The Environment Correspondent of the British Broadcasting Corporation.
It was supported by all major political parties in the UK.
We stopped putting more emissions into the atmosphere than we took out because of the policy.
The combination of a cost of living crisis and the need to find a new prime minister has called into question Britain's commitment to reach net zero greenhouse gas emissions.
Scientists agree that immediate action is needed if we are to have a chance of keeping global temperature rises below 1.5C.
The net zero policies are based on the fact that humans are warming the planet at an accelerated rate.
There are differences over whether net zero is an opportunity or a cost.
The remaining leadership candidates were asked at the hustings if they were still committed to reaching net zero.
According to a source in the room, the Foreign Secretary, the Chancellor and the Trade Minister said they would honor the 2050 commitment. The chair of the Foreign Affairs Select Committee, the former equalities minister, and the Attorney General all said they might try to change the date.
On the day after, Mr Tugendhat told journalists that he was still committed to 2050, but nobody had set out a path to achieve it.
"Pursuing net zero presents a huge opportunity for jobs and growth that will provide millions of new jobs," saidPenny Mordaunt.
Kemi doesn't want to. She called net zero policies "unilateral economic disarmament" and "arbitrary" She told The Times that people didn't want to answer difficult questions about how we should generate our electricity and instead wanted the government to do something crazy.
As Chancellor and now as a leadership candidate, Rishi Sunak has not talked about net zero. He was accused of blocking green policies that had spending implications while he was in the Treasury, but he promised to make the UK the first ever net zero aligned global financial centre.
Liz Truss did not mention the issue. She cut subsidies for solar farms.
Tom Tugendhat, a backbencher, has not said much on the issue in this campaign, but he did say that tackling climate change is a fundamental principle of the conservative movement.
There are a lot of people who question the cost and the speed of change of the climate. They asked if high energy prices and rising inflation meant a slowing down or pause, with meaningful action pursued in better times.
Important decisions will be made by the new prime minister in order to decide if the net zero goal is still reachable.
Should the UK develop its own sources of fossil fuels through fracks and new gas and oil fields in the north sea? Is there a coalmine in Cumbria? Is it possible to make it easier to build a wind turbine? Is the government doing enough to help people save energy?
The green levy is in the crosshairs of several leadership candidates.
There is a mix of social and green programmes in the levy. It funds schemes that support efficiency improvements in homes and businesses, help vulnerable people, and encourage the take-up of renewable technology.
At the hustings, both Liz andPenny said they would be suspending thelevy.
"Driving up energy costs to hit net zero, for example, comes at a greater cost for those places and parts of our economy that are still industrial," Kemi said.
The levy would be kept by Rishi Sunak.
The green levy has crept up on a typical bill as bills have sky rocketed. The percentage of the typical bill has fallen from 12 percent to 8 percent.
What would happen to the programmes which the green levy supports? Many are geared towards the poor and vulnerable. Others are the result of long standing agreements with energy companies.
Daniel Newport, head of Net Zero at the Tony Blair Institute for Global Change, said that it would be difficult to stop them even if the prime minister was determined.
He said that the Treasury would pay for it rather than just stop it.
It would be paid out of general taxation.
The pitches from the leadership candidates have been designed to appeal to the members of the Conservative party, who will have the final say. Both supporters and critics of net zero think their views are moving in a different direction.
The head of the Net Zero Scrutiny Group, Craig Mackinlay, said that the un-costed & impractical Net Zero agenda promoted thus far will not wash with Conservative Party members at this time.
Whoever wins this leadership contest will have a reset back to common sense with a new realism on the Net Zero agenda.
The net zero legislation was signed into law by the minister, but he initially thought it was in danger. He says that the candidates are aware of the polls that show people care about climate change.
We managed to say that this is a mainstream issue. Net zero would be electoral suicide. Our electoral grave would be made.
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