YOKOHAMA,
Japan — Climate change is already having sweeping effects on every
continent and throughout the world’s oceans, scientists reported Monday,
and they warned that the problem is likely to grow substantially worse
unless greenhouse emissions are brought under control.
The report
by the Intergovernmental Panel on Climate Change, a United Nations
group that periodically summarizes climate science, concluded that ice
caps are melting, sea ice in the Arctic is collapsing, water supplies
are coming under stress, heat waves and heavy rains are intensifying,
coral reefs are dying, and fish and many other creatures are migrating
toward the poles or in some cases going extinct.
The
oceans are rising at a pace that threatens coastal communities and are
becoming more acidic as they absorb some of the carbon dioxide given off
by cars and power plants, which is killing some creatures or stunting
their growth, the report found.
Organic
matter frozen in Arctic soils since before civilization began is now
melting, allowing it to decay into greenhouse gases that will cause
further warming, the scientists said.
And
the worst is yet to come, the scientists said in the second of three
reports that are expected to carry considerable weight next year as
nations try to agree on a new global climate treaty. In particular, the
report emphasized that the world’s food supply is at considerable risk —
a threat that could have serious consequences for the poorest nations.
“Nobody
on this planet is going to be untouched by the impacts of climate
change,” Rajendra K. Pachauri, chairman of the intergovernmental panel,
said at a news conference here on Monday.
The
report was among the most sobering yet issued by the intergovernmental
panel. The group, along with Al Gore, won the Nobel Peace Prize in 2007
for its efforts to clarify the risks of climate change.
The report
released on Monday in Yokohama is the final work of several hundred
authors; details from the drafts of this and of the last report in the series, which will be released next month, leaked in the last few months.
The
report attempts to project how the effects will alter human society in
coming decades. While the impact of global warming may actually be
outweighed by factors like economic or technological change, the report
found, the disruptions are nonetheless likely to be profound.
It
cited the risk of death or injury on a widespread scale, probable
damage to public health, displacement of people and potential mass
migrations.
“Throughout
the 21st century, climate-change impacts are projected to slow down
economic growth, make poverty reduction more difficult, further erode
food security, and prolong existing and create new poverty traps, the
latter particularly in urban areas and emerging hotspots of hunger,” the
report declared.
The
report also cites the possibility of violent conflict over land or
other resources, to which climate change might contribute indirectly “by
exacerbating well-established drivers of these conflicts such as
poverty and economic shocks.”
The
scientists emphasized that climate change is not just some problem of
the distant future, but is happening now. For instance, in much of the
American West, mountain snowpack is declining, threatening water
supplies for the region, the scientists reported. And the snow that does
fall is melting earlier in the year, which means there is less
meltwater to ease the parched summers.
In
Alaska, the collapse of sea ice is allowing huge waves to strike the
coast, causing erosion so rapid that it is already forcing entire
communities to relocate.
“Now
we are at the point where there is so much information, so much
evidence, that we can no longer plead ignorance,” said Michel Jarraud,
secretary general of the World Meteorological Organization.
The
experts did find a bright spot, however. Since the group issued its
report in 2007, it has found growing evidence that governments and
businesses around the world are starting extensive plans to adapt to
climate disruptions, even as some conservatives in the United States and
a small number of scientists continue to deny that a problem exists.
“I
think that dealing effectively with climate change is just going to be
something that great nations do,” said Christopher B. Field, co-chairman
of the working group that wrote the report, and an earth scientist at
the Carnegie Institution for Science in Stanford, Calif.
Talk
of adaptation to global warming was once avoided in some quarters, on
the grounds that it would distract from the need to cut emissions. But
the past few years have seen a shift in thinking, including research
from scientists and economists who argue that both strategies must be
pursued at once.
A
striking example of the change occurred recently in the state of New
York, where the Public Service Commission ordered Consolidated Edison,
the electric utility serving New York City and some suburbs, to spend
about $1 billion upgrading its system to prevent future damage from
flooding and other weather disruptions.
The
plan is a reaction to the blackouts caused by Hurricane Sandy. Con Ed
will raise flood walls, bury some vital equipment and launch a study of
whether emerging climate risks require even more changes. Other
utilities in the state face similar requirements, and utility regulators
across the United States are discussing whether to follow New York’s
lead.
But
with a global failure to limit greenhouse gases, the risk is rising
that climatic changes in coming decades could overwhelm such efforts to
adapt, the panel found. It cited a particular risk that in a hotter
climate, farmers will not be able to keep up with the fast-rising demand for food.
The
poorest people in the world, who have had virtually nothing to do with
causing global warming, will be high on the list of victims as climatic
disruptions intensify, the report said. It cited a World Bank estimate
that poor countries need as much as $100 billion a year to try to offset
the effects of climate change; they are now getting, at best, a few
billion dollars a year in such aid from rich countries.
The
$100 billion figure, though included in the 2,500-page main report, was
removed from a 48-page executive summary to be read by the world’s top
political leaders. It was among the most significant changes made as the
summary underwent final review during a days-long editing session in
Yokohama.
The
edit came after several rich countries, including the United States,
raised questions about the language, according to several people who
were in the room at the time but did not wish to be identified because
the negotiations are private.
The
language is contentious because poor countries are expected to renew
their demand for aid this September in New York at a summit meeting of
world leaders, who will attempt to make headway on a new treaty to limit
greenhouse gases.
Many
rich countries argue that $100 billion a year is an unrealistic demand;
it would essentially require them to double their budgets for foreign
aid, at a time of economic distress at home. That argument has fed a
rising sense of outrage among the leaders of poor countries, who feel
their people are paying the price for decades of profligate Western
consumption.
Two
decades of international efforts to limit emissions have yielded little
result, and it is not clear whether the negotiations in New York this
fall will be any different. While greenhouse gas emissions have begun to
decline slightly in many wealthy countries, including the United
States, those gains are being swamped by emissions from rising economic
powers like China and India.
For
the world’s poorer countries, food is not the only issue, but it may be
the most acute. Several times in recent years, climatic disruptions in
major growing regions have helped to throw supply and demand out of
balance, contributing to price increases that have reversed decades of
gains against global hunger, at least temporarily.
The
warning about the food supply in the new report is much sharper in tone
than any previously issued by the panel. That reflects a growing body
of research about how sensitive many crops are to heat waves and water
stress.
David
B. Lobell, a Stanford University scientist who has published much of
that research and helped write the new report, said in an interview that
as yet, too little work was being done to understand the risk, much
less counter it with improved crop varieties and farming techniques. “It
is a surprisingly small amount of effort for the stakes,” he said.
Timothy
Gore, an analyst for Oxfam, the anti-hunger charity that sent observers
to the proceedings, praised the new report for painting a clear
picture. But he warned that without greater efforts to limit global
warming and to adapt to the changes that have become inevitable, “the
goal we have in Oxfam of ensuring that every person has enough food to
eat could be lost forever.”
We speak to Chris Field, a leading member of the Nobel Prize-winning Intergovernmental Panel on Climate Change, about his warning that the amount of greenhouse gases in the atmosphere is rising more rapidly than expected in recent years. Field says the current trajectory of climate change is now much worse than the IPCC had originally projected. On Wednesday, Field told a Senate panel droughts caused by global warming could make parts of the American Southwest dangerous to live in. 
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