HER Twitter feed is awash with abuse, detractors dedicate blogs to tearing her down, and there are frequent attempts to get her fired from her job.
But Professor Katharine Hayhoe, the climate scientist who refuses to stay silent, somehow manages to keep smiling.
It is a trait that is part natural disposition and part clever communication strategy. She does not want to fight or instil fear - she wants to engage and encourage action. She hasn't much good news to impart, but a sunny outlook says all is not lost. Not yet, anyway.
Prof Hayhoe travelled to Ireland from her Texas base this week for a series of public talks where she is laying on the line the perils that await us if we do not get climate change under control - while stressing it is not too late for action.
She is packing eight talks into five days, starting at University College Cork last night before heading to NUI Galway tonight, Queen's in Belfast tomorrow, Trinity College Dublin on Thursday and Maynooth University on Friday.
In university settings she is often preaching to the converted but she is happy to take on the deniers, doubters and despairing.
It will not surprise her at all if somewhere along the way she comes up against the view that Ireland is too small to make a difference.
"I have heard that same argument in every single country. I'm from Canada and the number one thing people there say to me is, we're only 2% of the problem so we can't make a difference," she said.
"And in the United States every week I hear people tell me China produces much more than we do, so why does it matter what we do?
"But then in China people would say, per person we are one of the least industrialised countries in the world so per person we really have very little effect.
"This same refrain I hear in every single country when the reality is that we all make a difference.
"Our hands are not the only ones on this boulder trying to roll it up the hill. There are hundreds of millions of hands already on that boulder and the more hands we have the faster it moves."
She expects to hear too that climate change debate in Ireland often deepens the urban-rural divide, with farmers in particular feeling they are under attack.
Prof Hayhoe is a devout Christian, the daughter of missionaries who is married to a pastor, and her faith is an important part of what drives her.
Ironically, it is also among the faith community where she experiences the greatest resistance to her teachings.
"The greatest pushback comes from people I would categorise as political Christians. In the United States, Christianity is primarily associated with politics, not with theology," she explained.
"They view me as a traitor, a heretic, a false prophet. Our greatest hatred is reserved for those we believe are traitors within our ranks."
In Texas, the oil state, Christian, Republican-voting and conservative, she is never far from someone who views her as a traitor.
The online abuse and scary letter writers she can handle herself - but she feels for her employers at Texas Tech University who regularly have to deal with demands for her dismissal.
Prof Hayhoe came to Texas after an academic career that began with a science degree in physics and astronomy from the University of Toronto in Canada.
Climate science became her focus almost by chance, after she took one final semester class in the subject which left her hooked.
Her early research was in climate impact assessments and it remains a core part of her work.
Speaking tours became an add-on after she discovered, perhaps because it was in her evangelistic genes, she was good at it.
Quickly she realised that communicating the science was as important as the science itself, particularly in a field where public buy-in is essential.
She will explain that thinking in another of her lectures here: 'Talking Climate - why facts alone are not enough'.
"Despite all that we know about climate change, there are still people who believe it's just a natural cycle, that it's just something that we have to wait out," she said.
"Maybe some genuinely believe that, but I think many are reacting out of fear which can translate very quickly into anger.
"The world is changing too quickly and their identities and values are being left behind.
"We often think that to care about climate change, we have to be a certain type of person - a city dweller rather than an urban dweller; a liberal rather than a conservative.
"The reality is that we all live on this planet. We all need the water that we drink, the resources that we use to make everything that we have.
"My job is to explain that waiting for all this to somehow blow over is not an option."