Online fraudsters are targeting climate scientists through invitations to fake conferences, often at fictional five-star London hotels.
Scientists are sent e-mails directing them to fake conference websites - often imitating the style of real ones.
Typically they are told their travel costs will be refunded - but they have to pay first "to reserve a hotel room".
The "phishing" scammers appear to be after information such as e-mail addresses, as well as money.
One currently live website advertises a conference in February, run by the "Global Warming Volunteer Group" and claiming to "focus on the risks and opportunities posed to society by global warming and... promote the exchange of ideas and learning across the Globe".
The venue is given as the Crown London Hotel - whose address is the same as the real-life Crowne Plaza, just round the corner from Buckingham Palace.
Staff at the Crowne Plaza confirmed they have had at least one call enquiring about the non-existent conference.
The design of the website closely matches that of another supposed London-based conference, this time organised by the "Climate Change Working Group", scheduled for late January at an address in North London that is actually a pet shop.
A call to the contact number provided for the supposed organiser, Dr Louis Clarke, yielded a brief conversation with a man claiming to be Dr Clarke, speaking with an African accent and claiming to be "an expert in climate change issues".
UK phone numbers given in the scams typically begin with 0702 or 0844, which re-direct elsewhere.
The sender of another e-mail invitation, again for late January in London, has adopted the name "Christiana Figueres" - the real-life name of the executive secretary of the UN climate convention (UNFCCC) - and claims funding from the UN General Assembly.
US-based scientist Lee Schipper became aware of the global warming scams in 2009, and receives about one fake invitation each month.
The sums asked for "hotel reservation" are in the range of 200-300 euros per time, he told BBC News.
"My guess is they get a few dozen victims every time - which is not a bad return for essentially no cost," he said.
It is thought that the main targets are researchers in the developing world, whose institutions would be unlikely to have the resources to fund travel to a London conference.
BBC News has seen e-mails from two African researchers who had been in negotiations to speak at fake London conferences, but pulled out when money was asked for.
But Dr Schipper, who works on climate and transport issues at the University of California, Berkeley and Stanford University, said he was aware of cases where money had been exchanged.
And the anti-spam website spaminform.com carries comments from people who have apparently paid sums up front, including one who laments: "I am a victim".
Carole Theriault, a spokeswoman on security issues with online security company Sophos, said scammers could be after information as well as cash.
"These guys sell lists of contact details to each other, but they get a little old and dirty," she said.
"So if you've replied to an e-mail invitation you're saying 'hi, this is me, this is my e-mail address as of now' - that's valuable."
Once e-mail addresses had been passed on in this way, she said, people could find themselves deluged with spam - some possibly containing malware.
Together with Langston James "Kimo" Goree VI, of the International Institute for Sustainable Development in New York, Lee Schipper recently circulated an e-mail to people in the climate change community warning of the scams.
Mr Goree runs a reporting service called the Earth Negotiations Bulletin, which gives detailed accounts of proceedings in fora such as the UN climate summits.
"The scammers have lifted entire portions of the IISD website, doing a search and replace to find IISD and replace it with their own fake name and creating a fake website that they use to fool people into believing that they are legitimate," he said.
"The fake website is very cleverly done... they do speak the 'lingo' fluently."
This is borne out by the "Global Warming Volunteer Group" website, which boasts a scientific programme and a "peer-review" panel to decide which talks to feature, says that proceedings will be published in a scientific journal, and claims a hook-up with the real-life Carbon Zero Project to make the conference carbon neutral.
The "conference" claims to be sponsored by companies such as energy giant BP, accountants PriceWaterhouse Coopers and the National Australia Bank - as well as the "Crown London Hotel".
There are some indications of fakery, though, including citing the UK Government's Department of Climate Change - which does not exist - as a supporter.
A spokesman for BP told the BBC: "We can find no evidence that BP is a sponsor or otherwise connected with the conference advertised on this website.
"We are attempting to contact the organisers for clarification, and our trademarks team will also be checking the website's use of our company name and logo."
Ms Theriault noted that operators had become more sophisticated than the first instance of "climate-phishing" she was aware of - a 2007 email notifying the recipient of "Random Selection as Development/Campaign Partner... We hereby notify you that you have been selected as a partner in the World Campaign against Global Warming..."
At least one of the companies that the fraudsters claim is linked to the "Crown Hotel conference" is taking legal advice, aiming to have the site closed down.
How easy that will prove is another matter.
Lee Schipper has traced several scams over the years back through companies maintaining the fake websites and transmitting the emails; but has had mixed success in closing the operations down, despite flagging them up with UK police.
"The whole idea of tackling these 'crimes under the radar' is not promising," he said.
While some service providers acted to close operations down, others, he said, approached the issue with a "get me a court order or go to hell" attitude - and at times, navigating through a tangled, intercontinental web of ownership proved impossible.
"My fear is not just that people in my field get mud on their faces, but that the line between legitimate activity and crime on the internet is getting thinner and thinner," he said.
"The only way to tackle it will be if all the ISPs come together."