It was announced in December that California is currently experiencing the worst drought in 1,200 years. Looking ahead to the end of the century, conditions don’t look like they’re going to improve. A new open access paper published in the journal Science Advances describes how carbon emissions and a changing climate threatens to bring unprecedented drought conditions to the western states and Great Plains by the end of the century. The droughts will be more severe than the area has seen in 1,000 years. The researchers came to their conclusion after comparing 17 climate models to tree ring analyses covering the last millennium.

"We are the first to do this kind of quantitative comparison between the projections and the distant past, and the story is a bit bleak," senior author Jason Smerdon of Columbia University said in a press release. "Even when selecting for the worst megadrought-dominated period, the 21st century projections make the megadroughts seem like quaint walks through the Garden of Eden.”

It’s no secret that the Western states have had concerns about water security, as the Colorado River Basin is rapidly losing water. This river basin provides water to 40 million Americans in seven states, as well as use in many agricultural applications. As this reservoir continues to get depleted, water prices will increase, rations will go into effect, and it may even lead to food shortages. Unfortunately, this new paper doesn’t seem to indicate this will be improving. In fact, it could be getting a lot worse for a good portion of the country.

"The surprising thing to us was really how consistent the response was over these regions, nearly regardless of what model we used or what soil moisture metric we looked at," lead author Benjamin Cook added. "It all showed this really, really significant drying.”

The biggest factor in the severity of the drought risk is human carbon emissions. If the rates continue on as they have, the consequences will be quite dire. Drastically reducing the amount of carbon put into the atmosphere will lessen the effect, but it won’t be enough to bring the risk down to levels that won’t require big decisions regarding water usage.

"Changes in precipitation, temperature and drought, and the consequences it has for our society—which is critically dependent on our freshwater resources for food, electricity and industry—are likely to be the most immediate climate impacts we experience as a result of greenhouse gas emissions," concluded Kevin Anchukaitis from Woods Hole Oceanographic Institution, who was not involved with the research.