Runaway
growth in the emission of greenhouse gases is swamping all political
efforts to deal with the problem, raising the risk of “severe, pervasive
and irreversible impacts” over the coming decades, according to a draft
of a major new United Nations report.
Global
warming is already cutting grain production by several percentage
points, the report found, and that could grow much worse if emissions
continue unchecked. Higher seas, devastating heat waves, torrential rain
and other climate extremes are also being felt around the world as a
result of human emissions, the draft report said, and those problems are
likely to intensify unless the gases are brought under control.
The world may already be nearing a temperature at which the loss of the vast ice sheet covering Greenland would become inevitable, the report said. The actual melting would then take centuries, but it would be unstoppable and could result in a sea level rise of 23 feet, with additional increases from other sources like melting Antarctic ice, potentially flooding the world’s major cities.
Photographs
Rising Seas :
Some areas of the globe are especially vulnerable to
rising sea levels and inhabitants are being forced to make stark changes
in their lives.
Some areas of the globe are especially vulnerable to
rising sea levels and inhabitants are being forced to make stark changes
in their lives.
“Human
influence has been detected in warming of the atmosphere and the ocean,
in changes in the global water cycle, in reduction in snow and ice, and
in global mean-sea-level rise; and it is extremely likely to have been
the dominant cause of the observed warming since the mid-20th century,”
the draft report said. “The risk of abrupt and irreversible change
increases as the magnitude of the warming increases.”
The
report was drafted by the Intergovernmental Panel on Climate Change, a
body of scientists and other experts appointed by the United Nations
that periodically reviews and summarizes climate research. It is not
final and could change substantially before release.
The
report, intended to summarize and restate a string of earlier reports
about climate change released over the past year, is to be unveiled in
early November, after an intensive editing session in Copenhagen. A late
draft was sent to the world’s governments for review this week, and a
copy of that version was obtained by The New York Times.
Using
blunter, more forceful language than the reports that underpin it, the
new draft highlights the urgency of the risks likely to be intensified
by continued emissions of heat-trapping gases, primarily carbon dioxide
released by the burning of fossil fuels like coal, oil and natural gas.
The
report found that companies and governments had identified reserves of
these fuels at least four times larger than could safely be burned if
global warming is to be kept to a tolerable level.
That
means if society wants to limit the risks to future generations, it
must find the discipline to leave the vast majority of these valuable
fuels in the ground, the report said.
It
cited rising political efforts around the world on climate change,
including efforts to limit emissions as well as to adapt to changes that
have become inevitable. But the report found that these efforts were
being overwhelmed by construction of facilities like new coal-burning
power plants that will lock in high emissions for decades.
From
1970 to 2000, global emissions of greenhouse gases grew at 1.3% a
year. But from 2000 to 2010, that rate jumped to 2.2% a year,
the report found, and the pace seems to be accelerating further in this
decade.
A
major part of the jump was caused by industrialization in China, which
now accounts for half the world’s coal use. Those emissions are being
incurred in large part to produce goods for consumption in the West.
Emissions
are now falling in nearly all Western countries because of an increased
focus on efficiency and the spread of lower-emitting sources of
electricity. But the declines are not yet sufficient to offset rising
emissions in developing countries, many of whose governments are focused
on pulling their people out of poverty.
The
new report found that it was still technically possible to limit global
warming to an internationally agreed upper bound of 3.6 degrees
Fahrenheit, or 2 degrees Celsius, above the preindustrial level. But
continued political delays for another decade or two will make that
unachievable without severe economic disruption, the report said.
The
draft report comes a month before a summit of world leaders in New York
that is meant to set the stage for a potential global agreement on
emissions that would be completed next year. However, concern is growing
among climate experts that the leaders may not offer ambitious
commitments in their speeches on September 23, a potential continuation of
the political inaction that has marked the climate issue for decades.
The
draft report did find that efforts to counter climate change are
gathering force at the regional and local level in many countries. This
is especially clear in the United States, where Congress is paralyzed
and the national government has effectively ceded leadership on climate
to states like California, New York and Massachusetts.
President
Obama, using his executive authority under the Clean Air Act, is
seeking to impose national limits on emissions of greenhouse gases, but
he faces profound legal and political challenges as he seeks to put his
policy into effect before leaving office in early 2017.
The
draft report found that past emissions, and the failure to heed
scientific warnings about the risks, have made large-scale climatic
shifts inevitable. But lowering emissions would still slow the expected
pace of change, the report said, providing critical decades for human
society and the natural world to adapt.
“Continued
emission of greenhouse gases will cause further warming and
long-lasting changes in all components of the climate system, increasing
the likelihood of severe, pervasive and irreversible impacts for people
and ecosystems,” the report said.
The
earth has so far warmed by about 1.5 degrees Fahrenheit above the level
that prevailed before the Industrial Revolution, the report found, and
that seemingly modest increase is causing the effects already being seen
around the world.
A
continued rapid growth of emissions in coming decades could conceivably
lead to a global warming exceeding 8 degrees Fahrenheit, the report
found. The warming would be higher over land areas, and higher still at
the poles.
Warming
that substantial would almost certainly have catastrophic effects,
including a mass extinction of plants and animals, huge shortfalls in
food production, extreme coastal flooding and many other problems, the
report found.
The
report noted that severe weather events, some of them linked to human
emissions, had disrupted the food supply in recent years, leading to
several spikes in the prices of staple grains and destabilizing some
governments in poorer countries.
Continued
warming, the report found, is likely to “slow down economic growth,
make poverty reduction more difficult, further erode food security, and
prolong existing poverty traps and create new ones, the latter
particularly in urban areas and emerging hot spots of hunger.”
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