The spate of extreme weather events worldwide this summer has raised the profile of a major issue in climate change science: how does global warming impact weather and climate extremes? Increases in the frequency and severity of climate and weather extremes have been observed over the last fifty years, including droughts, heavy precipitation events, extreme temperatures, and intense tropical cyclone activity in the North Atlantic, and are projected to continue. However, most atmospheric scientists will not claim a given extreme weather event as “proof” of human influence on the climate based on the current evidence, and research continues on the complexities of attributing climate change to human activities versus natural climate variability. A new international research initiative will seek to elevate the priority and visibility of attribution activities, and create a “research activity and a framework for an ‘operational’ activity, that sets forth a goal of providing a lot more concrete information in near real time about what has happened and why in weather and climate.”
A group of atmospheric scientists, climate information users, and science communications experts met last week in Colorado for the first full session of the International Group on Attribution of Climate-related Events, a workshop convened by the U.S. National Center for Atmospheric Research (NCAR), the UK Met Office, and the National Oceanic and Atmospheric Administration (NOAA). The group will work to more accurately explain the complex causes behind extreme climate-related events, such as the recent flooding in Pakistan and intense wildfires induced by high heat and drought in Russia. The ability to trace the human fingerprint in specific weather events could significantly raise awareness about the impacts of human-caused global warming on regional and local scales, and make explicit the need for climate change adaptation and mitigation.
As explained by Climate Central scientists, in taking the example of the deadly 2003 European heat wave, this event could have occurred without human influence on the climate—but human-caused forcing increases the likelihood of such an event occurring.
Secretary of State Hillary Clinton made a similar connection recently, linking flooding in Pakistan and other extreme events to human influence on the climate. “You can’t point to any particular disaster and say ‘it was caused by,’ but we are changing the climate of the world,” she said.
Climate Science Watch Director Rick Piltz spoke recently on Al Jazeera English Television on whether the 2010 extreme weather events were a sign of a changing climate. “One of the main ways that we will experience long-term climate change is through the changes in the weather and the extremes that we are seeing now,” Piltz said.
Increases in the intensity and severity of extreme weather events pose great risks to human society, above all in the developing world. Our ability to build resiliency into our infrastructure depends on our awareness of the destructive potential of extreme events that are projected to move beyond the realm of modern human experience.
As quoted in The Guardian, Peter Stott of the UK Met Office said: “We need to be able to forecast events weeks or months ahead of their occurrence so people can mitigate their worst impacts. We also need to consider the longer-term context and see if we need to build better sea defences at a particular location and assess how high dykes or walls need to be. Certainly, one thing is clear: there is no time to waste. The effects of global warming are already upon us.”
And according to Claudia Tebaldi from Climate Central: “An analysis that is able to drill into the specific events and their causes could not only make us more aware of the effects that our actions have on our local climate, but be the strong basis for saying something about what people on the scorched ground in Moscow, or feet deep in the water in Pakistan, should be prepared to face in a world where greenhouse gases are not kept in check (or not to face, if the result of event attribution concluded that the component from global warming was not significant).”
Another excellent resource is a podcast featuring Dr. Kevin Trenberth, the head of climate analysis at the National Center for Atmospheric Research in Boulder, Colorado, discussing the meteorological dynamics at work in this summer’s heat wave in Russia and flooding in Pakistan, and the larger implications of climate change for extreme weather events.
Presentations from the workshop, the agenda, and an executive summary can be found here.