Invasive Species in Georgia Not Driven by Warming – Watts Up With That?

From ClimateREALISM

By H. Sterling Burnett

The August Chronicle published an article claiming climate change was causing the spread of invasive plant species. This is false. Data from Georgia does not show climactic changes, whether in temperatures or extreme weather, that would make the state more suitable than it already is for invasive plant species, which have, in fact, long been established there.

The author of the August Chronicle story, “Symptoms of climate change in Southeast fuel increase in invasive plant species,” Erica Van Buren writes:

Symptoms of climate change include extreme heat, drought, and extreme weather, all of which can significantly impact plant species.

“It’s kind of hard to pin it down, because climate change is so complicated,” said Eamonn Leonard, senior wildlife biologist for the Georgia Department of Natural Resources, Wildlife Resources Division. “It changes so many different things. From storm frequency to moisture to drought in general. I think invasives are able to sort of capitalize on changes that our native plant species aren’t able to.”

There are multiple problems with this claim. First, contra Leonard, the “expert,” Van Buren quotes in her story there is no reason whatsoever to believe that invasive species which thrive in present conditions in Georgia will be any more adaptable or able to thrive there if those conditions change than native species will be. Invasive species, that is species from other regions or foreign countries that are introduced either intentionally or accidentally and cause unintended harms, thrive because the climate conditions where they are introduced are suitable for their flourishing. When they outcompete native species, it is not due to climate conditions but rather because the insects, plants, species, management practices, and conditions that keep them in check in their native lands don’t exist here. More or less rainfall, fewer or increased storms, won’t disadvantage native species in competition with invasive species.

More importantly, weather and temperature trends in Georgia show no discernable “symptoms of climate change.” Temperatures have not increased significantly, or become more extreme, and neither droughts nor other types or extreme weather have increased in Georgia. There is no way invasive species can be benefitted in competition with native species from a changing climate if it is not, in fact, changing that much

Concerning temperatures, the Georgia state summary from the U.S. National Centers for Environmental Information (NCEI) shows that the temperatures in Georgia have risen just 0.8℉ since 1900, half the average rise measured across the nation. As a result, present temperatures and the temperature trend do not advantage invasive species in competition with native species. The has been no increase in extreme temperatures in Georgia, according to the NCEI, which reports that “The highest number of extremely hot days occurred during the late 1920s, early 1930s, and early 1950s; however, since 1955, the number of these days has generally been near or below average.” (See the graph, below)

Nor, the NCEI reports, have precipitation trends changed substantially during the recent century and a half of modern warming.

The U.S. Geological Survey has recorded extended, sometimes severe droughts across different regions of Georgia since it began recording and reporting such data in the 1890s. There is no evidence that droughts have increased in number or severity in Georgia in recent decades, with data indicating droughts in the early part of the 20^th century when temperatures were modestly cooler, were as severe, widespread, and frequent then as they are now. Streamflow has fallen in some areas in recent years beyond what might have been expected previously due to similar drought conditions but that is because the demands for water in Georgia have increased dramatically to supply intensive agriculture and to supply water for various uses to fast growing urban populations.

Hurricanes are a problem in for Georgia but not as big a problem as in other Atlantic and Gulf coast states, due, in part to a smaller coastline.

“The last system to make landfall in the state at hurricane intensity was Hurricane David in 1979,” Wikipedia reports. “Further, only three major hurricanes have struck Georgia, the most recent of which being in 1898.”

There has been no observable increase in the number or severity of hurricanes and tropical storms striking or passing through Georgia in recent decades during the period of slight warming.

So, since neither temperature, precipitation, drought, nor hurricane trends have changed much in Georgia, contrary to the Augusta Chronicle’s slant a “changing climate” can’t be behind any perceived or observed increase in the spread of invasive species. To the extent that invasive species are thriving or spreading, it is due entirely to same conditions or factors that made their growth here possible in the first place, human introduction, plant and pest management, and landscape modifications that have favored invasives compared to native species. Climate change is not an identifiable factor. No amount of spin or fearmongering from the Augusta Chronicle can change this one basic fact.

H. Sterling Burnett

H. Sterling Burnett, Ph.D., is the Director of the Arthur B. Robinson Center on Climate and Environmental Policy and the managing editor of Environment & Climate News. In addition to directing The Heartland Institute’s Arthur B. Robinson Center on Climate and Environmental Policy, Burnett puts Environment & Climate News together, is the editor of Heartland’s Climate Change Weekly email, and the host of the Environment & Climate News Podcast.