A trio of reports released this month finds that scientists remain concerned with melting permafrost and the increasingly consequential impact of global warming.
With amounts of greenhouse gases trapped below thawing permafrost will likely seep into the air over the next several decades, accelerating and amplifying global warming, the New York times reports that scientists are now flocking to the Arctic in an effort to understand what, exactly, the impact of increased rates of melting permafrost will have.
Arctic warming of 13.5 degrees Fahrenheit this century may unlock the equivalent of 380 billion tons of carbon dioxide as soils thaw, allowing carbon to escape as CO2 and methane, University of Florida and University of Alaska write in the latest issue of Nature.
Meanwhile, scientists now estimate the frozen north contains twice as much carbon as the entire atmosphere. With temperatures rising in the region, researchers are trying to determine how much of the trapped carbon is being released and what the impact will be on global warming. The research team’s observations showed that the permafrost is perforated and leaking large amounts of methane into the atmosphere. More than 80 percent of the deep water and more than half of surface water had methane levels around eight times higher than found in normal seawater, according to the study published in the journal Science. The researchers warned that the release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.
Scientists predict that upwards of 45 billion metric tons of carbon from methane and carbon dioxide will seep into the atmosphere when permafrost thaws during coming summers over the course of thirty years. The prediction is equal to the amount of heat-trapping gas the world spews during five years of burning coal, gas and other fossil fuels, adding to concerns that attempts to curtail carbon-spewing motors and power plants may not be enough halt the progression of global warming.
By 2100 the amount of carbon released by permafrost loss could be “1.7-5.2 times larger than those reported,” depending on how swiftly Earth’s surface warms, they said.
The release of various heat-trapping gases under the frozen Arctic ground may be a bigger factor in global warming than the cutting down of forests, resulting in a viscous cycle that could see the effects of global warming exacerbated in the coming decades.
The frozen soils of the northern hemisphere are thought to hold around 1,700 billion tonnes of organic carbon – around four times more than all the carbon ever emitted by modern human activity and twice as much as is currently in the atmosphere.
The study comes as a pair of NASA officials have released a two 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.