Research is a core activity for UBoC. It underpins our partnership and project work and is an output in its own right, both for UBoC and for our academic partners (LEAF) at the University of Leeds. The UBoC team are all also members of other research institutions who publish regularly in peer reviewed journals around meteorology, physical climate change, biosphere, aerosols and climate, biogeochemistry and related disciplines. You can access our publications via our personal university pages. This page lists recent research initiated and/or funded by UBoC. There are also up to 11 PhDs in development, plus regular reports and papers on topics related to our core activities, funded or partially funded by UBoC.
If you have topics that you would like us to explore (this may or may not require funding, according to circumstance), please get in touch.
“A brief guide to the benefits of urban green spaces” is a joint publication from the Leeds Ecosystem, Atmosphere and Forest (LEAF) centre, the United Bank of Carbon (UBoC), and the Sustainable Cities Group at the University of Leeds, with contributions from Catherine Mercer, Catherine Scott, Kirsty Pringle, Martin Dallimer and Dominick Spracklen.
We gratefully acknowledge funding from the Natural Environment Research Council (NERC) and UBoC.
Nature Communications 9 Article 157 11 01 2018
Impact on short-lived climate forcers increases projected warming due to deforestation
C. E. Scott, S. A. Monks, D. V. Spracklen, S. R. Arnold, P. M. Forster, A. Rap, M. Äijälä, P. Artaxo, K. S. Carslaw, M. P. Chipperfield, M. Ehn, S. Gilardoni, L. Heikkinen, M. Kulmala, T. Petäjä, C. L. S. Reddington, L. V. Rizzo, E. Swietlicki, E. Vignati & C. Wilson
The climate impact of deforestation depends on the relative strength of several biogeochemical and biogeophysical effects. In addition to affecting the exchange of carbon dioxide (CO2) and moisture with the atmosphere and surface albedo, vegetation emits biogenic volatile organic compounds (BVOCs) that alter the formation of short-lived climate forcers (SLCFs), which include aerosol, ozone and methane. Here we show that a scenario of complete global deforestation results in a net positive radiative forcing (RF; 0.12 W m−2) from SLCFs, with the negative RF from decreases in ozone and methane concentrations partially offsetting the positive aerosol RF. Combining RFs due to CO2, surface albedo and SLCFs suggests that global deforestation could cause 0.8 K warming after 100 years, with SLCFs contributing 8% of the effect. However, deforestation as projected by the RCP8.5 scenario leads to zero net RF from SLCF, primarily due to nonlinearities in the aerosol indirect effect.
Full paper here
Faraday Discussions 06 06 2017
Impact on short-lived climate forcers (SLCFs) from a realistic land-use change scenario via changes in biogenic emissions
More than one quarter of natural forests have been cleared by humans to make way for other land-uses, with changes to forest cover projected to continue. The climate impact of land-use change (LUC) is dependent upon the relative strength of several biogeophysical and biogeochemical effects. In addition to affecting the surface albedo and exchanging carbon dioxide (CO2) and moisture with the atmosphere, vegetation emits biogenic volatile organic compounds (BVOCs), altering the formation of short-lived climate forcers (SLCFs) including aerosol, ozone (O3) and methane (CH4). Once emitted, BVOCs are rapidly oxidised by O3, and the hydroxyl (OH) and nitrate (NO3) radicals. These oxidation reactions yield secondary organic products which are implicated in the formation and growth of aerosol particles and are estimated to have a negative radiative effect on the climate (i.e. a cooling). These reactions also deplete OH, increasing the atmospheric lifetime of CH4, and directly affect concentrations of O3; the latter two being greenhouse gases which impose a positive radiative effect (i.e. a warming) on the climate. Our previous work assessing idealised deforestation scenarios found a positive radiative effect due to changes in SLCFs; however, since the radiative effects associated with changes to SLCFs result from a combination of non-linear processes it may not be appropriate to scale radiative effects from complete deforestation scenarios according to the deforestation extent. Here we combine a land-surface model, a chemical transport model, a global aerosol model, and a radiative transfer model to assess the net radiative effect of changes in SLCFs due to historical LUC between the years 1850 and 2000.
- This article is part of the themed collection: Atmospheric chemistry in the Anthropocene
Atmospheric Environment March 2017
Heating with Biomass in the United Kingdom: Lessons from New Zealand
E.J.S. Mitchell, G. Coulson, J.M. Jones, A. Williams, E.W. Butt and P.M. Forster.
- • Residential wood combustion (RWC) currently accounts for >10% of renewable energy and >50% of renewable heat generation in the UK.
- • Models predict UK RWC to increase by a factor of 14 between 1990 and 2030, with heating stoves and fireplaces dominating.
- • Wood consumption per person in New Zealand is twice that of the UK, with significant air quality and climate impacts.
- • Black carbon has surpassed carbon dioxide to become the most important component of RSF radiative forcing.
In this study we review the current status of residential solid fuel (RSF) use in the UK and compare it with New Zealand, which has had severe wintertime air quality issues for many years that is directly attributable to domestic wood burning in heating stoves. Results showed that RSF contributed to more than 40 μg m−3 PM10 and 10 μg m−3 BC in some suburban locations of New Zealand in 2006, with significant air quality and climate impacts. Models predict RSF consumption in New Zealand to decrease slightly from 7 PJ to 6 PJ between 1990 and 2030, whereas consumption in the UK increases by a factor of 14. Emissions are highest from heating stoves and fireplaces, and their calculated contribution to radiative forcing in the UK increases by 23% between 2010 and 2030, with black carbon accounting for more than three quarters of the total warming effect. By 2030, the residential sector accounts for 44% of total BC emissions in the UK and far exceeds emissions from the traffic sector. Finally, a unique bottom-up emissions inventory was produced for both countries using the latest national survey and census data for the year 2013/14. Fuel- and technology-specific emissions factors were compared between multiple inventories including GAINS, the IPCC, the EMEP/EEA and the NAEI. In the UK, it was found that wood consumption in stoves was within 30% of the GAINS inventory, but consumption in fireplaces was substantially higher and fossil fuel consumption is more than twice the GAINS estimate. As a result, emissions were generally a factor of 2–3 higher for biomass and 2–6 higher for coal. In New Zealand, coal and lignite consumption in stoves is within 24% of the GAINS inventory estimate, but wood consumption is more than 7 times the GAINS estimate. As a result, emissions were generally a factor of 1–2 higher for coal and several times higher for wood. The results of this study indicate that emissions from residential heating stoves and fireplaces may be underestimated in climate models. Emissions are increasing rapidly in the UK which may result in severe wintertime air quality reductions, as seen in New Zealand, and contribute to climate warming unless controls are implemented such as the Ecodesign emissions limits.
Population exposure to hazardous air quality due to the 2015 fires in Equatorial Asia
P. Crippa, S. Castruccio, S. Archer-Nicholls, G. B. Lebron, M. Kuwata, A. Thota, S. Sumin, E. Butt, C. Wiedinmyer & D. V. Spracklen.
Vegetation and peatland fires cause poor air quality and thousands of premature deaths across densely populated regions in Equatorial Asia. Strong El-Niño and positive Indian Ocean Dipole conditions are associated with an increase in the frequency and intensity of wildfires in Indonesia and Borneo, enhancing population exposure to hazardous concentrations of smoke and air pollutants. Here we investigate the impact on air quality and population exposure of wildfires in Equatorial Asia during Fall 2015, which were the largest over the past two decades. We performed high-resolution simulations using the Weather Research and Forecasting model with Chemistry based on a new fire emission product. The model captures the spatio-temporal variability of extreme pollution episodes relative to space- and ground-based observations and allows for identification of pollution sources and transport over Equatorial Asia. We calculate that high particulate matter concentrations from fires during Fall 2015 were responsible for persistent exposure of 69 million people to unhealthy air quality conditions. Short-term exposure to this pollution may have caused 11,880 (6,153–17,270) excess mortalities. Results from this research provide decision-relevant information to policy makers regarding the impact of land use changes and human driven deforestation on fire frequency and population exposure to degraded air quality.
The impact of residential combustion emissions on atmospheric aerosol, human health and climate
E.W. Butt, A. Rap, A. Schmidt, C. E. Scott, K. J. Pringle, C. L. Reddington, N. A. D. Richards, M. T. Woodhouse, J. Ramirez-Villegas, H. Yang, V. Vakkari, E. A. Stone, M. Rupakheti, P. S. Praveen, P. G. van Zyl, J. P. Beukes, M. Josipovic, E. J. S. Mitchell, S. M. Sallu, P. M. Forster, and D. V. Spracklen
Combustion of fuels in the residential sector for cooking and heating results in the emission of aerosol and aerosol precursors impacting air quality, human health, and climate. Residential emissions are dominated by the combustion of solid fuels. We use a global aerosol microphysics model to simulate the impact of residential fuel combustion on atmospheric aerosol for the year 2000. The model underestimates black carbon (BC) and organic carbon (OC) mass concentrations observed over Asia, Eastern Europe, and Africa, with better prediction when carbonaceous emissions from the residential sector are doubled. Observed seasonal variability of BC and OC concentrations are better simulated when residential emissions include a seasonal cycle. The largest contributions of residential emissions to annual surface mean particulate matter (PM2.5) concentrations are simulated for East Asia, South Asia, and Eastern Europe. We use a concentration response function to estimate the human health impact due to long-term exposure to ambient PM2.5 from residential emissions. We estimate global annual excess adult (> 30 years of age) premature mortality (due to both cardiopulmonary disease and lung cancer) to be 308 000 (113 300 – 497 000, 5th to 95th percentile uncertainty range) for monthly varying residential emissions and 517 000 (192 000 – 827 000) when residential carbonaceous emissions are doubled. Mortality due to residential emissions is greatest in Asia, with China and India accounting for 50 % of simulated global excess mortality. Using an offline radiative transfer model we estimate that residential emissions exert a global annual mean direct radiative effect between −66 and +21 mW m−2, with sensitivity to the residential emission flux and the assumed ratio of BC, OC, and SO2 emissions. Residential emissions exert a global annual mean first aerosol indirect effect of between −52 and −16 mW m−2, which is sensitive to the assumed size distribution of carbonaceous emissions. Overall, our results demonstrate that reducing residential combustion emissions would have substantial benefits for human health through reductions in ambient PM2.5 concentrations.
A global analysis of deforestation in moist tropical forest protected areas
B. D. Spracklen, M. Kalamandeen, D. Galbraith, E. Gloor, D. V. Spracklen
Protected areas (PAs) have been established to conserve tropical forests, but their effectiveness at reducing deforestation is uncertain. To explore this issue, we combined high resolution data of global forest loss over the period 2000–2012 with data on PAs. For each PA we quantified forest loss within the PA, in buffer zones 1, 5, 10 and 15 km outside the PA boundary as well as a 1 km buffer within the PA boundary. We analysed 3376 tropical and subtropical moist forest PAs in 56 countries over 4 continents. We found that 73% of PAs experienced substantial deforestation pressure, with >0.1% a−1 forest loss in the outer 1 km buffer. Forest loss within PAs was greatest in Asia (0.25% a−1) compared to Africa (0.1% a−1), the Neotropics (0.1% a−1) and Australasia (Australia and Papua New Guinea; 0.03% a−1). We defined performance (P) of a PA as the ratio of forest loss in the inner 1 km buffer compared to the loss that would have occurred in the absence of the PA, calculated as the loss in the outer 1 km buffer corrected for any difference in deforestation pressure between the two buffers. To remove the potential bias due to terrain, we analysed a subset of PAs (n = 1804) where slope and elevation in inner and outer 1 km buffers were similar (within 1° and 100 m, respectively). We found 41% of PAs in this subset reduced forest loss in the inner buffer by at least 25% compared to the expected inner buffer forest loss (P<0.75). Median performance (P) of subset reserves was 0.87, meaning a reduction in forest loss within the PA of 13%. We found PAs were most effective in Australasia (P=0.16), moderately successful in the Neotropics (P=0.72( and Africa (P=0.83), but ineffective in Asia (P=1). We found many countries have PAs that give little or no protection to forest loss, particularly in parts of Asia, west Africa and central America. Across the tropics, the median effectiveness of PAs at the national level improved with gross domestic product per capita. Whilst tropical and subtropical moist forest PAs do reduce forest loss, widely varying performance suggests substantial opportunities for improved protection, particularly in Asia.
A Global Analysis of Deforestation in Moist Tropical Forest Protected Areas
Air quality and human health improvements from reductions in deforestation-related fire in Brazil
C. L. Reddington, E.W. Butt, D.A. Ridley, P. Artaxo, W.T. Morgan, H. Coe and D.V. Spracklen
Roughly 15% of the Brazilian Amazon was deforested between 1976 and 20101. Fire is the dominant method through which forests and vegetation are cleared. Fires emit large quantities of particulate matter into the atmosphere2, which degrades air quality and affects human health3, 4. Since 2004, Brazil has achieved substantial reductions in deforestation rates1, 5, 6 and associated deforestation fires7. Here we assess the impact of this reduction on air quality and human health during non-drought years between 2001 and 2012. We analyse aerosol optical depth measurements obtained with satellite and ground-based sensors over southwest Brazil and Bolivia for the dry season, from August to October. We find that observed dry season aerosol optical depths are more than a factor of two lower in years with low deforestation rates in Brazil. We used a global aerosol model to show that reductions in fires associated with deforestation have caused mean surface particulate matter concentrations to decline by ~30% during the dry season in the region. Using particulate matter concentration response functions from the epidemiological literature, we estimate that this reduction in particulate matter may be preventing roughly 400 to 1,700 premature adult deaths annually across South America.