By 2005, when Hurricane Katrina drew Americans' attention to the connection between climate change and coastal flooding, scientists were getting better at making their case to the public. George Bush, whose White House in 2003 deleted Mann's hockey stick graph from an environmental report, began talking about the need for biofuels. Then Barack Obama was elected on a promise to save a planet in peril.
But as Mann lays out in the book, the campaign to discredit climate change continued to operate, largely below the radar until November 2009, when a huge cache of email from the University of East Anglia's Climatic Research Unit was released online without authorization.
Right-wing media and bloggers used the emails to discredit an entire body of climate science. They got an extra boost when an embarrassing error about melting of Himalayan glaciers appeared in the U.N.'s IPCC report.
Mann now admits the climate community took far too long to realize the extent of the public relations debacle. Aside from the glacier error, the science remained sound. But Mann said now, "There may have been an overdue amount of complacency among many in the scientific community."
Mann, who had been at the center of so many debates in America, was at the heart of the East Anglia emails battle too.
Though he has been cleared of any wrongdoing, Mann does not always come off well in those highly selective exchanges of email released by the hackers. In some of the correspondence with fellow scientists, he is abrupt, dismissive of some critics. In our time at State College, he mentions more than once how climate scientists are a "cantankerous" bunch. He has zero patience, for example, for the polite label "climate skeptic" for the network of bloggers and talking heads who try to discredit climate change.
"When it comes to climate change, true skepticism is two-sided. One-sided skepticism is no skepticism at all," he said. "I will call people who deny the science deniers. ... I guess I won't be deterred by the fact that they don't like the use of that term and no doubt that just endears me to them further."
"It's frustrating of course because a lot of us would like to get past this nonsensical debate and on to the real debate to be had about what to do," he said.
But he said there are compensations in the support he gets from the public. He moves over to his computer to show off a web page: I [Heart] Climate Scientists. He's one of three featured scientists. "It only takes one thoughtful email of support to offset a thousand thoughtless attacks," Mann said.
And although there are bad days, he still seems to believe he is on the winning side.
Across America, this is the third successive year of weird weather. The U.S. Department of Agriculture has just revised its plant hardiness map, reflecting warming trends. That is going to reinforce scientists' efforts to cut through the disinformation campaign, Mann said.
"I think increasingly the campaign to deny the reality of climate change is going to come up against that brick wall of the evidence being so plain to people whether they are hunters, fishermen, gardeners," he said.
And if that doesn't work then Mann is going to fight to convince them.
"Whether I like it or not I am out there on the battlefield," he said. But he believes the experiences of the last decade have made him, and other scientists, far better fighters.
"Those of us who have had to go through this are battle-hardened and hopefully the better for it," he said. "I think you are now going to see the scientific community almost uniformly fighting back against this assault on science. I don't know what's going to happen in the future but I do know that my fellow scientists and I are very ready to engage in this battle."