|
2009 is expected to be one of the top-five warmest years on
record, despite continued cooling of huge areas of the tropical Pacific Ocean,
a phenomenon known as La Nina.
According to climate scientists at the Met Office and the
University of East Anglia (UEA) the global temperature is forecast to be more than
0.4 C above the long-term average. This would make 2009 warmer than the year
just gone and the warmest since 2005.
During La Nina, cold waters rise to the surface to cool the
ocean and land surface temperatures. The 2009 forecast includes an updated
decadal forecast using a Met Office climate model. This indicates a rapid
return of global temperature to the long-term warming trend, with an increasing
probability of record temperatures after 2009.
Professor Chris Folland from the Met Office Hadley Centre
said: "Phenomena such as El Nino and La Nina have a significant influence
on global surface temperature. Warmer conditions in 2009 are expected because
the strong cooling influence of the recent powerful La Nina has given way to a
weaker La Nina. Further warming to record levels is likely once a moderate El
Nino develops."
These cyclical influences can mask underlying warming trends
as Professor Phil Jones, Director of the Climatic Research Unit, University of
East Anglia, explains: "The fact that 2009, like 2008, will not break
records does not mean that global warming has gone away. What matters is the
underlying rate of warming - the period 2001-2007, with an average of 14.44 C,
was 0.21 C warmer than corresponding values for the period 1991-2000."
The Met Office, in collaboration with UEA, maintains a global temperature record which is used in the reports of
the Intergovernmental Panel on Climate Change. Each January the Met Office, in
conjunction with the University, issues a forecast of the global
surface temperature for the coming year. The forecast takes into account known
contributing factors, such as El Nino and La Nina, increasing greenhouse gas
concentrations, the cooling influences of industrial aerosol particles, solar
effects and natural variations of the oceans.
Global temperature for 2009 is expected to be 14.44C, the
warmest since 2005, when the value was 14.48C. The warmest year on record is
1998, which was 14.52C, a year dominated by an extreme El Nino.
|