The Committee on Climate Change is the independent advisor to Parliament, and the 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 responses to the questions provided below reflect the current available evidence. We will review the responses as new evidence is produced. If you are aware of evidence we should take into account please get in touch via our ‘Contacts’ page.
1) The climate has changed in the past. Isn’t this just another natural cycle?
There are natural cycles, but what we are seeing now is very different. The main cycle of global change over the last million years has been in and out of ‘ice ages’, in which Earth’s average surface temperature changed by about 4-7°C. For the last 10,000 years we have been in a warm phase between ice ages, meaning we would expect gradual cooling rather than the rapid further warming seen since 1950. The pattern of warming also matches what we expect from our emissions, and does not match that from other natural influences alone such as the Sun.
Scientists predict the Earth will warm 1.7-5.4°C by the end of this century without concerted efforts to reduce greenhouse gas emissions. This pace of global change is far faster than any of the ice age cycles.
2) Why trust climate models?
A model is simply a mechanism or 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 (such as astronomy, the behaviour of complex molecules and climate science). Building, testing and disputing models is a fundamental part of science. The inputs to the models are crucial. They are based on a range of evidence, including controlled experiments, historical observations and measurements.
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 the relevant processes of physics, chemistry and biology as thoroughly as possible, producing realistic-looking weather patterns. They do however have known flaws – they do not currently have enough detail to simulate individual clouds, for example, and their representation of the net effects of clouds is not completely accurate. But scientists are working continually to improve them and they are able to reproduce many of the large-scale climate changes seen this century.
Further, predictions of future climate do not solely rely on these complex models. Evidence also comes from basic theory and much simpler models, and from measurements of past climate change.
3) Hasn’t there been a pause in global warming?
Average surface temperature has risen more slowly over the last few years. This “pause” is still a short period of time for the climate, and it does not have a major impact on long-term projections.
Since 1998 global temperature has been rising at a rate of 0.04°C per decade, lower than the longer-term rate of 0.11°C per decade since 1950. The temperature record is noisy due to natural, unpredictable fluctuations which can mask (or add to) underlying changes. Scientists therefore use longer periods (around 30 years or more) to identify robust climate trends.
The cause of the current slowdown is a topic of research. Scientists have identified several plausible causes, from slightly reduced solar heating and a series of small volcanic eruptions to additional storage of heat in the oceans. But there is very strong evidence that the whole climate system is still heating up, and the global surface temperature rise will resume in the coming decades.
Other important indicators of a changing climate have not paused since 1998: Arctic sea ice is decreasing, global sea level is rising, and the hottest days of the year are becoming hotter.
4) Do wind turbines work? And are they really low-carbon?
Yes, wind turbines work. In reality, wind turbines rarely operate at their rated (peak) capacity, but do produce power around 80% of the time. Onshore wind turbines produce generation equivalent to around 30% of their rated power over a period of a year, with offshore wind turbines producing closer to 40%.
Yes, emissions from wind turbines are very low. There are no direct emissions from generating electricity from wind power, however there are emissions in the manufacture and transport of components, and in maintenance activities. These ‘lifecycle’ emissions are many times lower – perhaps 20 to 80 times lower – than for fossil fuel-based alternatives e.g. gas or coal.
Wind provided 8.6% of all UK power generation in 2013 and set a record in 2014 by producing 22% of all UK power generation over a 24 -hour period. However we do need other technologies to produce energy when the wind is not blowing strongly over much of the UK and we account for this in our cost and emissions estimates.
Whilst current backup power is normally in the form of gas, in the future this could come from a range of technologies including, for example, gas plant fitted with Carbon Capture and Storage (CCS), interconnection with other countries and energy storage.
5) Do electric cars save carbon?
Yes. Electric cars that run on average UK grid electricity emit 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 this is 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 still roughly 50% lower than conventional vehicles. This benefit will increase as we further decarbonise our electricity supply.
6) Can we manage the intermittency of renewable electricity generation?
Yes we can. Detailed engineering modelling of the electricity system suggests that even high levels of intermittency are manageable, at a cost, as long as we fully deploy options for providing system flexibility.
Variable and intermittent sources of electricity such as wind and solar pose challenges for managing the electricity system. For example, alternative ways to meet demand may be needed to cover times when the wind is not blowing or in the hours of darkness. On the other hand, there could be times when intermittent sources are generating more than the system can accommodate and need to be constrained.
Currently, where intermittent renewables account for a relatively small portion of electricity generation (10% in 2013), intermittency is managed through constraint payments. Generators of all kinds are compensated to reduce output when more electricity is being generated than can be used or transmitted (e.g. due to congestion on the network). In 2013/2014 constraint payments for wind generators accounted for 14% of total balancing payments (the rest was paid to coal and gas operators) and comprised less than 1% of total costs of wind generation in that year.
In future, higher levels of intermittent power generation can be managed through demand flexibility, energy storage, increased interconnection with European (including Scandinavian) systems, and additional back-up and balancing capacity from fossil fuel plants (e.g. gas power plants). Our scenarios for decarbonisation of the power sector include these options, for example with enough firm capacity (i.e. nuclear, gas and CCS plants) to meet peak demand even if there is no contribution from intermittent renewables. We include the costs of these options in our cost estimates, including our assessment of the impact of carbon budgets on energy bills.
Our best current estimate of the cost of deploying these options alongside low-carbon generating technologies is that these 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 renewables make up to two thirds of electricity generation, the cost could be up to an additional 1 p/kWh on electricity prices for each kWh of intermittent renewables added (contingent on roll-out/take-up of sufficient flexibility).
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?
First, it is important to remember that not doing anything also has a cost: it will increase the cost of adapting to the impact of the climate change that happens and leave the UK less prepared against a wide range of future events.
Setting that aside, economic growth is not incompatible with cutting carbon emissions. The economy has grown 23% since 2000 while greenhouse gas emissions have fallen by 18%.
Acting to reduce emissions is not expected to take long-term UK economic growth outside the 2-2.5% range estimated by the Office of Budget Responsibility. Under central economic forecasts, and our estimates of the costs of meeting targets, average incomes would still double by 2050 compared to 2013, although this might have occurred by 2049 if action to reduce emissions had not been required.
Finally, acting steadily and predictably will be cheaper than delaying action or pursuing stop-start policies and investment. For that reason the Climate Change Act provides for decisions to be made through a transparent process, allowing for independent advice and with sufficient time to allow the required adjustments to take place at least cost.
8) We pay extra for low-carbon and energy efficiency policies on our energy bills – what are we getting for our money?
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.
In 2013, householders paid around £55 per year to support energy efficiency schemes and £45 per year to support low-carbon electricity out of a typical £1140 bill.
This paid to:
- Install more than 200,000 new boilers and heating controls to provide affordable warmth to low-income homes and/or fuel poor families.
- Insulate almost 200,000 cavity walls, solid walls and lofts to both save carbon and reduce energy costs. 40% of these measures benefitted low-income and/or fuel poor families.
- Reduce carbon dioxide emissions by 20 million tonnes, equivalent to the annual emissions of 10 million cars, and reduce gas imports.
This support for low-carbon investment (£45 in 2013) is expected to rise (in real terms) to £100 by 2020 and £175 by 2030, after which costs should begin to fall. Our 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 2014 report, 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?
Onshore wind is one of the cheapest low-carbon technologies. If the potential role of onshore wind were reduced, other forms of low-carbon generation would need to be installed in order to ensure the power sector plays its part in reducing emissions. This would increase costs. For example, substituting offshore wind for onshore wind (assuming that onshore deployment is limited to the Government’s current 2020 ambition) would increase the costs of decarbonisation by around £900m per year by 2030, equivalent to £7 on each household bill.
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 by itself cannot fully offset the likely impacts of unchecked climate change. That is also true at a UK level: for example, sea level rise could not be held back by barriers or means other than retreating to higher ground.
Secondly, even though a lot of adaptation may be possible, the costs of adapting to climate change 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 one of 4°C. For example, the current Thames Barrier is able to protect London and the estuary even with a metre of sea-level rise. Without strong global emissions reductions, there is an increased chance of seeing more than a metre of sea level rise in this century or the next. Beyond a metre it may be necessary to build a new barrier, costing billions of pounds.
11) What are the main climate impacts we can expect in the UK?
The possible risks and opportunities are reported every five years in the UK Climate Change Risk Assessment. The Adaptation Sub-Committee (ASC) has been asked by Defra to lead the analytical input to the next report for publication in 2016.
There may be some benefits – potentially longer growing seasons and reduced deaths from cold. But in the UK the greatest impacts of climate change 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 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.
12) Despite reports of falling UK emissions, hasn’t our real carbon footprint actually risen?
The fall in emissions within the UK is real, reflecting- for example – reductions in emissions from power generation. But if we look at consumption emissions, then yes, our analysis suggests that our carbon footprint has increased since 1993, as growth in imported emissions has more than offset the reduction in emissions produced within the UK.
This increase in imported emissions is largely a result of rising incomes, with associated increased demand for consumer goods, many of them imported. This emphasises the need for policies globally to reduce emissions. It is very encouraging in this respect that countries, including China and the US*, have made ambitious commitments to reduce emissions. There is now widespread coverage by low-carbon policies of major emitting sectors around the world. The UK is not acting alone.
*China and US together made up about 45% of world CO2 emissions in 2011.