CORRECTED-ANALYSIS-Will Brexit distract Britain from net-zero emissions goal?

(Clarifies the affiliation of Alyssa Gilbert in the penultimate paragraph by removing the word ‘Research’.)

By Sonia Elks

LONDON, Jan 31 (Thomson Reuters Foundation) - As Britain leaves the European Union on Friday and starts work to rewrite its relationship with the bloc and quickly strike new global trade deals, some fear Brexit may undercut a similarly demanding key pledge to reach net-zero carbon emissions by 2050.

The Conservative government's celebrations on finally reaching divorce day may be short-lived as it now faces the monumental task of simultaneously repositioning Britain's global role and overseeing a massive green overhaul of the economy.

London cannot allow tricky trade and foreign policy negotiations to delay climate action if the 2050 net-zero target is to be met, said Mike Thompson, director of analysis at the Committee on Climate Change (CCC), which advises government.

"This is not about making a few tweaks at the edges of what we are doing," he told the Thomson Reuters Foundation on the shift required to meet the net-zero goal.

"We are talking about a fundamental overhaul of most of the systems that we use in everyday life. We have to start now if we are going to have a chance of meeting this target."

Britain was thrown into political turmoil by the 2016 referendum vote in favour of Brexit, leaving it with the complex task of dismantling years of European regulation and working out new deals to keep borders open and trade flowing.

In the midst of the messy divorce, former Prime Minister Theresa May announced the 2050 net-zero target, which was passed into law.

Climate experts say it will require vast changes across energy policy, transport, infrastructure, land use and diets.

But the country is not yet even on track to meet a lower target of cutting its emissions by 80% by 2050, with the CCC warning the government cannot afford to let Brexit elbow out climate action or result in climate pledges being watered down.

"This is the parliament that has got to crack net-zero really - if we don't break the back of it in this parliament, then we won't be able to make it by 2050," said Thompson.

REGULATION GAPS

Former top government scientist David King has described Brexit as an "enormous distraction" from meeting climate goals.

It will also create gaps in environmental laws and regulations previously covered by Europe, with climate groups saying they are watching closely to ensure those are filled.

Meanwhile, the European Commission has proposed a "Green Deal" that would make the bloc climate-neutral by 2050.

Much hangs on how closely Britain remains aligned to Europe, said Ed Matthew from climate-change think-tank E3G, adding that a trade deal between the two would be "critical" in deciding the extent of collaboration on environmental and climate issues.

"The UK has a choice," said Matthew. "Is it going to align itself with the EU on energy and environmental regulation, or is it going to go its own way?"

A spokesman for Britain's Department for Business, Energy and Industrial Strategy said tackling climate change was a priority, and the government would work with international partners to drive global action on the issue.

"Our net-zero commitment is underpinned by domestic emissions reduction targets that are more ambitious than those set by EU legislation and won't change as we leave the EU," he said in an emailed statement.

TRADE CONCERNS

Under the terms of Brexit, Britain has a transition period until the end of 2020, during which it will attempt to hammer out an ambitious European free trade agreement - or face an economically precarious no-deal situation if it fails.

London also wants to capitalise on its newfound freedom by striking agreements with other trading partners around the world, including the offer of a "massive" deal with the United States from President Donald Trump, a climate-change sceptic.

But there are concerns that any U.S. accord will depend on Britain watering down environmental standards, said Jean Blaylock from the Global Justice Now pressure group.

"Brexit means that the UK will be much more in the position of just having to take what the other side says," she said.

"We will have much less negotiating power - we are seen as in a weak position and it's much harder to ask for any changes in approach."

Thompson of the CCC said any deals must ensure that British efforts to cut emissions from its agriculture are not undermined by allowing imports of competing higher-carbon commodities.

OPPORTUNITIES?

Despite the uncertainties stirred by Brexit, climate experts said Britain was serious about meeting its net-zero target and is positioning itself as a climate leader on the global stage, not least by hosting this year's U.N. climate talks.

There is clear domestic political pressure to act on climate change. In a poll conducted last summer for charity Christian Aid, nearly three-quarters of British citizens said the problem was more important than Brexit in the long term.

And a series of colourful street protests by the Extinction Rebellion grassroots movement in London and beyond has also put climate change firmly on the political map.

Britain's role as host of the U.N. climate conference in Glasgow in November will turn the spotlight on the government to lead the way by announcing new initiatives, said E3G's Matthew.

Meanwhile, as Brexit forces rules and alliances to be remade, some believe the process could help carve out a roadmap to a greener future.

New laws and deals could spur fresh approaches on all sides, said Alyssa Gilbert of the London-based Grantham Institute on Climate Change and the Environment, adding it was now up to Britain to show it could meet the net-zero target.

"This could be a moment for the UK to work with international partners to bring up their environmental and climate standards," she said. "There's everything to play for." (Reporting by Sonia Elks @soniaelks; Additional reporting by Emma Batha @emmabatha; Editing by Megan Rowling and Tom Finn. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's and LGBT+ rights, human trafficking, property rights, and climate change. Visit http://news.trust.org)