US to feel more heat, more often in coming years: study
AFP – Targets set by policy makers to slow global warming are too soft to prevent more heatwaves and extreme temperatures in the United States within a few years, with grim consequences for human health and farming, a study warned this week.
Although the United States and more than 100 other countries agreed in Copenhagen last year to take action to reduce greenhouse gas emissions “so as to hold the increase in global temperature below two degrees Celsius,” a study conducted by Stanford University scientists showed that might not be enough.
Stanford earth sciences professor Noel Diffenbaugh and former postdoc fellow Moetasim Ashfaq wrote in the study, published in Geophysical Research Letters, that “constraining global warming to two degrees C above pre-industrial conditions may not be sufficient to avoid dangerous climate change.”
“In the next 30 years, we could see an increase in heatwaves like the one now occurring in the eastern United States or the kind that swept across Europe in 2003 that caused tens of thousands of fatalities,” said Diffenbaugh, lead author of the study.
“Those kinds of severe heat events put enormous stress on major crops like corn, soybean, cotton and wine grapes, causing a significant reduction in yields,” he said.
Diffenbaugh and Ashfaq used two dozen climate models to project what could happen in the United States if carbon dioxide emissions cause temperatures to rise 1.8 degrees Fahrenheit (one degree Celsius) between 2010 and 2039 — a likely scenario, according to the UN’s International Panel on Climate Change.
If that occurs, the mean global temperature in 30 years would be about 3.6 degrees Fahrenheit (two degrees Celsius) hotter than in the preindustrial era of the 1850s.
Many climate scientists and policy makers have set a two-degree Celsius increase as the upper threshold for temperature rise, saying beyond that the planet is likely to experience serious environmental damage.
But in their two-year study, Diffenbaugh and Ashfaq found that even if temperatures rise by less than two degrees Celsius above pre-industrial conditions, there is likely to be a spike in extreme seasonal temperatures and more and longer heatwaves.
The first impacts could be felt as early as during the next 10 years in the United States, the scientists said.
In the 2020s, an intense heatwave equal to the longest on record from 1951 to 1999 is likely to occur as many as five times a decade in parts of the United States — even if global temperatures rise by only one degree Celsius, it said.
The 2030s could be even hotter, with more and longer heatwaves and a spike in extreme seasonal temperatures in the United States.
Along with rising temperatures, there would be a fall in precipitation and soil moisture could lead to drought-like conditions in parts of the United States, which would harm crop yields and could increase the number of wildfires, the study showed.
“I did not expect to see anything this large within the next three decades. This was definitely a surprise,” said Diffenbaugh.
“It’s up to the policymakers to decide the most appropriate action, but our results suggest that limiting global warming to two degrees Celsius does not guarantee that there won’t be damaging impacts from climate change,” he said.
Geophysical Research Letters is a peer-reviewed publication of the American Geophysical Union.