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Abrupt Climate Change

NASA map


Comparison of Minimum Sea Ice between 2005 and 2007. California outline shown for comparison. Modified from NASA/Goddard Space Flight Center Scientific Visualization Studio. The Blue Marble data is courtesy of Reto Stockli.

In the 2004 disaster movie The Day After Tomorrow, tidal waves the size of skyscrapers hurtle toward New York City. This fantastic envisioning of abrupt climate change bears no resemblance to what could happen in reality, but abrupt climate change could potentially raise sea levels by meters in the span of a century. One of the most well-studied examples of extreme climate change occurred 12,800 years ago, at the end of the last Ice Age, in an event known as the Younger Dryas. During this time temperatures warmed and the glaciers receded, but scientists speculate that the thermohaline circulation, or THC, the ocean current which transports warm and cool water, shut down, causing a mini, 1,200-year-long ice age. The Younger Dryas ended just as abruptly as it began, with temperatures rising 10°C in just 10 years.

So abrupt climate changes happen. To better understand these potential threats to humanity, the U.S. Department of Energy’s Office of Biological and Environmental Research, or OBER, launched the Investigation of the Magnitudes and Probabilities of Abrupt Climate Transitions program.

Science Daily reports on the laboratories across the nation (Argonne, Los Alamos, Lawrence Berkeley, Lawrence Livermore, Oak Ridge, and Pacific Northwest) which will work with IMPACT to develop the computer models necessary to understand this complex phenomenon. OBER launched the program through its Climate Change Prediction Program. IMPACTS will study four possible causes of abrupt climate change:

  1. instability among marine ice sheets, particularly the West Antarctic ice sheet
  2. positive feedback mechanisms in subarctic forests and arctic ecosystems, leading to rapid methane release or large-scale changes in the surface energy balance
  3. destabilization of methane hydrates (vast deposits of methane gas caged in water ice), particularly in the Arctic Ocean
  4. feedback between the biosphere and atmosphere that could lead to megadroughts in North America, perhaps even greater than the 1930s Dust Bowl.

Each of these “Four Horsemen of the Apocalypse” could dramatically change the globe, with one potential impact being ocean level rise 13 to 20 feet. The computer model will help predict environmental shifts and provide information to scientists, government, and business leaders on strategies to prepare for or prevent extreme changes.

One significant a fear is that slowly rising temperatures could warm the methane-rich permafrost, releasing the greenhouse gas, which is has heat-trapping properties 26 times more powerful than carbon dioxide in the short term. As the permafrost melts, the organic material trapped in its warming soil will begin to decompose and release its stored methane and carbon, rapidly increasing temperatures and melting more permafrost, creating a feedback loop.

But a two-week-old study in Science suggests that the ancient permafrost may be more resilient to rising temperatures than previously thought. The study reports that a 700,000 year-old chunk of ground ice, buried in the Yukon permafrost, has survived some of warmest periods of the earth’s history. Scientists believed everything would have melted 120,000 years ago, but this piece of ice questions that theory.

This study shows the complicated nature of global climate modeling. As Jeremy Jacquot wrote in Science Progress, scientists didn’t expect the Arctic ice cap to melt as quickly as it has, with some new estimates predicting it will be gone by 2013.

The point being that climate scientists need the resources to study these potentially disastrous consequences of global warming before the “day after tomorrow” becomes today.

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