The Science for Determining Climate-Change Damage Is Unsettled

Tying individual weather events to global warming remains a challenge, and research on the causes of recent flooding in Pakistan yields mixed results

By Eric Niiler and Stacy Meichtrym of The WSJ. Excerpts:

"Questions remain about how the fund will operate and whether it can act quickly to help affected countries. As officials work out the details, scientific uncertainty over the attribution of human-induced climate change to individual weather disasters risks deterring wealthy nations from contributing funds.  

Attribution science is still evolving, according to Richard Spinrad, administrator of the National Oceanic and Atmospheric Administration. He said his agency’s focus is on understanding the effects of climate change—such as the duration and number of tropical storms or the extent of sea-level rise—rather than pinpointing the causes of specific weather events.

“I do not see NOAA getting involved in providing some attribution index for that typhoon or that hurricane,” Dr. Spinrad said.

Some weather events are made worse by increased atmospheric and ocean temperatures and rising sea levels, according to the Intergovernmental Panel on Climate Change. But it has been unable to attribute specific weather events to climate change.

Lisa Graumlich, a professor of environmental and forest sciences at the University of Washington, said scientists now face the challenge of developing tools to assess loss and damage and determine whether climate change is to blame for individual weather events.

“I think we’re in some very undefined territory right now,” said Dr. Graumlich, who is the president-elect of the American Geophysical Union."

"A recent study of the floods [in Pakistan] yielded mixed results. The research, which hasn’t been published in a journal, showed that total rainfall this year in the affected region was more than seven times higher than the historical average and that climate change had intensified rainfall in the region during a week-long period in late August. In addition, computer models showed that rainfall during that period was 75% more intense as a result of climate change than it would have been in the absence of climate change.

But the scientists didn’t detect a role for climate change throughout the two-month monsoon season. Other factors, including strong La Niña ocean-temperature conditions in the Pacific region, might explain the 50% surge in rainfall intensity during the season, according to Friederike Otto, lead author of the study and a senior lecturer in climate science at Imperial College, London."