The world must start a "complete" shift to a low carbon economy by 2014 — or risk making dangerous climate change almost inevitable, a report warned today.

The study for conservation charity WWF showed that waiting until after 2014 to fully develop the clean industries needed to reduce greenhouse gas emissions, such as renewable energy, would leave it too late to halt temperature rises of more than 2C.

With low-carbon industry only able to grow at a certain rate, a delay in taking action will make it almost impossible for countries to roll out the technology in time to cut emissions by the amounts needed to avoid the worst impacts of global warming.

The research by analysts Climate Risk (pdf) also said countries must take action across a range of industries at once, including renewable energy, technology to capture the carbon emissions from fossil fuel power stations, preventing deforestation and improving energy efficiency.

If countries fail to tackle emissions across all sectors, they will end up getting the lowest-cost industries up and running first and not developing other areas until they are affordable.

This would make it impossible to meet targets to reduce emissions, the study warned.

The report, published as representatives of 17 countries meet in the UK for the Major Economies Forum as part of efforts to secure a new global agreement on cutting emissions at UN talks in Copenhagen in December, called for long-term investment strategies to support clean technology.

Policies are also needed to improve energy efficiency standards, pay people set tariffs for generating power from renewables and end subsidies for the use of fossil fuels.

Keith Allott, head of climate change at WWF-UK, said: "Clean industry sectors can only expand so far, so quickly.

"If we wait until later than 2014 to begin aggressively tackling the problem, we will have left it too late to ensure that all the low-carbon solutions required are ready to roll out at the scale needed if we intend to keep within the world's remaining carbon budget.

He said the report highlighted the need for a "complete industrial shift towards a low-carbon future" which must begin with a fair and binding deal on climate change in Copenhagen in December.

An over-reliance on carbon trading - which by putting a price on pollution encourages cutting emissions where it costs least - would lead to a step-by-step approach to developing a low carbon economy that would leave the world struggling to reduce emissions on a sufficient scale and speed to prevent climate change, the study said.

The report also said that, even without a price on carbon, renewable energy could become competitive with fossil fuels between 2013 and 2025.