Beijing: The Earth's average temperature may increase by four degrees Celsius, compared to pre-industrial levels, before the end of 21st century, a study claims.
This increase translates to more annual and seasonal warming over land than over the ocean, with significant warming in the Arctic, researchers said.
"A great many record-breaking heat events, heavy floods, and extreme droughts would occur if global warming crosses the four degrees celsius level, with respect to the preindustrial period," said Dabang Jiang, a senior researcher at the Chinese Academy of Sciences.
"The temperature increase would cause severe threats to ecosystems, human systems, and associated societies and economies," Jiang said.
In the study published in the journal Advances in Atmospheric Sciences, researchers used the parameters of 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 develops and reviews climate models to ensure the most accurate climate simulations possible.
The study found that most of the models projected an increase of four degrees Celsius as early as 2064 and as late as 2095 in the 21st century, with 2084 appearing as the median year.
The variability of temperature throughout one year would be lower in the tropics and higher in polar regions, while precipitation would most likely increase in the Arctic and in the Pacific.
These are the same effects that would occur under 1.5 degrees Celsius or two degrees Celsius increases, but more severe, researchers said.
"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," said Jiang.
The researchers continue to investigate the changes associated with four degrees Celsius of global warming 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," said Jiang.
