In late March 2012, Kari Norgaard, a University of Oregon sociology and environmental studies professor, was flying home from a conference in England.

She landed in Washington, D.C., checked her email and noticed a message from Marc Morano, a global warming skeptic who runs the blog Climate Depot, criticizing the research she had presented at the conference.

Norgaard was surprised Morano had noticed her, because although her university had written a press release, she hadn't seen much coverage of her research, which focuses on why it is so difficult for societies to take action to respond to climate change.

"I'm not actually sure, at first, how Marc Morano found it," she said. Norgaard ignored the email and hopped onto her final connecting flight to Portland, Ore.

But Morano had also posted about Norgaard on his blog. The headline included her email address and the phrase: "Meet Prof. Kari Norgaard, the woman who wants to 'treat' global warming skeptics."

"I made it to Portland, and by then I was getting just swamped with emails," Norgaard recalled. They "were pretty vicious." As her inbox filled up, Norgaard talked with colleagues and began to realize her situation was far from unique.

"Anytime anybody says anything publicly about climate change, that gets reported in any paper, or in a blog -- that's when you get the emails," said Katharine Hayhoe, a Texas Tech University climate scientist who has at times received hundreds of harassing emails in a single day.

While no one has tracked how many researchers have been on the receiving end of email bombardments, such attacks seem relatively common.

At a time when climate scientists are increasingly encouraged to engage with the media, the activity also reveals them to the blogosphere of skeptics, who, with the push of a key, can focus their followers' attention on a given researcher.

An influx of vitriolic emails can be intimidating, Hayhoe said, but such experiences have also forged stronger links among researchers. "I think these attacks have really helped the climate science community think more about what we have in common than what divides us," she said.

"When I've been attacked in the past, [other researchers] have all been there to offer advice and help," Hayhoe added.

How to be a target
If one were to write a how-to guide for scientists on how to avoid being a target of climate skeptics, step one would be: Stay quiet.

"If you keep your head down and you publish only in scientific journals, and you never issue any press releases and you never talk to the media, you will not get hate mail, and you will not get on the blogs," Hayhoe said.

While being publicized in the mainstream media certainly makes researchers a target, being picked up in the skeptic blogosphere, which includes widely read blogs such asWatts Up With ThatClimate Audit and Morano's Climate Depot, can also lead to scientists receiving email barrages, even when, as in Norgaard's case, the research has not received mainstream media attention.

Step two on the list might be: Stay away from anything that can link you with Michael Mann.

Mann is a Pennsylvania State University professor whose so-called hockey stick graph reconstructed global surface temperatures back to the year 1000 and showed how those temperatures have skyrocketed since the industrial age. Bloggers, in return, have turned his name into an epithet.

Last spring, the following was posted on Climate Depot: "Will media retract claims?! New Hockey Stick Study author Shaun Marcott is now officially the new Michael Mann!"

Marcott's email address was also listed. Morano says he does this because he wants his readers, who number in the tens of thousands on any given day, to "drop them a line, and to let the professors hear from the public," he wrote in an email.

Marcott, a postdoctoral student at Oregon State University, received hundreds of emails over the weeks following the publication of his paper in the journalScience.

The researcher was surprised that his work, a reconstruction of temperatures reaching back 10,000 years, generated so much wrath. He received emails calling him a liar, a fraud and a troll, and was told he would be "spit upon in the streets."

'It is part of the process'
Morano says he targets climate scientists based on how outrageous he finds their research. "When a professor or activist is being particularly ridiculous or insulting, I think I am doing them a favor by posting their publicly available email addresses," Morano said.

The blogger acknowledges that emails targeting climate scientists can often be nasty in tone. He says that as a prominent skeptic, he too has received plenty of hate mail.

"I will have a nice long drive up to DC and have a very short and unpleasant conversation with your ass if you don't stop harrassing scientists," one email sent to Morano reads. Others, he said, have been filled with obscenities.

"I am not worried one bit about someone getting nasty emails, as it is part of the process," Morano said.

Another way to avoid a particularly nasty form of harassment: Don't be a female climate scientist.

According to Hayhoe and Norgaard, women who have been targeted for their climate change research, more than 90 percent of the harassing emails they receive are from men and often include gender-specific abuse.

Some emails tell them to get back in the kitchen. A few are more threatening. "I've filed a police report before," Hayhoe said, after emails have made her feel unsafe or threatened her family.

After Morano posted on Norgaard's research, Rush Limbaugh also picked it up, she said. After that, the researcher was getting an email every couple of minutes. Some were obscene, but there were other, cruder forms of abuse.

"Normally, I try to be a gentleman and treat a woman with respect, but in your case I am making exception. ... You are living proof that even people with Down syndrome can get a Ph.D.," one read.

"When people like you attempt to rape honest people with integrity we will come for you, with our firearms in hand. ... You will reap violence for the violence you sow," another said.

Hayhoe, who has been targeted a number of times, said the goal of such attacks is to quiet scientists. "It is intended to intimidate us, and discourage us, and make us think twice about opening our mouth in public," she said.

Turning hate mail into teachable moments
Hayhoe has used her experiences in communications training sessions for climate scientists that address harassment. "The training session I did last year at the American Geophysical Union conference, it was packed," she recalled. In fact, there was so much interest that the organizers had to turn people away.

Some of the advice Hayhoe offers to scientists includes having others read their emails when they are under attack. She also recommends researchers do not respond to emails or read or respond to online comments on news articles.

"It is so tempting as humans and as scientists to think, 'Oh, that person said something wrong, I'm going to correct them.' Well, you know what, correcting that person is not going to change their mind," she said. "It's going to take up your time and energy, and that's exactly what they want."

Norgaard agreed, pointing out that the correspondence she received was unrelated to her work. "Nobody who wrote an email had ever read anything of mine," she said. "It's not a genuine conversation."

"I have a little folder in my email that says 'hate mail,'" Norgaard added. She may have a graduate student analyze them for research.

While getting hate mail was not an exhilarating experience, the scientists said it connected them more deeply with peers. "It put me in touch with a lot of other higher-up climate science researchers. Other sociologists I admired wrote to me," Norgaard recalled.

Marcott also received encouragement through his ordeal. "I would get [positive emails] every once in a while, and it felt great. I was getting notes from people that I really respect in science, and that was really encouraging," he recalled.

Now, Marcott said, he tries to do the same. "When I notice someone getting beat up on these blogs, I'll email people and just say, 'Look, how are you doing? ... I think you are doing great work,'" he said.

That reinforcement bolstered Camilo Mora, an up-and-coming researcher at the University of Hawaii, when he published a high-profile paper in Nature last fall. The research, which got mainstream media attention, projected at what date certain regions would shift to new climates as a result of global warming (ClimateWire, Oct. 10, 2013).

Morano's Climate Depot pounced: "Meet Prof. Camilo Mora, the man who uses climate models to warn you of 'The Coming Plague,'" read the post, complete with Mora's email address.

After that, Mora received a number of harassing emails and phone calls, he said. But he was able to ignore them. "The reality was that there were just as many supportive emails," Mora said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500