MIAMI - The risk of extreme weather such as heat waves, floods and drought will rise significantly even if the commitments in the 2015 Paris climate accord are met, a study warned on Wednesday.
The report in the journal Science Advances analyzes the likelihood of hot spells, dry periods and excess rain in the coming years, all phenomena that are exacerbated by global warming and rising seas.
Already, the dire consequences of climate change are becoming clear. A new record was shattered in 2017 for the costliest year in history for hurricanes, fires, floods, drought and other extreme storm events, totaling $306 billion.
"These rising costs are one of many signs that we are not prepared for today's climate, let alone for another degree of global warming," said lead author Noah Diffenbaugh, a researcher at the Stanford Woods Institute for the Environment.
"We can use this kind of research to make decisions that both build resilience now and help us be prepared for the climate that we will face in the future."
Extreme weather forecast
The individual commitments by more than 190 nations under the Paris Agreement are forecast to limit the warming of the planet to between 3.6 and 5.4 degrees Fahrenheit (two and three degrees Celsius).
But this level of warming is "likely to lead to substantial and widespread increases in the probability of historically unprecedented extreme events," said the report.
"We find that humans have already increased the probability of historically unprecedented hot, warm, wet, and dry extremes, including over 50 to 90 percent of North America, Europe, and East Asia," said the study led by researchers at Stanford University, Columbia University and Dartmouth College.
Under the current national commitments, heat waves are more than five times as likely over half of Europe and one quarter of Asia.
Heavy rains are three times as likely over more than a third of North America, Europe, and East Asia.
The Paris accord aspired for even deeper cuts that would limit warming to 2.7 F (1.5 C).
This more aggressive scenario would limit but not eliminate the risk of extreme weather, the report found.
About 10 percent of most regions of the world would still see a tripling in risk of extreme weather.
And about 90 percent of North America, Europe, East Asia and the tropics "still exhibit sizable increases in the probability of record-setting hot, wet, and/or dry events."
Diffenbaugh said meeting the deeper, "aspirational" goals would make a difference.
"At the same time, even if those aspirational targets are reached, we still will be living in a climate that has substantially greater probability of unprecedented events than the one we're in now," he said.