Ecosystems shift as climate changes

Posted by Kate Taylor

By 2100, nearly 40 percent of land-based ecosystems - forest, grassland or tundra, for example - will have moved from one type to another.

According to a modeling study from NASA's Jet Propulsion Laboratory and the California Institute of Technology, global climate change will modify plant communities covering almost half of Earth's land surface.

The projections indicate that many plant and animal species face increasing competition for survival. Most land that's not covered by ice or desert is projected to undergo at least a 30 percent change in plant cover - meaning humans and animals will need to adapt and often relocate.

"For more than 25 years, scientists have warned of the dangers of human-induced climate change," says Caltech scientist Jon Bergengren.
"While warnings of melting glaciers, rising sea levels and other environmental changes are illustrative and important, ultimately, it's the ecological consequences that matter most."

The scientists used a model that predicts the type of plant community that is uniquely adapted to any climate on Earth. This was used to simulate the future state of Earth's natural vegetation in harmony with climate projections from 10 different global climate simulations.

The simulations are based on the intermediate greenhouse gas scenario in the United Nations' Intergovernmental Panel on Climate Change Fourth Assessment Report, which assumes greenhouse gas levels will double by 2100 and then level off. This predicts a warmer and wetter Earth, with global temperature increases of 3.6 to 7.2 degrees Fahrenheit.

The researchers found a shift of biomes toward the poles - most dramatically in temperate grasslands and boreal forests - and toward higher elevations.

Hotspots projected to undergo the greatest degree of species turnover include regions in the Himalayas and the Tibetan Plateau, eastern equatorial Africa, Madagascar, the Mediterranean region, southern South America, and North America's Great Lakes and Great Plains areas.

"In this study, we have developed and applied two new ecological sensitivity metrics - analogs of climate sensitivity - to investigate the potential degree of plant community changes over the next three centuries," says Bergengren.

"The surprising degree of ecological sensitivity of Earth's ecosystems predicted by our research highlights the global imperative to accelerate progress toward preserving biodiversity by stabilizing Earth's climate."