In a huge shift, a majority of Republicans now believe in climate change, but many still don't consider it to be a manmade phenomenon, according to a poll released Thursday.

Of the Republican U.S. adults surveyed by Monmouth University, 64 percent attribute extreme weather patterns and rising sea levels to a changing climate, the new study found. That figure represents a 15-percentage point spike for GOP respondents since Monmouth began asking the question in 2015. In contrast, 92 percent of Democrats share the same sentiment, up from 85 percent in 2015.

While a plurality of Republicans may believe in climate change, only 13 percent think human activity is a driving factor behind the issue. That number is stagnant compared to Monmouth's previous research from 2015. More than 2-in-5 Democrats, however, consider climate change to be exacerbated by people, an increase from 39 percent three years ago.

Although more than half of GOP respondents think the government should take action to mitigate the effects of climate change, 55 percent have little confidence in Congress's willingness to do so in the next few years. The same percentage of the survey takers doubt lawmakers can take meaningful action.

The poll was conducted after the deadly California wildfires broke out earlier this month but before the Trump administration published its National Climate Assessment on Black Friday. Among its findings, the report said climate change could cost the economy hundreds of billions of dollars by 2100 if no changes are made.

President Trump and White House press secretary Sarah Sanders have both questioned whether the report's findings are based on fact. "I don't believe it," Trump told reporters this week, after acknowledging he read "some" of the climate report put together with the help of 13 federal agencies and more than 300 climate scientists.

Trump has largely dismissed climate change during his two years in office and has taken a number of steps that have alarmed climate activists, including announcing the U.S. would exit the Paris climate agreement and overseeing a widespread effort to roll back Obama-era regulations aimed at protecting the environment and climate that he views as constricting on the U.S. economy.

Monmouth University surveyed 802 adults, 244 of whom identified as Republicans, from Nov. 9 to 12 via landlines and cellphones. The results regarding the GOP have a margin of error of plus or minus 6.3 percentage points.