CLICK TO ENLARGE - The climate exposure of 30 California vegetation types under the current time (A) and three future periods: (B) 2011-2039, (C) 2040-2069, and (D) 2070-2099. Red and orange areas above 95 percent are most at risk. UC Davis

If greenhouse gas emissions continue at their current levels, roughly half of California’s vegetation will become highly climatically stressed by the end of the century, according to a new study published in the journal Ecosphere. The stress could threaten the stability of many of the state’s most valuable ecosystems, such as California’s agricultural hub, the Central Valley, and the Sierra Nevada Mountains.

The research found that 61,190 to 75,866 square miles of plants are at risk under current rates of emissions, representing 45 to 56 percent of the state’s natural vegetation. At a more local level, as much as 68 percent of the lands surrounding Los Angeles and San Diego are at risk, the study said.

The study, which examined 30 different vegetation types across the state, warns that these estimates are conservative since they don’t take climate change-fueled increases in wildfire risk or insect attacks into account. Instead, the study only looks at changes in climatic conditions, such as precipitation, drought, and rising temperatures.

The scientists did say that if nations cut their emissions enough to limit global temperature rise to 2 degrees Celsius (3.2 degrees Fahrenheit) or below, the target of the Paris Climate Agreement, it would cut these impacts in half, with just a quarter of the state’s vegetation at risk.

“In California, we have good information on the vulnerability of fish and wildlife to climate change,” Whitney Albright, a project manager with the California Department of Fish and Wildlife and a co-author of the study, said in a statement. “But we were missing this crucial piece of climate risks to underlying habitat. This study helped fill the information gap. We’ve already started to use its data in our conservation planning efforts.”