The UK Government and devolved administrations should respond urgently to the publication this week of the long-awaited report by the expert and independent Committee on Climate Change about when the UK should stop emitting greenhouse gases.

The report’s main recommendation is: “The UK should set and vigorously pursue an ambitious target to reduce greenhouse gas emissions (GHGs) to ‘net-zero’ by 2050, ending the UK’s contribution to global warming within 30 years.”

Importantly, the report concluded: “While our scenarios demonstrate that some sectors (e.g. the power sector) could reach net-zero emissions by 2045, for most sectors 2050 currently appears to be the earliest credible date.”

Some campaign groups, such as Extinction Rebellion, have demanded a much earlier target date to reach net-zero emissions.

The report was produced in response to a request on 15 October 2018 from the UK Government and the devolved administrations in Scotland, Wales and Northern Ireland about how targets for cutting annual emissions of greenhouse gases should be updated in light of the Paris Agreement.

Article 2 of the Paris Agreement commits countries to “[h]olding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change”.

The Committee’s report took into account, in particular, the Special Report on Global Warming of 1.5°C, which was published by the Intergovernmental Panel on Climate Change (IPCC) in October 2018.

The IPCC’s assessment of published analyses concluded that global mean surface temperature has already risen by about 1°C since before industrialisation, and would continue to increase until the world’s emissions of greenhouse gases reach net zero.

Achieving net-zero means reducing emissions from human activities as much as possible, with any residual emissions counterbalanced by man-made removals of greenhouse gases from the atmosphere which are then stored in ‘carbon sinks’, through planting trees and other vegetation or artificial methods of creating ‘negative emissions’, such as the direct air capture of carbon dioxide.

The IPCC report found that annual global emissions of all carbon dioxide from human activities would need to reach net-zero by 2070, with other greenhouse gases phased out by about the end of the century, to have a 66 per cent probability of limiting the rise in global mean surface temperature to no more than 2°C above pre-industrial levels.

To limit global warming to 1.5°C, with no or limited overshoot of the threshold, annual emissions of carbon dioxide would need to reach net-zero by 2050, with all other greenhouse gases eliminated by about 2067.

The Committee’s report states that a target of reducing the UK’s annual emissions to net-zero by 2050 “goes beyond the reduction needed globally to hold the expected rise in global average temperature to well below 2°C and beyond the Paris Agreement’s goal to achieve a balance between global sources and sinks of greenhouse gas emissions in the second half of the century”.

Importantly, the Committee’s report warns that the 2050 target “is only possible if clear, stable and well-designed policies to reduce emissions further are introduced across the economy without delay”, adding that “[c]urrent policy is insufficient for even the existing targets”.

The Climate Change Act, which became law in 2008, commits the UK to reducing its annual emissions of greenhouse gases by at least 80 per cent by 2050 compared with 1990.

This long-term target is being met through a series of five-year carbon budgets that are each agreed by Parliament at least 12 years in advance. The UK has met its first two carbon budgets, for 2008–12 and 2013–17. However, the Committee on Climate Change warned in its latest Progress Report to Parliament that the country is likely to exceed its fourth and fifth carbon budgets. The latest emissions projections published by the Department for Business, Energy and Industrial Strategy indicate that its central scenario, assuming current policies, would mean the fourth carbon budget is missed by 7 per cent and the fifth carbon budget is busted by 14 per cent.

Furthermore, the current long-term target and the carbon budgets have been set on the assumption of the UK’s contribution to cutting emissions so that the world would have an approximately 50 per cent chance of limiting the rise in global mean surface temperature to no more than 2°C by 2100: this is a weaker goal than those contained in the Paris Agreement.

The carbon budgets are agreed by Parliament on the advice of the Committee on Climate Change, which takes into account the most cost-effective path to the long-term emissions goal.

It would be surprising if the fourth and fifth carbon budgets, which the UK is currently on track to miss, are consistent with the most cost-effective path to the goal of cutting annual emissions to net-zero by 2050. However, the request to the Committee from the Government and the devolved administrations explicitly stated that its report on a net-zero target should not consider changes to carbon budgets that have already been set.

How should the Government respond to the Committee on Climate Change’s report?

First, the Government should bring forward legislation as soon as possible to amend the Climate Change Act to set a long-term target for the UK of net-zero emissions by 2050. Parliament should pass the legislation within the next few months, and the public and businesses should put pressure on Parliamentarians to back it. Campaign groups that attack the Committee’s report as being unambitious should be careful that they do not create reasons to delay legislation.

Second, the Government should immediately commission the Committee to review the third, fourth and fifth carbon budgets and advise on whether they need to be tightened in order for the UK to pursue a cost-effective path to net-zero emissions by 2050.

Third, all government departments should draw up ambitious plans for delivering net-zero emissions by 2050 and the carbon budgets that lead up to it. These must go well beyond the policies that were outlined in the Clean Growth Strategy in October 2017. It is notable that the biggest emissions reductions achieved by the UK since 1990 have been in the power sector, which is currently the responsibility of the same government department that oversees the Government’s policies on greenhouse gas emissions. Urgent action is required by the Department for Transport and the Ministry for Housing, Communities and Local Government to tackle emissions from cars, vans and lorries, and heating in homes in particular.

Fourth, an early test of the Government’s commitment to achieving net-zero emissions by 2050 will be whether or not it is reflected in the results of the Spending Review, which is due to be completed later this year. HM Treasury must be central to the Government’s strategy for the UK to reach the target of net-zero emissions by 2050.

And fifth, the UK should make its target for net-zero emissions a key part of its international leadership on climate change. Other countries have already recognised the importance of the UK setting an example by reducing its annual emissions of greenhouse gases by 44 per cent by 2018 compared with 1990 while increasing its gross domestic product by 77 per cent. The UK is bidding to host the crucial 26th session of the Conference of the Parties to the United Nations Framework Convention on Climate Change in 2020, and will need to submit its nationally determined contribution to the Paris Agreement by the first quarter of 2020 if it has left the European Union by then.

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