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Scientists predict that if global warming continues, the world's major ice shelves will melt by 2100, causing oceans to rise by 7m to 14m, devastating coastal areas worldwide.
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1. Science Predictions about Global Warming
Most scientists today agree that the Earth is heating up, due primarily to an atmospheric increase in carbon dioxide caused mainly by the burning of fossil fuels such as coal and petroleum. 2005 was the hottest year on Earth since the late 19th century, when scientists began collecting temperature data. The past decade featured five of the warmest years ever recorded, with the second hottest year being 1998.
The image above shows the instrumental record of global average temperatures as compiled by the Climatic Research Unit of the University of East Anglia and the Hadley Centre of the UK Meteorological Office. The GNU Free Documentation License Version 1.2; with no Invariant Sections, Front-Cover Texts, or Back-Cover Texts.
Mean surface temperature anomalies during the period 1995 to 2004
The geographic distribution of surface warming during the 21st
Arctic Sea Ice Coverage - Flash Animation:
Global sea levels could rise by more than 20 feet (6 meters) with the loss of shelf ice in Greenland and Antarctica, devastating coastal areas worldwide.
There is little doubt that sea levels would rise by that much if
Greenland melted. But scientists disagree on when it could happen.
A recent Nature study suggested that Greenland's ice sheet will begin
to melt if the temperature there rises by 3ºC (5.4ºF) within the next
hundred years, which is quite possible, according to leading
Many experts agree that even a partial melting would cause a
one-meter (three-foot) rise in sea levels, which would entirely submerge
low-lying island countries, such as the Indian Ocean's Maldives.
The Arctic Ocean could be ice-free in summer by 2050.
Some climate models are more conservative, suggesting that there will
be no summer ice in the Arctic by the year 2100. But new research shows it could take as little as 20 years for the sea
ice to disappear.
"Since the advent of remote satellite imaging, we've lost about 20 percent of sea-ice cover. We think of the Arctic as the heat sink to the climate system. We're fundamentally changing this heat sink, and we don't know how the rest of the climate system is going to respond." -- Mark Serreze, a research scientist at the National Snow and Ice Data Center in Boulder, Colorado.
Arctic meltdown just decades away, scientists warn
By David Adam in London
Global warming in the Arctic might be accelerating out of control, scientists have warned, as new data revealed the floating cap of sea ice has shrunk to probably its smallest in at least a century.
Experts at the US National Snow and Ice Data Centre in Colorado fear
the region is locked into a destructive cycle, with warmer air melting
more ice, which in turn warms the air further. Satellite pictures show
that the extent of Arctic sea ice this month dipped 20 per cent below the
long-term average for September - melting an extra 1.3 million square
kilometres - an area about the size of the Northern Territory. If current
trends continue, the summertime Arctic Ocean will be ice-free well before
the end of this century.
The head scientist at the Colorado centre, Ted Scambos, said melting
sea ice accelerates warming because dark-coloured water absorbs heat from
the sun that was previously reflected back into space by white ice.
"Feedbacks in the system are starting to take hold. We could see
changes in Arctic ice happening much sooner than we thought and that is
important because without the ice cover over the Arctic Ocean we have to
expect big changes in Earth's weather," Dr Scambos said.
The findings are consistent with recent computer simulations showing
that a build-up of greenhouse gases could lead to a profoundly transformed
Arctic later this century. The North Pole ice cap always grows in winter
and shrinks in the summer. The average minimum area from 1979, when
precise satellite mapping began, until 2000 was 11 million square
kilometers. The new summer low, measured 11 days ago, was 20 per cent
This is the fourth consecutive year that melting has been greater than
average, and it pushed the overall decline in sea ice per decade to 8 per
cent, up from 6.5 per cent in 2001.
Walt Meier, also at the Colorado centre, said: "Having four years in a
row with such low ice extents has never been seen before in the satellite
record. It clearly indicates a downward trend, not just a short-term
Surface air temperatures over most of the Arctic Ocean often have been
2-3 degrees higher this year than from 1955 to 2004.
The notorious north-west passage through the Canadian Arctic from
Europe to Asia was completely open this summer, except for a 95-kilometre
swathe of scattered ice floes. The north-east passage, north of the
Siberian coast, has been ice-free since August 15.
Springtime melting in the Arctic has begun much earlier in recent
years. This year it started 17 days earlier than expected. The winter
rebound of ice, where sea water refreezes, has also been affected. Last
winter's recovery was the smallest on record and the peak Arctic ice cover
failed to match the previous year's level.
The decline threatens wildlife in the region, especially polar bears.
It is also the latest in a series of discoveries that have raised the
spectre of environmental tipping points: critical thresholds beyond which
the climate would be unable to recover.
Source: The Guardian, The New York Times
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