LONDON
- The world's cities face the brunt of
climate change but some are starting to respond vigorously to the threat,
experts say at a conference here staged ahead of the June Rio summit.
More
than half of the world's population of seven billion currently lives in cities
and by 2050, this is expected to increase to 70 per cent, or around 6.4
billion, according to UN figures.
More
than 60 per cent of the increase will occur in Asian cities - and nearly half
of the growth will happen in cities that currently have 500,000 inhabitants or
fewer.
It
means that cities will face unparalleled challenges when climate change starts
to bite, scientists said Monday at a meeting on the world's environment ahead
of the June 20-22 summit.
"Cities
are emerging as first responders. They are on the frontline, both in the cause
and effect of climate change," said Cynthia Rosenzweig, who heads the
Climate Impacts Group at the NASA Goddard Institute for Space Studies.
The
hazards facing cities are many.
By
2100, or sooner, heatwaves, droughts, storms and floods are expected to become
more frequent and last longer.
Cities
built on deltas or on the coast will face rising seas, which threaten homes and
drinking water.
That
raises mighty questions about water supplies, drainage and flood defences and
the resilience of homes, offices, factories and transport systems.
In
2003, one of the hottest summers on record killed around 35,000 people in
Europe.
Some
climate scientists predict that by the 2040s, more than half of the continent's
summers will be warmer than that of 2003.
Alex de
Sherbinin of the Earth Institute at New York's Columbia University pointed to a
dangerous phenomenon called the urban heat island.
Cities
can hold pockets of heat that are up to four to six degrees Celsius greater
than in the surrounding countryside.
The
warmth comes from the reflected radiation from treeless streets sealed in
heat-trapping black tarmac; from buildings in "street canyons" which
block cooling breezes; and from heat discharged by air conditioning ducts.
Those
most at risk are the elderly, battling heat stress and air pollution, and the
poor, who cannot afford to cool their homes or or move elsewhere, he said.
All
cities will be challenged by shifting climate, but some will be more exposed or
cope better than others, said Stephen Tyler, working with a group called the
Asian Cities Climate Change Resilience Network (ACCCRN).
He
sounded the alarm for cities that are middle-sized today but will soon face a
double whammy - heavy migration that can lead to slums, and the impact of
climate change.
"The
middle cities are often ignored by governments, yet they are also the primary
target for poor people who leave the countryside and aim for the nearest urban
centre," said Tyler.
"But
in terms of coping, it's not the city's size which counts, but its ability to
provide the services, the infrastructure."
Far
from being sitting ducks, many cities are working to shore up their climate
defences and ease their greenhouse-gases, said Rosenzweig.
Around
70 per cent of carbon dioxide (CO2) emissions can be attributed to city needs.
Initiatives
include painting roofs white to reflect sunlight, having porous pavements that
allow rainwater to replenish the aquifer, planting trees and parks to alleviate
heat islands and regulating traffic pollution, which has benefits for health
and carbon mitigation.
Hospitals
and neighbourhood groups are also asked to watch out for old people who may be
struggling in a heatwave.
Cities
that are set to expand can plan their zoning laws, urban density, energy use
and traffic system accordingly, which saves having to expensively fix things
afterwards.
Rosenzweig,
who co-authored a report by a group called the Urban Climate Change Research
Network into how global warming will hit urban dwellers, said local governments
had powers and the ability to act.
Municipalities
are moving into the vacuum left by the UN or national governments, whose work
on climate change has marked time since the ill-fated 2009 Copenhagen Summit,
she explained.
In
2005, the so-called C40 Cities Climate Leadership Group was set up, and this
was followed five years later by the World Mayors Council on Climate Change.
It has
60 cities on its roster, swapping ideas and networking.
"City
leaders are practical and responsive," she said.
"They
are there day after day, and they have experience in climate-related
disasters."
AFP
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