Carbon Dioxide
Continues Its Rise
By David Shukman
01 April, 2005
BBC
Online
The
atmospheric concentration of the greenhouse gas carbon dioxide has reached
a new high, say US researchers.
The figures - 378
parts per million (ppm) - were gathered by a Hawaiian lab regarded by
experts as one of the most reliable in climate research.
The rise in the
past year is smaller than it was in the previous two years.
But the trend remains
upwards, as it has for every year since measurements began on top of
the Mauna Loa volcano nearly half a century ago.
The research was
carried out by the US government's Climate Monitoring Diagnostics Laboratory,
part of the National Oceanic and Atmospheric Administration (Noaa).
The laboratory's director, Dr Pieter Tans, told the BBC: "The most
striking thing about the data is that we've seen an increase in carbon
dioxide levels every single year since 1958."
At an altitude of
3,500m (11,500ft), the research station must rank as one of the world's
most spectacular and most remote scientific outposts.
Reaching it involves
leaving the tropical heat and humidity of the Hawaiian coast and climbing
up a narrow road that twists through barren fields of solidified lava.
The thin Pacific
air is ideal for this research since it is "well-mixed", meaning
that there is no obvious nearby source of pollution, such as a heavy
industry, or a natural "sink", such as forest which would
absorb CO2.
For that reason
the data from Mauna Loa has come to be seen as the benchmark by which
atmospheric data is judged.
According to Dr
Tans, one significant finding is that the annual rate at which the CO2
is rising has itself increased.
The growth rate
over the past decade was about twice as fast as that found in the 1960s.
He says that variations
in the growth rate year by year can be explained by natural factors;
for example, changes in the rate at which plants and the oceans soak
up carbon dioxide.
But he and his colleagues
conclude that the steady rise overall can be attributed to man-made
emissions of carbon.
Dr David Hoffman,
director of Noaa's Climate Monitoring and Diagnostics Laboratory, said:
"Even though man's contribution is not increasing dramatically
- in fact it's steady - it is adding up; there's a cumulative increase."
In the year that
the long-awaited Kyoto treaty finally came into force, with its aim
of constraining greenhouse gases, the latest evidence highlights what
a challenge that will be.