A March 2017 Gallup poll found that 45% of Americans worried "a great deal" about global warming, and 68% believed humans were causing it. AP

The year has already shaped up to be a flashpoint for environmental issues.

President Donald Trump pledged to withdraw the US from the Paris agreement, a move which led mayors, governors, leading academics, and some of the biggest businesses in the US to start a movement to remain by the Paris Agreement pledges even if the country won't.

And EPA administrator Scott Pruitt plans to pit "red" teams against "blue" teams to debate climate change.

With so much disagreement about environmental policy in the air, many people are turning to their representatives on the issue.

We dug into the League of Conservation Voters' annual scorecard to find the 15 most environmentally friendly US senators, based on the nonprofit political action organization's "lifetime score" of lawmakers' voting records on environmental legislation. The most recent scorecard is from 2016, so new senators who were elected in November weren't included.

Here are the 10 best senators for the environment, according to the scorecard: