Climate calamity
The change in climate due to carbon dioxide emissions and deforestation
is far worse than thought before, says Joydeep Gupta
GLOBAL
alarm over climate change and its effects has risen manifold after the
2007 report of the Intergovernmental Panel on Climate Change (IPCC).
Since then, many of the 2,500-odd IPCC scientists have found climate
change is progressing faster than the worst-case scenario they had
predicted. Their studies will be considered for the next IPCC report,
but since that will come out only in 2013, the University of New South
Wales in Sydney has just put together the main findings in the last
three years. Most are by previous IPCC lead authors "familiar
with the rigour and completeness required for a scientific assessment
of this nature", a university spokesperson said.
The most significant
findings are:
l Global
carbon dioxide emissions from fossil fuels in 2008 were 40 per cent
higher than in 1990. The recent Copenhagen Accord said warming should
be contained within two degrees, but every year of delayed action
increases the chances of exceeding the 2º warming mark.
l Carbon
dioxide is the main greenhouse gas (GHG) warming the atmosphere.
l To keep
within the 2`BA limit, global GHG emissions need to peak between 2015
and 2020 and then decline rapidly. To stabilise climate, near-zero
emissions of carbon dioxide and other long-lived GHG should be reached
well within this century.
l Over the
past 25 years, temperatures have increased at a rate of 0.19`BAC per
decade. The trend has continued over the last 10 years despite a
decrease in radiation from the sun.
l Also the
intensity of cyclones has increased in the past three decades in line
with rising tropical ocean temperatures.
l Satellites
show recent global average sea level rise (3.4 mm/year over the past
15 years) to be about 80 per cent above IPCC predictions.
l New
estimates of ocean heat uptake are 50 per cent higher than previous
calculations. Global ocean surface temperature reached the warmest
ever recorded in June, July and August 2009. Ocean acidification and
ocean de-oxygenation due to global warming have been identified as
potentially devastating for large parts of the marine ecosystem.
l By 2100,
global sea level is likely to rise at least twice as much as projected
by the IPCC in 2007; if emissions are unmitigated the rise may well
exceed one metre. The sea level will continue to rise for centuries
after global temperatures have been stabilised.
l A wide array
of satellite and ice measurements demonstrate that both the Greenland
and Antarctic ice sheets are melting at an increasing rate. Melting of
glaciers and ice-caps in other parts of the world has also accelerated
since 1990. The contribution of glaciers and ice-caps to global sea
level rise has increased from 0.8 mm per year in the 1990s to 1.2 mm
per year today. The adjustment of glaciers and ice caps to present
climate alone is expected to raise sea level by about 18 cm.
l The net loss
of ice from the Greenland ice sheet has accelerated since the
mid-1990s and is now contributing 0.7 mm per year to sea level rise
due to both increased melting and accelerated ice flow.
l Summer-time
melting of Arctic sea-ice has accelerated far beyond the expectations
of climate models. The area of summertime sea-ice 2007-09 was about 40
percent less than the average prediction from IPCC climate models in
the 2007 report.
l The
studies say avoiding tropical deforestation could prevent up to 20 per
cent of carbon dioxide emissions.
l New
ice-core records that carbon dioxide levels are higher now than they
have been during the last 800,000 years. — IANS
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