In another grim reminder of the threat posed by global warming, the Inter-governmental Panel on Climate Change (IPCC) on Monday warned that the average global temperatures would rise by more than two degree Celsius by 2100 compared to pre-industrial times unless “deep reductions” in greenhouse gas emissions are initiated immediately.
The IPCC released the first part of its Sixth Assessment Report (AR6), its latest evaluation of the state of earth’s climate, the changes happening therein, and the impacts these are having on the planet, and life forms. The voluminous assessment reports are the most widely-accepted scientific opinion on the status of earth’s climate.
The first part of AR6, which presents scientific evidence for climate change, says that global temperatures had already risen by about 1.1 degree Celsius from pre-industrial times, a reference to the period between 1850 and 1900, and warns that a 1.5 degree Celsius warming was likely to be achieved before 2040.
The stated objective of the 2015 Paris Agreement, the international architecture to fight climate change, is to limit temperature increase to within 2 degree Celsius from pre-industrial times, hopefully within 1.5 degrees Celsius itself. Scientists say a temperature rise beyond 2 degree Celsius would result in catastrophic and irreversible changes that would make it difficult for human beings and other species to survive.
The sixth assessment report says that even if very wide-ranging and ambitious cuts in greenhouse gas emissions are initiated immediately, the temperature rise was expected to cross 1.5 degree Celsius, and reach 1.6 degree Celsius, before being reined back to 1.5 degrees Celsius.
Limiting the temperature rise to 1.5 degree Celsius, or even 2 degree Celsius, would be “beyond reach”, unless “immediate, rapid and large-scale” reductions in greenhouse gas emissions takes place, the report says.
The report says that there was now “unequivocal” evidence to say that global warming was being caused by human activities. It says “multiple lines of evidence” now supports this.
The IPCC, which was set up in 1988 by the World Meteorological Organisation (WMO) and UN Environment Programme (UNEP), does not produce any new science itself. Instead, it assembles scientists from all over the world to review all the relevant scientific literature on climate change, and arrive at general conclusions about the trends being observed.