The federal government has launched a research project to evaluate the threat of abrupt and rapid climate change.
Through its Climate Change Prediction Program, the U.S. Department of Energy’s Office of Biological and Environmental Research (OBER) recently launched IMPACTS–Investigation of the Magnitudes and Probabilities of Abrupt Climate Transitions–a program that brings together six national laboratories to attack the problem of abrupt climate change, or ACC.
The goal of IMPACTS is to understand possible mechanisms of abrupt climate change
well enough to build comprehensive computer models and to make accurate
predictions before abrupt climate change takes place.
Most people think of climate change as something that occurs only gradually, with average temperature changing two or three degrees Celsius over a century or more. This is the rate at which ‘forcing’ mechanisms operate, such as the accumulation of carbon dioxide in the atmosphere due to the burning of fossil fuels or widespread changes in land use.
But climate change has occurred much more rapidly in the past and will almost certainly do so again, according to an IMPACTS release. Perhaps the most famous example is the reverse hiccup in a warming trend that began 15,000 years ago and eventually ended the last ice age.
Roughly 2,000 years after it started, the warming trend suddenly reversed, and temperatures fell back to near-glacial conditions; Earth stayed cold for over a thousand years, a period called the Younger Dryas (named for an alpine wildflower). Then warming resumed so abruptly that global temperatures shot up 10 °C in just 10 years.
Because civilizations hadn’t yet emerged, complex human societies escaped this particular roller-coaster ride. Nevertheless, some form of abrupt climate change is highly likely in the future, with wide-ranging economic and social effects.
William Collins of Berkeley Lab’s Earth Sciences Division (ESD), who heads the Climate Science Department in ESD, is the principal investigator for IMPACTS, which will bring together the work of experts in physical, chemical, and biogeochemical climate processes and in computer simulations of the whole Earth system. Argonne, Los Alamos, Lawrence Berkeley, Lawrence Livermore, Oak Ridge, and Pacific Northwest are the participating national laboratories.
"IMPACTS is one part of a two-pronged approach to studying abrupt climate change, one based in the universities and the other in the national labs," says Collins.
Collins coordinated the development of the most recent version of the Community Climate System Model (CCSM), one of the leading models underpinning the physical science basis of the IPCC’s 2007 climate change assessment; the IMPACTS program will be based on CCSM and will add new capabilities and new diagnostics for processes that could initiate abrupt climate change.
"There are lots of names for abrupt climate change: nasty surprises, the jokers in the deck, the tipping point," Collins says. "When the national lab participants first met to decide on the most significant potential sources of abrupt climate change in future, the first thing we had to do was define what we meant: a large-scale change that happens more quickly than that brought on by forcing mechanisms–on a scale of years to decades, not centuries–and that persists for a very long time."
The IMPACTS team will initially focus on four types of ACC:
- instability among marine ice sheets, particularly the West Antarctic ice sheet
- positive feedback mechanisms in subarctic forests and arctic ecosystems, leading to rapid methane release or large-scale changes in the surface energy balance
- destabilization of methane hydrates (vast deposits of methane gas caged in water ice), particularly in the Arctic Ocean
- feedback between biosphere and atmosphere that could lead to megadroughts in North America.
Only half joking, Collins refers to these as "the Four Horsemen of the Apocalypse."
What to Do Next
A believable ACC prediction would mean "we are facing the largest
imaginable negative impacts on human civilization, conditions that will
take society outside all normal modes of adaptation very quickly," says
Collins. "The consequences will be especially dire for resource-limited
populations. This is a huge threat to the security and stability of our
nation and the world, which is one reason DOE has made a major
investment in CCSM."
One of the great benefits of IMPACTS, in Collins’s view, will be to
bring together parts of the climate community whose communication has
traditionally been poor. For scientists concerned with the effects of
climate change and those concerned with modeling it, "the working
relationship hasn’t been there," says Collins. "For example, of the
major threats to human health from global warming, the worst is
malnutrition–but the second worst is extreme weather!"
Collins says that modelers now have the ability to take lessons from
likely impacts back into their basic research. "Modeling a specific
region with a specific set of circumstances in high resolution and
making a solid prediction of what’s going to happen in the next few
decades is much tougher than modeling what’s going to happen to the
whole globe a century from now," he says. "Those concerned with the
effects of climate change on humans have never asked modelers to do
this before. We hope that IMPACTS will demonstrate that it can be done."
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