Report: Global Warming Has Changed Our Weather — Worse Heat Waves, Floods, Hurricanes, Storms To Come

Weather ExtremesThe traditional media rarely discusses extreme weather events in the context of global warming. However, as the Wonk Room Global Boiling series has documented, scientists have been warning us for years that climate change will increase catastrophic weather events like the California wildfires, the East Coast heatwave, and the Midwest floods that have been taking lives and causing billions in damage in recent days.

Today, the federal government has released a report that assembles this knowledge in stark and unequivocal terms. “Weather and Climate Extremes in a Changing Climate,” by the multi-agency U.S. Climate Change Science Program with the National Oceanic and Atmospheric Administration in the lead, warns that changes in extreme weather are “among the most serious challenges to society” in dealing with global warming. After reporting that heat waves, severe rainfall, and intense hurricanes have been on the rise — all linked to manmade global warming — the authors deliver this warning about the future:

In the future, with continued global warming, heat waves and heavy downpours are very likely to further increase in frequency and intensity. Substantial areas of North America are likely to have more frequent droughts of greater severity. Hurricane wind speeds, rainfall intensity, and storm surge levels are likely to increase. The strongest cold season storms are likely to become more frequent, with stronger winds and more extreme wave heights.

Unfortunately, some of the cautions in this long-delayed report have come too late for the victims of the Midwest Flood:

Some short-term actions taken to lessen the risk from extreme events can lead to increases in vulnerability to even larger extremes. For example, moderate flood control measures on a river can stimulate development in a now “safe” floodplain, only to see those new structures damaged when a very large flood occurs.

Climate change is threatening our health, our lives, our economy, and our security already. Now the only question is when our media will take notice, and when our leaders will respond. Our future depends on it.

From the accompanying brochure comes this chart summarizing the findings:

Observed changes in North American extreme events, assessment of human influence for the observed changes, and likelihood that the changes will continue through the 21st century1.
Phenomenon and direction of change Where and when these changes occurred in past 50 years Linkage of human activity to observed changes Likelihood of continued future changes in this century
Warmer and fewer cold days and nights Over most land areas, the last 10 years had lower numbers of severe cold snaps than any other 10-year period Likely warmer extreme cold days and nights, and fewer frosts2 Very likely4
Hotter and more frequent hot days and nights Over most of North America Likely for warmer nights2 Very likely4
More frequent heat waves and warm spells Over most land areas, most pronounced over northwestern two thirds of North America Likely for certain aspects, e.g., nighttime temperatures; & linkage to record high annual temperature2 Very likely4
More frequent and intense heavy downpours and higher proportion of total rainfall in heavy precipitation events Over many areas Linked indirectly through increased water vapor, a critical factor for heavy
precipitation events3
Very likely4
Increases in area affected by drought No overall average change for North America, but regional changes are evident Likely, Southwest USA.3 Evidence that 1930’s & 1950’s droughts were linked to natural patterns of sea surface temperature variability Likely in Southwest U.S.A., parts of Mexico and Carribean4
More intense hurricanes Substantial increase in Atlantic since 1970; Likely increase in Atlantic since 1950s; increasing tendency in W. Pacific and decreasing tendency in E. Pacific (Mexico West Coast) since 19805 Linked indirectly through increasing sea surface temperature, a critical factor for intense hurricanes5; a confident assessment requires further study3 Likely4
1Based on frequently used family of IPCC emission scenarios
2Based on formal attribution studies and expert judgment
3Based on expert judgment
4Based on model projections and expert judgment
5As measured by the Power Dissipation Index (which combines storm intensity, duration and frequency)

(HT: The Daily Green.)

UPDATE: At Warming Law, Sean Siperstein notes the EPA’s draft Advanced Notice for Proposed Rulemaking — which they are using as a tactic to avoid regulating greenhouse gases — also recognizes the threat climate change poses through extreme weather. He continues:

And seeing as the EPA is now ready– however problematic and in utter defiance of the U.S. Supreme Court its policy response might be, and barring White House revisions– to acknowledge the catastrophic effects of human-driven climate change, that attention should come from voices much stronger than a handful of scientists and bloggers.

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