Millions of members of environmental groups from the RSPB to the WWF, give money and support to campaign to protect our environment: bio-diversity, flora, fauna, countryside, rivers and seas. Their work is rightly valued, helping to improve our well-being and protect our natural resources. Yet, one organisation, as important, arguably more, doesn’t normally feature in the accolades: that organisation is the European Union.

Our natural world has received untold support through EU protection laws. The EU has been a beacon of environment progress and remains a critical institution for future progress. It is time therefore to widen the referendum debate from arguments on economics and immigration to show that there is much more at stake.

As environmental journalist Michael McCarthy recently outlined in the Independent, European environment laws are the strongest there are: stronger than laws on National Parks and Sites of Special Scientific Interest. These have been agreed by European countries for European countries and that includes the UK. European laws and regulations have helped ensure cleaner beaches, reduced pesticides and toxins, improved air quality, wildlife and natural sites protection, and maintained environmental standards across industries.

‘Outers’ can rail against this: it is the UK they say that should make its own laws and it can put in place equivalent protections. This argument is wrong. Notwithstanding that European laws are our laws too - Britain contributes to the process - common European standards ensure there isn’t a Dutch auction between countries leading to a path of weaker and weaker protections. It provides a strong bulwark against lobbying interests seeking to pick off countries. It provides a mechanism for green NGOs like the RSPB in which to work: it would be much harder for these groups to try and keep track of negotiations and campaigns in all countries on multiple different standards and laws, particularly giving the resources of interests marshalled against them.

Outers might argue that it doesn’t matter what happens in Europe. It is about the UK. Wrong again. Bird migrations don’t respect country boundaries. Air pollution doesn’t stop at Dover or Calais. Seas don’t flow by country designation or waste and effluent keep to borders. Europe is a complex eco-system with Britain a part. Leaving the EU doesn’t change Britain’s geography: the Channel is still the Channel.

This is why EU wide laws are so important. If Britain leaves, Britain citizens will lose leverage over countries that effect our environment and EU countries will lose leverage over the UK. The environment loses. We lose.

The Outers need to explain how withdrawing from the EU will mean protections will be maintained and laws will be as strong? Common standards keeps countries on the right track. Do we honestly think that if environmental laws are recast after leaving the EU that they would be as effective with all the corollary opportunities for lobbying interests to weaken them. This process let’s not forget would happen under a government that has welcomed fracking across our countryside with open arms and has described low carbon measures as ‘green crap’. Many leading Out campaigners share a disdain not only for the EU but for regulation, and environmental protections will undoubtedly be a target.

Of course any country can put in place stronger environmental protections: the UK could do that now. What makes no sense is losing strong collective safeguards which we have through being part of the EU.

Outers are likely to point to the Common Agricultural Policy or the Common Fisheries Policy as examples of EU failure and suggest that the UK should act alone. It is true both policies have not been unqualified successes but there has been some progress and it also shows that environmental issues are not easy to resolve. Importantly the EU provides a mechanism to solve them; and policies can be revised. Taking fish, even if countries instead retain rights in their own waters what about outside territorial waters? Do we really think every country acting alone is the way to manage threatened fish stocks?

We should also not forget one of the very foundations of the EU and one of its greatest achievements. Since the EU’s creation no EU nation has gone to war with another EU nation. What preceded this was near continuous war between nations. Under the EU regular discourse and shared agendas between countries and peoples have created strong bonds. War is one of the most destructive impacts there can be, including on the environment. Why give up on the strongest bulwarks we have against European war?

But the environment argument isn’t just about past successes it is very much about the potential for future ones. Climate change threats are becoming ever more acute with the recent Paris talks highlighting just what is at stake. The EU is a very powerful vehicle to drive change and push for global action, commitments and higher standards globally. It has diplomatic, cultural and economic power. Outers scoff at the economic power of the EU, but they are wrong. The EU is the largest exporter in the world and the largest single market. Its high standards have an impact globally. Of course constant vigilance and campaigning is needed and much more still needs to be done. But, it is simply nonsense that greater progress will be made by the UK acting alone.

These powerful arguments need to be central elements of the referendum debate. I was pleased many were aired at the recent launch of the Environmentalists for Europe campaign. But, there is a danger. Pro-Europeans often talk as though the debate is about laying all the facts on the table and the arguments will be obvious to all. It isn’t that simple. Business organisations like the CBI and EEF have produced lengthy reports and facts and figures. Outers, ignore these. They focus on emotion. Let’s us do the same as our emotional case is much stronger.

Being part of the European Union isn’t a cold economic calculation but it is about being part of a collaboration that has led to a greener Europe, a greener Britain, and a greener England, Wales, Scotland and Northern Ireland. Our European environment protection is working today for us. Our collective European clout will work for us tomorrow.

So Outers, you want out. You want to take this away. You need to tell us how it will be better. But you can’t because it won’t be. It is something Outers don’t want to focus on. It is a gaping green hole in their case.

This is what environment NGOs can deploy. They campaign on a myriad of environmental issues, asking members to lobby MPs, sending in the postcards, emails and petitions. It is time to do the same on the EU referendum. The environmental case can resonate in every area from rural communities to cities (this is not a metropolitan argument) and environment NGOs have the reach to make the argument in all these areas. There are no party political constraints. It isn’t a party political issue and it isn’t an election. It is a policy decision and a big one. It isn’t a time to be timid. It is a time to make a stand, to put Outers on the spot, defend what we have, and explain what is at stake to each and every member. All of us who care about the environment and who campaign on environmental issues have to make sure this argument is made as loudly and effectively as possible.

Jake Sumner is the Co-Chair of SERA, Labour's Environment Campaign. You can find more information about them on their website.