Net Zero; The UK's contribution to stopping global warming
May 2019 (Committee on Climate Change)
Executive Summary
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.
Reflecting their respective circumstances, Scotland should set a net-zero GHG target for 2045 and Wales should target a 95% reduction by 2050 relative to 1990.
A net-zero GHG target for 2050 will deliver on the commitment that the UK made by signing the Paris Agreement. It is achievable with known technologies, alongside improvements in people's lives, and within the expected economic cost that Parliament accepted when it legislated the existing 2050 target for an 80% reduction from 1990.
However, this is only possible if clear, stable and well-designed policies to reduce emissions further are introduced across the economy without delay. Current policy is insufficient for even the existing targets.
A net-zero GHG target for 2050 would respond to the latest climate science and fully meet the UK's obligations under the Paris Agreement:
• It would constitute the UK's 'highest possible ambition', as called for by Article 4 of the Paris Agreement. The Committee do not currently consider it credible to aim to reach net-zero emissions earlier than 2050.
• It 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.
• If replicated across the world, and coupled with ambitious near-term reductions in emissions, it would deliver a greater than 50% chance of limiting the temperature increase to 1.5°C.
Now is a crucial time in the global effort to tackle climate change, with revised pledges of effort currently being considered ahead of the UN climate summit in late-2020. An ambitious new UK target would encourage increases in ambition elsewhere, including the adoption of other netzero GHG targets, such as the 2050 target currently under consideration by the European Union.
In committing to a net-zero GHG target, Parliament must understand that, while many of the policy foundations are in place, a major ramp-up in policy effort is now required:
• The foundations are in place. Policy development has begun for many of the components needed to reach net-zero GHG emissions: low-carbon electricity (which must quadruple its supply by 2050), efficient buildings and low-carbon heating (needed throughout the building stock), electric vehicles, carbon capture and storage (CCS), diversion of biodegradable waste from landfill, phase-out of fluorinated gases, increased afforestation and measures to reduce emissions on farms. These policies must be strengthened and they must deliver action.
• A net-zero GHG target is not credible unless policy is ramped up significantly. Most sectors will need to reduce emissions close to zero without offsetting; the target cannot be met by simply adding mass removal of CO2 onto existing plans for the 80% target.
‒ Delivery must progress with far greater urgency. Many current plans are insufficiently ambitious; others are proceeding too slowly, even for the current 80% target:
2040 is too late for the phase-out of petrol and diesel cars and vans, and current plans for delivering this are too vague.
Over ten years after the Climate Change Act was passed, there is still no serious plan for decarbonising UK heating systems and no large-scale trials have begun for either heat pumps or hydrogen.
Carbon capture (usage) and storage, which is crucial to the delivery of zero GHG emissions and strategically important to the UK economy, is yet to get started. While global progress has also been slow, there are now 43 large-scale projects operating or under development around the world, but none in the UK.
Afforestation targets for 20,000 hectares/year across the UK nations (due to increase to 27,000 by 2025), are not being delivered, with less than 10,000 hectares planted on average over the last five years. The voluntary approach that has been pursued so far for agriculture is not delivering reductions in emissions.
‒ Challenges that have not yet been confronted must now be addressed by government. Industry must be largely decarbonised, heavy goods vehicles must also switch to low-carbon fuel sources, emissions from international aviation and shipping cannot be ignored, and a fifth of our agricultural land must shift to alternative uses that support emissions reduction: afforestation, biomass production and peatland restoration. Where there are remaining emissions these must be fully offset by removing CO₂ from the atmosphere and permanently sequestering it, for example by using sustainable bioenergy in combination with CCS.
‒ Clear leadership is needed, right across Government, with delivery in partnership with businesses and communities. Emissions reduction cannot be left to the energy and environment departments or to the Treasury.1 It must be vital to the whole of government and to every level of government in the UK. Policies must be fully funded and implemented coherently across all sectors of the economy to drive the necessary innovation, market development and consumer take-up of low-carbon technologies, and to positively influence societal change.
• Overall costs are manageable but must be fairly distributed.
‒ There have been rapid cost reductions during mass deployment for key technologies (e.g. offshore wind and batteries for electric vehicles). As a result, we now expect that a net-zero GHG target can be met at an annual resource cost of up to 1-2% of GDP to 2050, the same cost as the previous expectation for an 80% reduction from 1990.
‒ The transition, including for workers and energy bill payers, must be fair, and perceived to be fair. Government should develop the necessary frameworks to ensure this. An early priority must be to review the plan for funding and the distribution of costs for businesses, households and the Exchequer.
The background for this report is one of increased awareness of climate risks and falling lowcarbon technology costs, but where global emissions continue to rise:
• Global average temperature has already risen 1°C from pre-industrial levels and climate risks are increasingly apparent. The Special Report of the Intergovernmental Panel on Climate Change (IPCC) in October 2018 emphasised the critical importance of limiting further warming to as low a level as possible and the need for deep and rapid reductions in emissions to do so.
• Current pledges of effort from countries across the world would lead to warming of around 3°C by the end of the century. This is an improvement on the warming of over 4°C expected when the UK Climate Change Act was passed, but it is well short of the Paris Agreement's long-term goal to limit the rise to well below 2°C and to pursue efforts to 1.5°C.
• While the UK has demonstrated that it is possible to cut emissions while growing the economy, global emissions continue to rise.
• However, falling costs for key technologies mean that the future will be different from the past: renewable power (e.g. solar, wind) is now as cheap as or cheaper than fossil fuels in most parts of the world.
This report responds to a request from the Governments of the UK, Wales and Scotland, asking the Committee to reassess the UK's long-term emissions targets. 2 The UK Government has already committed to reducing UK emissions to net-zero3 - the key question for this report is by when.
We do not start from an assumption that the world will meet the Paris Agreement's temperature goal. Instead, we have sought to identify a UK target that is within reach and best supports an increase in global effort, consistent with bringing the expected temperature rise down from the current trajectory. Success will bring huge benefits for the world and for the UK by limiting some of the worst climate risks.
In developing our advice we have consulted widely, issued a public Call for Evidence, and compiled an extensive evidence base. Our new emissions scenarios draw on ten new research projects, three expert advisory groups, and reviews of the work of the IPCC and others.
We also make recommendations for the statutory frameworks in Scotland and Wales, which are contingent on the UK adopting a net-zero GHG target for 2050, given the importance of reserved UK policy levers alongside devolved action…
Is now the right time to set a net-zero target?
A net-zero target requires deep reductions in emissions, with any remaining sources offset by removals of CO₂ from the atmosphere (e.g. by afforestation). Net emissions, after accounting for removals, must be reduced by 100%, to zero.
The Paris Agreement (Article 4) includes an objective in order to achieve its long-term temperature goal, which is widely interpreted as requiring net-zero GHG emissions globally in the second half of the century (expressed as 'a balance between anthropogenic emissions by sources and removals by sinks'). The UK Government has also recognised the need to reach netzero GHG emissions in the UK, a position with which the Committee agreed in our 2016 report on UK climate action following the Paris Agreement.
In 2016 we advised that the Government should not set a net-zero target at that time, but should instead keep a target under review as the evidence develops. We now conclude that the evidence supports setting a net-zero target in the UK and that this evidence is robust: a net-zero target should now be set. It is also an important moment for the UK to make a positive international impact…
Should the net-zero target be for CO₂ or all GHGs?
All greenhouse gases (GHGs) contribute to climate change and must be reduced substantially to meet the Paris temperature goal. To stabilise global temperatures, emissions of long-lived gases like CO₂ must be reduced to net-zero. Emissions of short-lived gases like methane must be stabilised, but need not reach net-zero. We develop scenarios in this report that reduce UK emissions of CO₂ and other long-lived gases to net-zero. Alongside cuts in methane emissions these would result in a UK reduction across greenhouse gases of around 97% relative to 1990.4 This would end the UK's contribution to rising global temperatures…
When should the UK reach net-zero GHGs and what should the longterm targets be for the UK, Scotland and Wales?
The Governments asked for advice on when the UK should achieve a net-zero GHG target and on what the long-term emissions targets should be for the UK, Scotland and Wales.
• UK. We recommend that the UK should achieve net-zero GHG emissions by 2050 (i.e. a 100% reduction from 1990). This would be an appropriate UK contribution to the Paris Agreement. Based on our current understanding, it is the latest date for the UK credibly to maintain its status as a climate leader and the earliest to be credibly deliverable alongside other government objectives.
• Scotland (Box 2) has different capabilities, notably its larger land area per person and its significant CO2 storage potential, meaning it can credibly reach net-zero GHGs earlier. We recommend that Scotland legislates for net-zero GHGs in 2045.
• Wales (Box 3) has less opportunity for CO2 storage and relatively high agricultural emissions that are hard to reduce. On current understanding it could not credibly reach net-zero GHGs by 2050. We recommend it sets a target for a 95% reduction in emissions by 2050 relative to 1990. This would still cut Welsh net emissions of long-lived greenhouse gases to below zero and therefore end Wales's contribution to rising global temperatures…
How can the UK reach net-zero GHGs?
Scenarios for UK net-zero
GHGs in 2050 It is impossible to predict the exact mix of technologies and behaviours that will best meet the challenge of reaching net-zero GHG emissions, but our analysis in this report gives an improved understanding of what a sensible mix might look like. The scenarios (Figure 2 and Box 4) include:
• Resource and energy efficiency, that reduce demand for energy across the economy. Without these measures the required amounts of low-carbon power, hydrogen and carbon capture and storage (CCS) would be much higher. In many, though not all, cases they reduce overall costs.
• Some societal choices that lead to a lower demand for carbon-intensive activities, for example an acceleration in the shift towards healthier diets with reduced consumption of beef, lamb and dairy products.
• Extensive electrification, particularly of transport and heating, supported by a major expansion of renewable and other low-carbon power generation. The scenarios involve around a doubling of electricity demand, with all power produced from low-carbon sources (compared to 50% today). That could for example require 75 GW of offshore wind in 2050, compared to 8 GW today and 30 GW targeted by the Government's sector deal by 2030. 75 GW of offshore wind would require up to 7,500 turbines and could fit within 1-2% of the UK seabed, comparable to the area of sites already leased for wind projects by the Crown Estate.
• Development of a hydrogen economy to service demands for some industrial processes, for energy-dense applications in long-distance HGVs and ships, and for electricity and heating in peak periods. By 2050, a new low-carbon industry is needed with UK hydrogen production capacity of comparable size to the UK's current fleet of gas-fired power stations.
• Carbon capture and storage (CCS) in industry, with bioenergy (for GHG removal from the atmosphere), and very likely for hydrogen and electricity production. CCS is a necessity not an option. The scenarios involve aggregate annual capture and storage of 75-175 MtCO₂ in 2050, which would require a major CO₂ transport and storage infrastructure servicing at least five clusters and with some CO₂ transported by ships or heavy goods vehicles.
• Changes in the way we farm and use our land to put much more emphasis on carbon sequestration and biomass production. Enabled by healthier diets and reductions in food waste, our scenarios involve a fifth of UK agricultural land shifting to tree planting, energy crops and peatland restoration…
What are the expected costs and benefits of a UK net-zero GHG target for 2050?
In considering the costs of a net-zero GHG target for the UK, we are interested in the overall cost and its distribution: costs to the Exchequer and the risks of an unfair burden on vulnerable people or of undermining UK competitiveness. Against these there will also be large benefits, including reduced climate risks and cleaner air.
Our assessment integrates changes across the energy system, including the need to provide low-carbon electricity and hydrogen and to strengthen networks so that they reach consumers when needed. We exclude taxes and subsidies from our assessment - these constitute a transfer from one part of the economy to another while we are interested in the extra resource cost for the economy as a whole…
Next Steps
Setting the net-zero target and determining the cost-effective path
The Committee expects to advise on the sixth carbon budget (covering the years 2033-2037), once Parliament has considered the setting of a new long-term target. The advice of the Committee on the sixth carbon budget is due in 2020. The net-zero GHG target for 2050 should be set in legislation as soon as possible - and before the end of 2019 to allow time to develop advice on the cost-effective path to the new target.
We do not recommend changes to the fourth or fifth carbon budgets at this time, but note that both were set on the path to the existing 80% target and therefore are likely to be too loose.
We already recommend that the Government aim to out-perform the legislated budgets based on revisions to our estimate of the cost-effective path to the 80% target.9 We reiterate that recommendation and we will consider whether the fourth and fifth carbon budgets should be tightened in legislation as part of our advice on the sixth carbon budget…
Conclusion
There have been significant changes in the decade since the Climate Change Act was passed. Those changes can be accommodated within the Act, but they require an increase in the headline ambition.
We now have an understanding of how UK emissions can be reduced by 100% to net-zero and expect it to be delivered within the costs previously agreed by Parliament, provided all parts of government act quickly, effectively and in a coordinated fashion. Many businesses in the UK are ready to implement it; some have already set net-zero targets of their own.
A new UK target for net-zero GHGs by 2050, backed by a robust set of plans to achieve it within the UK’s strong and widely-respected legislative framework, would send a strong international signal at a critical time. It can act as the benchmark for developed nations and position the UK as a progressive climate leader on the global stage.
The changes required are substantial, but the foundations are already in place. Strong leadership is now required from governments throughout the UK, beginning with acceptance of the need to ramp up policy effort significantly and a rapid adoption of our recommendations by the Parliaments of the UK…
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