Measurements from BT Tower observatory show impact of reduced activity in UK’s capital due to COVID-19 pandemic
UK Centre for Ecology & Hydrology
A new comprehensive analysis has revealed carbon dioxide (CO2) emissions in London have reduced by almost 60 per cent during the COVID-19 lockdown.
Previous analyses of CO2 emission reductions have been based on estimates of changes in traffic, industrial and commercial activity during the lockdown. Changes in atmospheric concentrations of this and other greenhouse gases can be difficult to interpret because they depend strongly on meteorological conditions.
Direct measurements of the emissions themselves are hence required but relatively few sites are equipped to do this, one being the BT Tower Atmospheric Observatory in London. Scientists from the UK Centre for Ecology & Hydrology and the University of Reading say their measurements from the BT Tower have shown clear evidence of a significant reduction in CO2 emissions in London between the start of the lockdown on 23 March and the first week of May, compared with the long-term average for this time of year.
For the period 8am-8pm, the reduction in CO2 emissions was 58 per cent which very closely mirrors the daily reduction of 60 per cent in traffic flow in central London reported by Transport for London during the first five weeks of the UK’s lockdown.
Dr Eiko Nemitz of the UK Centre for Ecology & Hydrology (UKCEH) says: “The 190m-tall BT Tower in central London is an excellent platform for pollution monitoring at the heart of Europe’s largest city; these measurements offer a unique insight into changes in fossil fuel use and CO2 emissions both during the lockdown and as we gradually come out of it. They will also help us understand how emissions of other pollutants have changed over this unprecedented period.”
The lockdown has significantly reduced London’s daytime population and commercial activity. However, it is difficult to quickly calculate the emissions from individual sources such as vehicle traffic, natural gas usage for heating of buildings, plus exhalation from people – particularly as these are mitigated slightly by carbon ‘sinks’, mainly through the uptake of CO2 by vegetation in parks, gardens and streets.
But Dr Nemitz says: “The fact that the reduction in CO2 emissions in central London almost exactly correlates with the reduction in traffic provides further evidence that vehicle emissions are a major source of CO2 in London, and that traffic is closely linked with other CO2-emitting activities such as the heating of shops and offices.
“The short-term reductions in emissions will not markedly change global atmospheric concentrations of CO2 and global warming. However, measurements of pollution during the lockdown and as it eases will provide valuable evidence on how air quality might change as sources of emissions are reduced, for example as part of the UK’s transition to net zero greenhouse gas emissions.”
Professor Janet Barlow of the University of Reading explains the longer-term impact of the lockdown on emissions is difficult to predict because behaviours might change as lockdown rules are relaxed. She says: “Some people may prefer to use private cars rather than public transport to avoid the risk of contracting COVID-19, which may cause a fast growth of emissions that may exceed those of the pre-lockdown period. On the other hand, the lockdown may kick-start a new enthusiasm for walking and cycling, and some cities are now investigating measures to promote alternatives to car use. In addition, regular home working may remain the norm for many people.”
The BT Tower Atmospheric Observatory collaborates with the Integrated Carbon Observation System (ICOS), a European-wide greenhouse gas research network. Measurements of CO2 emission reductions from monitoring sites elsewhere in Europe, over a 24-hour period compared with the same time last year, ranged from 8 per cent in a highly vegetated urban area of Berlin to 75 per cent in the city centre of Heraklion, Greece. Reductions in CO2 emissions in parts of Florence, Basel and Helsinki during the lockdowns were around 40 per cent.
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NOTES TO EDITORS
1. The ICOS study used slightly different methodology and timeframes to the measurements quoted for London in this release. The study, which has not yet been peer reviewed, is available at https://data.icos-cp.eu/objects/w6pTmRGYKqAm3c-siQrg5kgd
2. The BT Tower Atmospheric Observatory is a collaboration between UKCEH, the University of Reading and the National Centre for Atmospheric Science. Measurements of CO2 and methane emissions first began in 2006. The research is supported by National Capability funding from the Natural Environment Research Council (NERC). UKCEH is a strategic delivery partner for the NERC, part of UK Research and Innovation (UKRI).
I notice they don’t shout about the much less reduction in particulates and Nox, the nasty stuff that might kill in the near future not alllegedly in some 30 years from now, or did Greta say CO2 was going to kill us all in 10 years time?
London is included in this analysis
https://adriankerton.wordpress.com/071-lockdown-europe-pollution-before-after/
Evil Britts-they are suffocating their plants!
I’m not surprised that a major urban CO2 source is showing a decline because it hasn’t had a chance to be exposed to potential CO2 sinks. The important question is whether or not the average world-wide concentration, of what is a ‘well-mixed’ gas, can be demonstrated because London alone doesn’t potentially warm the world.
I completely agree with you about needing to look at world-wide data on CO2 concentration away from local fluctuations. On your first point: estimated emissions are prior to exposure to natural sinks, as you say, but it seems to me that immediately any CO2 is released into the atmosphere, including in the middle of a city, it becomes part of, and indistinguishable from, the local natural CO2 variations which dominate the diurnal cycle seen in CO2 concentration. See, for example, figure 3c here: https://www.researchgate.net/publication/284710670_Analysis_of_the_potential_of_near_ground_measurements_of_CO2_and_CH4_in_London_UK_for_the_monitoring_of_city-scale_emissions_using_an_atmospheric_transport_model
So, despite the sudden influx of emissions every morning in the rush hour, the dominant charateristic of measured CO2 concentration is virtually the opposite, with it declining every morning as soon as the sun gets up due to local photosynthesis and increasing later in the day as the sun goes down and respiration becomes the dominant factor. As far as I can see, this diurnal CO2 cycle looks almost exactly the same in city centres as it does further away (e.g. http://weybourne.uea.ac.uk/currentData.php).