(This article was published by BBC Focus on 14th February 2020).

Belatedly, the world has realised it has to eliminate greenhouse gases within a few decades. The UK has promised ‘net zero’ by 2050. Is this is an achievable aim? How much will it cost? In what ways will our lifestyles need to change?

In summary, the answer to these questions is that reducing carbon emissions sharply is feasible but the change will be expensive and requires hard adjustments to some aspects of our lives. It will be almost as disruptive as the first Industrial Revolution. But, at the end of the process of decarbonisation, we might reasonably expect to have built a far safer world and a society that is both more prosperous and more equal.

The UK needs to set out a programme of carbon-cutting actions across all parts of today’s society, starting with energy supply but spreading across activities as diverse as agriculture and clothing manufacture. Alongside the plan, the book also demonstrates how ‘net zero’ can be made politically attractive by improving the availability of decent jobs and by cutting the cost of living.

Many people assume that this country is already well on the route to zero emissions. But the sharp reductions in greenhouse gases that the UK has achieved thus far have almost entirely come from improving electricity supply by switching out of coal and increasing wind and solar power. This was the easy bit. The challenge now gets far more difficult because we still use carbon-based fuels for about half our electricity supply as well as almost all our other energy needs.

We can, of course, increase our low-carbon energy sources by installing more wind farms, on- and off-shore, and by welcoming more solar parks around the country. But, as sceptics are fond of pointing out, the cheapest renewable energy sources do not always provide electricity when we need it. The sun doesn’t shine at night and we can have weeks of low winds around the British Isles.

A clear proposal is that we hugely expand our renewable installations - perhaps twenty fold - so that almost all the time we have enough electricity to match demand. This will be the case even after we have switched as many energy uses as we conceivably can from fossil fuels to electric power, such as by driving battery cars and powering many of our homes with heat pumps.

Oversupplying the UK with renewable power means that most of the time we have too much electricity. Isn’t this wasteful? No, we can use this surplus to generate hydrogen - the key low carbon energy source - by electrolysis. Large numbers of major experiments around the rest of Europe are now looking at using hydrogen to help balance the electricity system. The UK should do likewise but, with the exception of real development on Orkney, interest is limited. Hydrogen stored in depleted oil fields or in underground salt caverns can be used to generating electricity when the wind isn’t blowing either using rapidly improving fuel cells or even modified gas turbines. We can also replace natural gas for domestic use with central heating boilers that burn hydrogen instead.

Over the course of the year we will still have too much hydrogen for our electricity needs. The second use of the surplus will be to provide energy for all the activities we cannot electrify. This will include almost all aviation, long distance shipping and some heavy industrial processes. We can use standard chemical engineering processes to create synthetic alternatives to conventional oil and gas.

Fossil fuels are largely composed of atoms of hydrogen and carbon (hence the name ‘hydrocarbons’). We know from where we are going to get our hydrogen for our alternatives to fossil fuels. Our carbon will come from capturing CO2, either directly from the air or from industrial processes such as cement manufacture. although not yet cost competitive in most circumstances. If we then burn the synthetic hydrocarbons as fuel, the CO2 will return to the atmosphere so the UK will also need to invest in long-term storage for further carbon capture.

We therefore have a well-defined route to ‘net zero’ when it comes to energy supply. But this only covers about two thirds of all emissions. The next most important source of greenhouse gases is agriculture, either in the UK or arising from the growing of foodstuffs that are imported. As is becoming increasingly well understood, cattle farming is a particularly important source of methane which, like CO2, helps heat the global atmosphere. Perhaps 10% of all greenhouse gases arise from cows and other ruminants. Other animals are less bad but are still significant contributors to the climate change problem. It is very uncomfortable to say this but climate stability is impossible to reconcile with today’s levels of meat-eating.

The world’s diet needs to shift towards plant-based foods. Grains, pulses, seeds and vegetables use far less land than meat animals, allowing us to reforest a substantial fraction of the world’s surface. As an aside, global food production is currently about 6,000 calories per person per day. So there’s no shortage of food; it’s just that most of it is fed to animals. And, of course, a varied diet that avoids farmed meat is likely to improve human health in rich countries such as the UK. Artificial meats and new forms of indoor agriculture will help us reduce the area of land we require.

We will also need to create an agricultural system that helps rebuild the depleted levels of carbon in our soils. This means moving away from our destructive emphasis on intensive monocultures and recreating an agriculture that improves local ecologies. As with many recommendations in the book, this change will be highly disruptive and farmers will need to be properly protected.

What else else do we need to do? The next most important sources of emissions are steel-making, cement and fertiliser production. In each case, we can use some of the renewable hydrogen that we generated from surplus electricity production. Steel-makers around Europe, all aware that the coal used in making new metal is having destructive effects on the environment, are committed to using hydrogen for their energy source as soon as possible. Cement is somewhat more difficult but fertiliser production can shift very easily to renewable hydrogen.

Alongside the proposals for the reduction in carbon emissions, we need to examine how the UK can increase the capture of CO2 from the atmosphere. Building a restorative agriculture is one step but needs to be accompanied by a programme of reforestation. The UK is the least wooded major country in Europe and we can comfortably double or triple the land area given over to forests. This will help build a natural sink for carbon worth many tens of millions of tonnes of CO2 per year. It will also help us decrease the £8bn or so that is spent each year on imports of wood products and provide an important source of jobs in rural areas.

What about energy efficiency? The single most important need is for the UK is to improve its almost medieval standards of home insulation. Existing programmes have failed dismally but new approaches towards complete or ‘deep’ refurbishment of houses show enormous promise, though they are likely to be expensive. The scope for high quality job creation is obvious.

Other steps we will all need to take include a move away from flying, better public transport and the creation of large car-free areas across towns and cities to encourage cycling and walking, while reducing the need to own a car. We’ll want to reduce our purchase of clothes, a major current of emissions and environmental degradation, as well as making sure that we create a fully ‘circular’ economy that recycles and reuses everything we need.

There’s no denying the painful nature of many of the changes we need to make to get to zero carbon. It would be nice to pretend that we could continue with minor measures such as banning plastic bags or turning the lights off. Unfortunately, the reality is that we will need to spend at least ten per cent of our national income for the next twenty years on investments to secure a liveable future. The good thing is that the UK - and the rest of the world - has the spare capital to invest on the scale that we require.

And at the end of the process we will have low energy costs, more comfortable housing, better public health, more nutritious food and more jobs embedded in the less prosperous parts of the UK. Put like that, I don’t think we should be too frightened of the challenge.