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) Something is wrong with humanity. We have a broken relationship with the world.

After decades of inaction to slow climate warming that's causing sea level rise, sea levels are -- wait for it -- rising. A new report projects worse than previous predictions (due to aforementioned inaction), possibly 6 feet in this century.

It could swamp large proportions of cities like New York and Shanghai, as well as island nations, and other places where seawater could displace a newly estimated 187 million people (four times the number of immigrants living in the US). It would be "catastrophic," scientists warn -- meaning, of course, that the United States will ignore it.

This report follows on the heels of one early this month from the United Nations estimating that roughly one million species face extinction because of us.

The United Nations -- or at least the chairman of the panel issuing the report, Robert Watson -- doesn't seem to grasp how bad this is. "The most important thing isn't necessarily that we're losing ... 1 million species -- although that's important, don't misunderstand me," said Watson, a British chemist. "The bigger issue is the way it will affect human well-being, as we've said many times — food, water, energy, human health."

Watson appears to be concerned with wrecking the planet only because it threatens "our economies, livelihoods, food security, health and quality of life." "We care about nature, but we care about human well-being," he said . "We need to link it to human well-being; that's the crucial thing. Otherwise we're going to look like a bunch of tree-huggers."

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In other words, the world is all about us. Nature matters only to the extent that humans get things from it. But that stance is exactly what's causing the planet's problems. It is the problem.

Caring only about people is why we have these problems affecting nature and people. Not caring about nature is degrading the entire planet and its life-supporting systems, causing suffering and misery to life in every corner of the world. Endangering just 100 species constitutes an emergency. Eradicating a million is a catastrophe. And it's well under way.

Consider that humans and our livestock now constitute 96% of all mammals on Earth. Wild mammals are down to a measly 4% of the total. We have wiped more than 80% of mammals off the face of the Earth.

Nearly all the livestock is penned for eventual slaughter, usually in miserable conditions, including dairy cows and laying hens. About a tenth of agriculturally bred varieties of plants and animals have gone extinct as agribusiness has become a global juggernaut, inducing a simplifying sameness into everything as it throttles more and more out of the land.

As crop production has tripled since 1970, and logging increased by 45%, land degradation has now reduced productivity in 23% of tilled lands, "indicating that gains... are often not sustainable," while "annual global crop output is at risk as a result of pollinator loss," according to the UN report. Pesticides are devastating insects, including those our crops crucially need.

Though a third of Earth's land area is farmed or used for livestock, more food doesn't solve the problem of hunger in the face of more and more people. With more food than ever in history, almost 1 billion people face food shortages -- also a historic high.

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Humans have had such a brutalizing effect on the world that we've driven hundreds of species extinct in the last five centuries, with a sharp uptick since the baby boom, when I was born. My arrival and the disappearance of varied multimillion-year-old lineages of animals and plants is no coincidence.

The human population has doubled in my lifetime, but I would not say the world is twice as nice. The fact is there are too many of us or the rest of the planet to bear. Too many for human dignity. Too many to alleviate hunger.

This topic of human population is nearly totally off-limits, though it drives every problem we create for humanity and the rest of the planet. It's not a question of whether there are too many rich people or poor people. Rich people damage the world in rich ways; poor people do their damage in poor ways. And numbers keep poor people poor.

One secret of rich people and their children is: smaller families make for bigger lives. The problem is, rich people help destroy the world with our collective overconsumption. In order to survive on minimal resources, poor people are forced to ruin the land and water around them, burning forests for more scrawny cattle, and eating essentially all the wild animals they can. Being rich or poor doesn't make you a bad person. Eight or 10 billion of us: that's bad.

Look, think of the chytrid fungus, the amphibians' apocalypse that has already caused 90 extinctions, with hundreds more on the way. I t's been called the world's worst invasive killer . Think of the white-nose disease that has killed millions of bats . Or let us pause here to consider one problem among the many, a whale of a problem you could call it.

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Meanwhile, gray whales, who had made a spectacular recovery on the West Coast, have been washing up dead or showing signs of distress. Mainly, they are starving, with a warming ocean being the likely reason for their lack of food.

And since January, 1,200 dolphins have washed up dead on French beaches, just a fraction of what is likely 10,000 or so dolphins drowned in those waters by fishing nets. So that is just a brief and very partial roundup of one group of animals. One could catalog dozens of groups with differing existential problems. If one had the fortitude.

What is wiping out amphibians and bats qualify as plagues; the deaths of whales and dolphins, epidemics of multiple causes. What then would you call something that is wiping out everything besides itself? Here's a short thesaurus of synonyms: disaster, cancer, Armageddon.

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From the standpoint of almost every other living thing, humans, with a strategy of economic growth at all costs, have become a kind of hybrid deadly fungus, predatory lender and concentration camp management agency.

Don't say you are just one person, or ask what you can do. Decide what you will do, whom you will vote for, what you will eat and drive and whom you will talk to about the position of humans and our future prospects for dignity and beauty, at this moment on Earth.