invasive species

Warmer temperatures and rising sea levels are already forcing migrations of animals and plants, and invasive species may be some of biggest winners as habitat are disrupted by climatic changes.

Whether species survive new conditions brought by a changing climate will depend on their ability to move with those changes, says a study in the current issue of the journal Nature. Plants and animals, on average, will have to be able to migrate at a rate of about a quarter mile (0.42 km) a year in order to stay within the ecological "envelope" to which they are adapted, it says.

But as some species' envelopes shrink, others' are expanding, particularly those of invasive species and often at significant economic and ecological cost.

The Midwest's cold winters play an important role for farmers: They prevent devastating crop pests such as corn earworms and corn borers from becoming established in their fields. Corn earworm pupae, for example, can't survive more than about five days at temperatures below 14 degrees Fahrenheit.

As global warming continues, however, the range of crop pests and their ability to survive the winter increases.

"Increases in temperatures, even summer temperatures, generally benefit these pests. An effectively longer season, or more days exceeding their minimum temperature range, provides them with additional time to feed, mate and reproduce," said Purdue University entomologist Christian Krupke, who studies the impact of climate change on crops pests.

The corn earworm is just one clear threat. It's already established in the South and has resistance to many of the current pesticides, making it tough to manage.

Scientists expect climate change will similarly impact many types of crop production across the U.S. in the next several decades as deadly crop pests and fungi flourish in the warmer and, in some areas, wetter weather.