Co se stalo s globálním oteplováním
Whatever happened to global warming? How freezing temperatures are starting to shatter climate change theory
Daily Mail Reporter
14. říjen 2009
In the freezing foothills of Montana, a distinctly bitter blast of revolution hangs in the air.
And while the residents of the icy city of Missoula can stave off the -10C chill with thermals and fires, there may be no easy remedy for the wintry snap’s repercussions.
The temperature has shattered a 36-year record. Further into the heartlands of America, the city of Billings registered -12C on Sunday, breaking the 1959 barrier of -5C.
Closer to home, Austria is today seeing its earliest snowfall in history with 30 to 40 centimetres already predicted in the mountains.
Such dramatic falls in temperatures provide superficial evidence for those who doubt that the world is threatened by climate change.
But most pertinent of all, of course, are the growing volume of statistics.
According to the National Climatic Data Centre, Earth’s hottest recorded year was 1998.
If you put the same question to NASA, scientists will say it was 1934, followed by 1998. The next three runner-ups are 1921, 2006 and 1931.
Which all blows a rather large hole in the argument that the earth is hurtling towards an inescapable heat death prompted by man’s abuse of the environment.
Indeed, some experts believe we should forget global warming and turn our attention to an entirely differently phenomenon – global cooling.
The evidence for both remains inconclusive, which is unlikely to help the legions of world leaders meeting in Copenhagen in December to negotiate a new climate change deal.
There is no doubt the amount of man-made carbon dioxide, the gas believed to be responsible for heating up the planet, has increased phenomenally over the last 100 years.
For the final few decades of the 20th century and as the atmosphere’s composition changed, scientists recorded the planet was warming rapidly and made a positive correlation between the two.
But then something went wrong. Rather then continuing to soar, the Earth’s temperature appeared to stabilise, smashing all conventional predictions.
The development seemed to support the view of climate change cynics who claimed global warming was simply a natural cycle and not caused by man.
Some doubters believe that the increase was actually down to the amount of energy from the Sun, which provides 98 per cent of the Earth’s warmth.
Previously, the fluctuating amount of radiation given out by the sun was thought to play a large role in the climate.
But Dr Piers Forster from Leeds University, who was part of the team to win the 2007 Nobel Peace Prize for his work on climate change, studied solar output – the heat leaving the sun’s surface – and cosmic ray intensity over the last 40 years, and compared those figures with global average surface temperature.
He told the BBC: ‚Warming in the last 20 to 40 years can’t have been caused by solar activity.‘
Scientists have intensified the search for alternative explanations
Professor Don Easterbrook from Western Washington University believes the key to the connumdrum may be the temperature of the world’s seas.
Figures show the Pacific Ocean has been cooling over the last few years, and Easterbrook’s research shows a correlation between this and global temperatures.
He says the oceans have a cycle in which they warm and cool cyclically, known as Pacific decadal oscillation (PDO).
And after a 30-year heating cycle in the 1980s and 1990s, pushing temperatures above average, we are now moving into a cooler period.
Professor Easterbrook said: ‚In the last few years [the Pacific Ocean] has been losing its warmth and has recently started to cool down.
‚The PDO cool mode has replaced the warm mode in the Pacific Ocean, virtually assuring us of about 30 years of global cooling.‘
In Alberta, Canada (above), temperatures dropped to -16C on Monday, breaking the day’s previous record, from 1928, by about three degrees
His figures show that the global cooling from 1945 to 1977 coincided with one of these cold Pacific cycles.
Mojib Latif, a member of the IPCC (Intergovernmental Panel on Climate Change), stressed the impact of the ocean currents in the North Atlantic – a phenomenon called the North Atlantic Oscillation (NAO) and the Atlantic Meridional Oscillation.
He believes we may be in a period of cooling – but that it will be temporary before global warming reasserts itself.
He said the NAO may have been responsible for some of the rapid rise in temperatures of the last three decades.
‚But how much? The jury is still out,‘ he said.
So is the sun really going down on global warming?
The Met Office is not convinced.
They incorporate solar and oceanic cycles into their models, and they say that – even if there are periods of slower warming, or temporary cooling, the long-term trend in global temperatures is still on the up.