IPCC Report Adds to Studies Tying Climate Change to Extreme Weather

East Coast snowstorms in October. The suburbs of Bangkok under water. Extreme droughts in the Horn of Africa.

Such "freak" weather events have dominated headlines for over a year, and with good reason.

Now, a new report from the International Panel on Climate Change (IPCC) is making the connections between these extreme weather events and climate change. According to media coverage, the forthcoming “Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation” warns that a warmer world will likely lead to disruptive changes in the frequency and magnitude of extreme events, such as wildfires, heat waves and cyclones.

These findings are consistent with those from other authoritative scientific assessments:

• In 2009, the U.S. Climate Change Science Program, which is sponsored by 13 federal government agencies in the United States, issued an assessment concluding that human activities have likely been contributing to warmer nights, heat waves, and heavy downpours. They also warned that drought in the American Southwest is likely to worsen in a warming world, with severe implications for water availability and wildfires.

• In 2011, a climate science assessment by the U.S. National Academy of Sciences reached the same conclusions, noting that the U.S. has been no exception to these global trends.

• The IPCC’s Fourth Assessment Report has also determined that there has been an increase in extreme weather events such as heat waves, intense rainfall events, and category 4 and 5 storms, as well as drying trends across much of the northern and southern hemispheres..

These findings are also consistent with the trends that WRI has found in the recent scientific literature. For example, as included in our review of climate science literature from 2009-2010, research suggests that in the last 15 years, tropical storms have produced significantly more heavy rain events in the United States than over the previous century (30% greater than more than double the long-term average).

Several scientific studies have recently found some strong links between climate change and extreme events. For example, the Russian heat wave of July 2010 has been directly connected to climate change. Researchers have likewise established links between climate change and more frequent Mediterranean droughts.

And, these events are costly. According to the insurance group Munich Re, there were more than 950 natural disasters in 2010, 90 percent of them weather related, causing $130 billion worth of damage. In the United States, there have already been more than 10 weather-related disasters of $1 billion dollars each so far this year. These events have lead to $45 billion in damages. And the year isn’t over yet. [Update: Shortly after posting this piece, we received word of a new tally putting the number of U.S. billion-dollar weather-related disasters in 2011 at 14, a new record.]

Together, these findings underline the urgency of global action to address climate change. Put simply, the more our climate warms, the more extreme our weather will likely become.

As climate negotiators prepare to meet in Durban, South Africa later this month, they should come prepared to advance solutions that will swiftly reduce global greenhouse gas emissions. In Durban, governments need to formalize action that not only supports current national commitments, but also increases the level of ambition in curbing emissions.

As the new IPCC report also recognizes, beyond cutting emissions, countries need to do more to prepare for extreme weather events and adapt to climate impacts. WRI explores these issues in the recently released report, Decision Making in a Changing Climate, which looks at how national leaders can prepare for and respond to extreme events, as well as other longer-term climate impacts.

In the coming weeks, we will continue to look into the latest IPCC report to help draw out and explain the connections between extreme weather and climate change.