President Obama’s legacy on clean energy and climate will be widely considered one of his greatest achievements -- and one of his most polarizing endeavors.

In a recent victory, the president helped finalize the most ambitious international climate agreement to date. In last night’s State of the Union address, the final one of his two-term presidency, Obama engaged critics of his climate action plan head on.

“Look, if anybody still wants to dispute the science around climate change, have at it,” he said. “You’ll be pretty lonely, because you’ll be debating our military, most of America’s business leaders, the majority of the American people, almost the entire scientific community, and 200 nations around the world who agree it’s a problem and intend to solve it.”

Putting the science aside, the solutions to climate change will also bolster the U.S. economy, he said. “Why would we want to pass up the chance for American businesses to produce and sell the energy of the future?”

While he can’t take credit for everything, there’s no denying the U.S. advanced energy sector has boomed on Obama’s watch.

Shortly after taking office, Obama spearheaded the American Recovery and Reinvestment Act of 2009 (ARRA), which included more than $90 billion in government investment and tax incentives to boost the clean energy economy. Investments were made in everything from advanced clean-energy manufacturing to efficiency retrofits to smart meters.

“Those were serious dollars for clean energy -- an order of magnitude greater than what has been seen before,” said Malcolm Woolf, senior vice president of policy and government affairs at Advanced Energy Economy, who testified on the ARRA bill in 2009 as chair of the National Association of State Energy Officials. The Recovery Act allocated roughly $3 billion for state energy programs.

Obama built on this foundation by enacting regulations that will double the fuel efficiency of cars and light trucks by 2025, as well as issuing the first-ever set of standards for heavy-duty vehicles.

His administration then turned to stationary polluters with the launch of the Clean Power Plan. Last August, the EPA finalized historic carbon regulations on new and existing power plants that will cut pollution from the power sector by 32 percent by 2030 and spur investments in clean energy.

In another major win for clean energy, the Obama administration helped push through five-year extensions of the Production Tax Credit for wind and the Investment Tax Credit forsolarin the final moments of last year.

"Obama got us past the tipping point"

One indication that Obama’s strategy has worked is that clean technologies like wind and solar have reached the point where they’re economically viable, said Woolf. Wind power PPAs in the U.S. are now coming in below 2.5 cents per kilowatt-hour, while utility-scale solar project prices have hit record lows and the overall solar industry booms. According to GTM Research, cumulative solar capacity in the U.S. has grown by a factor of 33 over the course of Obama’s presidency.

At the same time, corporations are buying more renewable energy than ever before, and a majority of companies have put in place some kind of sustainability plan. Furthermore, grid operators are now starting to see renewable energy as a way to offer affordable, reliable electricity, rather than as a problem.

Obama did not meet his goal of putting 1 million electric vehicles on the road by 2015, but Woolf still counts the initiative as a win. Arguably, Obama’s push for electric vehicles through research and regulations is responsible for spurring automakers from General Motors to Mercedes to Porsche to bring mainstream electric vehicles to market.

The entire suite of advanced energy technologies has been on an upswing. In 2014, the sector grew a record 14 percent -- five times faster than the GDP -- to a market worth of nearly $200 billion, according to AEE.

In addition to specific policy actions, Woolf chalked up the success of the advanced energy sector to the “presidential prestige” Obama put behind the sector.

“He went to so many ribbon-cutting events highlighting this industry,” said Woolf. “It helped encourage investor confidence and enabled these technologies to mature to the point where they reach scale.”

“We’re fairly optimistic [going forward], regardless of the result of the presidential election, because we see the technologies being economically competitive in their own right, so that we’re no longer dependent on the president being the cheerleader,” he added. “Obama got us past the tipping point.”

Still earning his legacy

While Obama has advocated for clean energy over the past seven years, climate policy was not his top priority at the outset. The U.S. was supportive of a deal at the 2009 Copenhagen climate conference, but ultimately the talks failed, in part because of U.S. resistance. And in 2010, Obama chose not to rally behind a Democrat-led climate change bill. Instead, the president focused his political capital on his landmark healthcare law.

Climate became a much stronger focus of the Obama presidency in his second term. “That inaugural address was the turning point,” Heather Zichal, Obama’s former climate change adviser, told the New York Times last fall.

Over time, environmental regulations emerged as an area where the White House could act without hitting congressional roadblocks. It was also a strategic move. Obama could win support from progressives as calls for climate action and opposition to the Keystone XL pipeline intensified, led by groups like 350.org.

But despite his efforts, Obama still has some winning over to do.

“Spurred by the growing strength and diversity of the climate movement, President Obama is the first U.S. president to sincerely champion the fight against climate change,” Annie Leonard, executive director of Greenpeace USA, said in a statement. “However, to secure his legacy, President Obama must pursue solutions that match the scale of the problem, which means keeping fossil fuels in the ground and putting the needs of the people ahead of the polluters.”

Obama said in his speech that he plans “to push to change the way we manage our oil and coal resources, so that they better reflect the costs they impose on taxpayers and our planet.” Environmental groups -- and oil and coal companies -- will surely be eager to learn more.

While U.S. oil and gas production is booming, many people argue that Obama has been a hindrance to the industry overall. According to Frank Maisano, senior principal at the D.C. law firm Bracewell & Giuliani, Obama’s drawn-out rejection of the Keystone XL pipeline has also opened the door for opponents to block infrastructure projects for whatever parochial reason -- that goes for pipelines and transmission projects needed for the Clean Power Plan.

“The way Keystone XL played out has made it much more difficult to win support for all big infrastructure projects -- to build the type of infrastructure projects necessary to have renewable energy projects built out,” said Maisano.

Obama has only paid lip service to the need for infrastructure improvements, said Maisano, which is part of the reason why grid operators have pushed back so strongly against the carbon rule.

A great success. And a failure?

As Obama’s second term winds down, legal suits against the Clean Power Plan continue, a number of states have moved to roll back their renewable energy policies, and public opinion on climate change remains deeply divided.

Many prominent politicians continue to oppose climate action. Sen. James Inhofe (R-Okla.), chair of the Environment and Public Works Committee (who once famously brought a snowball to the Senate floor as evidence against global warming), firmly believes climate change is a “hoax.” Donald Trump and several other presidential candidates are also climate skeptics. And although Marco Rubio says he’s “not skeptical," he believes that Obama’s climate policies will “destroy our economy.”

Many of Obama’s critics also believe that his focus on climate in the wake of the Paris terrorist attacks made the U.S. look weak on national security.

Ironically, one of Obama’s greatest failings is that his advocacy for clean energy and climate solutions may have turned these issues into political punching bags.

“The iPhone 6 is not a partisan piece of technology; it’s a cool device that people like. Because Obama was such a champion for clean energy, he inadvertently made clean energy technologies more partisan than they should have been,” said Woolf. “So it’s interesting to see what might have happened had he not been as engaged. The industry might have lost a market signal, but we might not have the partisan fights that we now seem to have.”

Obama actually acknowledged in his State of the Union address that the political divide that’s grown over the past seven years -- on all issues -- is one of his biggest missteps.

“It’s one of the few regrets of my presidency  --  that the rancor and suspicion between the parties has gotten worse instead of better,” he said.

Obama pledged to try and bridge the divide during his remaining months in office, and called on all Americans “to change the system to reflect our better selves.”