In as roundtable discussion at the Bulletin of Atomic Scientists, Ken Caldeira argues for a consideration of the need to geoengineer, despite the risks of such an effort. He cites an especially alarming study, Global and Regional Drivers of Accelerating CO2 Emissions, by Michael Raupach, with a particularly vivid graph.
While we might prefer near-universal cooperation in carbon dioxide
emissions reduction, it’s clearly time to plan what we will do if those
emissions reductions don’t come quick enough or are not deep enough to
prevent a climate crisis.
The graph fits all too well with another roundtable discussion — completely with consequences modeled in the UK — by climate writer Mark Lynas, in a piece for the Guardian called Climate Chaos is Inevitable.
This is the depressing bit: no politically plausible scenario we
could envisage will now keep the world below the danger threshold of
two degrees, the official target of both the EU and UK. This means that
all scenarios see the total disappearance of Arctic sea ice; spreading
deserts and water stress in the sub-tropics; extreme weather and
floods; and melting glaciers in the Andes and Himalayas. Hence the need
to focus far more on adaptation: these are impacts that humanity is
going to have to deal with whatever now happens at the policy level.
the other great lesson is that sticking with current policy is actually
a very risky option, rather than a safe bet. Betting on Kyoto could
mean triggering the collapse of the West Antarctic ice sheet and
crossing thresholds that involve massive methane release from melting
Siberian permafrost. If current policy continues to fail – along the
lines of the "agree and ignore" scenario – then 50% to 80% of all
species on earth could be driven to extinction by the magnitude and
rapidity of warming, and much of the planet’s surface left
uninhabitable to humans. Billions, not millions, of people would be
As much as I dislike the remedies, I respect the need for a diagnosis. Next obvious step is to compare and contrast the costs of geoengineering with the costs of doing nothing. Perhaps that’s already been considered: will look at Nicholas Stern’s analysis.
For now, the point is inescapable…we have to start thinking about the unthinkable. If you take a look at this graph, it’s amply evident that our chances of reducing emissions to a relatively safe level of 450 ppm are rapidly approaching zero.