|
 The 40-page synthesis, summing up 5,000 pages of work by 800
scientists already published since September 2013, said global
warming was now causing more heat extremes, downpours, acidifying
the oceans and pushing up sea levels.
"Science has spoken. There is no ambiguity in the message. Leaders
must act, time is not on our side," U.N. Secretary-General Ban Ki-moon
said in presenting the report in Copenhagen that is meant to guide
global climate policy-making.
With fast action, climate change could be kept in check at
manageable costs, he said, referring to a U.N. goal of limiting
average temperature rises to 2 degrees Celsius (3.6 degrees
Fahrenheit) above pre-industrial times. Temperatures are already up
0.85 C (1.4F).
The study by the Intergovernmental Panel on Climate Change (IPCC),
approved by more than 120 governments, will be the main handbook for
negotiators of a U.N. deal to combat global warming due at a summit
in Paris in December 2015.
To get a good chance of staying below 2C, the report's scenarios
show that world emissions would have to fall by between 40 and 70
percent by 2050 from current levels and to "near zero or below in
2100".
Below zero would require extracting carbon dioxide from the
atmosphere - for instance by planting forests that soak up carbon as
they grow or by burying emissions from power plants that burn wood
or other biomass.
RENEWABLES, NUCLEAR
To cut emissions, the report points to options including energy
efficiency, renewable energies from wind to solar power, nuclear
energy or coal-fired power plants where carbon dioxide is stripped
from the exhaust fumes and buried underground.
But carbon capture and storage (CCS) is expensive and little tested.
Last month, Canada's Saskatchewan Power opened the world's first big
CCS unit at a coal-fired power plant after a C$1.35 billion ($1.21
billion) retrofit.
"With CCS it's entirely possible that fossil fuels can be used on a
large scale," IPCC chairman Rajendra Pachauri said. In most
scenarios, the report says "fossil fuel power generation without CCS
is phased out almost entirely by 2100".
Without extra efforts to cut emissions, "warming by the end of the
21st century will bring high risks of severe, widespread, and
irreversible impacts globally," the IPCC said.
[to top of second column] |
"Irreversible" could mean, for instance, a runaway melt of
Greenland's vast ice sheets that could swamp coastal regions and
cities or disruptions to monsoons vital for growing food.
"The cost of inaction will be horrendously higher than the cost of
action," Pachauri said.
Deep cuts in emissions would reduce global growth in consumption of
goods and services, the economic yardstick used by the IPCC, by just
0.06 percentage point a year below annual projected growth of 1.6 to
3.0 percent, it said.
So far, major emitters are far from curbs on emissions on a scale
outlined by the IPCC. China, the United States and the European
Union are top emitters.
John P. Holdren, Director of the White House Office of Science &
Technology Policy, said the report was "yet another wake-up call to
the global community that we must act together swiftly and
aggressively in order to stem climate change."
"We must safeguard the world for future generations by striking a
new climate deal in Paris next year," British Secretary of State for
Climate and Energy Ed Davey said.
Environmental groups welcomed the report, including its focus on
zero emissions. "This is no longer about dividing up the pie. You
need to get to zero. At some stage there is no pie left for anyone,"
said Kaisa Kosonen of Greenpeace.
The report also says that it is at least 95 percent sure that
manmade emissions of greenhouse gases, rather than natural
variations in the climate, are the main cause of warming since 1950,
up from 90 percent in a previous assessment in 2007.
(editing by Ralph Boulton)
[© 2014 Thomson Reuters. All rights
reserved.] Copyright 2014 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
