Human actions still have the potential to determine the future course of the climate through “strong, rapid, and sustained reductions in greenhouse gas (GHG) emissions, and reaching net zero CO2 emissions”, according to the Intergovernmental Panel on Climate Change’s (IPCC’s) latest report.
The Working Group I report, ‘Climate Change 2021: the Physical Science Basis’ is the first installment of the IPCC’s Sixth Assessment Report (AR6), which will be completed in 2022.
It said that the evidence is clear that carbon dioxide (CO2) is the main driver of climate change, even as other greenhouse gases and air pollutants also affect the climate.
The report shows that emissions of GHGs from human activities are responsible for approximately 1.1°C of warming since 1850-1900, and finds that averaged over the next 20 years, global temperature is expected to reach or exceed 1.5°C of warming.
However, unless there are immediate, rapid and large-scale reductions in GHG emissions, limiting warming to close to 1.5°C or even 2°C will be beyond reach, it added.
IPCC said the assessment is based on improved observational datasets to assess historical warming, as well progress in scientific understanding of the response of the climate system to human-caused greenhouse gas emissions.
IPCC Working Group I co-chair Valerie Masson-Delmotte said: “This report is a reality check. We now have a much clearer picture of the past, present and future climate, which is essential for understanding where we are headed, what can be done, and how we can prepare.”
The report noted that climate change is not just about temperature, but is bringing multiple different changes in different regions which will all increase with further warming.
These include changes to wetness and dryness, to winds, snow and ice, coastal areas and oceans, it said.
Masson-Delmotte added: “It has been clear for decades that the Earth’s climate is changing, and the role of human influence on the climate system is undisputed.”
Good Energy chief executive Nigel Pocklington said: “The IPCC has stated that it is ‘unequivocal’ that human action is causing climate change, and its warnings are stark.
“Many people will be feeling overwhelmed, but the good news is that it is equally unequivocal that we need human action to avert the worst.
“That’s why the best antidote to anxiety about the climate crisis is to do something – like switch to real renewable power or clean transport.”
Further AR6 reports are due later in the year from Working Group II covering impacts, adaptation and vulnerabilities, and from Working Group III assessing mitigation options.