Days after scientists expressed concerns over the climate reaching a tipping point, the Inter-governmental Panel on Climate Change warned of dangerous trends, saying that Earth will hit the critical 1.5 degrees Celsius warming in two decades. The body remarked human activities as an "unequivocal" driver of climate change.

The report, a successor to the 2013 assessment, paints a grim picture of emissions and human activities to identify key drivers of climate change.

The Sixth Assessment Report (AR6) 'Climate Change 2021: The Physical Science Basis' said every region in the world is witnessing irreversible changes in climate due to human influence.

The report, approved by 195 member governments of the IPCC through virtual sessions held over two weeks since July 26, projected that in the coming decades climate change will increase in all regions. "Today's IPCC Working Group 1 Report is a code red for humanity," said UN Secretary-General, António Guterres.

Earth to hit 1.5-degree warming limit

It is the first time that the UN Intergovernmental Panel on Climate Change (IPCC) has quantified the likelihood of these extreme events in a wide variety of scenarios.

The report said that for 1.5 degrees Celsius of global warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons. At 2 degrees Celsius of global warming, heat extremes would more often reach critical tolerance thresholds for agriculture and health.

The report found that once-in-a-decade heavy rain events are now 1.3 times more likely and 6.7% wetter, compared with the 50 years up to 1900 when major human-driven warming started to occur. Previously once-in-a-decade droughts could happen every five or six years.

“Coastal areas will see continued sea-level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion with extreme sea-level events that previously occurred once in 100 years could happen every year by the end of this century,” said the IPCC Working Group in the report, which is the first instalment of the AR6, to be completed in 2022.

A grim future

The future looks even grimmer, with more warming meaning more frequent extreme events. Should the world become 4 degrees Celsius hotter, as could happen in a high-emissions scenario, those heat waves would happen every one to two years. It found that further warming of the earth will amplify permafrost thawing, and the loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of summer Arctic Sea ice.

According to the report, many characteristics of climate change directly depend on the level of global warming, but what people experience is often very different to the global average.

“Climate change is already affecting every region on earth, in multiple ways. The changes we experience will increase with additional warming,” said IPCC Working Group I Co-Chair Panmao Zhai.

There is some hope

The report, however, gave hope that it is still possible from a physical science point of view, to limit global warming to 1.5 degrees which means these changes could be slowed and stopped from getting worse.

“If we reduce emissions globally to net-zero by 2040 there is still a two-thirds chance to reach 1.5 degrees and if we globally achieve net-zero emissions by the middle of the century, there is still a one-third chance to achieve that,” said Dr Friederike Otto, Associate Director of the Environmental Change Institute at the University of Oxford and one of the authors of the IPCC report.

The report said while benefits for air quality would come quickly, it could take 20-30 years to see global temperatures stabilise. “To limit global warming, strong, rapid and sustained reductions in CO2, methane and other greenhouse gases are necessary. This would not only reduce the consequences of climate change but also improve air quality and have a lot of other co-benefits,” Otto said.

For the first time, the sixth assessment report provides a more detailed regional assessment of climate change, including a focus on useful information that can inform risk assessment, adaptation, and other decision-making, and a new framework that helps translate physical changes in climate into what they mean for society and ecosystems.

Source: 09 August, 2021, India Today