Dr. Jeff Masters' WunderBlog

Western U.S. wildfires expected to increase due to climate change
Expect a large increase in fires over much of the globe late this century due to climate change, says research published this month in the Journal Ecosphere. Using fire models driven by output from sixteen climate models used in the 2007 IPCC report, the researchers, led by Max Moritz of UC Berkeley, found that 38% of the planet should see increases in fire activity over the next 30 years. This figure increases to 62% by the end of the century. However, in many regions where precipitation is expected to increase--particularly in the tropics--there should be decreased fire activity. The scientists predicted that 8% of Earth will see decreases in fire probability over the next 30 years, and 20% will see decreases by the end of the century. The models do not agree on how fire danger will change for a large portion of the planet--54% for the period 2010 - 2039, and 18% for the period 2070 - 2099. Six key factors were found to control fire probabilities in the models. Most important was how much vegetation there was (NPP, Net Primary Productivity). Three other factors, about half as important, were precipitation of driest month, mean temperature of warmest month, and the difference between summer and winter temperature. Two other minor factors were mean temperature of wettest month, and annual precipitation. The authors found that future fire occurrence appears to primarily be a function of available moisture in many areas, and that the expected global increase in temperature of 3.5°C used in the models will not become the single dominant control on global wildfire. In the U.S., the regions most at risk of increased fires are the tundra regions of northern Alaska, and the West, with Arizona and Colorado at particularly high risk.


Figure 4. Predicted fractional change in fire probability for the period 2010 - 2039 (top) and 2070 - 2099 (bottom) for the average of sixteen climate models used for the 2007 IPCC report. For the 2010 - 2039 period, the models agree that 8% of Earth will see decreases in fire probability, 38% will see increases, and the models are too uncertain to tell for the other 54%. For the 2070 - 2099 period, the models agree that 20% of Earth will see decreases in fire probability, 62% will see increases, and the models are too uncertain to tell for the other 18%. Image credit: Climate change and disruptions to global fire activity, Moritz et al., 2012, from the journal Ecosphere.

Rare tornado hits Venice, Italy
A tornado hit Sant'Erasmo island in the lagoon surrounding Venice on Tuesday, ripping the roofs off of at least 12 buildings. No injuries were reported. The Capital Weather Gang has more videos and information on the event. Tornadoes are not unheard of in Venice; a strong one hit the city in 1970, killing 30 people.


Video 1. A waterspout/tornado in the Venice Lagoon on June 12, 2012.

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The NOGAPS and GFS models are predicting formation of a broad area of low pressure in the Western Caribbean early next week, and we will have to watch this area for development. The waters offshore of North Carolina may be another region to watch, over the next few days, along the edge of a cold front that has moved off the U.S. East Coast.

I'll have a new post Thursday or Friday.

Jeff Masters and Angela Fritz