By 2100, global climate change will modify plant communities covering
almost half of Earth's land surface and will drive the conversion of
nearly 40 percent of land-based ecosystems from one major ecological
community type -- such as forest, grassland or tundra -- toward another,
according to a new NASA and university computer modeling study.
Researchers from NASA's Jet Propulsion Laboratory and the California
Institute of Technology in Pasadena, Calif., investigated how Earth's
plant life is likely to react over the next three centuries as Earth's
climate changes in response to rising levels of human-produced
greenhouse gases. Study results are published in the journal Climatic Change.
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. 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.
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.
"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."
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. While 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, they often
are not equipped to keep up with the rapidity of modern climate changes
that are currently taking place. Human activities, such as agriculture
and urbanization, are increasingly destroying Earth's natural habitats,
and frequently block plants and animals from successfully migrating.
No comments:
Post a Comment