A recent study conducted by the US National Oceanic and Atmospheric Administration (NOAA) found that global warming may already be irreversible, even in the event of significant and immediate reduction in carbon emissions worldwide. According to the study, the Arctic has already plummeted over a precipice and passed the point at which global warming might have been halted or substantially slowed.
From The Independent:
A record loss of sea ice in the Arctic this summer has convinced scientists that the northern hemisphere may have crossed a critical threshold beyond which the climate may never recover. Scientists fear that the Arctic has now entered an irreversible phase of warming which will accelerate the loss of the polar sea ice that has helped to keep the climate stable for thousands of years.
They believe global warming is melting Arctic ice so rapidly that the region is beginning to absorb more heat from the sun, causing the ice to melt still further and so reinforcing a vicious cycle of melting and heating.
The greatest fear is that the Arctic has reached a “tipping point” beyond which nothing can reverse the continual loss of sea ice and with it the massive land glaciers of Greenland, which will raise sea levels dramatically.
Significant evidence of global climate change became apparent in the 1970s and has slowly escalated over the past thirty years. However, a more dramatic melt began approximately 4 years ago:
Satellites monitoring the Arctic have found that the extent of the sea ice this August has reached its lowest monthly point on record, dipping an unprecedented 18.2 per cent below the long-term average.
Experts believe that such a loss of Arctic sea ice in summer has not occurred in hundreds and possibly thousands of years. It is the fourth year in a row that the sea ice in August has fallen below the monthly downward trend – a clear sign that melting has accelerated.
As more and more sea ice is lost during the summer, greater expanses of open ocean are exposed to the sun which increases the rate at which heat is absorbed in the Arctic region, Dr Serreze said.
Sea ice reflects up to 80 per cent of sunlight hitting it but this “albedo effect” is mostly lost when the sea is uncovered. “We’ve exposed all this dark ocean to the sun’s heat so that the overall heat content increases,” he explained.
Current computer models suggest that the Arctic will be entirely ice-free during summer by the year 2070 but some scientists now believe that even this dire prediction may be over-optimistic, said Professor Peter Wadhams, an Arctic ice specialist at Cambridge University.
Where once the assumption had been that a catastrophic global warming crisis would last only 200-300 years, scientists now say that there is evidence indicating that such a crisis could last a millennium.
A team of environmental researchers in the US has warned many effects of climate change are irreversible.
The scientists concluded global temperatures could remain high for 1,000 years, even if carbon emissions can somehow be halted.
[. . .]
The team warned that, if carbon levels in the atmosphere continued to rise, there would be less rainfall in already dry areas of southern Europe, North America, parts of Africa and Australia.
The scientists say the oceans are currently slowing down global warming by absorbing heat, but they will eventually release that heat back into the air.
They say politicians must now offset environmental damage already done by man-made pollution.
“People have imagined that if we stopped emitting carbon dioxide the climate would go back to normal in 100 years, 200 year – that’s not true,” said researcher Susan Solomon, the lead author of the report, quoted by AP news agency.
If global warming is indeed unstoppable, the consequences will be disastrous. In addition to a tragic and permanent loss of wildlife,
Rising sea levels would cause “irreversible commitments to future changes in the geography of the Earth, since many coastal and island features would ultimately become submerged,” the study said.
Decreases in rainfall that last for centuries can be expected to have a range of impacts, said the authors. Regional impacts include — but are not limited to — decreased human water supplies, increased fire frequency, ecosystem change and expanded deserts.
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