“It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change.”

— Charles Darwin

This has to be an enormously frustrating time for scientists, particularly for those who work in climate, vaccinations and evolution. Despite hundreds of millions of hours of research and testing, large segments of the public continue to ignore their voices, encouraged by those who seem to gleefully embrace the virtues of ignorance over “elitist” science.

Scientists have been warning us about climate change since the 1970s, with articles, seminars and research papers signed by hundreds of top scientists. They have been as clear as scientific integrity allows: Without significant changes in our reliance on dirty fuels, we and our children will face incomprehensible consequences to our environment, weather, food, health and security.

Last week, 772 of the world’s most accomplished climate scientists issued an SOS to the world, through the United Nations, warning about the spread of disease, extreme weather, sea level rise, property losses, threats to the food chain and increasing political instability.

The response to decades of these warnings has been multi-faceted. Industry-funded “movements” have sprung up to undermine science. Vest-pocket scientists have been hired to turn every small unknown into an indictment. Conservative activists and politicians, eager to embrace any argument against government, have been actively enlisted and duly rewarded. Meaningful action has ground to a halt.

But climate change doesn’t care much about politics, and it is accelerating now at a rate that is faster than scientists projected a decade ago.

Today, public attitudes about climate change are shifting as more people see unusual events, around the world and here. USA Today and Stanford polling in December showed that 71 percent say that can see the effects of global warming. Gallup this week reported that 57 percent of Americans now believe that climate change is caused by human behavior.

Meanwhile, an analysis of climate polling shows majority support in every state — red or blue — for offering incentives for solar, wind and water power and limiting greenhouse gases from businesses and power plants.

What is happening with public attitudes about climate change follows a familiar arc that other transformative debates have taken. First comes a long period of discussion, learning, reflection and resistance. Support grows slowly and then accelerates to a tipping point.

Examples abound, ranging from the end of apartheid in South Africa to the fall of the Soviet Union and in the sudden overthrow of dictatorships across the globe. We’ve seen that same progression in America with shifts in public attitudes about race, women, gays and the environment.

Each of those changes simmered quietly over a long period, then heated up and finally and suddenly boiled over. In the end, the rapidity of change after a tipping point was reached has invariably surprised people.

Who in the 20th century, for instance, anticipated a black president? Who imagined that the leading candidate for president today would be a woman? Who foresaw the sudden acceptance of gay marriage? All seemed impossible until they weren’t.

When I was growing up along the banks of the Kennebec River in Waterville, some things were thought to be forever unchanging. Among them were a stinking, Technicolor river, ashtrays in every home, high rates of cancer in almost every family and roadsides littered with trash.

We had a big conversation about all of those things, not unlike the one we’re having now about climate. People offered dire warnings, both for and against change. Groups formed to protect industry or the rest of us. Then change happened.

Today, people fish and swim in the river, returnable bottles are in our garages rather than on the roadsides and ashtrays are more common in antique stores than living rooms.

The tipping point on climate is approaching, not because scientists are becoming better communicators, but because people are seeing climate change both in their backyards and the daily news. Growing seasons are changing. New birds and animals are at the feeders or in the garden. Cod and lobsters are migrating offshore and northward to cooler waters. Increasing acidity and warming water are weakening shellfish and expanding the range of invasive species such as green crabs.

The climate change conversation is broadening from the educated elites to the people who work with their hands every day. And that, more than anything else, tells us that a tipping point is fast approaching.

Alan Caron, a Waterville native, is president of Envision Maine, a nonprofit organization working to promote Maine’s next economy, and co-author of an upcoming book titled “Maine’s Next Economy.” Email at [email protected]