Former congressman Beto O'Rourke speaks at the University of Nevada at Las Vegas. (John Locher/AP)

— Former congressman Beto O’Rourke (Tex.), in the first major policy plan of his presidential candidacy, proposed Monday slicing carbon emissions to net zero in 30 years, spending $5 trillion to make the country’s infrastructure more climate-friendly and ending oil and gas drilling on public lands.

O’Rourke, part of a historically large and diverse field of Democrats running for the White House, frequently talks during his town hall meetings about the urgency of reversing climate change. When asked recently to name his “north star” issue, he said, “If we are to do nothing else but save the planet from us, we’ll have been successful.”

It’s the first detailed proposal released by O’Rourke, who is known for his inspirational message, eloquence on the stump and feel-good campaign events but who has been light on policies and specifics. He toured Yosemite National Park on Monday and visited California’s Central Valley to highlight his new initiative, and met with farmers and climate scientists at Modesto Junior College here.

He’s not the only one in the Democratic field focusing on climate change. Washington Gov. Jay Inslee is making the issue the focus of his bid and plans to release his own initiative in the coming days.

O’Rourke’s proposal comes as several Democratic presidential hopefuls are seeking to move beyond the initial buzz of their campaigns and offer distinctive policy ideas. Sen. Kamala D. Harris (Calif.), for example, has proposed boosting teacher pay and expanding gun control. Sen. Elizabeth Warren (Mass.) has made detailed policy plans, particularly on income and racial inequality, a centerpiece of her campaign from the outset.

O’Rourke’s climate policy drew criticism from some climate activists for not being as ambitious as the Green New Deal framework offered by a group of congressional Democrats. That plan — which has animated the left but faced criticism from Republicans and some Democrats as unrealistic — calls for transforming the power sector so that 100 percent of demand is met by “clean, renewable, and zero-emission energy sources” within 10 years.

The longer period laid out by O’Rourke for transitioning the economy to net-zero emissions — 30 years — dismayed some activists.

“Unfortunately, Beto gets the science wrong and walks back his commitments from earlier this month,” said Varshini Prakash, executive director of the Sunrise Movement, which supports aggressive measures to address climate change. “Beto claims to support the Green New Deal, but his plan is out of line with the timeline it lays out.”

A campaign aide disagreed, saying O’Rourke’s 30-year goal, unlike the Green New Deal’s 10-year time frame, does not include solely the power sector but covers all greenhouse emissions — including, for example, gases from transportation and farming. The campaign also said his plan is “in line” with the Green New Deal.

“There is not a more aggressive plan out there,” O’Rourke told reporters Monday.

Others concerned with climate change said the Green New Deal’s 10-year benchmark is aspirational and that O’Rourke’s proposal is a contribution.

“Everything we can do is good,” said Mark Jacobson, a Stanford University professor and climate expert.

Inslee’s campaign issued a statement Monday criticizing O’Rourke’s environmental record.

“Beto O’Rourke will need to answer why he did not lead on climate change in Congress and why he voted on the side of oil companies to open up offshore drilling,” the statement said.

Environmental advocates generally describe O’Rourke’s performance as mixed. Last June, O’Rourke joined House Republicans to support legislation that the League of Conservation Voters said would “slash funding for clean energy programs” and jeopardize some imperiled species.

A campaign spokesperson noted that O’Rourke earned a 95% lifetime score from the LCV. 

And important details about O’Rourke’s climate plan remain unclear. It calls for the “single largest investment in fighting climate change in history” but says only that the initiative would be funded by unspecified “structural changes to the tax code.”

The plan calls for O’Rourke to use his presidential executive power on his first day in office to quickly enact priorities such as reentering the Paris climate agreement and “rapidly accelerating” the proliferation of zero-emission vehicles.

In addition, the plan would set aside funding for parts of the country that feel the brunt of changing weather patterns.