Global warming: Latest evidence from UN panel
Pastor Dale Morgan
Global warming: Latest evidence from UN panel*
PARIS, April 30 (AFP) Apr 30, 2007
Following is an encapsulation of the latest evidence on global warming,
published in reports issued in February and early April by the
Intergovernmental Panel on Climate Change (IPCC).
The UN's top scientific authority on global warming is meeting in
Bangkok from Monday and will issue its third report on Friday, this time
touching on ways of tackling greenhouse-gases.
PAST WARMING:
-- Evidence for Man's warming of the climate system is now unequivocal.
From 1906 to 2005, global surface temperatures rose by 0.74 C (1.33 F).
-- Global warming over the past half century has been nearly twice that
of the century as a whole, coinciding with a surge in greenhouse-gas
emissions from fossil fuels. Eleven of the past 12 years rank among the
dozen warmest years on record.
-- Ocean warming now extends to a depth of at least 3,000 metres (9,750
feet) as the seas take up heat from the air. Mountain glaciers and snow
cover have declined in both hemispheres. Sea levels rose globally by 1.8
millimetres (0.07 inches) per year from 1961 to 2003, a pace that
accelerated to 3.1 mm (0.12 inch) per year from 1993 to 2003.
-- The top layers of the Arctic permafrost have warmed by up to 3.0 C
(5.4 F) since the 1980s. The maximum area of seasonally frozen ground
has decreased by around seven percent in the northern hemisphere since 1900.
FORECAST FOR 21ST CENTURY:
-- By 2100, global average surface temperatures could rise by between
1.1 C (1.98 F) and 6.4 C (11.52 F) compared to 1980-99 levels, depending
on levels of carbon dioxide (CO2) in the air. Within this range, the
likeliest rise will be 1.8-4.0 C (3.24-7.2 F).
-- Sea levels will rise by between 18 and 59 centimetres (7.2 and 23.2
inches), although this could be amplified by accelerating melting of
icesheets.
-- Warming will occur most over land at high northern latitudes and
least over the Southern Ocean and the North Atlantic.
-- Carbon emissions this century "will contribute to warming and
sea-level rise for more than a millennium", due to the timescale
required for greenhouse gases to degrade.
LIKELY IMPACTS THIS CENTURY:
-- Heatwaves, flooding, drought, tropical storms and surges in sea level
are among the events that "will become more frequent, more widespread
and/or more intense" this century.
-- By mid-century, water availability is likely to increase in high
latitudes but fall by up to 30 percent in mid-latitudes and the dry
tropics, some of which are already badly water-stressed. Water from
glaciers and snow melt is also projected to decline, reducing resources
for regions where more than a sixth of the world population currently lives.
-- Between 20-30 percent of plant and animal species are likely to be at
increased risk of extinction if increases in global average temperature
exceed 1.5-2.5 C (2.7 F to 4.5 F).
-- Food production will rise slightly at mid-to-high latitudes if the
global temperatures increases 1-3 C (1.8-5.4 F) but fall beyond this
range. At lower latitudes, especially seasonally dry and tropical
regions, crop productivity is projected to decrease for even small local
temperature increases (1-2 C, or 1.8-3.6 F), which would increase the
risk of hunger.
-- By the 2080s, sea-level rise will place "many millions" of people at
risk of flooding and tropical storms. The mega-deltas of Asia, Africa
and small islands are the most vulnerable."
-- Malnutrition, deaths from heatwave, storms and drought, diarrhoea,
malaria and other pest-borne diseases are some of the heightened risks.
ECONOMIC COST
-- There is no consensus on the cost of global warming, as calculations
depend on different factors, such as storm damage and the impact on
biodiversity. Every tonne of CO2 emitted into the air costs from 10
dollars to 350 dollars, according to the estimates.
-- Investing money now in measures to cope with the future threat and
reduce emissions could reduce and delay some of the impacts, although
these actions are also limited by political, technical and financial
constraints.