In a recent Policy Forum in Science, Jason Blackstock
and Jane Long summarize the rationale for giving scientific research into
geoengineering a serious look:
Despite mounting evidence that severe
climate change could emerge rapidly, the global reduction of carbon emissions
remains alarmingly elusive. As a result, concerned scientists are now asking
whether geoengineering—the intentional, large-scale alteration of the climate
system—might be able to limit climate change.
They continue:
SRM [solar radiation management] could
substantially influence the climate in months, but with much greater
uncertainty about the net effects. SRM schemes such as stratospheric aerosols
and cloud brightening aim to cool the planet by reflecting a fraction of the
incoming sunlight away from Earth.
Like Blackstock and Long,
and many others, I worry a great deal about the uncertainty and risks
associated with geoengineering. But here I want to focus on something else: the
faulty framing of the problem from the outset.
Those now advocating
exploration of large-scale manipulation of the Earth’s climate seem most
focused on rapid, unexpected climate shifts, which might need to be
counteracted by a cooling impulse (See papers by Paul Crutzen and Michael
McCracken published in the August 2006 issue of Climatic Change). But why suppose
that such shifts will take the form of simple warming?
What would a climate
emergency look like? Consider the following scenario. A rapid climatic shift
during January through March gives rise to storms that dump tremendous rainfall
over the US Midwest from late spring through mid-summer. Farmers are unable to
plant wheat and corn because fields are flooded. Prices on global commodity
markets skyrocket. Countries worldwide begin hoarding grain. The world’s poor
begin to see immediate shortages as a result of rising prices. The threat of malnutrition
and hunger emerge as a serious threat in the months to come. Geoengineering
advocates begin to lobby the U.S. president to put aerosols into the
stratosphere to cool the planet.
Wait. What good will that
do? Prevailing models, based on events like the eruption of Mt. Pinatubo,
suggest that a release of aerosols could cool the Earth over a period of a few
months. In this scenario, however, even if it works perfectly, with no
unintended side effects, such a strategy would be useless. Even if the cooling impulse
arrives by mid-summer, fields may still not be dry enough to plant. Major
agricultural operations run on reasonably tight calendars. Fixing the climate a
few months from now is likely to be too late if the climatic shift happens at a
critical time of the year. A searing drought a month before harvest could
destroy an entire year’s crop. In a month, rising floodwaters could overtop
dams and destroy communities all along major rivers. A single hurricane,
strengthened by high surface ocean temperatures and rising sea level, could
wipe out a major city.
A few months may not seem
like much time to a climate model. Sure, in a few months, we can reduce the
Earth’s temperature, such a model might say. But in a few months, it may simply
be too late to avoid major climatic disasters.
Indeed, what leads people
to think that climatic shifts will be reversible at all? What if they’re more
like system state shifts, from one meta-stable state to another? Is there
really any reason to believe that such a rapid shift would necessarily reverse
itself if we pump aerosols into the air? Suppose, for example, a rapid shift to
higher Arctic temperatures occurs. Here’s a case where rapid cooling might
actually counteract the general problem over time. But what if, in the
meantime, polar sea ice melts much more rapidly than expected or melting tundra
outgases enormous quantities of methane. In neither case may subsequent cooling
simply return the system to the state it was in beforehand.
For years, climate
scientists have complained that public imaginaries of global warming – in which
the weather just got a little warmer everywhere – were dangerously misleading.
Real climatic change would involve unpredictable shifts in temperature, rainfall,
wind, and storm patterns. Indeed, the real impacts would likely come not only
from climate changes but also via unpredictable weather variations that cannot
be modeled accurately in climate models. Now it’s the prospective climate
engineers who seem to be following back on the old, over-simplistic logic of
global warming.
Policymakers – indeed, the
community of scientists looking into climate engineering – should demand
realistic assessments of both what real climate emergencies might look like,
from a human systems perspective, and whether SRM might even remotely plausibly
“fix” such emergencies. And they should demand such assessments before they
commit to uncertain field experiments of technologies that even they admit are
unpredictable, risky, and potentially highly dangerous.
