Global warming has burst into national politics as major Democratic 2020 hopefuls release aggressive plans and the party's voters prioritize the topic.

Where it stands: Several polls show climate change has broken through. This month, a CBS News survey found 78% of Democratic voters in early primary states call the topic "very important," putting it behind only health care.

Quick take: Forces prompting the increased attention from Democratic voters and candidates include...

Trump abandoning Obama-era policies.

High-profile Democrats led by Rep. Alexandria Ocasio-Cortez promoting the Green New Deal.

Heatwaves and scientific reports over the last year warning of the dangers of failing to stem emissions.

What they're saying: Zac McCrary with the Democratic polling firm ALG Research said the voter interest isn't a fad. Instead there's been a "fundamental, foundational shift in voters' attitudes, rather than reacting to any given event or point in time," he said.

Voter interest and a record of campaign trail promises could prompt a Democratic president to devote real political capital to tougher policies.

But, but, but: Absent unexpectedly large Democratic gains in the Senate or a change to filibuster rules, major legislation faces daunting odds.

What to watch: CNN will host a presidential candidate forum on climate change in September, and MSNBC is a media partner on another event — strong signals of the topic's entry to the national political stage.

Read more about the impacts of climate change we're tracking: