July 8 G8 leaders were due to agree a goal of
limiting global warming to 2 degrees Celsius (3.6 Fahrenheit)
above pre-industrial levels at a summit in Italy on Wednesday.
Here are some facts about the target, previously adopted by
European Union nations and due to be widened to the United
States, Russia, Japan and Canada.
For more news on the G8 summit in Italy, click on [G8] or
2 DEGREES DOESN'T SOUND MUCH?
The temperature difference between the last Ice Age and now
is only about 5 Celsius. Average world temperatures rose by 0.7
Celsius in the 20th century, according to the U.N.'s
Intergovernmental Panel on Climate Change (IPCC).
It estimates that temperatures will rise further, by between
1.1 and 6.4 Celsius during the 21st century, depending on
policies chosen by governments. It says it is at least 90
percent likely that greenhouse gases from human activities, led
by burning of fossil fuels, are to blame for most of the recent
WHAT HAPPENS IF TEMPERATURES RISE BY 2 CELSIUS?
Hundreds of millions of people would be exposed to increased
stress on water supplies, according to the IPCC in its last
major report in 2007, based on research by 2,500 experts. It
says more people would suffer from malnutrition, some infectious
diseases and there would be more deaths from heatwaves, floods
and droughts. Up to 30 percent of species of animals and plants
would be at increasing risk of extinction. Coral reefs would be
damaged. Cereals production would decline in tropical areas but,
in one benefit, would improve nearer the poles. Coasts would
suffer increased damage from floods and storms.
WHY 2 CELSIUS?
The European Union settled upon 2 Celsius in 1996 as a
yardstick for measuring success in fighting climate change. It
says that anything more would be "dangerous" for life on the
planet. Many environmental groups also have the same target.
Small island states, which fear being wiped off the map by
rising sea levels, say that dangerous impacts will start at a
rise of only 1.5 Celsius.
WHAT WOULD IT COST TO LIMIT WARMING TO 2 CELSIUS?
The EU says that meeting the 2 Celsius target could be
achieved with world gross domestic product (GDP) losses of at
most 2.5 percent by 2050, reducing annual growth by at most 0.05
percent a year.
"When taking into account co-benefits in terms of air
pollution reduction, net costs could be significantly lower. The
costs of actions to mitigate climate change are small when
compared to the relative costs of impacts due to inaction,"
according to an EU brochure about the goal.
WHAT GREENHOUSE GAS CUTS WOULD BE NEEDED?
"To avoid a warming in excess of 2 Celsius, global
greenhouse gas emissions should peak by 2020 at the latest and
then be more than halved by 2050 relative to 1990," the EU says,
based on IPCC findings.
"In order to have a 50 percent chance of keeping the global
mean temperature rise below 2 Celsius relative to pre-industrial
levels, atmospheric greenhouse gas concentrations must stabilise
below the equivalent of 450 parts per million (ppm) of carbon
dioxide in the atmosphere," it says.
"Stabilisation below 400 ppm will increase the probability
to roughly 66 percent to 90 percent," it says. Greenhouse gas
concentrations are now around 380 ppm and rising.
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(Editing by Patrick Graham)