Tim Kaine, the new Senator from Virginia, published a good piece today calling on President Obama to reject the Keystone XL pipeline, not just because of the merits or demerits of the project itself, but because it will “hurt our nation’s work to reduce carbon emissions.” Meanwhile, all indications are that Dem Rep. Ed Markey — one of the leading voices on climate change in the House — is on his way to the Senate to join him.

These two things are related. They are only the latest signs that the Democratic caucus in the Senate is steadily getting greener than ever — which may prove an important counterweight to the climate denialism that continues to persist among Republicans.

It’s been widely noted that recent years have resulted in an influx of new, energetic liberals into the Senate. As Reid Wilson detailed recently, a new, “younger generation of Democratic senators” all but ensures the Democratic Party’s “long-term liberalization” on issues from gay rights to immigration to filibuster reform.

With Obama set to mount a new push for climate change this summer, the emphasis on climate change in particular among many of these new Senators is noteworthy and could prove extremely consequential. There are a number of examples of this. Kaine’s opposition to Keystone contrasts sharply with predecessor Jim Webb’s reluctance to support climate change legislation. Markey coauthored the first major legislative response by Congress to the climate crisis.

Tammy Baldwin, the new Senator from Wisconsin, helped author that legislation and has a strong environmental rating from green groups. Martin Heinrich, the new Senator from New Mexico, devoted his maiden speech in the Senate to climate science and the need to pioneer new energy technology. Heinrich and Chris Murphy, the new Senator from Connecticut, both began their careers in conservation. They recently declared in a joint statement that protecting the environment and investing in clean energy are national priorities, and vowed to keep pushing Congress in that direction. (This trend could escalate: Dem Rep. Gary Peters, a leading contender for Michigan’s open Senate seat, has garnered attention for his aggressive criticism of the negative environmental impact of the “pet coke” — a byproduct of the sort of tar sands oil that Keystone would transport — that’s piling up along the Detroit River in his district.)

“As a generational thing, the new Senators that are emerging view climate change as a central issue to be dealt with,” Navin Nayak, the senior vice president for campaigns at the League of Conservation Voters, tells me. “The Senate is getting greener.”

But does this matter, given that GOP hostility to climate science is all but certain to paralyze Congressional action on climate change? Yes. Obama is going to have to resort almost entirely to executive action to move forward on climate issues. Having more voices raised on behalf of the urgency of acting could help blunt the inevitable conservative attacks on the supposed “tyranny” of such actions. And Washington’s unwillingness to act has created a situation in which networks tend to devote woefully little attention to climate issues. The way to change this is for public officials to talk about them — which this new generation is plainly willing to do.

“A lot of these leaders are going to be frustrated that we can’t get stuff done legislatively, but we’ll see a lot of them standing with the president, saying they will support him as he addresses this crisis by executive action” Nayak says. “This is a set of leaders committed to making this a priority fight. Having senators who are willing to lead on this issue and talk about it — and even campaign on it — will matter. A lot.”