NASA officials have released a pair of new studies showing that global warming could lead to a major transformation for Earth’s plants and animals over the next century.
New research into the Earth’s paleoclimate history by NASA’s Goddard Institute for Space Studies director James Hansen suggests the potential for rapid climate changes this century, including multiple meters of sea level rise, if global warming is not abated.
“The paleoclimate record reveals a more sensitive climate than thought, even as of a few years ago. Limiting human-caused warming to two degrees [Celsius] is not sufficient,” Mr. Hansen said. “It would be a prescription for disaster.”
The NASA official warn that an increase in temperature would likely lead to widespread destruction of ecological habitats, mainly by the introduction of invasive species drawn to warmer or cooler climates.
By looking at how the Earth’s climate responded to past natural changes, Mr. Hansen noted that the recent study sought insight into a fundamental question raised by ongoing human-caused climate change. The NASA climatologist said the study focused on determining the level at which climate change became dangerous, noting that a number of international leaders have suggested a goal of limiting warming to two degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial times in order to avert catastrophic change.
However, Mr Hansen said at a press briefing at a meeting of the American Geophysical Union in San Francisco that a warming of two degrees Celsius (3.6 degrees Fahrenheit) would lead to drastic changes, such as significant ice sheet loss in Greenland and Antarctica.
In recent research, Mr. Hansen and co-author Makiko Sato, also of Goddard Institute for Space Studies, compared the climate of today, the “Holocene”, with previous similar “interglacial” epochs — periods when polar ice caps existed but the world was not dominated by glaciers.
In studying cores drilled from both ice sheets and deep ocean sediments, Mr. Hansen found that global mean temperatures during the “Eemian” period, which began about 130,000 years ago and lasted about 15,000 years, were less than 1 degree Celsius (1.8 degrees Fahrenheit) warmer than today. If temperatures were to rise two degrees Celsius (3.6 degrees Fahrenheit) over pre-industrial times, global mean temperature would far exceed that of the Eemian, when sea level was four to six meters higher than today, said Mr. Hansen.
Meanwhile, researchers from NASA’s Jet Propulsion Laboratory and the California Institute of Technology in Pasadena, California, 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.
“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.”
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.
The study comes as scientists have warned that increases in temperature could cause large areas of permafrost to melt, resulting in the released of large amounts of methane gas.