Are We Moving into Another Era of 'Abrupt' Climate Change?

vostok ice core

Image courtesy of NOAA

Will the next large-scale manifestation of global warming prove to be just another blip in time or, as Mike Tidwell put it in a recent Orion piece, a violent "snap" -- signaling a fundamental shift in our planet's climate? The idea, also advanced by noted environmental writer Fred Pearce in his latest book, has everything to do with what scientists call "abrupt" climate change.

The U.S. Climate Change Science Program, which is currently seeking public comments for revision of its synthesis and assessment report, defines abrupt climate change as: "A large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems."The notion of abrupt climate change has been in the news again of late, with scientists and writers connecting the dots to point out that a crucial tipping point, or "snap," may not be far off in the making. As Tidwell notes in his piece, decrying talk of climate "snaps" and tipping points as alarmist rhetoric is no longer a valid proposition -- especially in light of the past year's events:

A climate snap? Really? It sounds so much like standard fear-mongering and ecohyperbole. But here’s proof: One of the most prestigious scientific bodies in the world, the group that just shared the Nobel Peace Prize with Al Gore for its climate work, predicted fourteen months ago that unchecked global warming could erase all of the Arctic Ocean’s summertime ice as early as 2070. Then, just two months later, in April 2007, a separate scientific panel released data indicating that the 2070 mark was way off, suggesting that ice-free conditions could come to the Arctic as early as the summer of 2030. And as if this acceleration weren’t enough, yet another prediction emerged in December 2007. Following the year’s appalling melt season, in which vast stretches of Arctic ice the size of Florida vanished almost weekly at times, a credible new estimate from the U.S. Naval Postgraduate School in Monterey, California, indicated there could be zero—zero—summer ice in the Arctic as early as 2013.

And here's what the Climate Science Program's report had to say on the issue:

This report considers progress in understanding four types of abrupt change in the paleoclimatic record that stand out as being so rapid and large in their impact that if they were to recur, they pose clear risks to society in terms of our ability to adapt: (1) rapid change in glaciers, ice sheets and hence sea level; (2) widespread and sustained changes to the hydrologic cycle; (3) abrupt change in the northward flow of warm, salty water in the upper layers of the Atlantic Ocean associated with the Atlantic meridional overturning circulation (AMOC); and (4) rapid release to the atmosphere of methane trapped in permafrost and on continental margins.

So what does this report tell us about abrupt climate change? For one thing, though the warning signs are starting to appear, the authors, Peter Clark from Oregon State University and Andrew Weaver from the University of Victoria, remain conservative in their projections -- particularly with respect to predictions of future abrupt events.

The report provides a fascinating insight into the current state of climate science and makes some fairly pessimistic predictions about potential long-term trends in weather patterns and climactic phenomena. The slowing down of the ocean conveyor belt (by about 25-30% by century's end) and rapid rise in permafrost methane emissions pose some significant threats with possible large-scale ramifications for the global climate. The report's executive summary, which makes for an interesting (if disturbing, at times) read, can be seen here.

While it's still too early to say what climate "snaps" the future holds -- and, for that matter, if and when those currently projected will take place -- we certainly can't just let the existing warning signs (Arctic melting, surging methane emissions, etc) pass us by without action. Whether that means geo-engineering, as Tidwell advocates, or pushing for drastic emissions cuts along the lines of Bill McKibben's effort, there is much room for improvement.

NOAA, which has a great summary of the science behind abrupt climate change, says that abrupt climate change is a "reality" and that it will happen again. How and when it will happen (and going by the data, the trends don't seem favorable) remains open to question, however.

Via ::Orion Magazine: Snap into Action for the Climate (magazine)

See also: ::Fossilized Gnat Heads Point to Past Climate Change Incidents, ::The Intergovernmental Panel on Climate Change Report

Are We Moving into Another Era of 'Abrupt' Climate Change?
Will the next large-scale manifestation of global warming prove to be just another blip in time or, as Mike Tidwell put it in a recent Orion piece, a violent "snap" -- signaling a fundamental shift in our planet's climate? The