The Paris Agreement of the United Nations is a global effort to prevent an increase in the Earth’s climate of 2°C. Almost every country on the planet has agreed to do what it takes to prevent this level of warming becoming a reality – minus the United States, the only country to withdraw. But now, a collaborative research team from China has published a new analysis that predicts the Earth’s climate could increase by 4°C by 2084, compared to pre-industrial levels.
Researcher Dabang Jiang of the Institute of Atmospheric Physics of the Chinese Academy of Sciences and his team used the parameters of a scenario in which there was no mitigation of rising greenhouse gas emissions. They compared 39 coordinated climate model experiments from the fifth phase of the Coupled Model Intercomparison Project, which creates and reviews climate models in order to ensure the climate simulations are as accurate as possible.
The results showed that most models project an increase of 4°C as early as 2064 and as late as 2095 in the 21st century.
“A great many record-breaking heat events, heavy floods, and extreme droughts would occur if global warming crosses the 4 °C level, with respect to the preindustrial period,” says Jiang. “The temperature increase would cause severe threats to ecosystems, human systems, and associated societies and economies.”
This temperature increase is a result of more annual and seasonal warming over land than over the ocean, and significant warming in the Arctic. Precipitation would likely increase in the Arctic and the Pacific, and the variability of temperature throughout a year would be lower in the tropics and higher in the polar regions.
“Such comparisons between the three levels of global warming imply that global and regional climate will undergo greater changes if higher levels of global warming are crossed in the 21st century,” says Jiang.
The research team is continuing to study the changes that are associated with a 4°C increase in extreme climates. “Our ultimate goal is to provide a comprehensive picture of the mean and extreme climate changes associated with higher levels of global warming based on state-of-the art climate models, which is of high interest to the decision-makers and the public,” says Jiang.