Michael E. Mann is a professor of atmospheric science and director of the Earth System Science Center at Penn State University. He co-authored, with Washington Post cartoonist Tom Toles, “The Madhouse Effect: How Climate Change Denial Is Threatening Our Planet, Destroying Our Politics, and Driving Us Crazy.”

My Penn State colleagues looked with horror at the police tape across my office door.

I had been opening mail at my desk that afternoon in August 2010 when a dusting of white powder fell from the folds of a letter. I dropped the letter, held my breath and slipped out the door as swiftly as I could, shutting it behind me. First I went to the bathroom to scrub my hands. Then I called the police.

It turned out to be cornstarch, not anthrax. And it was just one in a long series of threats I’ve received since the late 1990s, when my research illustrated the unprecedented nature of global warming, producing an upward-trending temperature curve whose shape has been likened to a hockey stick.

I’ve faced hostile investigations by politicians, demands for me to be fired from my job, threats against my life and even threats against my family. Those threats have diminished in recent years, as man-made climate change has become recognized as the overwhelming scientific consensus and as climate science has received the support of the federal government. But with the coming Trump administration, my colleagues and I are steeling ourselves for a renewed onslaught of intimidation, from inside and outside government. It would be bad for our work and bad for our planet.

(The Washington Post)

Donald Trump, of course, famously dismissed global warming as a Chinese hoax and “a big scam for a lot of people to make a lot of money.” This month, he framed his position on climate change as “nobody really knows — it’s not something that’s so hard and fast.” He has vowed to cancel U.S. participation in the Paris climate agreement and threatened to block the Clean Power Plan, a measure to reduce carbon emissions in the power sector.

The strong anti-science bent of his advisers is similarly ominous. Among the members of his Environmental Protection Agency transition team are some of the most notorious climate change deniers. One adviser has threatened to cut NASA’s entire climate research program , disparaging it, with no apparent sense of irony, as “heavily politicized.”

Trump’s nominee for energy secretary, Rick Perry, wrote in his 2010 book that “we have been experiencing a cooling trend” (in reality, 2016 will go down as the third consecutive record-breaking year for global temperatures), and when he was governor of Texas, his administration removed all references to climate change from a report on rising sea levels. Trump’s proposed interior secretary, Rep. Ryan Zinke (R-Mont.), plays down climate change as “not proven science” and has a dismal record on the environment, voting again and again in favor of the fossil fuel industry. Rex Tillerson, Trump’s choice for secretary of state, represents those interests even more directly as the chief executive of ExxonMobil.

And then there’s Scott Pruitt, the attorney general of Oklahoma and Trump’s pick for EPA administrator. When it comes to fossil fuel advocacy and climate inaction, Pruitt checks all the boxes. He has received substantial campaign funding from the oil and gas industry and is a self-professed “leading advocate against the EPA’s activist agenda.” Among the various lawsuits he has brought against the agency is his current suit against the Clean Power Plan. Fox, meet henhouse.

But it is the disrespect Pruitt displays for science that my colleagues and I find most distressing. Consider this statement from a commentary he published this year in National Review: “Scientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind. That debate should be encouraged — in classrooms, public forums, and the halls of Congress.” The assertion betrays profound ignorance of the state of our scientific knowledge (which is that climate change is real, human-caused and already disruptive). Even more pernicious, Pruitt actively encourages others to promote that ignorance, even to children, who will most bear the brunt of unmitigated climate change.

Add to all this the Trump transition team’s alarming request that the Energy Department identify employees and contractors who have been involved in climate meetings during the Obama administration. Trump’s people backed away from the request Wednesday, stating that it had not been authorized. Still, it was enough to prompt a massive effort to archive government climate data in ways that would protect it from Trump administration tampering. It was enough to motivate my fellow climate scientists and me at an annual meeting in San Francisco this past week to stage a rally in support of science. “This is a frightening moment,” Harvard professor Naomi Oreskes told the crowd. “We have seen in the last few weeks how the reins of the federal government are being handed over to the fossil fuel industry.”

We are afraid that four (possibly eight) years of denial and delay might commit the planet to not just feet, but yards, of sea level rise, massive coastal flooding (made worse by more frequent Katrina and Sandy-like storms), historic deluges, and summer after summer of devastating heat and drought across the country.

We also fear an era of McCarthyist attacks on our work and our integrity. It’s easy to envision, because we’ve seen it all before. We know we could be hauled into Congress to face hostile questioning from climate change deniers. We know we could be publicly vilified by politicians. We know we could be at the receiving end of federal subpoenas demanding our personal emails. We know we could see our research grants audited or revoked.

I faced all of those things a decade ago, the last time Republicans had full control of our government.

Before an important climate bill vote in 2005, Sen. James Inhofe (R-Okla.) — sometimes called “Senator Snowball” for his stunt introducing a snowball on the Senate floor as ostensible evidence against global warming — attacked me by name in a Senate speech, maligning my research methods and findings.

Later that year, Rep. Joe Barton (R-Tex.), then chairman of the House Energy and Commerce Committee — like Inhofe, a leading recipient of fossil fuel funding, and known for his apology to BP after the Deepwater Horizon Gulf of Mexico oil spill — threatened a congressional subpoena against me to obtain all the correspondence, notes and back-of-the-napkin scribbles spanning my entire career.

I’ve also been harassed at the state level. In Pennsylvania, an organization funded by conservative Richard Mellon Scaife persuaded Republican state senators to threaten to hold my university’s funding hostage until “appropriate action” was taken against me. In Virginia, then-Attorney General Ken Cuccinelli, a tea party Republican, sued the University of Virginia for all my personal emails from when I was teaching there. After Cuccinelli was unsuccessful, a Koch brothers-funded front group attempted to sue for the same emails. That effort, too, was ultimately blocked by the Virginia Supreme Court, which ruled that unpublished research should be protected in the interest of academic freedom.

In all, I’ve been through roughly a dozen investigations prompted by climate change deniers. Each time, I’ve been exonerated. Investigators find that my methods are sound and my data is replicable. (And, indeed, I’ve been recognized by the scientific community with numerous awards and accolades for my work.) But by then, much time has been lost, expense has been incurred and I’ve endured abuse and vilification.

And then there have been the threats of violence. I’ve received email warnings that “the public will come after you,” suggesting that I’ll find myself “six feet under” and hoping to read that I had “committed suicide.”

Such threats could spike again under a president and Congress hostile to climate science. As we’ve seen recently, a segment of Americans is receptive to fake news, and some are eager to act on it. Wild conspiracy theories have propelled a woman to make death threats against the parent of a child killed at Sandy Hook Elementary and motivated a man to discharge an assault rifle in a family pizza restaurant in Washington.

I fear the chill that could descend. I worry especially that younger scientists might be deterred from going into climate research (or any topic where scientific findings can prove inconvenient to powerful vested interests). As someone who has weathered many attacks, I would urge these scientists to have courage.

The fate of the planet hangs in the balance.

Twitter: @MichaelEMann