An Emerald Tucanette eats papaya near a visitor center at Bosque de Paz, an eco-tourism resort in Costa Rica

The impact of global warming has become obvious in high-latitude regions such as Alaska, Siberia and the Arctic, where melting ice and softening tundra are causing profound changes. But, contrary to popular belief, the most serious impact will likely be in the tropics, says a group of researchers led by ecologist Josh Tewksbury, assitant professor in the Department of Biology.

Modeling indicates that temperatures will warm by six degrees or more in temperate climates by 2100, double or triple the increase expected in equatorial regions, Josh Tewksbury said. But organisms in the tropics normally do not experience much temperature variation because there is very little seasonality, so even small temperature shifts can have a much larger impact.

The group examined several closely related populations of plants, animals and insects to determine how they tolerated changing temperatures. Then they developed models based on the average temperatures between a region’s warmest and coldest months and programmed the region’s expected temperature changes due to climate warming.

“What we find is that organisms in the tropics have very low tolerance,” Tewksbury said. “The evidence indicates the breadth of temperature to which they’re adapted affects the range of temperatures in which they can live.”
This also implies that warming could forever alter life on Earth because the vast majority of species live in the tropics and many will be driven to extinction because of their inability to adapt.

Tewksbury presented his findings at the Ecological Society of America’s annual meeting in Montreal. Collaborators include Curtis Deutsch, a oceanography research associate; Raymond Huey and Carl Bergstrom, both UW biology professors; Cameron Ghalambor, from Colorado State University; and UW biology doctoral students Kimberly Sheldon, David Haak and Paul Martin.

“Evolution only happens if you don’t go extinct. From an evolutionary standpoint, a model of the climate change impact reflects a race between adaptation and extinction.” - Josh Tewksbury, Assistant Biology Professor

Read the full length version of this UWeek article published here.