Environmental teams have urged the prime minister to keep away from watering down laws on local weather change and wildlife safety after Brexit.
The letter, signed by WWF, Greenpeace and others, says motion is required to halt ongoing environmental decline.
The UK authorities beforehand mentioned it will depart the atmosphere in a greater state for future generations.
However the letter expresses concern that Brexit might power ministers to backtrack on this promise.
Quantity 10 mentioned it will examine the letter earlier than responding.
Newspaper reports primarily based on leaked documents have recommended that commerce and progress could be prioritised on the expense of efforts to deal with international warming and the unlawful commerce in wildlife.
The letter says: “We’re alarmed by current media experiences suggesting that the UK’s commitments to tackling local weather change and ending the unlawful wildlife commerce could possibly be watered right down to safe post-Brexit commerce offers.”
It added: “To be a terrific, international buying and selling nation, the UK should ship on its guarantees for the atmosphere and the local weather and honour our worldwide commitments.
“In doing so we’ll assist construct a greener, higher and extra affluent future for everybody, somewhat than driving an environmental race to the underside.”
Marketing campaign teams which have signed the letter embody WWF, the Born Free Basis, Cafod, Mates of the Earth, Greenpeace and Oxfam.
A lot of high-profile people are additionally signatories: they embody Andy Murray, Anna Friel, Will Younger, Lord Stuart Rose and environmentalist Sir Crispin Tickell.
“A majority of environmental protections derive from the EU – we have most likely received the world’s main environmental framework. In order the UK leaves the EU, the chance is that a few of these protections do not get introduced over into UK legislation,” Trevor Hutchings, director of advocacy at WWF-UK, instructed BBC Information.
These protections embody a bundle of laws to make sure the EU meets local weather and vitality targets for 2020. He mentioned the EU establishments additionally offered a strict system of accountability, in order that fines could possibly be invoked if member states didn’t ship on their obligations to the atmosphere.
“We, on the one hand, welcome the federal government’s dedication to nature and to bringing these legal guidelines over by way of the Nice Repeal Invoice… however in current weeks various issues have occurred that query that dedication,” Mr Hutchings defined.
He mentioned this included not solely the leaked memo, but additionally the delayed release of the government’s 25-year plan for nature in England and the Clear Development Plan on decreasing carbon emissions, which Mr Hutchings mentioned was anticipated earlier than March this 12 months.
“Issues like entry to environmental data, the ‘precautionary precept’, the ‘polluter pays’ precept are all established in EU treaties. The sense is that these may not come throughout [into UK law],” he defined.
Spokespeople for Quantity 10 and the Division for Setting, Meals and Rural Affairs (Defra) mentioned officers would have a look at the element of the letter earlier than issuing a response.
However sources mentioned the federal government’s dedication to inexperienced points remained as sturdy as ever.
Nonetheless, some observers throughout the environmental group have expressed issues that inexperienced points might grow to be bargaining chips within the effort to safe commerce offers.
“Environmental rules and requirements do make up so-called non-tariff commerce boundaries – as some folks may understand them,” mentioned Mr Hutchings.
“It most likely does not come as a shock that a few of these non-tariff boundaries might grow to be a central negotiating level for commerce offers with nations which have decrease requirements. That is the worry, although we have no clear proof of that.”
Comply with Paul on Twitter.