Over the course of several years, turbulent water overflow from a large melt lake carved this 60-foot deep canyon. Note the people for scale. Photo by: Ian Joughin.
A massive team of scientists have used multiple methods to provide the best assessment yet of ice loss at the world’s poles, including Greenland and a number of Antarctic ice sheets. Their findings—that all major ice sheets are shrinking but one; that ice loss is speeding up; and that this is contributing to the rise in sea levels—add more evidence to the real-time impacts from global climate change. Melting ice sheets at the poles have raised sea levels 11.1 millimeters, or about 20 percent of observed sea level rise, in the past twenty years, according to the landmark study in Science.
“It provides a simpler picture,” said co-author Benjamin Smith, a research scientist at the UW’s Applied Physics Laboratory. “In the 1990s, not very much was happening. Sometime around 1999, the ice sheets started losing more mass, and probably have been losing mass more rapidly over time since then.”
The rate of ice loss in Greenland has jumped five-fold over the past two decades, while changes in Antarctica have been more variable, but still trend toward total and increasing ice loss. Only East Antarctica may be seeing some gain in ice, but the estimated range could also mean the ice sheet there is either stable or melting a little.
The major study—with 47 authors—has settled some of the uncertainty surrounding ice sheet loss at both poles by combining three different ways that experts in the past have studied polar ice loss, including imagery from ten different satellites. However, the scientists say more long-term monitoring will be required to note just how quickly ice sheets are responding to warming oceans and atmosphere.
“We are just beginning an observational record for ice,” explains another co-author Ian Joughin, a glaciologist in the University of Washington’s Applied Physics Laboratory. “This creates a new long-term data set that will increase in importance as new measurements are made.”
Scientists have been particularly surprised by the fact that ice sheet decline is speeding up.
“We don’t fully understand why it’s accelerating,” Joughin adds. “But the longer-term observations we have, the more solid predictions we will be able to make.”
Climate change is pushing sea levels higher through a variety of impacts, including melting ice sheets, glaciers, and the fact that warmer water physically expands. A study last week found that sea levels were rising 60 percent faster than predicted by the Intergovernmental Panel on Climate Change (IPCC) at around 3.2 millimeters every year. Our rising oceans are already exacerbating storm surges worldwide and flooding some low-lying islands and coastal regions. The only way to slow rising sea levels is to slash global greenhouse gas emissions, according to experts.
Government representatives from around the world are currently meeting in Doha, Qatar for the annual UN Climate Summit. The UN, the World Bank, the International Energy Agency (IEA), and scientists worldwide have all warned that governments need to considerably scale up their ambitions in greenhouse gas cuts in order to have any chance of keeping global temperatures below the 2 degrees Celsius agreed on target. In the first week of the conference there was little sign of progress towards greater cuts.
CITATION: A. Shepherd; H. Briggs; M. McMillan; A.V. Sundal et al. A Reconciled Estimate of Ice-Sheet Mass Balance. Science. 2012.
(11/28/2012) Arctic snowfall accumulation plays a critical role in ringed seal breeding, but may be at risk due to climate change, according to a new study in Geophysical Research Letters. Sea ice, which is disappearing at an alarming rate, provides a crucial platform for the deep snow seals need to reproduce. Ringed seals (Phoca hispida) require snow depths of at least 20 centimeters (8 inches): deep enough to form drifts that seals use as birth chambers.
(11/28/2012) Sea levels are rising 60 percent faster than Intergovernmental Panel on Climate Change (IPCC) has estimated, according to a new study in the open access Environmental Research Letters. In addition to imperiling coastal regions and islands, global sea level rise is worsening the damage inflicted by extreme weather such as Hurricane Sandy, which recently brought catastrophic flooding to the New Jersey coast and New York City.
(11/26/2012) A number of observers have expressed hope that the Obama Administration, fresh from a re-election victory in the U.S., will take a more active and ambitious role at this year’s UN Climate Summit, held in Doha, Qatar. The summit opens amid fresh—and increasingly dire—warnings over climate change from the World Bank, the International Energy Agency, and the UN itself.
(11/26/2012) The Yasuni-ITT Initiative has been called many things: controversial, ecological blackmail, revolutionary, pioneering, and the best chance to keep oil companies out of Ecuador’s Yasuni National Park. But now, after a number of ups and downs, the program is beginning to make good: the Yasuni-ITT Initiative has raised $300 million, according to the Guardian, or 8 percent of the total amount needed to fully fund the idea.
(11/26/2012) Even as the clamor to reduce greenhouse gas emissions reaches a new high—echoed recently by such staid institutions as the World Bank and the International Energy Agency (IEA)—a new analysis by the World Resources Institute (WRI) finds that 818 new coal-fired plants are under proposal in China and India. In all 1,199 new coal-fired plants are currently planned worldwide, according to the report, totaling 1.4 million megawatts of energy.
(11/26/2012) As the 18th meeting of the UN Framework Convention on Climate Change (UNFCCC) kicks off this morning in oil and gas rich Qatar, the world body warns that much more ambitious greenhouse gas cuts are needed to keep catastrophic climate change at bay. A new report by the UN Environment Program (UNEP) and the European Climate Foundation finds that even if all current emissions pledges are kept, the world will still spew 8 billion tonnes of CO2 equivalent above what is needed by 2020, putting the globe on a fast-track to dangerous climate change.
(11/20/2012) As expected, greenhouse gas concentrations in the Earth’s atmosphere hit another record last year, according to a new UN World Meteorological Organization (WMO). The increasing concentrations of greenhouse gases means that radiative forcing—changes in the atmosphere’s energy balance that leads to warming—has jumped 30 percent in the last twenty years.
(11/20/2012) A new report by the World Bank paints a bleak picture of life on Earth in 80 years: global temperatures have risen by 4 degrees Celsius spurring rapidly rising sea levels and devastating droughts. Global agriculture is under constant threat; economies have been hampered; coastal cities are repeatedly flooded; coral reefs are dissolving from ocean acidification; and species worldwide are vanishing. This, according to the World Bank, is where we are headed even if all of the world’s nations meet their pledges on cutting greenhouse gas emissions. However, the report also notes that with swift, aggressive action it’s still possible to ensure that global temperatures don’t rise above 4 degrees Celsius.