Often when a noteworthy or devastating extreme event disrupts lives, I am often asked, could this be due in part to climate change?
Weather extremes and climate events have links to climate change
The Intergovernmental Panel on Climate Change (IPCC) just released an authoritative summary of a report that sheds light on this question. For historical trends there is broad agreement that it is 66 to 100 percent likely that worldwide the extreme daily high temperatures and minimum temperatures are warming due in large part to human activities. For historical trends there is medium confidence that rain or snow has intensified whereas there are major measurement issues with historical tornado records resulting in low confidence regarding any such links. For the United States 2011 was a record breaker regarding extreme eventsand the report makes clear that many of these events are due in large part to the growing risks from climate change.
The historic evidence linking certain extreme events to climate change is stronger for some and weaker for others. Credit: image created by B. Ekwurzel; tornado; tropical cyclone, and coast images from NOAA, extreme heat image from IN.gov, intense precipitation images from B. Ekwurzel.
The future of climate extremes
According to the IPCC extreme events report, the historical trends that are evident only grow stronger with climate change toward the end of this century. The links between climate change and extreme weather or climate events is unmistakable. Over most land areas it is 90 to 100 percent likely that heat waves increase in length, frequency and/or intensity in the future. Over high latitudes and tropical regions and particularly during winter in northern mid-latitudes it is 66 to 100 percent likely the proportion of total precipitation from heavy rain or snow falls increases. This holds true even when the total amount that falls each year might remain the same in some places. It is 66 to 100 percent likely to increase maximum wind speed of tropical cyclones in some basins whereas the total worldwide frequency is 66 to 100 percent likely to either decrease or remain the same. Bottom line – if a typhoon or hurricane or cyclone occur, the chances are higher for it to be more powerful than today.
Update March 28, 2012: The full IPCC report is now available.