By Rachel Ramirez | CNN
The historic of the West, multi-year drought it is threatening water supplies, food production and electricity generation. Have drained reservoirs at an incredible rate and fueled one of the most extreme wildfire seasons the region has ever experienced.
In California, this summer’s drought conditions were the most extreme in the entire 126-year record, a clear sign of the role climate change plays in the dangerous decline of the state’s water resources. Data from the National Oceanic and Atmospheric Administration shows that dry months are becoming the new normal, and rainy months are becoming less and more distant from each other.
Climate researchers say two main factors contributed to this summer’s severe drought: a lack of precipitation and an increase in evaporative demand, also known as the “thirst of the atmosphere.” Warmer temperatures increase the amount of water the atmosphere can absorb, which then dries out the landscape and prepares the environment for wildfires.
“As we’re getting these very extreme heat waves, the drought gets even worse, although initially the drought is caused by a lack of rainfall,” said Julie Kalansky, a climate scientist at the Scripps Institution of Oceanography in San Diego, previously told to CNN. “But during the dry months of much of the West, these heat waves continue to dry out through the summer and fall.”
According to the Palmer Drought Severity Index, July 2021 was the driest month on record for California since records began in 1895. June, July and August were three of the five driest months on record in the states.
The index, also known as PDSI, takes into account precipitation, runoff, and the amount of moisture that evaporates from the soil. It is widely used by scientists and researchers and is a key factor informing the weekly US Drought Monitor report.
On the PDSI scale, anything below -4.0 is considered “extreme drought”. California’s PDSI this summer ranged from -6.7 in June to -7.07 in July.
This summer tied the Dust Bowl summer in 1936 as the hottest on record in the U.S. It was also the hottest summer on record in California, where persistent heat pushed almost 50% of the state in what the US Drought Monitor classifies as “exceptional drought”, its most extreme classification.
The prolonged drought California is experiencing began in 2012. Since then, the wet months have been rare, with only two notable wet spells: winter 2016-2017 and spring 2019.
Before this year, 2014 held the record for the most extreme drought conditions, with June and July of that year facing similar circumstances to today.
Scientists reported in August that as the planet warms, droughts that may have occurred only once every decade or so now happen 70% more frequently. In the Southwest, National Oceanic and Atmospheric Administration officials predict the drought is about to get worse with La Niña on the horizon.
Justin Mankin, assistant professor of geography at Dartmouth College and co-chair of the NOAA Drought Task Force, previously told to CNN that the only way to replenish the thirst in the atmosphere that is fueling the West’s historic drought is to make deep cuts in global greenhouse gas emissions.
“The long-term fate of this particular drought is murky, although we expect more droughts to look like this in the coming years,” he said. “The temperatures and evaporation demands associated with this drought would not be possible without the global warming that has occurred.”
™ and © 2021 Cable News Network, Inc., a WarnerMedia company. All rights reserved.