The Committee on Climate Change is the independent adviser to Parliament, and Government, on climate change issues. We are established by legislation passed by Parliament and are funded to provide independent advice consistent with the legislation. As such, we review existing and emerging evidence on a regular basis.
- The climate has changed in the past. Isn’t this just another natural cycle?
- Why trust climate models?
- Hasn’t there been a pause in global warming?
- Do wind turbines work? And are they really low-carbon?
- Do electric cars save carbon?
- Can we manage the intermittency of renewable electricity generation?
The costs and benefits
- Won’t curbing greenhouse gas emissions cost too much and damage our economy?
- We pay extra for low-carbon and energy efficiency policies in our energy bills. What are we getting for our money?
- What are the costs of limiting the expansion of onshore wind?
- Why don’t we just adapt to the changes that are happening, rather than spend money trying to curb emissions?
- What are the main climate impacts we can expect in the UK?
- Despite reports of falling UK emissions, hasn’t our real carbon footprint actually risen?
1) The climate has changed in the past. Isn’t this just another natural cycle?
There are natural cycles in the Earth’s climate, but the current changes to the climate are different. The main cycle of global climate change over the last million years has been in and out of ‘ice ages’, during which the Earth’s average surface temperature has fluctuated by about 4-7°C. For the last 10,000 years the Earth has been in a warm phase between ice ages. This means a gradual cooling of the planet would now be expected, rather than the rapid warming that has occurred since 1950. The pattern of warming currently being seen also matches what scientists would expect as a result of the greenhouse gas emissions caused by human activities. In contrast, the current level of warming exceeds what would be expected as a result of natural influences alone, such as fluctuations in the warming effect of the Sun.
Scientists predict the Earth will warm by 1.7-5.4°C by the end of this century without concerted international efforts to reduce greenhouse gas emissions. This pace of global temperature change is far faster than has occurred in any previous ice age cycle, further suggesting it is not part of a natural cycle.
2) Why trust climate models?
A model is simply a tool for using our knowledge to investigate some aspect of the real world. Models are used in many areas of science, especially where controlled experiments on the real system are very difficult to conduct (such as with astronomy, the behaviour of complex molecules and with the climate). Building, testing and verifying models is a fundamental part of science.
There are many different climate models developed by scientists, from simple one-line equations to complex simulators that run on supercomputers. The most complex models calculate physical, chemical and biological processes as thoroughly as possible, and are able to accurately reproduce many of the large-scale climate changes seen this century. They do however have known flaws. For example they do not currently have enough detail to simulate individual clouds, and their representation of the effects of clouds is not completely accurate. But scientists are working continually to improve these models.
Importantly, predictions of future climate change do not rely only on these complex models. Evidence also comes from basic scientific theory, from much simpler models, and from measurements of past climate change.
3) Hasn’t there been a pause in global warming?
Since 1950, global average surface temperature has been rising at a rate of 0.12°C per decade. But during 1998-2013, temperatures rose more slowly at 0.06°C per decade, leading some to say global warming had paused. However, the so-called pause was followed by record high temperatures in 2014, 2015 and 2016. In addition, long-term projections of global temperature rises have been largely unaffected by it. This is because scientists use periods of around 30 years or more to identify genuine climate trends in order that the short-term fluctuations that naturally occur in the Earth’s temperature record do not mask (or add to) longer-term trends. Looking over the most recent 30 years, including the so-called pause, there is no obvious underlying slowdown in global warming.
Furthermore, other important indicators of a changing climate have continued unabated: arctic sea ice has continued to decrease, global sea level has continued to rise, and the hottest days of the year have continued to get hotter.
4) Do wind turbines work? And are they really low-carbon?
Yes, wind turbines work. While they only occasionally operate at their peak capacity, they do produce power around 80% of the time. On average during a year, onshore wind turbines produce generation equivalent to around 30% of their peak power output, with offshore wind turbines producing closer to 50%.
Meanwhile, greenhouse gas emissions from wind turbines are very low. While a wind turbine is in operation there are no direct emissions from it. However, there are emissions resulting from the manufacture and transport of components, and in maintenance activities. Taken as a whole, these ‘lifecycle’ emissions are between 20 and 80 times lower than fossil fuel-based alternatives, such as gas or coal.
The total amount of UK power being produced by wind turbines is increasing. Wind provided 13% of all UK based power generation in 2016 and set a record in 2016 by producing 33% of all UK based power generation in a single day. However other sources of electricity generation are needed for when the wind is not blowing strongly over much of the UK – known as “intermittency”. The CCC already accounts for these intermittency costs in its cost and emissions estimates (see Question 6).
Moreover, wind is now one of the cheapest forms of electricity generation. Technological progress, such as larger turbines, combined with successful government policy have led to significant cost reductions. This was demonstrated in the 2017 ‘Contract-for-Difference’ auctions, which saw a significant decrease in the price of offshore wind. These prices, along with recent estimates for the cost of onshore wind, are now lower than projected costs for gas-fired power stations in 2020 based on the UK government’s central gas price scenario.
Currently, if there is little wind, backup power usually comes from gas-fired power stations (see Question 6). But in the future this could come from a range of technologies including, for example, gas power stations fitted with Carbon Capture and Storage (CCS), interconnection with other countries and energy storage such as batteries.
5) Do electric cars save carbon?
Yes. Electric cars that run on electricity from the UK grid emit on average around 30% of the carbon dioxide of a conventional (petrol or diesel) vehicle. Electric vehicles typically take more energy to manufacture than conventional vehicles, but the quantities are small compared to the energy used to power a vehicle over its lifetime. This means that, even when you take account of the emissions from the manufacture of electric vehicles, the total lifecycle emissions are roughly 60-65% lower than conventional vehicles according to one of the latest reputable studies. This benefit will grow as our electricity supply becomes increasingly decarbonised.
6) Can we manage the intermittency of renewable electricity generation?
Yes we can. Detailed modelling of the electricity system suggests that even high levels of intermittency are manageable, at a cost, as long as the system is designed with flexibility in mind.
Variable sources of electricity such as wind turbines and solar panels do pose challenges for managing the electricity system. When the wind is not blowing or in the hours of darkness alternative ways to meet demand are needed. At the other end of the scale, there could be times when intermittent sources are generating more than the system can accommodate, and this over-supply needs to be managed or ‘constrained’. Currently, if a network area is oversupplied with energy, generators of all types are payed ‘constraint payments’ to turn down their power output. In the longer term, network reinforcements will reduce the need for these payments. Payments to renewable generators under Ofgem’s ‘Connect and Manage’ scheme can be up to 20% of total electricity system balancing costs, but are forecast to decrease as new transmission network assets come online.
Intermittent power generation can be managed through demand flexibility, energy storage, increased interconnection with Europe, including Scandinavia, and additional back-up and balancing capacity from fossil fuel plants (for example, gas power plants). The CCC’s scenarios for decarbonisation of the power sector include these options, for example with enough firm capacity (i.e. nuclear, gas and Carbon Capture and Storage plants) to meet peak demand even if there is no contribution from intermittent renewables. The CCC includes the costs of these options in its cost estimates, including in its assessment of the impact of carbon budgets on energy bills.
The CCC’s best current estimate of the cost of deploying these options alongside low-carbon generating technologies is that these costs are small relative to generation costs. However, the costs are dependent on the various flexibility measures being rolled out and taken up. For example, in a future where intermittent renewables make up 40% of the electricity generation mix, the costs associated with their intermittency could be up to an additional £10/MWh for each MWh of intermittent renewables added, provided that appropriate flexibility measures are implemented. The potential costs of managing intermittency are further being assessed by Government and the CCC and will inform our ongoing advice on the costs and feasibility of decarbonising the power sector by 2030.
The costs and benefits
7) Won’t curbing greenhouse gas emissions cost too much and damage our economy?
Economic growth is not incompatible with cutting carbon emissions. The UK economy has grown 65% since 1990 while greenhouse gas emissions have fallen by 43%.
Taking action to reduce the UK’s emissions is not expected to take annual average long-term UK economic growth outside the 2-2.5% range estimated by the Office of Budget Responsibility. Under central economic forecasts, and the CCC’s estimates of the costs of meeting climate change targets, average incomes would still double by 2050 compared to 2013, although this doubling might have occurred by 2049 if action to reduce emissions had not been required.
Acting on climate change steadily and predictably will be cheaper than delaying action or pursuing stop-start policies and investment. For that reason the Climate Change Act specifies a transparent decision-making process that incorporates independent advice. It also requires plans to be made sufficiently in advance to allow for the required adjustments to be made at the lowest cost.
It is important to remember that not doing anything also has a cost. Delaying action will increase the cost of reducing future emissions and adapting to the impact of the climate change. Delays will also leave the UK less prepared against a wide range of future events.
8) We pay extra for low-carbon and energy efficiency policies in our energy bills. What are we getting for our money?
Aside from emissions reduction, the money spent on low-carbon and energy efficiency policies via our energy bills pays for measures (such as insulation) that make homes warmer, as well as for low-carbon electricity generation (such as renewable energy) which provide insurance against fluctuating gas prices.
Costs for support for low-carbon electricity and energy efficiency are expected to rise in real terms to £200 per household by 2030, after which they should begin to fall. The CCC’s analysis suggests that if households take up energy efficiency measures they can on average more than offset these increases. We have suggested, in our Energy prices and bills – impacts of meeting carbon budgets report in 2017, that measures should be more targeted at households that are most likely to have difficulty paying energy bills.
9) What are the costs of limiting the expansion of onshore wind?
Estimates from both the government and industry suggest onshore wind is the cheapest form of new build generation in the UK, and cheaper than new build fossil fuel generation. Therefore deploying onshore wind in the UK can reduce consumer energy bills over the long-term. We do not believe that the government’s approach to procuring low-carbon generation should exclude cost-competitive renewable technologies, such as onshore wind and solar PV. Where they are cost-competitive and meet local planning criteria, these technologies should be allowed to compete for contracts against other low-carbon options.
10) Why don’t we just adapt to the changes that are happening, rather than spend money trying to curb emissions?
Scientists from all countries agree that adaptation alone will not be sufficient to deal with the likely impacts of unchecked climate change. This is true in the UK. For example, if global greenhouse gas emissions are not reduced the sea level rise that would occur in the UK could not be held back by barriers and retreating to higher ground would be the only option.
In addition, even if it may be possible to adapt to significant levels of climate change, the costs of adapting will be much higher if greenhouse gas emissions are not brought under control. It will be much easier and cheaper to adapt to a global temperature rise of 2°C than to 4°C of warming. For example, the current Thames Barrier is able to protect London and the Thames estuary even with a metre of sea-level rise. Beyond a metre it may be necessary to build a new barrier, costing billions of pounds. Without large scale global emissions reductions, there is an increased chance of seeing more than a metre of sea level rise in this century or the next.
11) What are the main climate impacts we can expect in the UK?
The greatest impacts of climate change in the UK are expected to be from inland and coastal flooding, water scarcity, and heatwaves. These will all put additional stress on the built and natural environments, potentially resulting in damage, reduced business activity, and loss of human life. For example, the number of properties in areas of significant flood risk is expected to double by the mid-2030s. Hot weather already contributes to around 2,000 premature deaths per year at present, and this is likely to increase in the future.
Temperature contrasts in the North Atlantic region will change as different areas warm at different rates. These temperature contrasts are the basic energy source for the Atlantic storms that hit the UK and so these storms will change. This means that we can expect increasing changes in our weather.
There may be some benefits to the UK: potentially longer growing seasons and reduced deaths from cold.
These risks and opportunities are reported every five years in the UK Climate Change Risk Assessment. The Adaptation Sub-Committee (ASC) of the Committee on Climate Change produced a comprehensive Evidence Report in 2016 outlining these risks and opportunities.
12) Despite reports of falling UK emissions, hasn’t our total carbon footprint actually risen?
The fall of 43% since 1990 of emissions within the UK’s borders – known as ‘production emissions’ – is real. But if we look at the wider emissions associated with our consumption of goods and services (such as televisions made in Asia and purchased here) then the UK’s carbon footprint has not fallen as much. These are known as ‘consumption emissions’. The UK carbon footprint was 19% lower in 2015 than in 2007, though between 2014 and 2015, it actually increased by 2%.
Estimates of UK consumption emissions are more uncertain than estimates of the emissions produced here, but data covering 1997 to 2015 suggest emissions increased until 2007 before falling back. Several lines of evidence show that this is mainly a result of increased international trade, rather than UK industries moving overseas in response to the UK’s climate policies. For instance, the divergence in consumption and production trends was occurring before low-carbon policies were introduced; most of the fall in UK emissions has come from the electricity generation and waste sectors rather than industry; and industries deemed by the Government to be at risk of “offshoring” (i.e. moving abroad) receive compensations and exemptions from policy costs.
The difference between UK production and consumption emissions emphasises the need for a global effort to reduce emissions, covering all countries. The Paris Agreement, reached in 2015, is very encouraging in this respect. The UK is not acting alone.