Gordon Brown has today set out his vision for a low-carbon Britain, claiming that the "decarbonisation" of the economy will provide huge opportunities for businesses and create hundreds of thousands of jobs over the next two decades.

In a heavily trailed speech at the Foreign Press Association in London, the prime minister set out the government's climate change strategy, announcing a series of new measures to help the UK meet the soon to be legally binding target of cutting carbon emissions by 60 per cent by 2050.

Brown explained that meeting this target while maintaining economic growth would mean that "within four decades each pound of GDP needs to produce just one sixth to one twelfth of the CO2 equivalent it does today". He insisted this ambitious target was attainable but it would "require no less than a fourth technological revolution".

"In the past, the steam engine, the internal combustion engine and the microprocessor transformed not just technology but the way society was organised and the way people lived," Brown said. "Now we are about to embark on a comparable technological transformation – to low-carbon energy and energy efficiency."

Citing the findings of a new report published today by The Commission on Environmental Markets and Economic Performance, Brown insisted that with the UK's environmental industries already worth £25bn a year and employing 400,000, this technology revolution presented a sizable opportunity.

"Globally, the overall added value of the low-carbon energy sector could be as high as $3tr per year worldwide by 2050, and it could employ more than 25 million people," he said. "If Britain maintains its share of this growth, there could be over a million people employed in our environmental industries within the next two decades."

To help enable this revolution, Brown pledged to "step up support" for clean tech companies, announcing that the first programmes of the £1bn public-private Energy Technologies Institute will be focused on R&D in offshore wind, wave and tidal stream energy, while a £370m domestic Environmental Transformation Fund would be used to help commercialise these products.

Brown also committed to working with employers to expand the government's apprenticeship and "Train to Gain" schemes to ensure the skills demanded by the new clean tech sector are supplied.

In an attempt to quash recent reports that the government was looking to water down EU targets demanding 20 per cent of energy from renewable sources by 2020, the prime minister insisted the government remained "completely committed " to meeting its share.

To achieve this, Brown pledged to do more to remove the planning barriers currently obstructing many renewable energy projects and announced plans for greater co-operation between the departments for business, transport and defence to identify sites for offshore wind farms and new subsidies for tidal lagoons and barrages below one gigawatt capacity, such as those being proposed for Rhyl and Swansea Bay.

He added that a full Renewable Energy Strategy would be published in Spring 2009 detailing how the UK will meet its renewables targets.

The announcement was welcomed by Tony Juniper of Friends of the Earth, but he insisted more details were required on precisely how the government will support the burgeoning renewables sector. "After a summer of lobbying, wriggling, and confusion, the Government's apparent change of heart on renewable power is fantastic news," he said. "But [it] will only be credible if new policies emerge to actually meet targets."

The speech coincides with the formal launch of the government's tendering process for the UK's first carbon capture and storage project, a technology Brown identified as essential to limiting carbon emissions from the US, China and India. He also hinted that should the project prove successful, the government could make the technology's installation mandatory for all new British fossil fuel plants.

In addition, Brown announced the launch of a new one-stop Green Homes advisory service; revealed the UK is pressing to further tighten proposed EU car fuel efficiency standards for 2012 by introducing follow-up rules demanding cars emit no more than 100 grammes of CO2 per kilometre by 2025; and announced the convening of a new forum of supermarkets, the British Retail Consortium and environmental groups to work out the best and quickest way to phase out single-use plastic bags.

Brown also reiterated the UK's support for a global agreement on binding emission reduction targets ahead of the UN conference on climate change in Bali next month. And in a thinly-veiled swipe at the current US administration's opposition to climate change legislation, he drew parallels between the urgent need for investment in clean technologies and the post-1945 Marshall Plan for rebuilding war-torn Europe.