In recent days, nearly two-thirds of the population of the United States of America has been under either a flood warning or watch or a heat advisory. Temperatures in the Atlantic Ocean are the highest ever recorded. Wildfires ravage parts of Greece. A typhoon has forced tens of thousands of people from their homes in Beijing. And July was the hottest month in recorded history.

To face this crisis, we must act quickly on two fronts: fostering international cooperation and holding accountable those most responsible for the crisis in the first place.

The latest report from the United Nations’ Intergovernmental Panel on Climate Change is clear and foreboding. If the United States, China and the rest of the planet do not act swiftly to cut carbon emissions decisively, our planet will face enormous and irreversible damage.

Let me be clear about that last part: If the entire world, led by its largest economies — the United States of America and China — does not get its act together quickly, we will leave our children and future generations a world that is increasingly unhealthy and uninhabitable.

Dealing with this crisis is so difficult and so complicated no individual nation can solve it alone. It is a global crisis. It requires the cooperation of every nation on Earth. Whether we like it or not, we are all in this together. 

For example, the U.S. faces frightening impacts from climate change, but highly populated Asian countries are confronting even worse challenges. Sea levels on China’s coastline are rising more quickly than the global average. Major coastal cities like Shanghai, Tianjin and Shenzhen could face catastrophic flooding in years to come — creating havoc with the entire Chinese economy. Some project that Shanghai, a city of 24 million, could be underwater by the end of the century.

Developing a mutually beneficial relationship with China to save the future of this planet will not be easy. Sadly, “hawks” in both countries are working hard to create a new cold war.

But we — the United States, China and other countries around the world — still have time to aggressively combat climate change and prevent irreparable damage to our countries and the planet.

In addition to fostering international cooperation on climate change, in the United States, and around the world, we all must also ask a very simple question: How did we get here? 

How did we get to a place in time where the health and well-being of the entire planet, and the lives of billions of people, is under enormous threat? 

Recognizing the cause of this complicated crisis clarifies our way forward. Fortunately, the answer is straightforward. The scientific community, for many decades, has made it crystal clear that climate change — and all the dangers it poses in terms of drought, floods, extreme weather and disease — is the result of carbon emissions from the fossil fuel industry. 

In the 1950s, physicist Edward Teller and other scientists warned executives in the fossil fuel industry that carbon emissions were “contaminating the atmosphere” and causing a “greenhouse effect” that could eventually lead to temperature increases “sufficient to melt the icecap and submerge New York.” That’s what they were saying 60 years ago!

The industry’s own scientists agreed. In 1975, Shell-backed research concluded that increasing atmospheric carbon concentrations could raise global temperatures and drive “major climatic changes.” The researchers compared the dangers of burning fossil fuels to nuclear waste. And beginning in the late 1970s, Exxon — now ExxonMobil — conducted extensive research on climate change that predicted current rising temperatures “correctly and skillfully,” according to a recent study.

The fossil fuel companies knew.

They knew they were causing global warming and threatening the very existence of the planet.

Yet, in pursuit of profit, fossil fuel executives not only refused to publicly acknowledge what they had learned, but, year after year, lied about that existential threat. And they continue to fund misinformation campaigns today.

So what happened to the CEOs who betrayed the American people and the global community? Were they fired from their jobs? Were they condemned by pundits on cable television and the editorial boards of major newspapers? Were they prosecuted?

Nope. Not a one of them. These CEOs got rich.

It’s obscene. 

When a criminal walks into a store and shoots the clerk behind the counter, we make the moral judgment that this behavior is socially unacceptable, and that the gunman should be punished. 

When a public official misuses and steals taxpayer money, we make the moral judgment that the embezzler should lose his job and, perhaps, be incarcerated.

Yet, when fossil fuel executives make calculated decisions that threaten millions of lives — and the planet itself — we are told that “it’s just business.”

That’s not acceptable.

That is why, earlier this week, I sent a letter to Attorney General Merrick Garland urging him to bring lawsuits against the fossil fuel industry in relation to its longstanding and carefully coordinated campaign to mislead consumers and discredit climate science in pursuit of massive profits. The letter was co-signed by Sens. Jeff Merkley, Elizabeth Warren and Ed Markey.

Like the tobacco industry before them, the fossil fuel companies’ actions represent a clear violation of federal racketeering laws, truth in advertising laws, consumer protection laws, and potentially other laws. The Justice Department must hold them accountable.

More than 40 states and municipalities have filed lawsuits that seek to hold the fossil fuel industry liable in relation to its campaign of misinformation around climate change. The Justice Department must join the fight and work with partners at the Federal Trade Commission and other law enforcement agencies to file suits against all those who participated in the fossil fuel industry’s conspiracy of lies and deception.

The fossil fuel industry must begin to pay for the extraordinary damage it has caused and continues to cause every day. Climate change is an existential threat to every person on Earth. At every level, in every country, we must work together to save the planet for our kids and future generations. And those most responsible for this global crisis must finally be held accountable.