* UK has 12-18 month window to set policies-CCC report
* Petrol and diesel phase out needed by 2035 at least
* More carbon capture, hydrogen trials needed
* Plans to adapt to climate change needed
By Susanna Twidale
LONDON, July 10 (Reuters) - Britain has failed to set sufficient policies to combat climate change and must act urgently to cut greenhouse gas emissions to meet its new net zero target, a report by the government's climate advisers said on Wednesday.
The Committee on Climate Change (CCC) report comes after Britain last month became the first G7 country to adopt an ambitious law to reach net zero emissions by 2050.
The report said the lack of policies meant the country was already struggling to meet its old target to cut Britain's emissions of carbon dioxide and other greenhouse gases by 80% compared with the 1990 level by 2050.
"I still don't think the enormity of the task has sunk in yet. It (the net zero target) needs to be the lens through which the government views all other areas," Chris Stark, CCC chief executive said in an interview with Reuters.
He said Britain has a 12-18 month window, ahead of next year's international climate conference which it hopes to host, to get policies in place to make the target a reality and ensure the country's credibility at the event.
The CCC, which is independent of the government, is chaired by former British environment secretary John Gummer and includes business and academic experts.
Stark said Britain must develop plans to curb emissions from transport and phase out new petrol and diesel cars by 2030 or 2035 at the latest, rather than the current 2040 goal.
Climate campaigners have also criticised Britain's decision to back a third runway at London's Heathrow airport which is likely to increase emissions from the country's aviation sector.
When she announced the net zero target, outgoing Prime Minister Theresa May said the country was a world leader in tackling climate change and had cut its emissions while also seeing economic growth.
Britain's greenhouse gas emissions have fallen 43.5% since 1990 largely due to a rapid increase in renewable power such as wind and solar, and a move away from polluting coal plants.
The CCC, however, said the government has been too slow to develop technology to capture, store and use carbon dioxide emissions, held back the development of onshore wind farms, and failed to launch large-scale trials to use low-carbon hydrogen.
Action in the housing and agriculture sectors was also lagging, while tree planting rates in England have been below 5,000 hectares in every year since that was adopted as an aspiration in 2013, the report said.
Under the Climate Change Act, Britain must produce proposals on how it intends to reach its climate targets, set in five-yearly carbon budgets.
The CCC said government policies are insufficient to even meet the fourth (2023-2027) and fifth (2028-2032) carbon budgets set under the old target.
The planet is already witnessing the effects of climate change, and Britain is also not doing enough to make sure it is prepared to cope with its impact such as rising sea levels, floods and more extreme weather, it said.
"Climate change adaptation is a defining challenge for every government, yet there is only limited evidence of the present UK Government taking it sufficiently seriously," the report said.
(Reporting by Susanna Twidale; editing by Emelia Sithole-Matarise)
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