In its final and most powerful report, a United Nations panel of scientists meeting here describes the mounting risks of climate change in language that is both more specific and forceful than its previous assessments, according to scientists here.
Synthesizing reams of data from its three previous reports, the United Nations Intergovernmental Panel on Climate Change for the first time specifically points out important risks if governments fail to respond: melting ice sheets that could lead to a rapid rise in sea levels and the extinction of large numbers of species brought about by even moderate amounts of warming, on the order of 1 to 3 degrees.
The report carries heightened significance because it is the last word from the influential global climate panel before world leaders meet in Bali, Indonesia, next month to begin to discuss a global climate change treaty that will replace the Kyoto protocol, which expires in 2012. It is also the first report from the panel since it was awarded the Nobel Peace Prize in October — an honor that many scientists here said emboldened them to stand more forcefully behind their positions…
“This document goes further than any of the previous efforts,” said Hans Verolme, director of the World Wildlife Fund’s Global Climate Change Program. “The pressure has been palpable — people know they are delivering a document that will be cited for years to come and will define policy.”
The previous three sections, released between February and April, focused on one issue at a time: the first on science, the second on how the world could adapt to warming and the third about how countries could “mitigate,” or reduce the greenhouse gases produced.
This fourth and final assessment — the so-called synthesis report — seeks to combine lessons from all three. Its conclusions are culled from data contained in the thousands of pages that were essentially technical supplements to the panel’s previous publications. How that data is summarized and presented to the world is a powerful guide to what the scientists consider of utmost importance at the end of a five-year process, offering concrete guidelines for policy makers…
Even though the synthesis report is more alarming than its predecessors, some researchers believe that it still understates the trajectory of global warming and its impact. The I.P.C.C.’s scientific process, which takes five years of study and writing from start to finish, cannot take into account the very latest data on climate change or economic trends, which show larger than predicted development and energy use in China.
“The world is already at or above the worst case scenarios in terms of emissions,” said Gernot Klepper, of the Kiel Institute for World Economy in Kiel, Germany. “In terms of emissions, we are moving past the most pessimistic estimates of the I.P.C.C., and by some estimates we are above that red line.”
The panel presents several scenarios for the trajectory of emissions and climate change. In 2006, 8.4 gigatons of carbon were put into the atmosphere from fossil fuels, according to a study in the proceedings of the National Academy of Science, which was co-written by Dr. Klepper. That is almost identical to the panel’s worst case prediction for that year.
Likewise, a recent International Energy Agency report looking at the unexpectedly rapid emissions growth in China and India estimated that if current policies were not changed the world would warm six degrees by 2030, a disastrous increase far higher than the panel’s estimates of one to four degrees by the end of the century.