Global warming has increased the severity of the ongoing drought in California, as part of a larger trend of human-caused climate change intensifying dry weather spells, scientists said on Thursday.



Scientists predict that “enhanced drought” will continue in California throughout this century because global warming has “substantially increased” the likelihood of extreme droughts in the state.

Recent studies have looked at climate models to predict the future frequency of droughts while others have analyzed historical records to see the probability of drought. The paper published on Thursday in the journal Geophysical Research Letters, however, looks at how much of the current drought can be blamed on global warming.

Scientists looked at factors that could impact the drought, including temperature, rainfall, humidity, wind speed and other factors and found that climate change intensified the drought in California between 8% and 27% in the period from 2012 to 2014.

Park Williams, a climate scientist at Columbia University and the lead author of the paper, said he hoped the findings would motivate the state to continue thinking about its response to the drought with a long-term strategy.

“California, I believe, has a history of when droughts end, they have a history of discontinuing their efforts to improve resiliency to future drought because those efforts are costly in the short-term,” Williams said.

But this strategy is not sustainable, according to the study. “I hope that the measures that are under way now to improve resilience to droughts don’t end as soon as it gets wet again in a few years,” Williams said.

His comments are particularly prescient as California prepares for rain from the El Niño weather phenomenon – which the National Weather Service said could be one of the strongest to ever hit the state. The storm system is known for bringing heavy rains to California, though it is not expected to have a significant impact on the drought.

A Public Policy Institute of California report released earlier this week cautioned that “it would not be prudent to count on El Niño to end the drought”.

The report predicts that if the current drought continues, it will most acutely harm low-income rural communities and California’s forests and wetlands, putting the region’s biodiversity under “extreme threat”.

The National Oceanic and Atmospheric Administration announced on Thursday that July was the hottest month in history since record-keeping began in 1880. This came a month after scientists announced that the first half of 2015 was the hottest recorded.

Jessica Blunden, a Noaa climate scientist, said that heat records like this were “getting to be a monthly thing”.