The UK government is to set standards for carbon offsetting schemes to bring "greater clarity" to the industry.
Consumers want to limit the damage of their emissions
The move comes as an increasing number of consumers try to limit the environmental impact of actions such as driving a car or flying by plane.
However, carbon offsetting schemes have been attacked for a lack of transparency and inconsistent prices.
Environment Secretary David Miliband said the voluntary standards would help consumers pick "genuine" projects.
Trees and bulbs
There are a number of ways that consumers can offset their carbon emissions, including paying for trees to be planted and buying energy-efficient light bulbs for use in developing nations.
The worry for the government has been that the benefits of many of the projects have proved difficult to verify and may be open to abuse.
NEW UK STANDARDS
Schemes must have certified credits to meet the standards
The key is less the type of scheme and more how projects are assessed to meet international standards
The Kyoto protocol's CDM produces such credits
CDM schemes - such as methane capture or windfarms - only take place in the developing world
Many small schemes - like installing more efficient cookers in developing nations - are not certified under Kyoto
Credits under the EU's carbon allowances system also qualify
The Department for Environment, Food and Rural Affairs (Defra) has named just four offset providers that meet its new guidelines - Pure, Global Cool, Equiclimate and Carbon Offsets.
However, Defra underlined that these non-binding standards were the start of a consultation period, not an accreditation scheme.
A Defra spokeswoman said the move aimed to bring "greater clarity and certainty for business and consumers".
But she added: "It shouldn't be expected that everyone will meet it immediately, and we will be continuing to work with the offsetting industry and those who wish to offset."
The new standards will be based only on projects that can be certified, including flexible schemes agreed under the Kyoto Protocol on climate change.
But the standards have met with mixed reactions. Mike Mason from offset firm Climate Care told the BBC he did not approve of the government's approach.
"They've proposed a standard with no consultation with the industry and the standard that they're proposing, I believe, will do the environment a disservice," he said.
"It's not that we want low standards, but that we want things that amplify the existing arrangements and make use of the voluntary sector, not shut it down."
Meanwhile, others are grateful that what has been a hitherto confusing industry is being examined and made more clear.
"I'm delighted that the government has finally acted," said Phil Levermore, managing director of Ebico - the not-for-profit energy firm behind Equiclimate, which meets Defra's standards.
"Our research shows that many people who would consider offsetting are confused by the various ad hoc project-based schemes on offer."
Some carbon offsetting schemes have been criticised for failing to bring about real carbon emission reductions - because projects are hard to verify, reductions are only temporary or the reductions would have happened anyway.
UK charity Pure, for example, does not run any projects itself, but invests donor money into certified credits.
The code of practice proposes that offset providers supply consumers with clear information and transparent prices.
Environment Secretary David Miliband said offsetting "isn't the answer to climate change".
"The first step should always be to see how we can avoid and reduce emissions," he said.
But offsetting has a role because "some emissions can't or won't be avoided", he added.