This op-ed appeared in CQ Researcher .
By Jay Gulledge
The risk of extreme weather is rising because of climate change. In the United States, long-term trends show an increasing number of heat waves and heavy downpours and longer, more destructive droughts and wildfires. Climate models simulate these same trends when scientists examine the effects of increases in global warming’s main ingredient – greenhouse gases.
Risk is the best way to understand the link between climate change and extreme weather. Just as smoking and high cholesterol are risk factors for heart disease, natural cycles and global warming are risk factors for extreme weather. This year’s weather impacts have been particularly severe because multiple risk factors are aligned: A long, intense La Nina – a temporary cool period in the equatorial Pacific Ocean that is associated with extreme temperatures, droughts, and flooding in other parts of the world – is occurring at the same time we are experiencing the warmest decade in at least 130 years. The big difference between these risk factors is that natural cycles come and go, whereas global warming increases over time as atmospheric greenhouse gases grow, constantly adding more weather risk to the climate system.
Escalating weather impacts are cutting deeply into the economy. The world’s largest re-insurance company says the number of weather- and climate-related disasters worldwide more than doubled over the past 30 years. Economic losses attributable to weather variability run $485 billion annually . Several multi-billion-dollar events have occurred this year, including Texas’ worst single-year drought, the Mississippi floods, and Hurricane Irene, which is expected to rank among the ten costliest hurricanes  in U.S. history. As the weather becomes more volatile, economic risk will continue to grow.
As recent weather events teach us more and more about our vulnerabilities, the taxpayer-funded National Flood Insurance Program is already $18 billion in debt . Because most of the damage from Hurricane Irene is not privately insured, this financially-strapped program is under pressure once again. And the Federal Emergency Management Agency (FEMA) is running out of money to respond to disasters, even as Congress bickers over how to refill the coffers.
Flood insurance is the federal government’s second-largest fiscal liability  after social security. Ignoring rising climate risk will only allow these hidden costs to suck up more taxpayer money. Reducing greenhouse gas emissions and adapting to changes already under way bends down the risk curve, just as exercise and medical insurance lower health risks. If we don’t take these steps, our children and grandchildren will inherit a more dangerous and costlier climate.
Jay Gulledge is the Senior Scientist and Director of the Science and Impacts Program at the Pew Center on Global Climate Change.