Econ_Sep_22

The Economist

September 22nd 2018

EOPLE living on opposite sides of the

planet have in recent days felt the disas-

trous consequences of distant rumblings

in the deep ocean. InAmerica, they are still

suffering the devastation left by Hurricane

Florence, which made landfall in North

Carolina on September 14th. Less than 12

hours later super-Typhoon Mangkhut tore

into the Philippines, subsequently to hit

Hong Kong and southern China. Mang-

khut packed a bigger punch: a category 5

storm when it first hit land, to Florence’s

category 1. But the impact of both was

linked to rising levels of greenhouse gases

in the atmosphere, which are changing the

climate andwarming the sea.

For that reason, future storms are also

likely to be more severe than in the past.

Florence and Mangkhut have shown the

progress that has been made in preparing

for them and mitigating the damage—but

also highlighted how vulnerable many

communities remain, especially inAsia.

The link with climate change comes

from the accumulation in the atmosphere

of greenhouse gases produced by the in-

dustrial burning of fossil fuels and by de-

forestation. They create an imbalance in

the energyflowing in and out of the planet,

driving temperatures up. About 90% of

that additional energy ends up stored in

the oceans. Researchers who monitor sea

temperatures down to 2,000 metres have

plotted a steady rise since the 1950s, reach-

ing a record high last year (see chart). So far,

fects in detail, using real events. Earlier this

year, for instance, Mr Trenberth showed

that deep-ocean temperatures just before

Hurricane Harvey, which led to disastrous

flooding inHouston inAugust 2017, were at

a peakglobally and in the Gulf ofMexico.

Data recorded just after the storm re-

vealed a drop in the heat content of the

Gulf that closely matched the amount of

rain unleashed by the hurricane. Mr Tren-

berth and his colleagues concluded that

Harvey “could not have produced somuch

rain without human-induced climate

change.” Kerry Emanuel, of the Massachu-

setts Institute ofTechnology, estimates that

a hurricane like Harvey in 2017 was made

six times more likely by human green-

house-gas emissions, and that by 2100 the

risk will be 18 times higher than it was in

the late 20th century.

Amanwho knows his stormy

Florence received an awestruck presiden-

tial reception. “One of the wettest we’ve

ever seen from the standpoint of water”,

noted President Donald Trump. In fact,

America has endured far wetter and more

damaging. Moody’s estimates that Flor-

ence caused between $17bn and $22bn in

damage. Katrina, which devastated New

Orleans in 2005, cost $160bn in current dol-

lars; Harvey cost $125bn; Maria, which af-

fected Puerto Rico in 2017, cost $90bn.

The death toll of Florence, estimated at

37, is well behind those seen by Katrina,

which killed 1,833, and Harvey (88). A re-

cent study calculated that Maria killed

2,975, over a longer period, though Mr

Trump, sensitive to criticism of his admin-

istration’s flat-footed response to that di-

2018 is on course to set a newrecord.

Kevin Trenberth of the

National

Centre for Atmospheric Research says this

explains storms like Florence and Mang-

khut. Tropical storms in the Atlantic

(known as “hurricanes”) and Pacific (“ty-

phoons”) drawtheir energy fromthis abys-

sal heat store. Warmer oceans mean more

intense and longer-lasting storms. Climate

models have long forecast this. Moreover,

sea levels are rising at a rate of 3mm per

year. Two factors explain this: water ex-

pands as it warms; and glaciers aremelting

at both poles. Higher seas mean storm

surges reach farther inland. And, as the at-

mosphere warms, it can hold more mois-

ture that eventually falls as precipitation.

Recent studies have explored these ef-

Hurricanes and typhoons

Stormyweather

HONG KONG, MANILA, WASHINGTON, ZHUHAI

Climate changemeansmore severe storms inboth theAtlantic and the Pacific. But

governments are getting a bit better at preparing for them

International

Also in this section

56 Hong Kong weathers the storm

Getting into hot water

Source: Lijing Cheng and Jiang Zhu

Global ocean heat content, 0-2,000m

Deviation from 1981-2010 average, 10

joules

–

1960 70 80 90 2000 10 17

Correction

: Our article last week on subnational climate

initiatives stated that 11 cities had recently joined the

Under2 Coalition. In fact, the coalition is led by states

and regions and 16 new jurisdictions joined, bringing

membership to 222.