A recent Sky News article carried the headline “UK carbon emissions ‘at lowest level since days of Jack the Ripper’”. It sounded like some rare good news in the world of climate change and carbon emissions, so Stuart Walker, researcher at the University of Derby’s Institute for Innovation in Sustainable Engineering, decided to investigate.
Earth’s safety blanket
First of all, there is a very important distinction to make between atmospheric CO2 and CO2 emissions. Atmospheric CO2 is the amount of CO2 in the earth’s atmosphere. This, along with other greenhouse gases, is what traps heat in the atmosphere and provides an insulating blanket around the planet. The fine balance of some heat being trapped and some escaping is what allowed life to develop on earth, and what keeps us here. Too little and the planet is too cold for life, too much and it’s too hot. Atmospheric CO2 has risen inexorably from around 280 ppm (parts per million) at the time of Jack the Ripper, to over 410ppm today. And it is still rising: The level of atmospheric CO2 is higher today than ever before in the history of our planet.
However, there is good news! UK annual CO2 emissions are falling. In 2018 we produced less CO2 than the previous year, according to analysis by Carbon Brief on which the Sky News article is based.
These emissions and the level of atmospheric CO2 are obviously linked, but there’s a delay. This week’s climate change is not caused by last week’s CO2. The delay is estimated at between 25 and 50 years, so if we can sustain this reduction in our emissions we may see atmospheric CO2 stop increasing in around 2045. However, there are a few more details to consider. Firstly, let’s consider what caused our CO2 emissions to fall in 2018.
How did we reduce our CO2 emissions?
In fact, UK emissions have fallen every year since 2013. An average person in the UK now emits 5.4 tonnes of carbon dioxide every year. Unfortunately though, the good news here is again tempered with a note of caution. A huge part (97%) of this annual reduction over the last few years has been due to one thing: We’re burning less coal to make electricity. As the author of the Carbon Brief article puts it, “The UK’s emission reductions are being flattered by reductions in the use of coal”. This year’s 1.5% reduction is actually the smallest in six years, and over the next few years there is a real chance we will see our emissions rise again, simply because there aren’t many coal-fired power stations left to close.
What can we do to continue the reduction?
Burning less coal is undoubtedly a good thing. Coal has a carbon factor of around 1000gCO2/kWh, meaning that to generate one unit of electricity (enough to use an electric shower for about 10 minutes) emits 1kg of CO2. Oil produces 750g of CO2 for the same amount of electricity, and gas around 400g, but renewable energy sources are the winners here: Wind power has a carbon factor of 12gCO2 per kWh, solar around 30g and tidal power 20g . Clearly, decarbonisation of the electricity supply is key.
However, before we even think about where our energy comes from there’s another important step: Energy efficiency. This makes logical sense; first reduce the amount you need, then get it from a lower carbon source. This is where some of the work we do at the University of Derby comes in. Working with small and medium sized business across the D2N2 region, we improve energy efficiency, reduce waste, and help businesses use renewable and sustainable sources of energy and products. As electricity supply carbon emissions have reduced over recent years, transport has taken over as the largest source of UK greenhouse gases. Through the Rail Research and Innovation Centre, we are working with the transport sector to improve train performance and test the next generation of power systems.
No man is an island
There’s one final point to consider here, and that’s the global nature of this problem. Earth has one atmosphere, and what anyone puts into it affects us all. Developing nations are growing at incredible speed and the demand for power and products is huge. This places demands on power generation, and the CO2 emissions of growing economies now reflect those of the UK over the past few decades. For example, 75% of power generated in India is currently from the burning of coal. India currently has average annual emissions of 1.7 tonnes of CO2 per person , but continued rapid development will see this increase exponentially, bringing with it global challenges in decarbonisation. The UK needs to develop technology to reduce CO2 emissions from power generation and transport rapidly, not just for ourselves, but for the world.
 – Carbon Brief
 – IPCC 2014
 – World Bank 2014 data