UK Government Calls for International Action as Scientists Discuss Oceans' Role in Climate Change

ice core extraction
Shallow ice core drilling at Dome C. The ice core will be used to study the climate for the last 2000 years. Here the ice core is extracted from the drill barrel. Photo: Robert Mulvaney/British Antarctic Survey

Addressing the Rapid Climate Change (RAPID) conference in Birmingham, England, on October 25, Sir David King, the UK government’s chief scientific advisor, warned that, “Governments ignore the capabilities of science today at the peril of their own population.” King observed that while scientists often publish warnings about the consequences of disasters like tsunamis and hurricanes before they hit, government officials don’t always use this information to take precautionary action. As a result, worst-case scenarios—like the effects of the 2004 Indian Ocean tsunamis and 2005’s Hurricane Katrina—come to pass. The next big disaster, King said, could be global warming.

King noted that 92 percent of the British public believes global warming is a serious issue, and that his country’s three main political parties battle not so much over the science of climate change than over which party is willing to take the greatest action to address it. Already, the UK has committed to reducing its greenhouse gas emissions 60 percent by 2050, though the nation accounts for only about 2 percent of total global emissions. The rest of the world needs to join the fight to prevent catastrophic climate change, King urged, noting that limiting temperature rises to less than 2 degrees Celsius is all but impossible without radical, immediate international action. A two-degree warming would make heat waves like those experienced in Europe in the summer of 2003 the norm, he warned, and if current trends continue, about 50 percent of the planet’s ice sheets would disappear in the next 1,000 years and all land-based ice within 3,000 years.

Scientists from around the world gathered at the four-day conference to discuss their research on climate change, in particular the role of ocean circulation in modulating climate worldwide. The Atlantic portion of the thermohaline current, which transports warm tropical surface water northwards, is an important factor in regulating the temperature in northern Europe, allowing it to remain more temperate than other countries at the same latitude. But, according to scientists, higher surface temperatures and increased freshwater in the oceans, especially in the North Atlantic, pose major threats to the stability of this current. The last major disruption occurred some 8,200 years ago when the ice dams holding back Lake Agassiz, which covered 841,000 square kilometers in Canada and the United States, collapsed. The influx of more than 163,000 cubic kilometers of freshwater into the North Atlantic in less than a year decreased the density of the ocean surface water, preventing it from sinking, and shut off the Atlantic current, plunging the world into a 400-year cold spell.

Climate predictions for the 21st century indicate a weakening of the Atlantic current, according to Johann Jungclaus with Germany’s Max Planck Institute for Meteorology. He told conference participants that although the influx of freshwater in the North Atlantic from melting ice sheets in Greenland and elsewhere will accelerate this weakening, it is unlikely to cause rapid climate change. However, the weakening may cause a 0.5 to 1 degree Celsius cooling in some areas, though the effects will be relatively limited, he said. This cooling could result in areas of non-warming in the North Atlantic as global temperatures rise, but high latitudes may still experience severe warming.

Most attendees agreed that any cooling caused by collapses in the Atlantic current would not spare Northern Europe from rising temperatures. Bette L. Otto-Bliesner with the U.S. National Center for Atmospheric Research explained that disruptions to the current and resulting climate perturbations are rarely permanent, with the current usually able to recover within a few hundred years.

Changes to the thermohaline circulation in the Atlantic could have global effects as well. Another conference participant, Buwen Dong from the UK’s University of Reading, explained that a weakened thermohaline circulation in the Atlantic could lead to enhanced variability in the Pacific Ocean’s El Niño Southern Oscillation (ENSO), which controls the cycle of climate-altering El Niño and La Niña events. Dong’s model predicts an increase in the amplitude and skewness of the oscillations, resulting in more severe ENSO activity, with warmer El Niño events occurring more frequently than La Niña events. 

This story was produced by Eye on Earth, a joint project of the Worldwatch Institute and the blue moon fund. View the complete archive of Eye on Earth stories, or contact Staff Writer Alana Herro at aherro [AT] worldwatch [DOT] org with your questions, comments, and story ideas.