The Climate Change Act 2008 turned a UK climate goal into a legal duty. Section 1 makes the Secretary of State responsible for ensuring the net UK carbon account for 2050 is at least 100% below the 1990 baseline. In plain terms, that is net zero.

Parliament passed the Act in November 2008 with an overwhelming majority across the parties. The Grantham Research Institute at the LSE describes it as the first legally binding climate mitigation target that any country set for itself.

The target got tougher in 2019

The original Act asked for an 80% cut in greenhouse gas emissions by 2050, measured against 1990 levels. In 2019 the UK became the first major economy to commit to net zero instead.

The change came through a statutory instrument, not a new Act. The Climate Change Act 2008 (2050 Target Amendment) Order 2019 swapped the figure in section 1 for 100%, with effect from 27 June 2019. The Climate Change Committee had recommended the net zero date in a May 2019 report.

Five-year budgets do the work in between

A distant target invites delay. So the Act also sets up carbon budgets, each capping emissions over a five-year stretch.

According to the Grantham Research Institute, the UK met its first three budgets, the third with a 15% surplus. The Committee found it was not on track for the fourth budget, covering 2023 to 2027, or the fifth, covering 2028 to 2032. The sixth budget, for 2033 to 2037, was the first set in line with net zero.

A committee to keep score

The Act created the Climate Change Committee, an independent body that advises the government and Parliament on each carbon budget. It also requires the government to draw up a National Adaptation Programme, setting out five years of action on the effects of climate change that can no longer be avoided.

The Act reaches further than its name suggests. Its long title gives ministers powers to create emissions trading schemes and to charge for single-use carrier bags. It also covers household waste collection and renewable transport fuel.

Has it cut emissions?

A 2018 review by the Grantham Research Institute found that the Act and its budgets helped bring UK emissions down, especially in power generation. The economy kept growing over the same period.

The harder test is the one the Committee has already flagged. A law can set a budget, but it cannot make the fourth or fifth one balance.