Mankind is the 'Earth's biggest threat'
Pastor Dale Morgan
Mankind is the 'Earth's biggest threat'*
By Roger Highfield Science Editor
Last updated: 12:22 AM BST 15/05/2008
Global warming is causing significant changes to the Earth's natural
systems and it is highly unlikely that any force but man-made climate
change can be blamed .
Researchers who analysed 30,000 academic studies dating back to 1970
said man was responsible for changes that ranged from the loss of ice
sheets to the collapse in numbers of many species of wildlife.
"Humans are influencing climate through increasing greenhouse gas
emissions, and the warming world is causing impacts on physical and
biological systems," said Cynthia Rosenzweig, at the Nasa Goddard
Institute for Space Studies.
The effects on living things include the earlier appearance of leaves on
trees and plants; the movement of animals and birds to more northerly
latitudes and to higher altitudes in the northern hemisphere; rapid
advances in flowering time and earlier egg-laying in Britain; and
changes in bird migrations in Europe, North America and Australia.
On a planetary scale the changes include the melting of glaciers on all
continents; earlier spring river run-off; and the warming of oceans,
lakes and rivers.
The study's conclusions go further than the most recent report by the
Intergovernmental Panel on Climate Change, which concluded last year
that man-made climate change was "likely" to have had a discernible
effect on the planet.
It says natural climate variations cannot explain the changes to the
Earth's natural systems.
In the study, published in the journal Nature, Miss Rosenzweig and
researchers from 10 institutions across the world analysed data from
published papers on 829 physical systems – such as glaciers and ice
sheets – and 28,800 plant and animal systems. They produced a picture of
the changes to each continent. The changes were most marked in North
America, Asia and Europe but mainly because far more studies had been
carried out there.
The authors said there was an urgent need to study environmental systems
in South America, Australia and Africa, especially in tropical and
subtropical areas.
In North America, the researchers found that 89 species of plants were
flowering earlier, such as the American holly and box elder maple; a
decline in the population of polar bears; and the rapid melting of
Alaskan glaciers.
In Europe, they found evidence of glaciers melting in the Alps; earlier
pollen release in the Netherlands; and apple trees producing leaves 35
days earlier in Spain.
In Asia they reported a change in the freeze depth of permafrost in
Russia; and the earlier flowering of ginkgo in Japan.
In Antarctica, the population of emperor penguins had declined by 50 per
cent. In South America, the melting of the Patagonia ice-fields were
contributing to a rise in sea levels.
Prof Barry Brook, of the University of Adelaide, described the evidence
that mankind was altering the world as "overwhelming".
He said: "These changes are only a minor portent of what is likely to come."