Mon, May 01, 2017 - Page 4 News List

Experts warning cities to brace for climate challenges


A demonstrator wearing a US President Donald Trump mask prepares to swing at a globe during the People’s Climate Movement March in Washington on Saturday.

Photo: Bloomberg

Faced with exploding populations and steadily rising temperatures worldwide, cities must make haste in reinforcing defenses against climate change-induced flooding and heat waves, experts said last week.

City temperatures are forecast to shoot up in the coming years, exposing inhabitants to killer heat spikes, while rising sea levels and river flooding threaten homes, drinking water, and transport and electricity infrastructure.

Cities are vulnerable to a unique risk called the “urban heat island” (UHI) effect — their concrete surfaces retain more of the sun’s heat than undeveloped areas, scientists said at a meeting in Vienna of the European Geosciences Union (EGU).

By midcentury, if planet-warming fossil fuel emissions continue unabated, city temperatures in Belgium could exceed today’s heat-alert levels by as much as 10?C for 25 days each summer, according to one research paper.

Another study showed that heat waves will become a frequent challenge for European cities — more numerous in the south of the continent, more intense in the north.

Floods, a major risk to Europe’s dense urban settlements, will become more common because of an increase in freak rainstorms, as well as sea-level increases caused by polar ice melt and warmer ocean water expanding.

In flood-prone Southeast Asia, precipitation is set to increase by 20 percent this century, one researcher said in Vienna.

The stakes are especially high given the projections for expansion of urban areas, which are often ill equipped to deal with nature’s vengeance.

Already, more than half the world’s population live in cities. By 2050, 80 percent of people in rich nations, and 60 percent in developing states, will be concentrated in built-up areas, according to recent calculations.

This corresponds to the appearance of a settlement of 1 million inhabitants somewhere on the globe every week for the next 40 years.

Occupying only a small portion of Earth’s available land, cities are responsible for 80 percent of all energy consumed and generate more than 60 percent of the planet-warming greenhouse gases emitted when humans burn fossil fuel for heating, power and transportation.

In spite of efforts to curb emissions, the planet has already warmed about 1?C on average from pre-Industrial Revolution levels.

Many scientists say the planet may be on track for 3?C of warming or more, exceeding the 2?C cap politicians set in Paris in 2015.

This means cities must act now to shore up their defenses against impacts that can no longer be avoided, French climatologist Herve le Treut said at the annual EGU gathering.

“It’s already happening,” Le Treut said of climate change impacts. “We have to start structural action quickly: transportation, houses... mainly in the cities, especially in vulnerable places.”

Most of the infrastructure constructed by humanity is in urban zones.

“The ways cities are built is not optimal” for today’s climate reality, said Daniel Schertzer, a hydrometeorologist at the engineering school Ecole des Ponts ParisTech.

“Historically, humans have settled near water, thinking of its usefulness, but not of the risk! Cities were conceived without taking geophysics into consideration, now they are discovering that nature is complicated, not just good,” he said on the sidelines of the conference.

Paris, for example, is due for its next so-called one-in-a hundred-year flood. The last major Paris flood, in 1910, saw the Seine river rise 8.62m, shutting down much of the City of Light’s basic infrastructure.

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