Carbon
dioxide levels indicate rise in temperatures that could lead agriculture to
fail on Climate change is amplifying risks from drought, floods, storm and
rising seas. Photograph: Simon Maina/AFP
It is increasingly likely that
hundreds of millions of people will be displaced from their homelands in the
near future as a result of global warming. That is the stark warning of
economist and climate change expert
Lord Stern following the news last week that concentrations of carbon dioxide
in our atmosphere had reached a level of 400 parts per million (ppm).
Massive movements of people are
likely to occur over the rest of the century because global temperatures are
likely to rise to by up to 5C because carbon dioxide levels have risen unabated
for 50 years, said Stern, who is head of the Grantham Research Institute on
Climate Change.
"When temperatures rise to that
level, we will have disrupted weather patterns and spreading deserts," he said.
"Hundreds of millions of people will be forced to leave their homelands
because their crops and animals will have died. The trouble will come when they
try to migrate into new lands, however. That will bring them into armed
conflict with people already living there. Nor will it be an occasional
occurrence. It could become a permanent feature of life on Earth."
The news that atmospheric carbon
dioxide levels have reached 400ppm has been seized on by experts because that
level brings the world close to the point where it becomes inevitable that it
will experience a catastrophic rise in temperatures. Scientists have warned for
decades of the danger of allowing industrial outputs of carbon dioxide to rise
unchecked.
Instead, these outputs have
accelerated. In the 1960s, carbon dioxide levels rose at a rate of 0.7ppm a
year. Today, they rise at 2.1ppm, as more nations become industrialised and
increase outputs from their factories and power plants. The last time the
Earth's atmosphere had 400ppm carbon dioxide, the Arctic was ice-free and sea
levels were 40 metres higher.
The prospect of Earth returning to
these climatic conditions is causing major alarm. As temperatures rise, deserts
will spread and life-sustaining weather patterns such as the North Indian monsoon
could be disrupted. Agriculture could fail on a continent-wide basis and
hundreds of millions of people would be rendered homeless, triggering
widespread conflict.
There are likely to be severe
physical consequences for the planet. Rising temperatures will shrink polar ice
caps – the Arctic's is now at its lowest since records began – and so reduce
the amount of solar heat they reflect back into space. Similarly, thawing of
the permafrost lands of Alaska, Canada and Russia could release even more
greenhouse gases, including methane, and further intensify global warming.
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