82 Finance & economics The EconomistSeptember 21st 2019
A
fter destructivestorms like Hurricane Dorian, those affect-
ed have decisions to make. Should they invest in cellar pumps
and better drainage? Should they rebuild with more robust design
and materials? Should they move? These judgments are informed
by a harsh reality: the weather will get worse. Seas will be higher,
rain more diluvial and storms fiercer. People with means will nat-
urally adjust—as they should. Adaptation is essential to reduce the
human and economic costs of climate change. But spending on ad-
aptation may further complicate already-confounding politics.
Efforts to slow global warming must overcome devilish politi-
cal obstacles. The benefits to reduced warming accrue over de-
cades and centuries, whereas the cost of cutting emissions must
be paid upfront by taxpayers who cannot expect to see much re-
turn in their lifetimes. And mitigation (as efforts to curb emissions
are called) is subject to a vicious collective-action problem. Cli-
mate harms are determined much more by what everyone else
does than by what you do. Each actor has an incentive to free-ride
on the sacrifices of others. Cutting emissions requires every large
country saddling voters with expense and inconvenience that will
mostly help people elsewhere, or not yet born.
Adaptation, by contrast, can pay off even when a person acts
alone, out of pure self-interest. Homeowners who invest in air-
conditioning or flood defences do so in the expectation of captur-
ing most of the returns in the form of reduced harm to themselves,
or perhaps higher property values. There are no political-economy
problems to untangle (though without investment in green ener-
gy, air-conditioning adds to the general problem while mitigating
it for individuals). Government actions are only slightly more
complicated. It requires political consensus to spend public mon-
ey on reinforcing infrastructure or building seawalls. But the
benefits will mostly be felt in the place where the funds are raised.
And at most a few governments and agencies will be required to
co-operate, rather than tens or hundreds.
All this means that adaptation is likely to play a large role in hu-
manity’s response to climate change. Indeed, research suggests
that the price of agricultural land already incorporates the expect-edimpactofclimate change. Consumers already react to extreme
weather events. Purchases of air-conditioning systems rise after
heatwaves, for example. Some adaptation plans are explicitly la-
belled as such—New York City’s proposal to construct a “Big U” of
raised flood-control berms around the southern end of Manhat-
tan, for example. Others are not, such as individual decisions to
take a job in a place less prone to extreme weather.
As demand rises for ways to ease the pain of climate change,
supply will respond. A growing market for goods prompts produc-
ers to innovate—and work by Matthew Kahn of Johns Hopkins
University and Daxuan Zhao of Renmin University suggests that
the same logic applies to adaptation. Firms researching zero-emis-
sion energy and carbon sequestration hope to create a market (or
are betting that governments will eventually do the job for them by
getting serious about emissions). By contrast the market for better
means of coping with climate change is already growing daily.
That is in many ways a good thing. Predictions of the costs of
climate change are often far higher when analysts rule out the pos-
sibility of adaptive behaviour. A study published last year consid-
ering the global costs of coastal flooding, for example, estimated
that floods will reduce real global gdp in 2200 by 4.5%—unless the
effects of adaptive investments and migration are considered, in
which case the loss works out as just 0.11%. A new report by the
Global Commission on Adaptation, a group convened by 20 ad-
vanced and emerging economies, identifies $1.8trn in potential
adaptation investments which, if realised between 2020 and 2030,
would yield estimated net benefits of $7.1trn.The ark of history
But the march to adaptation is not an unalloyed good. Just as better
safety features in cars may make for less careful drivers, invest-
ments in adaptation that blunt the effects of climate change could
reduce the appetite for spending on mitigation. Serious decarbo-
nisation will impose significant cost and inconvenience on nearly
everyone. People will be persuaded that it is in their interests only
if there are tangible harms in the not-too-distant future that might
reasonably be averted. Investments in adaptation that reduce the
likelihood or severity of those looming harms undercut the case
for accepting the hardship of decarbonisation. The longer govern-
ments fail to act to curb warming, the more people and firms will
spend to safeguard themselves, and the less troubled they may be
by governments’ failures to decarbonise.
But even if some people can adapt to a warmer world, it is still a
big problem. Unmitigated global warming could result in cata-
strophic scenarios that outstrip any capacity to adapt. Moreover,
the ability to adapt varies dramatically from place to place. Rich
people in North America and mainland Europe, both of which
have relatively temperate climates, have money to spend on adap-
tation and can move from the worst-hit spots with relative ease.
Poor people have little spare cash, mostly live in hotter places and
face far more obstacles when they try to migrate. Indeed, some re-
search suggests they may even migrate less when temperatures
rise, because hotter, drier conditions harm agricultural yields,
thus depriving them of the capital they would need to move.
Part of the attraction of mitigation as a primary response is that
the steps rich countries take to help themselves also help poorer
ones, which are both less responsible for global warming and more
vulnerable to its effects. Residents of advanced economies must
recognise that spending to shield themselves increases, rather
than decreases, their obligations to others. 7Free exchange Learning to live with it
People will adapt to climate change. That is no reason to give up on stopping it