A new and dire global warming report from the Obama administration warns of a growing link between human activity and extreme weather across the country -- but Republicans charge the findings will be used to muscle through costly emissions regulations.

The National Climate Assessment, four years in the making, gave a region-by-region breakdown of how climate change is impacting the United States -- in the form of droughts, heat waves and increasingly intense hurricanes, though it is still uncertain how much of that is due to "human activity." The report stopped short of definitively attributing a rash of extreme weather to man-made climate change, concluding "there is new and stronger evidence that many of these increases are related to human activities."

"Climate change, once considered an issue for a distant future, has moved firmly into the present," the 840-page report states. "Corn producers in Iowa, oyster growers in Washington state and maple syrup producers in Vermont are all observing climate-related changes that are outside of recent experience."

The report predicts that the weather-related repercussions of climate change "are expected to become increasingly disruptive across the nation throughout this century and beyond."

The report, though, quickly came under fire from Republicans, who said the administration would use it to push job-killing regulations.

"Instead of making the environment drastically better, the president's strategy will make the climate for unemployed Americans even worse," Sen. John Barrasso, R-Wyo., said in a statement. "The American people have made it clear that they want Washington to focus on the economy and make it easier for them to find good jobs. Once again, President Obama is completely ignoring their concerns -- and doubling down today on extreme regulations that will put more Americans out of work."

In a counterpoint of sorts to the report, Barrasso and other congressional Republicans representing western states released their own findings later Tuesday morning highlighting state efforts to protect the environment. The report highlights local air and water policies, and criticizes "one-size-fits-all" regulations it accuses the administration of imposing.

Senate GOP Leader Mitch McConnell said the cost of such federal regulations will be "borne by the middle class."

The administration's latest report comes as the administration battles congressional Republicans over its climate agenda. White House counselor John Podesta said Tuesday that the report shows there "is no debate" about climate change, and said those who deny it are "working themselves in a froth."

A day earlier, he warned that attempts by congressional lawmakers to block the administration's climate action plan will fail.

Podesta told reporters during a briefing at the White House that President Obama is committed to moving forward with controversial Clean Air Act regulations to cut carbon dioxide emissions for all new coal and gas-fired power plants.

Republicans have branded the president's climate plan as a "war on coal" and have sponsored legislation to roll back planned Environmental Protection Agency greenhouse gas standards they argue will harm the nation's economy.

"They'll find various ways, particularly in the House, to try to stop us from using the authority we have under the Clean Air Act. All I would say is that those have zero percent chance of working. We're committed to moving forward with those rules," Podesta said.

The report also comes as the administration delays a decision on the controversial Canada-to-Texas Keystone pipeline. Environmentalists oppose it, but Republicans and some Democrats are pressuring the administration to approve it.

The climate report looked at regional and state-level effects of global warming, compared with recent reports from the United Nations that lumped all of North America together. A draft of the report was released in January 2013, but this version has been reviewed by more scientists, the National Academy of Science and 13 government agencies and had public comment.

Even though the nation's average temperature has risen by as much as 1.9 degrees since record keeping began in 1895, it's in the big, wild weather where the average person feels climate change the most, said co-author Katharine Hayhoe, a Texas Tech University climate scientist. Extreme weather like droughts, storms and heat waves hit us in the pocketbooks and can be seen by our own eyes, she said.

And it's happening a lot more often lately.

Winter storms have increased in frequency and intensity and shifted northward since the 1950s, the report also claims. Also, it says, heavy downpours are increasing -- by 71 percent in the Northeast. Heat waves, such as those in Texas in 2011 and the Midwest in 2012, are projected in the report to intensify nationwide. Droughts in the Southwest are likewise forecast to become stronger. The report claims sea levels have risen 8 inches since 1880, and projects them to rise between one foot and four feet by 2100.

Critics of the report, however, contend that its dire projections are more political than scientific. "The Administration's Climate Assessment suffers from problems similar to those in reports put forward by the IPCC, while intended to be a scientific document it's more of a political one used to justify more government overreach," said Sen. David Vitter, R-La., ranking Republican on the U.S. Senate Environment and Public Works Committee. "Definitive policy decisions and regional planning based on far too many uncertainties could hurt our nation's economic viability and competitiveness. Look no further than the European nations whose policy decisions led to economic failure."

The Associated Press contributed to this report.