Human influence causing global warming at unprecedented rate: senior climatologist
It is human influence that is largely driving global warming at unprecedented rates, with the current century standing out as the hottest in 2,000 years, R Krishnan, director and senior climatologist at the Indian Institute, said on Tuesday. Tropical Meteorology (IITM) from Pune.
He was speaking on the “response of the hydrological monsoon cyclone to global climate change” based on findings published in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) the second day of the International Scientific Conference on the Indian Ocean.
“More than natural drivers like solar heating or volcanic activities, it is human influence on climate change that has increased since the 1850s,” Krishnan said.
“Since the middle of the 20th century, global warming can be attributed to greenhouse gases as well as other influences such as sulfur dioxide, organic carbon and other non-greenhouse gases. Aerosols also contribute to climate change and hydrological changes.
Referring to AR6, the senior climatologist noted that the observed temperature rise between 1850-1900 and 2010-2019 was around 1.1 degrees. “But that was offset by anthropogenic factors like sulfur dioxide and other factors, especially important for understanding hydrological and monsoon scenarios.”
Ongoing accelerated warming has led to a reduction in Arctic sea ice and this depletion, Krishnan said, has been more pronounced since the 1990s, leading to sea level rise.
Increased warming has led to wetter seasons in many parts of the globe, with AR6 reporting an increase in global rainfall since the mid-20th century, once again driven by human activities, particularly along high and mid latitude countries. It was not just the land or sea surface that was warming, but also the deep oceans that were warming at an unprecedented rate.
“Even subterranean oceans at 700 m or less (baseline values calculated for the period 1971-2018) are warming rapidly. The ocean heat content recorded in the deeper layers from 0 to 2000 m depth is high. Significant warming has been observed along the Indian Ocean compared to the Pacific Ocean or North Atlantic Ocean region, where the warming varies more spatially,” Krishnan pointed out.
According to the report, wetter monsoons are likely over South Asia, Southeast Asia, Africa and rainfall over already wet areas is expected to increase. In contrast, dry and arid seasons are predicted in the subtropics due to a possible decrease in rainfall, including areas around the Mediterranean Sea and southwestern Australia.