Few things strike fear into the hearts of politicians like a disgruntled grandparent entering a voting booth. Seniors wield immense political power in the United States, a fact made plain by their voting record. In the 2014 midterm elections, a year of historically low voter turnout, nearly 59 percent of adults aged 65 and older pulled the lever on Election Day. Just 23 percent of 18- to 24-year-olds bothered to do the same. It’s numbers like these that have made Social Security and Medicare the third rail of American politics.

So, what happens when America’s seniors find out what climate change means for their grandkids?

Recently, dozens of retirees descended on Capitol Hill to advocate for climate action. Organized by the Conscious Elders Network, the Grandparents Climate Action Daybrought together seniors from around the country. Following a day of training, during which renowned NASA climatologist James Hansen spoke to those assembled, the gray-haired activists headed for the Hill. They urged their representatives to support the Clean Power Plan and they advocated for pricing carbon emissions using systems like cap and dividend.

Grandmothers and grandfathers even formed a flash mob in the cafeteria of the Longworth House Office Building, dancing and singing about the need to address climate change.

It was an inspiring sight, and a reminder that old age does not destine one to political irrelevance. “We represent a very big block of voters,” said John Sorensen, co-founder of the Conscious Elders Network. He pointed to his peers, who were gearing up to lobby their member of Congress. Said Sorensen, “There’s a lot of people that don’t want to go play shuffleboard and bingo. They want to go do stuff.”

For the seniors in attendance, that means fighting to safeguard an uncertain future. Sunny Thompson, a small business owner from Ashford, Washington, said, “If you have children or grandchildren, or you are an aunt or an uncle, or you just care about life in general, it upwells within you to make sure you’re leaving it in good standing, and we’re not.” It was a sentiment echoed by many of those in attendance.

Erv DeSmet, a retired lawyer from Woodinville, Washington, said, “A special sense that I have is I’m a grandfather. I have four grandkids.” He added, “I’ve come to understand that it’s time for me to open my big mouth and talk about these things.” DeSmet expressed his frustration at the dearth of meaningful climate legislation at the federal level. As he correctly noted, “A majority of people want some action on the climate; It’s not, ‘You lose, we win.’ No, it’s ‘everybody wins.’”

Although casual observers of politics will note that common sense often carries little weight on Capitol Hill, lawmakers answer to political pressure. They answer to the threats of party leaders, to the pleas of rich financial backers, and to the angry letters of aggrieved constituents. For Thompson, Desmet and the rest of the elder activists, power and influence comes less from the strength of their argument than from the strength of their numbers. As they quietly mill about a congressional waiting room, they serve as a visible reminder of what many voters care about: climate change and environmental care.

If the lawmakers don’t respond to their concerns, they say, there’s always Election Day.

Jeremy Deaton writes for Nexus Media, a syndicated news service covering climate, energy, policy, art and culture. You can follow him @deaton_jeremy.