Announcing a target to cut greenhouse gases by at least 100% below 1990 levels in 2050 is a necessary step to tackle the climate emergency. But it won’t be enough on its own

One of Theresa May’s most consequential decisions of her unhappy premiership is to set a legally binding target for the UK to cut its greenhouse gas emissions by 2050. If it were to be achieved, this would mark the end of Britain’s contribution to global warming, apart from the those emissions “exported” by buying products made abroad. It is undoubtedly a very good thing that her successor will not only be left with draft laws to enact, but also with raised public expectation that they do so.

Mrs May’s decision comes not a moment too soon. The influential BP review of worldwide energy use estimates that global CO 2 emissions grew by 2% in 2018, the fastest growth for seven years. This country ought to reach net-zero emissions before the middle of the century. Clear policy direction is essential to change the way we produce, distribute and consume energy. The cleaning of the British economy can be traced back to the landmark decision by the European Union in 2007 to implement “20-20-20” green targets: reducing greenhouse gases by at least 20% below 1990 levels by 2020; for 20% of energy consumption to come from renewables; and 20% reduction in energy use. The impact has been dramatic.

A decade ago, 80% of the UK’s electricity came from fossil fuels. Now, not only is electricity demand falling in the UK, but the country also gets about a half of it from low-carbon sources. What flowed from the historic 2007 EU deal was a series of national decisions in the UK, such as phasing out coal and investing in renewables. Ministers, however, have recently lost the focus on climate change, despite its existential threat, and the UK is recklessly opening new coal mines, extending Heathrow airport and pushing fracking.

The climate emergency requires ministers to dispense with such political expediency. Net zero means no one will be able to emit much greenhouse gas in 30 years’ time. Ministers will have to come up with a route map to deal with the carbon-intensive sectors of transport, heating homes and businesses, and agriculture. In these bits of the economy carbon, emissions are either rising or flatlining. What is needed is a government that will balance the ecosystem, rather than obsessing with balancing its budget.

The market won’t deliver technological change on its own. The state is needed to design regulation so environmental and social objectives can be met. The UK ought to copy California and require carmakers to sell a fixed proportion of their overall sales as electric cars. It must start subsidising bus routes, not cut funding for them. Big cities will need mass transport systems. Agriculture will have to peel itself away from oil-intensive farming. Perhaps the biggest challenge is the heating of homes and businesses, 90% of which rely on fossil fuels. That needs a hydrogen economy built almost from scratch. All this is feasible; the technologies are available and could become much cheaper if they were widely deployed. What has been missing is the political ambition; it is a shame that Mrs May only supplied this as she is departing.