World Bank warns of
‘4-degree’ threshold of global temperature increase
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The World Bank is urging
stepped-up efforts to meet world carbon-reduction goals after
looking at what it says would be the catastrophic consequences
if average world temperatures rise more than 4 degrees Celsius
(7.2 degrees Fahrenheit) by the end of the century.
In what World Bank President Jim Yong Kim acknowledged was a
“doomsday scenario,” a
new study by the organization cited the 4-degree increase as
a threshold that would be likely to trigger widespread crop
failures and malnutrition and dislocate large numbers of people
from land inundated by rising seas.
World climate goals aim to hold the mean temperature increase to less than 2
degrees Celsius, by curbing emissions of greenhouse gases that trap heat — a
phenomenon already thought to have boosted average temperatures nearly 1 degree
from levels present before the start of the industrial age, Kim said in a
briefing last week.
That goal is unlikely to be met, he said, with an increase of 3 or 3.5
degrees Celsius now considered probable.
The report noted that a drop in average temperature of around 4.5 degrees
Celsius (8.1 degrees Fahrenheit) triggered the last ice age, and it predicted
that a temperature increase of that magnitude would similarly reshape the
planet.
In looking at the effects of a 4-degree increase, Kim said the bank was
hoping to encourage countries to act more aggressively to achieve climate goals
and to prompt poorer nations to begin planning ways to offset the long list of
potential impacts.
Those could include sea levels as much as three feet higher than currently
expected — a potentially devastating problem for large coastal cities in Asia
and Africa. Warming on such a scale could also limit access to fresh water for
irrigation and cause heat, drought and disease-related problems that could make
it more difficult to meet world food demands and improve health.
“The kind of sea level rise we are talking about is going to make the process
of urban planning and services to the poor absolutely fundamental,” said Rachel
Kyte, the World Bank’s vice president for sustainable development. “The race to
[develop] heat-resistant and drought-resistant strains [of staple food crops]
becomes fundamental.”
Kyte said the organization has begun more intense and frequent talks with
poorer nations over how to prepare for climate change — usually at the
instigation of officials who have seen the effects of shifting weather and
climate patterns and now feel they need to plan for the worst.
Countries such as Nigeria, Vietnam and Thailand “are coming and saying, ‘help
us think through the options,’ ” Kyte said. “This is an absolute change in the
conversation we are having with our clients.”
The bank’s report, “Turn Down the Heat,” cast some doubt on how much can be
done to avoid the worst outcomes.
Predicting the course of the world’s climate is a difficult science, and it
is impossible to forecast how technology, demographics and politics will shape
what the world looks like in 90 years — regardless of the temperature.
But the report concluded that a 4-degree jump in average temperatures would
push some countries or regions to the brink of collapse, regardless of how hard
they try to adapt.
“A 4°C world is likely to be one in which communities, cities and countries
would experience severe disruptions, damage, and dislocation,” the report said.
“There is no certainty that adaptation to a 4°C world is possible.”
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