The Climate Change Act 2008 establishes a new approach to managing and responding to climate change in the UK. The Act creates a legally binding target to reduce the UK’s emissions of greenhouse gases (GHGs) to at least 80% below 1990 levels by 2050.

Emissions of greenhouse gases are instrumental in causing global warming and climate change. In order to reduce their levels and meet the 80% target, carbon budgets place legally binding ceilings on the level of allowed UK emissions over five year periods.

What is a carbon budget?

A 'carbon budget' is a cap on the total quantity of greenhouse gas emissions emitted in the UK (net of credits purchased within the EU Emissions Trading Scheme or other international schemes, e.g. the Clean Development Mechanism - CDM) over a specified time. Under a system of carbon budgets, every tonne of greenhouse gas emitted between now and 2050 will count. Where emissions rise in one sector, we will have to achieve corresponding falls in another.

Each carbon budget covers a five-year period, with three budgets set at a time. The first three carbon budgets run from 2008-2012, 2013-2017 and 2018-2022.

The Committee will advise on the level of the 4th carbon budget, 2023-2027 by the end of 2010.