Estimates of sea level rise are being drastically underestimated, according to a group of scientists.
The last report by the Intergovernmental Panel on Climate Change (IPCC) predicted a range of potential increases in sea level from 18 to 59cm by the end of the century, but an improved understanding of the melting of ice sheets could add as much as 84cm to the current estimates of increases by 2100.
Writing in Nature Climate Change, Jonathan Bamber and Willy Apsinall from the University of Bristol concluded that around 29cm should be added to account for ice sheets’ unstable future with a one in 20 chance that this figure could actually be as much as 84cm.
“This is the first study of its kind on ice sheet melting to use a formalized mathematical pooling of experts’ opinions,” Bamber said.
“It demonstrates the value and potential of this approach for a wide range of similar problems in climate change research, where past data and current numerical modelling have significant limitations when it comes to forecasting future trends and patterns.”
The IPCC issues an assessment report (AR) roughly every five years with the next, AR5, due out in the Autumn of 2013. It is the main scientific contribution to policy debates.
Some of the last report’s authors have raised concerns that external pressures are encouraging scientists to be conservative with their estimates.
“If the process is leading to an understatement of impacts then it’s leading to an understatement of the threats,” leading climate scientist Michael Mann recently told RTCC.
“As Kevin Trenberth has laid out very convincingly – the fear is that the IPCC in part by these attacks [by climate sceptics] has heightened instincts to be reticent.”
Water levels in New York are an estimated 45cm higher than a century ago, a fact which contributed to the storm surge created by Hurricane Sandy overcoming the city’s flood defences.