Leading climate scientists are urging the government to pause plans for a billion pound investment in “green technologies” they say are unproven and would make it harder for the UK to reach its net zero targets. Labour has promised to invest £1bn in carbon capture, usage and storage (CCUS) to produce blue hydrogen and to capture carbon dioxide from new gas-fired power stations – with a decision on the first tranche of the funding expected imminently. However, in the letter to the energy security and net zero secretary, Ed Miliband, the scientists argue that the process relies on unproven technology and would result in huge emissions of planet-heating CO2 and methane – gases that are driving the climate crisis. “We strongly urge you to pause your government’s policy for CCUS-based blue hydrogen and gas power, and delay any investment decision … until all the relevant evidence concerning the whole-life emissions and safety of these technologies has been properly evaluated,” they write. The letter, which is signed by leading climate scientists from the UK and US as well as campaigners, argues the plans would: Lock the UK into fossil fuel production for generations to come. Result in huge upstream emissions from methane leaks, transport and processing of liquefied natural gas (LNG) from the US. Rely on carbon capture and storage (CCS) during the production of hydrogen – technology they say has been abandoned in the vast majority of similar projects around the world. Pose a danger to the public if there are any leaks from pipes carrying the captured carbon. At least 45 people had to be taken to hospital after a leak in the US. A recent study found a proposed multibillion-pound CCS project in Teesside would be responsible for more than 20m tonnes of planet-heating CO2 over its lifetime. Dr Andrew Boswell, an energy analyst who carried out the research on the Teesside project, said: “Investing now into CCUS and blue hydrogen would dangerously lock the UK into increasing imports of liquified natural gas, which carry a very-high footprint of methane emissions in its production and transport, to well past 2050.” He said that following David Lammy’s Kew speech last week, in which the foreign secretary, said tackling the climate emergency had to be central to everything the Labour government did, it must now “walk the talk”. A spokesperson for the Department for Energy Security and Net Zero said CCUS would “play a vital role in a decarbonised power system” that would “make us less, not more, reliant on natural gas”. “This technology will boost our energy independence, and the Climate Change Committee describe it as a necessity, not an option for reaching our climate goals.” The spokesperson added: “Through our national wealth fund, we will support carbon capture and hydrogen to make the UK a world leader in these technologies of the future.” However, Claire James, from the Campaign against Climate Change, a pressure group that also signed the letter, said Labour had “a great opportunity” to tackle the climate crisis and create jobs by investing in “basic things we know work” such as insulating homes, renewable energy and public transport. She added: “When it comes to carbon capture and storage, which has a track record of repeated failure, or considering the risks of methane emissions from importing gas to make hydrogen, we can’t see this as a good use of big public subsidies.” Another signatory, David Cebon, a professor of mechanical engineering at Cambridge University, said the government should be 100% focused on reducing carbon emissions through proven technologies. He added: “The CCUS projects (inherited from the previous government’s cosy relationship with the fossil fuel industry) will do precisely the opposite. They will lock the UK into significantly higher gas consumption for the next 30-50 years and will increase energy costs, at taxpayers’ expense.” Cebon said CCUS technology had “a very poor track record for reducing emissions” and came “with significant health, safety and cost risks”. “The secretary of state should think very carefully before embarking on these projects,” he added.