Summit County Citizens Voice

Climate change could convert nearly 40 percent of the Earth’s land-based ecosystems

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By Summit Voice

SUMMIT COUNTY —Global warming and climate change has the potential to change plant communities across nearly half the Earth’s land surface and drive the conversion of nearly 40 percent of land-based ecosystems from one major ecological community type, changing forest to grasslands and tundra to forest, for example.

Most of Earth’s land that is not covered by ice or desert is projected to undergo at least a 30 percent change in plant cover – changes that will require humans and animals to adapt and often relocate.

Ecologically sensitive hotspots will see the greatest degree of species turnover, including 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.

The largest areas of ecological sensitivity and biome changes predicted for this century are, not surprisingly, found in areas with the most dramatic climate change: in the Northern Hemisphere high latitudes, particularly along the northern and southern boundaries of boreal forests.

Those are the rather bleak projections of a new climate modeling study that tries to project how Earth’s plant life is likely to react over the next three centuries in response to rising levels of human-produced greenhouse gases. The study included researchers from  NASA’s Jet Propulsion Laboratory and the California Institute of Technology in Pasadena, Calif. Results were published in the journal Climatic Change.

“For more than 25 years, scientists have warned of the dangers of human-induced climate change,” said Jon Bergengren, a scientist who led the study while a postdoctoral scholar at Caltech. “Our study introduces a new view of climate change, exploring the ecological implications of a few degrees of global warming. 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 model projections paint a portrait of increasing ecological change and stress in Earth’s biosphere, with many plant and animal species facing increasing competition for survival, as well as significant species turnover, as some species invade areas occupied by other species.

In addition to altering plant communities, the study predicts climate change will disrupt the ecological balance between interdependent and often endangered plant and animal species, reduce biodiversity and adversely affect Earth’s water, energy, carbon and other element cycles.

When faced with climate change, plant species often must “migrate” over multiple generations, as they can only survive, compete and reproduce within the range of climates to which they are evolutionarily and physiologically adapted.

Earth’s plants and animals have evolved to migrate in response to seasonal environmental changes and to even larger transitions, such as the end of the last ice age. But they often are not equipped to keep up with the rapidity of modern climate change. Human activities,including agriculture and urbanization, have fragmented habitats, frequently block plants and animals from successfully migrating.

The models simulated the future state of Earth’s natural vegetation in harmony with climate projections from 10 different global climate simulations based on the intermediate greenhouse gas scenario in the United Nations’ Intergovernmental Panel on Climate Change Fourth Assessment Report.

With greenhouse gas levels doubling by 2100 and then leveling off, The U.N. report predicts a warmer and wetter Earth, with global temperature increases of 3.6 to 7.2 degrees Fahrenheit (2 to 4 degrees Celsius) by 2100, about the same warming that occurred following the Last Glacial Maximum almost 20,000 years ago, except about 100 times faster. Some regions become wetter because of enhanced evaporation, while others become drier due to changes in atmospheric circulation.

The researchers found a shift of biomes, or major ecological community types, toward Earth’s poles — most dramatically in temperate grasslands and boreal forests — and toward higher elevations.

“Our study developed a simple, consistent and quantitative way to characterize the impacts of climate change on ecosystems, while assessing and comparing the implications of climate model projections,” said JPL co-author Duane Waliser. “This new tool enables scientists to explore and understand interrelationships between Earth’s ecosystems and climate and to identify regions projected to have the greatest degree of ecological sensitivity.”

“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,” said 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.”

Filed under: biodiversity, climate and weather, Environment, global warming, Summit County news Tagged: | climate change, Environment, global warming, IPCC, NASA, Summit County News