By Richard Black
Environment correspondent, BBC News website
Climate campaigners have occupied the offices of one of Britain's leading carbon management companies to protest against carbon offsetting.
Offset funds can be invested in renewable energy projects
London Rising Tide activists say offsetting, which sees firms pay for emissions cuts elsewhere rather than curbing their own emissions, is a scam.
The group has occupied meeting space of the CarbonNeutral Company, formerly Future Forests, in central London.
Offsetting is practised by a number of UK companies and the government.
"The CarbonNeutral Company is working away from solutions to climate change, because offsetting is a smokescreen," Sam Chase from London Rising Tide told the BBC News website.
"It lets us continue with our absurd high emission lifestyle, and lets politicians tell the public they are finding solutions to climate change when in fact they are sweeping the issue under the carpet."
Rising Tide has been invited to give evidence to the All-Party Parliamentary Group on Climate Change (APPGCC), which it says has been "privatised", with its operations co-ordinated by the CarbonNeutral Company.
The politicians' group has already heard evidence from other activists that companies running offset schemes are "seriously misleading" the public.
Speaking for CarbonNeutral, Sue Welland told the BBC: "This group (Rising Tide) has never asked for a meeting with us, so we don't know what they do, and I don't think they know what we do.
"What we do is help companies measure and reduce their emissions; and where they can't reduce their emissions, we help them offset. So we're a carbon management company, not a carbon offsetting company."
The government has endorsed offsetting as a method of curbing greenhouse gas emissions.
"Offsetting isn't the answer to climate change," said Environment Minister David Miliband last month.
"The first step should always be to see how we can avoid and reduce emissions. However, some emissions can't or won't be avoided, and that's where offsetting has a role to play."
The carbon dioxide produced during flights taken by ministers and officials is calculated, and money invested in clean energy or energy efficiency projects in developing countries. In principle, these investments will prevent the same volume of emissions as were generated by the flights.
But activists allege that many schemes funded by companies and government bodies do not generate emissions reductions, and do little to benefit developing countries. They are particularly critical of tree-planting schemes.
The government has just launched a consultation on setting a code of practice for companies and organisations running offset schemes.