By AFP - Agence France Presse
Leading climate scientist declares the 2C climate target 'dead'
Keeping long-term global warming to two degrees Celsius - the alternative target of the Paris climate agreement - is now “impossible”, according to a rigorous new analysis published by leading scientists.
The article, led by renowned climatologist James Hansen, was published in the journal Environment: Science and Policy for Sustainable Development and concludes that the Earth's climate is more sensitive to rising greenhouse gas emissions than previously thought.
Hansen and his colleagues argued that the recent decline in aerosol pollution, which blocks sunlight, caused by the shipping industry, which had been mitigating some of the warming, has exacerbated the crisis.
The ambitious climate change scenario outlined by the UN climate panel, which gives the planet a 50% chance of keeping warming below 2°C by the year 2100, “is an implausible scenario”, Hansen told a meeting on Tuesday.
“That scenario is now impossible,” said Hansen, a former NASA climate scientist who became famous for announcing to the US Congress in 1988 that global warming was underway.
“The two-degree target is dead.”
Instead, he and his co-authors argued, the amount of greenhouse gases already pumped into the atmosphere by the burning of fossil fuels means that increased warming is now guaranteed.
Temperatures will remain at or above 1.5°C for the next few years - devastating coral reefs and fueling more intense storms - before rising to around 2.0°C by 2045, according to the authors' forecast.
They estimated that the melting of polar ice and the injection of freshwater into the North Atlantic will trigger the closure of the Atlantic Meridional Overturning Circulation (AMOC) over the next 20 to 30 years.
This current brings heat to various parts of the globe and also transports the nutrients needed to sustain ocean life.
Its end “will lead to major problems, including a rise in sea levels of several meters - we therefore describe the closure of the AMOC as the ‘point of no return, ’” the document argues.
The world's nations agreed, during the historic 2015 Paris climate agreement, to try to keep end-of-century warming to 1.5ºC above pre-industrial levels.
Scientists have identified this limit as essential to avoid the collapse of the main ocean circulation systems, the abrupt melting of boreal permafrost, and the collapse of tropical coral reefs.
The 1.5°C target has already been exceeded in the last two years, according to data from the EU's climate monitoring system, Copernicus, although the Paris Agreement referred to a long-term trend over decades.
At 2°C, the impacts would be even greater, including the irreversible loss of the Earth's ice sheets, mountain glaciers and snow, sea ice, and permafrost.
The authors acknowledged that the findings seemed gloomy but argued that honesty is a necessary ingredient for change.
“Failing to be realistic in assessing the climate and not drawing attention to the inoperability of current policies to curb global warming does not help young people,” they said.
“Today, with the growing crises, including global climate change, we have reached a point where we must address the problem of special interests,” they added, emphasizing that they were ‘optimistic’ about the future.
ia/des
Comments