Low precipitation, not rising temperatures, may have caused the 2021 drought
More than 100 scientists gathered at the 47th annual National Oceanic and Atmospheric Administration’s (NOAA) Climate Diagnostics & Prediction Workshop at USU.
As the main coordinator of this NOAA workshop, Assistant Professor Wei Zhang in the Plants, Soils & Climate department chaired the session on hydroclimate, which is the interplay between weather patterns and water systems.
“So basically, we focus on the current efforts to understand and predict the hydroclimate in the Western U.S. Those talks during this session discuss the current efforts and the state-of-the-art modeling and observing systems that are being used to understand the Western hydroclimate,” Zhang said.
Grace Affram, a PhD student in the Zhang lab, is studying the ongoing Western U.S. drought. Using observed precipitation and temperature data, Affram diagnosed the conditions that led to the 2021 drought.
“We thought it was the increase in temperature, because we all know global warming and greenhouse gases increase the temperature. But when we started with this research, we later realized that temperature could only be a temporary, secondary driver," Affram said. "And it was actually the failed 2020 summer monsoon and the low precipitation over the Western U.S. that influenced the drought event."
Her data suggests that the primary driver of the 2021 drought was a diminished 2020 monsoon season, and not an increase in global temperatures.
Zhang said they don’t know the exact mechanism that caused the weak 2020 monsoon, but their model suggests that greenhouse gas emissions made drought conditions 25 times more likely.
“Finding out that human activities are actually causing an increase in this event is alarming. And I feel it's very important to tell people about this so that we know how to use our resources. I feel it's more important to make farmers and other stakeholders know about this. So they know how to manage our water resources, because we know precipitation is reducing, and this is causing a lot of droughts on the land, especially the Western U.S.,” Affram said.