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Warming Linked to Giant Ants: Study

by Marlo Lewis on May 4, 2011

in Blog, Features

A study published today in Proceedings of the Royal Society reports that an extinct species of giant ant (Titanomyrma lubei, from the Greek word “Titan”) lived in Wyoming during the Eocene Epoch, about 50 million years ago. As colorfully described by Physorg.Com, the ant “had a body just over five centimeters long — comparable to a hummingbird — a size only rivaled today by the monstrously large queens of an ant species in tropical Africa.”

So how did this ‘monstrous’ ant come to live in Wyoming, a place not usually associated with tropical conditions? The Eocene included “brief, cyclic warming events of approximately 2-4°C” with Arctic temperatures shooting up by as much as 5-10°C. This combined with early Eocene “land bridges” enabled “thermophilic” (heat loving) ants to “cross between Europe and North America via the Arctic.”

One of the study’s authors, Bruce Archibald of Simon Fraser University in Canada, opined that the intercontinental migration of the titanic prehistoric ant may shed light on species migration in an era of greenhouse warming. Archibald told Physorg.Com:

As the Earth’s climate changes, we are seeing tropical pest species extend their ranges into mid-latitudes and dragonflies appear in the Arctic. Understanding the details of how life forms adapted to global warming in the past will be of increasing importance in the future.

Just out of curiosity, though, why is it that big ants live in hot climates? The study does not address this question, but the authors surely thought about it. According to Physorg.Com, “The researchers also looked at the habitats of the largest modern ants, and found that almost all live in the tropics, indicating that there might be something about being big that requires ants to live in hot temperatures.”

Maybe, just maybe, hot, wet climates — tropics — are more bioproductive, and a more bioproductive food chain is necessary to sustain colonies of large insects. A bioproductive planet is a good thing, right?

Climate doomsters warn that global warming will ravage the biosphere by increasing drought and desertification. Although the science on this is far from settled, there is empirical evidence that the world is greening. As summarized on WorldClimateReport.Com,  a recent satellite study found a significant net increase in terrestrial vegetation since the early 1980s.

Spatial distribution in linear trends in estimated Leaf Area Index (half the total leaf area per ground unit) from July 1981 through December 2006 (Liu, S., R. Liu, and Y. Liu. 2010. Spatial and temporal variation of global LAI during 1981–2006. Journal of Geographical Sciences, 20, 323-332)

In the map above, red areas indicating increased vegetative growth clearly dominate the blue areas indicating diminished growth.

The researchers, Liu et al., attribute the upward trend in the Northern latitudes to global warming:

The growth of the vegetation in these middle and high latitude areas is mainly limited by temperature. Many studies correlating NDVI [Normalized Difference Vegetative Index] with land surface temperature indicate warming might be the most important factor accounting for the LAI [Leaf Area Index] increase in this area. Warming, causes longer active growing season length and higher growth magnitude, therefore leads to increase in LAI in this area.

So do we have to worry about an invasion of giant ants from Africa into Wyoming via Europe and the Arctic? The authors of the Royal Society study don’t say. Could the Orkin Man wipe out a colony of ‘monstrous’ ants in your backyard? If he wants to keep your business, he’ll figure out how to do it!

One thing seems clear. Global warming, like any change of any sort, has benefits and costs, winners and losers. Warming is extending the northward range of some pests. It is also extending growing seasons and increasing leafy biomass in more places than not. Tropical climates sustain giant ants. They are also immensely bioproductive and biodiverse. If they weren’t, people would not care so much about saving the rain forests.

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