and 2008 are anomalously high temperatures in the Arctic and greater than average precipitation in the tropics. Near-zero CH4 growth in the Arctic during 2008 suggests we have not yet activated strong climate feedbacks from permafrost and CH4 hydrates.
Yes, early this year I reported that NOAA found “Methane levels rose in 2008 for the second consecutive year after a 10-year lull,” but so far that most dangerous of all feedbacks “” Arctic and tundra methane releases “” does not appear to have been fatally triggered.
The anti-science crowd use smoke and mirrors to distract as many people as possible, but the rest of us need to listen to the science and keep our eyes on the prize — reversing greenhouse gas emissions trends as quickly and rapidly as possible.
Please use the comments to add links to any major studies I didn’t cover here. I will be updating this post continuously.