Greenhouse gases increase in 2005
- Greenhouse gases increase in 2005
May 2, 2006 - 10:54AM
Greenhouse gases - the heat-trapping chemicals linked to global
warming - continued to increase steadily in 2005, the US National
Oceanic and Atmospheric Administration reported.
Carbon dioxide, emitted by coal-burning power plants and cars,
increased last year, according to the federal climate agency's Annual
Greenhouse Gas Index, or AGGI. So did nitrous oxide, a byproduct of
farming and industry.
But methane emissions levelled off and chlorofluorocarbons,
artificially-made chemicals used in refrigerators and air
conditioners, declined, the agency said in a statement.
"Overall, the AGGI shows a continuing, steady rise in the amount of
heat-trapping gases in the atmosphere," the agency said.
The AGGI showed a 1.25 per cent rise in overall greenhouse gases in
2005. The index stood at 1.215 in 2005 compared to a 1990 base of
1.00, reflecting a steady rise in greenhouse gases over the past 15
The index is based on the levels of greenhouse gases in the
atmosphere in 1990, a year chosen because the global Kyoto Protocol
that aims to limit emissions of these gases also picked it as a
The constant or dropping rates of methane and chlorofluorocarbons,
also known as CFCs, have slightly slowed the overall growth rate.
By contrast, global carbon dioxide increased from an average of 376.8
parts per million in 2004 to 378.9 parts per million last year. The
pre-industrial era level of carbon dioxide, a major influence on
global warming, was about 278 parts per million.
A global network has measured levels of these chemicals, and
chemicals that have replaced CFCs, since 1979. The first AGGI was
released last year.
The increase of 1.25 per cent in 2005 was relatively small compared
to previous years, which have seen rises since 1979.
The largest annual increase was between 1987 and 1988, when levels
jumped 2.8 per cent; the smallest was .81 per cent, from 1992 to 1993.
Greenhouse gases fluctuate naturally, but human and industrial
factors play a role, and the rise in greenhouse gases has contributed
to global warming.
Over the past 50 years, the average temperature on Earth has risen at
the fastest rate in recorded history, with the 10 hottest years on
record occurring since 1990.
The Bush administration was initially sceptical but now accepts the
reality of global climate change, which has been associated with
stronger hurricanes, severe droughts, intense heat waves and the
melting of polar ice.