My worst global warming fear: buckeyes in Ann Arbor

Last week, I blogged about how wintertime minimum temperatures in the U.S. have risen so much in recent decades, that the United States Department of Agriculture (USDA) had to update their Plant Hardiness Zone Map for gardeners for the first time since 1990. The Plant Hardiness Zone Map is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. I got to looking at the new zone map for Ann Arbor, Michigan, where I live, and saw how we've shifted one 5-degree Fahrenheit half-zone warmer. Ann Arbor used to be in Zone 5, but is now solidly in the warmer Zone 6. This got me to wondering, what sort of plants in Zone 6, until now rare or unknown in Ann Arbor, might migrate northwards in coming decades into the city? Then, with a sudden chill, I contemplated a truly awful possibility: The Ohio Buckeye Tree.


Figure 1. Comparison of the 1990 and 2012 USDA Plant Hardiness Zone Maps. Image credit: USDA and Arbor Day Foundation.

Buckeyes in Ann Arbor? The Horror!
For those of you unfamiliar the the buckeye tree, it is the emblem of Ohio State University. The Buckeyes of Ohio State have one of the most fierce rivalries in sports with that "school up north", the University of Michigan. As someone who spent twelve years of my life as a student at the University of Michigan, the thought of Buckeye trees in Ann Arbor is not one I care to contemplate. But the USDA Forest Service has published a Climate Change Tree Atlas which predicts that the most favorable habitat for the Ohio Buckeye Tree can be expected to move northwards with a warming climate. While they give their model for the Buckeye Tree a rating of "low reliability", it is nonetheless chilling to contemplate the potential infestation of Ann Arbor with this loathsome invader. I can only sadly predict that to stem the invasion, non-ecologically-minded University of Michigan students will unleash genetically engineered wolverines that eat buckeye seeds.


Figure 2. Potential changes in the mean center of distribution of the Ohio Buckeye tree. The green oval shows the current center of the range of the Buckeye Tree, well to the south of Ann Arbor. In a scenario where humans emit relatively low amounts of heat-trapping gases like carbon dioxide (light blue oval), the most favorable climate for the Buckeye Tree edges into Southern Michigan, and marches into Ann Arbor under the medium and high scenarios for emissions (other ovals.) Image credit: USDA Forest Service Climate Change Tree Atlas.

Libyan snowstorm triggered major Saharan dust storm
On February 6, a rare snow storm hit North Africa, bringing 2 - 3 inches of snow to Tripoli, Libya. It was the first snow in Tripoli since at least 2005, and may be the heaviest snow the Libyan capital has seen since February 6, 1956. The storm responsible for the North African snow also had strong winds that kicked up a tremendous amount of dust over Algeria during the week. This dust became suspended in a flow of air moving to the southwest, and is now over the Atlantic Ocean.


Figure 3. Dust storm on February 7, 2012, off the coast of West Africa, spawned by a storm that brought snow to North Africa on February 6. Note the beautiful vorticies shed by the Cape Verde Islands, showing that the air is flowing northeast to southwest. The red squares mark where fires are burning in West Africa. Image credit: NASA.

Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters