OSLO (Reuters) - Continued global warming will cause more extreme events such as floods and droughts in the 21st century, but the effects of greenhouse gas emissions will be felt for at least a millennium. climate report, confirming the responsibility of man in this evolution.
The Intergovernmental Panel of Experts on Climate Change (IPCC), sponsored by the UN, is due to present the 2 February in Paris its new report summarizing the work of 2.500 researchers from more than 130 countries. His writing took six years.
According to scientific sources, this paper refines the range of forecast of rising temperatures in the twenty-first century. It now expects an increase between 2 and 4,5 degrees Celsius compared to pre-industrial levels, with the preferred estimate being 3 degrees based on a hypothesis of stabilization of carbon dioxide levels at a higher 45% threshold. at current levels.
The previous IPCC report, rendered in 2001, referred to an increase between 1,4 degrees and 8 degrees, without specifying which end of the range was preferred.
Continuing, global warming is expected to cause more droughts and floods in the 21st century and melting ice caps and glaciers.
UNCERTAINTIES
In addition, the sea-level rise should be between 28 and 43 cm (against 9 at 88 cm in the previous report) and it should continue for at least a millennium, even if governments manage to curb the concentration in the atmosphere of greenhouse gases, responsible for global warming.
"The anthropogenic emissions (editor's note, of human origin) of carbon dioxide in the XNUMXst century will contribute to the warming and to the rise of the sea level for more than a millennium, because of the delays necessary for the dilution of this gas ", is it written in the report, according to the same scientific sources.
The rise in sea level was 17 cm in the 20th century. This rise threatens many parts of the world, from the Pacific Islands to the shores of Bangladesh or Florida to cities such as Shanghai or Buenos Aires.
This report also emphasizes the increasingly assertive beliefs of the scientific community about human responsibility for global warming.
He considers "very likely" - a probability of over 90% - that human activities, including the use of fossil fuels, are responsible for the warming observed since 1950.
The previous report only used the adjective "probable".
The IPCC stresses, however, that uncertainties remain on the phenomenon of global warming.
For example, atmospheric pollution and dust from volcanic eruptions seem to have curbed warming by reflecting some of the sunlight back to space.
Likewise, higher temperatures could favor the formation of clouds, the summit of which also rejects heat to space.
Finally, the Gulf Stream, a warm current in the Atlantic Ocean, could weaken, but not enough to reverse the global warming trend.
source: yahoo news
