Theresa May’s premiership is not famous for success. She is not much talked of as a prime minister to be emulated. But in her final days at number 10 she did something that has since been copied by countries, regions, cities and businesses around the world, and the UN is busy encouraging others.

In June 2019, Theresa May made the UK the first major economy to set a legally binding net-zero target for greenhouse gas emissions by 2050. Now the UN reports that 130 countries have either set or are considering setting a target for becoming net zero by mid century. Most are aspirations rather than legally binding, but there is no doubt that the net-zero targets are proliferating.

To understand how popular the net-zero target was when it was first announced, but before it became law, Deltapoll asked a representative sample of people in Britain the following question.

“Reducing UK greenhouse-gas emissions to net-zero involves heavily cutting the use of fossil fuels and finding ways of taking any remaining greenhouse-gas emissions out of the atmosphere. Do you approve or disapprove of changing the law to require the government to reduce UK greenhouse-gas emissions to net-zero by 2050?”

That survey question was repeated in March 2020 and November 2021. The results are in the table below.

Note: Surveys by Deltapoll in June 2019, March 2020, Nov 2021

Support for the net-zero 2050 law is, at 63%, very similar to the 60% it was after it was first announced in June 2019. What is more, the distribution of responses, from “strongly disapprove” to “strongly approve”, was roughly the same all three times the question was asked. With the exception of a decline in “don’t know” from 10% to 6%, and a corresponding small rise in approval, from 2019 to 2020, any differences are tiny and could be due to the random sampling variation that is a normal feature of any opinion poll.

Back in 2019, the net-zero announcement came after record breaking protests and a peak of public concern about climate change. Various polls showed substantial support for Extinction Rebellion, that the environment was one of the top three issues facing Britain, record levels of worry about climate change and widespread willingness to take action.

Yet, there were reasons to think that support for net zero would not hold. The 60% who supported net zero in 2019 included some 13% who did not believe that climate change was mostly human caused. Only 47% both thought climate change mostly due to humans and approved of the net-zero 2050 law.

Rather than crumble because of shaky foundations, support for net zero has remained steady. It was not shaken in March 2020, at the start of the first covid-19 lockdown. It also remained at the same level in the Deltapoll survey taken during the COP 26 UN Climate Conference this month.

Some will take heart that support for net-zero has held up. Others will be dismayed that it has not risen more, especially given the problems of climate change have become more urgent after record and near record global greenhouse gas emissions over the last two years.

Since, current policies, even including pledges, are not enough to keep global warming below the required 1.5C safety level, it is a shame Theresa May did not set more of a trend for actual emissions reductions, as well as target setting.

Stephen Fisher is an Associate Professor in Political Sociology at the Department of Sociology, University of Oxford