Antarctica lost much more ice to the sea
than it gained from snowfall according to
a NASA survey done between 1992 and 2002.
Credit: NASA/SVS
The rise of human-produced greenhouse gases has now pushed the Earth’s climate to the brink of “critical tipping points” that could endanger the planet with runaway meltdown, sea level rise and widespread warming.
Want to feel a chill up your spine? The West Antarctic ice sheet may be about to fall apart, and the Arctic ice cap is on the brink of summer shrinkage.
A new analysis of climate models, satellite data, and paleoclimate records looked at these important ice habitats — essential to regulating the Earth’s climate — and concluded that continued warming had pushed them to a point where they could simply disintegrate.
“If global emissions of carbon dioxide continue to rise at the rate of the past decade, this research shows that there will be disastrous effects, including increasingly rapid sea level rise, increased frequency of droughts and floods, and increased stress on wildlife and plants due to rapidly shifting climate zones,” says lead author James Hansen, NASA Goddard Institute for Space Studies in New York.
Time is running out for people to reduce emissions of carbon dioxide and methane.
Scientists from NASA and Columbia University Earth Institute published the research in the current issue of Atmospheric Chemistry and Physics.
Credit: NASA
What is a tipping point? A release from NASA’s Goddard Space Center explains:
Tipping points can occur during climate change when the climate reaches a state such that strong amplifying feedbacks are activated by only moderate additional warming.
This study finds that global warming of 0.6 °C in the past 30 years has been driven mainly by increasing greenhouse gases, and only moderate additional climate forcing is likely to set in motion disintegration of the West Antarctic ice sheet and Arctic sea ice.
Amplifying feedbacks include increased absorption of sunlight as melting exposes darker surfaces and speedup of iceberg discharge as the warming ocean melts ice shelves that otherwise inhibit ice flow.
To figure out how close the Earth was getting to a “tipping point,” Hansen and the other scientists analyzed data on earlier warm periods, zipped through supercomputer climate modesla and then examined new satellite data.
Credit: NCDC-NOAA
They also took into account the steps people could take to avoid massive climate catastrophes — what was outlined by researchers also investigate what would be needed to avert large climate change, thus helping define practical implications of the United Nations Framework Convention on Climate Change.
This 1992 treaty (signed by the United States and other countries) set goals to stabilize atmospheric greenhouse gases “at a level that prevents dangerous human-made interference with the climate system.”
Bottom line?
Hansen and the other scientists say we’re about two degrees from the cliff.
“Based on climate model studies and the history of the Earth the authors conclude that additional global warming of about 1 °C (1.8 °F) or more, above global temperature in 2000, is likely to be dangerous,” they said.
The rise of carbon dioxide has almost maxed out safe levels as well. Current levels of about 383 parts per million — the highest levels seen on Earth in 650,000 years — has leapt about 36 percent above pre-industrial levels. With CO2 concentrations rising about 2 ppm per year, people have about 35 years before the globe hits the “tipping point” of runaway climate change.
“The temperature limit implies that CO2 exceeding 450 ppm is almost surely dangerous, and the ceiling may be even lower,” said study co-author Makiko Sato of Columbia’s Earth Institute.
“We probably need a full court press on both CO2 emission rates and non-CO2 forcings, to avoid tipping points and save Arctic sea ice and the West Antarctic ice sheet,” Hansen added.