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BY CAROLYN GRAMLING
Extremes in rainfall — whether intense
drought or flash floods — can catastroph-
ically slow the global economy, a new
study finds. And those impacts are most
felt by wealthy, industrialized nations,
researchers report in the Jan. 13 Nature.
In a global analysis of rainfall’s effects
on economic output over 40 years,
episodes of intense drought led to the
biggest shocks to economic productiv-
ity. But days with intense deluges — such
as occurred in Europe in July 2021 — also
produced strong shocks to the economic
system. Most surprising, though, was
that agricultural economies appeared
to be relatively resilient against both of
these types of shocks, says Maximilian
Kotz, an environmental economist at the
Potsdam Institute for Climate Impact
Research in Germany. Instead, two other
business sectors — manufacturing and
services — were the most hard-hit.
As a result, the nations most affected
by rainfall extremes weren’t those that
tended to be poorer, with agriculture-
dependent societies, but the wealthiest
nations, whose economies are tied more
heavily to manufacturing and services,
such as banking, health care and enter-
tainment.
It’s well-known that rising tem-
peratures can take a toll on economic
productivity, for example, by contribut-
ing to increased doctor visits or missed
workdays. Extreme heat also has clear
impacts on human behavior (SN: 9/11/21,
p. 14). But what effect climate change–
caused shifts in rainfall might have on
changes in the global economy hasn’t
been so straightforward.
That’s in part because previous stud-
ies looking at a possible connection
between rainfall and productivity have
focused on changes in yearly precipi-
tation, a time frame that “is just too
coarse to really describe what’s actually
happening [in] the economy,” Kotz says.
Such studies have shown that more rain
in a given year is basically beneficial,
which makes sense in that having more
water available is good for agriculture
and other human activities, Kotz says.
“But these findings were mainly focused
on agriculturally dependent economies
and poorer economies.”
In the new study, Kotz and colleagues
looked at three timescales — annual,
monthly and daily rainfall — and exam-
ined what happened to economic output
for time periods in which the rainfall
deviated from average historical values.
The analysis included two measures
not considered in previous studies,
Kotz says: the amount of rainy days
that a region gets in a year and extreme
daily rainfall. The team then examined
these factors across 1,554 regions glob-
ally — which included many subregions
within 77 countries — from 1979 to 2019.
The disparity over which regions were
hit hardest is “at odds with the con-
ventional wisdom” — and with some
previous studies — that agriculture is
vulnerable to extreme rainfall, atmo-
spheric scientist Xin-Zhong Liang of
the University of Maryland in College
Park wrote in a commentary in the same
issue of Nature. Researchers may need
to incorporate other factors in future
assessments, such as growth stages of
crops, land drainage or irrigation, to
really understand how these extremes
affect agriculture, Liang wrote.
“That was definitely surprising for us
as well,” Kotz says. The study doesn’t spe-
cifically try to answer why manufacturing
and services were so affected, but it
makes intuitive sense, he says. Flooding,
for example, can damage infrastructure
and disrupt transportation, effects that
can then propagate along supply chains.
“It’s feasible that these things might be
most important in manufacturing, where
infrastructure is very important, or in the
services sectors, where the human expe-
rience is very much dictated by these
daily aspects of weather and rainfall,”
Kotz says.
Including daily and monthly rain-
fall extremes in this type of analysis is
“an important innovation” because it
reveals new economic vulnerabilities,
says Tamma Carleton, an environmental
economist at the University of California,
Santa Barbara. However, Carleton says,
the findings “are not yet conclusive on
who is most vulnerable and why, and
instead raise many important questions
for future research to unpack.”
Extreme rainfall events, including
both drought and deluge, will occur more
frequently as global temperatures rise,
the United Nations’ Intergovernmen-
tal Panel on Climate Change noted in
August (SN: 9/11/21, p. 8). The new find-
ings offer yet another stark warning to
the industrialized, wealthy world, Kotz
says. Human-caused climate change will
have “large economic consequences.”
s
Heavy rains, like those that caused severe
flooding in Alexandria, Va., on October 29,
2021, can disrupt global economics, a new
study suggests.
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1/26/22 11:15 AM
1/26/22 11:15 AM
www.sciencenews.org
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February 12, 2022
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