Businesses are increasingly advertising how green they are – but often these claims are more about perception than science.

We are being drawn into a world of simplistic solutions. Less plastic, different plastic; eat less meat, keep fewer cattle; swap highly efficient diesel vehicles for unproven electric technology. Green is the new seal of approval, but too often the ideas being sold are not based on rigorous science, particularly in agriculture.

In this area there is little to choose between EU with its Green Deal and the UK commitment to a dramatic reduction in carbon by an arbitrary date. Boris Johnson is demonstrating the zeal of a convert, but his is a political green calculation. Having delivered Brexit on his terms, he now wants to appeal to a different constituency with his apparent belief in green technologies. For someone who admits to not liking detail, it is no surprise the many questions about the practicalities of these policies are ignored.

The EU is showing logic that is lacking in the UK debate. Its green policies are equally suspect, but Brussels is trying to root them in some science. It recently acknowledged its new land use plans would take account of the positives as well as the negatives on carbon associated with farming. This is about its role in locking up as well as generating greenhouse gases. Its new forestry strategy, which has many flaws, also makes the same distinction. This is far from perfect, but it does have some science behind it.

In the UK there is no debate in government around the need for balance and science. This is certainly the case in England and it is a big test of devolution to make sure it stays there and does not become a UK policy. Westminster thinking is that green outcomes will be achieved by giving farming a new role that is not about food production. That is simply wrong.

Covid is continuing to highlight the importance of food security. Trade policy based on taking the UK back to the 1950s, when it depended on food imports from around the world, is neither green or a guarantee supermarket shelves will be full. This is why the EU is developing contingency plans to ensure that in another pandemic food supplies will not be threatened. That is a lead the UK needs to follow. Just because it is the EU doing it does not make it a bad idea.

The list in agriculture where there is a need for greater engagement by the government in London is long. Farmers need to know a lot more about how the new regulatory environment will work and whether the UK will go it alone or continue to follow what the EU does. A big issue for the industry is food promotion. The EU, as our biggest global competitor, is splashing the cash with a budget increase to over £170 million this year to promote food. Its thinking is flawed because it is unrealistically focused on organics. But its slogan – Enjoy, it's from Europe – successfully links promotion to a food production heritage. The UK has an equally proud heritage but turning it into business success is going to demand a lot more imagination and government money than is evident now.

The challenge with green issues is to make solutions more than political sound bites. There are sound ways to encourage green thinking, but they are more about detail and practical thinking than the big gestures politicians love. In agriculture, the greenest solution is to encourage people to eat food produced as close as possible to home. This is a lot more green than importing cheap food, but instead Westminster wants to shoehorn green policies into agriculture that only make sense to those who know little about farming.

This week we were reminded of the vulnerability of the food supply chain, with empty shelves because of Covid-linked supply problems. The UK has taken food for granted for too long. A robust food supply chain offers both security and green outcomes. The EU has announced plans to block imported products linked to environmental damage, particularly deforestation. Targets include palm oil and beef. The UK has hinted at a similar policy and if the government is wise it will see this as a radical green solution. It is however hard to deliver while offering trade deals that would fill supermarket shelves with imported food whose environmental credentials are deeply suspect.