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Editor’s Note: Carl Safina’s most recent book is “Beyond Words: What Animals Think and Feel.” A MacArthur Fellow, he holds the Endowed Chair for Nature and Humanity at Stony Brook University and is founder of the not-for-profit Safina Center. The opinions expressed in this commentary are solely those of the author. View more opinion at CNN.

(CNN) —  

I first saw that climate was changing in 2000, when I went to Antarctica to study penguins. A senior scientist showed me how much a glacier near the research station had shrunk during his 20 years there. I later saw accelerated melting in the high Arctic in Svalbard, Norway, and in southern Alaska, I saw entire forests dying because winters were now warm enough for bark beetle infestations.

Carl Safina
PHOTO: Christian Åslund/Greenpeace NORDIC - Denmark/Finl/© Christian Åslund / Greenpeac
Carl Safina

Close to home, my best friend, a lobster fisherman for 25 years, lost his living over an eight-week span when all the lobsters in Long Island Sound died because the water was now too warm.

It will get worse. The scientifically measured predictions have panned out and the bad times have begun. Centuries of burning fossil fuels and raising countless billions of farm animals have put so much heat-trapping, ocean-acidifying gas into the atmosphere that the planet is overwhelmed.

Raging fires and monster hurricanes, flooded coasts and drowning islands, dying coral reefs and vanishing glaciers – we are witnessing change on a scale that has never happened in human history.

On Wednesday, CNN will be holding a major Town Hall with 10 Democratic presidential candidates, giving each candidate about a half-hour to discuss how they would confront the climate crisis if elected.

Here are a few things I’d like to tell them, and you.

Climate change isn’t what I’d call urgent. Not any more. The time for urgency has passed. Our government and the rest of the world largely ignored the red lights and warning bells. It’s now much bigger, and much worse, than urgent.

Heat waves, wildfires and monster storms are killing people outright. Unstable weather is threatening the global food supply. So is seawater acidification, which is destroying coral reefs that support the ocean food chain.

Rising seas threaten to inundate all low-lying seacoasts and islands.

Climate change so dominates news about the environment that many of us seem to have forgotten that we have a ton of other major problems not directly linked to a warming planet. Shrinking wild lands, polluted air, poisoned waters, exhausted farmlands and depleting irrigation and drinking wells, overfished seas, species going extinct, clearcutting for more farms and more wood, a plasticizing ocean, mercury in seafood. It goes on.

And even if there were no warming, and no acidification, fossil fuels are a nightmare at their sources. There are the spills and blowouts. Fracking and tar sand development is are destroying lands and polluting drinking water; petrochemical refineries and plastic factories have created a so-called Cancer Alley along the Mississippi River.

Meanwhile, the Trump administration wants to weaken fuel efficiency regulations (a move even automakers object to), to roll back methane regulations, weaken endangered species protections, and cut more ancient trees in Alaska’s jewel, the Tongass national forest.

These are not all climate related but they are part of a vile and perverse war against the natural, against the living world and public health.

I’d like to tell candidates, first, focus on cutting fossil-fuel subsidies. Corporate subsidies are nothing more than a deformed kind of socialism where our tax money distorts markets for private gain against public interests. Let’s give capitalism a chance.

Second, restore all the environmental and conservation rules and protections that Trump and his hooligans have undermined.

Political critics of climate science and denialists are simply wrong. But the main deniers are not uninformed. They’re just appallingly self-serving corporate and private entities such as Exxon and the Koch, whose political ideology and societal influence-buying were shaped to serve their fossil-fuel profits, a very practical strategy to make sure nothing changes—for them. They managed to buy influence and strategically mislead our country.

Their strategy has represented not just willful ignorance but the determined destruction of knowledge. Trump, his appointees and his party have waged a prolonged war against science and journalism with a campaign of confusion, wreaking havoc to public understanding and derailing informed, prudent guidance and decision-making.

Climate action is a moral matter. It is a way of caring for our grandchildren, whose world is theirs to live in but not ours. The founders of the United States were moral people in the main. We live in the country and enjoy the freedoms that their vision created. Two and a half centuries after they wrote the Constitution, we thank them every day with the ability to speak our minds, argue our ideas, and rely on their continued guidance through the courts.

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But in their time, the founders had a choice: create the greatest nation with the finest Constitution in the history of the world, or say, “Screw it; let’s just make money.”

Thankfully they chose not to think only of themselves. Those who will live centuries from now will either thank us for doing the same, or curse our willful disregard.