Saturday, September 15, 2012

welcome to the tipping point

9 Sep 2012 IARC-JAXA graph screenshot

And welcome back. Fall term has started, after a summer that was personally one of the happiest in my life, but that signifies to all of us an extremely troubling phase transition.  Old records are toppling left and right.  Everything is now happening much faster than expected.

On August 28, George Monbiot summed up this summer's events:
What we are seeing, here and now, is the transformation of the atmospheric physics of this planet.  Three weeks before the likely minimum, the melting of Arctic sea ice has already broken the record set in 2007.  The daily rate of loss is now 50% higher than it was that year. ... In 2007, the Intergovernmental Panel on Climate Change noted that 'in some projections, Arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century.'  These were the most extreme forecasts in the panel's range.  Some scientists now forecast that the disappearance of Arctic sea-ice in late summer could occur in this decade or the next.
On August 31, John Atcheson counted the weather records:
Arctic sea ice hits lowest extent ever measured (and it's still melting) ... Hottest winter, spring, summer, year, decade ever measured ... Most extensive drought in fifty years, and getting worse ... Worst floods in recorded history ... Hottest seas in eons ... Most acidic oceans ever measured ... Most greenhouse gases released in a single year ... Highest sea levels since the Pleistocene ... Most permafrost melted (with record releases of methane) ever measured ... Massive crop failures and record high food prices ... Most severe weather events ever recorded.
But climate change coincides with the American Disenlightenment:
Meanwhile, in Tampa, the fossil fuel funded Republican Party is doubling down on climate denial, pushing greater use of oil, coal and gas, and trying to gut programs designed to save energy and use more renewables.  In short, they're working diligently to hasten our demise.
So what is the outlook?
Imagine a world where vast regions of an acidic ocean are dominated by jellyfish.  A world where tuna, salmon, halibut, swordfish, crabs, shellfish, shrimp and the rest of the seafood we take for granted--the primary source of protein for more than a billion people--is virtually gone.  ... The land?  An unending series of drought, flood, fire and famine.  Throw in some disease, a little social chaos--with as many as a billion climate change refuges desperately swarming the planet by 2050. ... Ports will have to be abandoned.  The richer countries might get away with extraordinarily expensive dikes, levies, and pumps for a while, but eventually even they'll have to be abandoned. ... International trade will become difficult and unreliable. 
Bill McKibben wrote several updates this summer as well.  Widely read, deservedly so, has been his Rolling Stone essay Global Warming's Terrifying New Math in July.  His August RS essay The Arctic Ice Crisis zeros in on the tipping point in Greenland:
Fresh snow bounces back 84 percent of the light that hits it; warm, rounded crystals can reflect as little as 70 percent.  Slushy snow saturated by water--which gives it a gray cast, or even a bluish tint--reflects as little as 60 percent.  Add dust or soot, and the albedo drops below 40 percent. ... Satellite data has shown a steady darkening of Greenland's albedo, from a July average of 74 percent when the century began to about 68 percent last year.  And then came this summer: Without warning, the line on the albedo chart dropped deep into uncharted territory.  At certain altitudes, the ice sheet in Greenland was suddenly four percent less reflective--in a single season ... The heat accumulating in the ice sheet year after warm, sunny year was suddenly making it far easier to melt the surface.  What's more, in a vicious feedback loop, soot from the wildfires raging in Colorado and Siberia--themselves spurred by climate change--may be helping to darken the surface of the ice.  [Byrd Polar Research Center scientist Jason Box] had conservatively predicted that it might take up to a decade before the surface of Greenland's ice sheet melted all at once.  That it actually happened in just a few weeks only underscores how consistently cautious ice scientists have been in forecasting the threat posed by global warming.  Now, however, that caution is being replaced by well-founded alarm.
McKibben's A Summer of Extremes Signifies the New Normal, at Environment 360, points to James Hansen's new findings (in PNAS):
There's always been extreme heat, [Hansen] showed--but the one-degree increase in global temperature we've seen so far has been enough to shift the bell curve sharply to the left.  In the old summer, the one most of us grew up in, 0.1 to 0.2 percent of the surface area of the planet was dealing with 'extreme heat anomalies' at any given moment.  Now it was approaching 10 percent.
I used to sign off posts with a link to One Hundred Months.  After publication of the AR-4 (2007), a consensus emerged that action within a decade is vital, because there is a good chance that unmitigated climate change would be irreversible by 2017 or thereabouts.  The Guardian started running the One Hundred Months blog, and the climate clock was set.  In 100 Months: Technical Note, Victoria Johnson and Andrew Simms write:
We calculate that 100 months from 1 August 2008, atmospheric concentrations of greenhouse gases will begin to exceed a point whereby it is no longer likely we will be able to avert potentially irreversible climate change.  'Likely' in this context refers to the definition of risk used by the IPCC to mean that, at that particular level of GHG concentration, there is only a 66-90 per cent change of global average surface temperatures stabilizing at 2 C above pre-industrial levels.  Once this concentration is exceeded, it becomes more and more likely that we will overshoot a 2 C level of warming.  This is the maximum acceptable level of temperature rise agreed by the European Union and others as necessary to retain reasonable confidence of preventing uncontrollable and ultimately catastrophic warming.  We also believe this calculation to be conservative.
Indeed.  For policy action, crossing this threshold means that from then on out climate policies would be reactive only; the window for proactive policy initiatives will have closed then.  It also means that the policy goals will shift from sustainability and mitigation (unattainable beyond the threshold) to adaptation and resilience, which, of course, are polite words for damage control and managed decline.  Now the clock ticks at fifty-one months

The problem is that Johnson and Simms coordinate the countdown with the likelihood of averting irreversible change.  But what does "averting irreversible change" mean?  Does it mean we can undo the changes that have already occurred?  Does anyone seriously believe we can still reverse the summer sea ice trend? It seems wildly implausible to assume things can still be turned around.  Does it mean we can prevent more changes from occurring?  But that seems improbable too, since positive feedback loops are already at it: the thaw feeds on itself because of the dropping albedo caused by the thaw; and GHG concentrations soar higher because CH4 outgassing has started on the Arctic landmasses from the warming permafrost.  We are not fifty-one months away from the point of no return.  We have already entered the new climate regime.  We cannot go back to the way things used to be.  And while we can presumably still slow things down, we cannot prevent more changes from occurring either.  Welcome to the tipping point.

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