Newswise — A post-lockdown economic recovery plan that incorporates and emphasises climate-friendly choices could help significantly in the battle against global warming, according to a new study.

This is despite the sudden reduction of greenhouse gas emissions and air pollutants during lockdown having a negligible impact on holding down global temperature change.

The researchers warn that even with some lockdown measures staying in place to the end of 2021, without more structural interventions global temperatures will only be roughly 0.01°C lower than expected by 2030.

However, the international study, led by the University of Leeds, estimates that including climate policy measures as part of an economic recovery plan with strong green stimulus could prevent more than half of additional warming expected by 2050 under current policies.

This would provide a good chance of global temperatures staying below the Paris Agreement's aspirational 1.5?C global warming limit and avoiding the risks and severe impacts that higher temperatures will bring.

Piers Forster began working with his daughter, Harriet, after her A levels were cancelled. They analysed the newly accessible global mobility data from Google and Apple. They calculated how 10 different greenhouse gases and air pollutants changed between February and June 2020 in 123 countries. They then brought in a wider team to help with the detailed analysis.

The team's findings, published today in Nature Climate Change, detail how despite carbon dioxide (CO2), nitrogen oxides (NOx) and other emissions falling by between 10-30% globally, through the massive behavioural shifts seen during lockdown, there will be only a tiny impact on the climate, mainly because the decrease in emissions from confinement measures is temporary.

The researchers also modelled options for post-lockdown recovery, showing that the current situation provides a unique opportunity to implement a structural economic change that could help us move towards a more resilient, net-zero emissions future.

Study lead author Professor Piers Forster, director of the Priestley International Centre for Climate at Leeds and Principal Investigator of the CONSTRAIN consortium, said: "The choices made now could give us a strong chance of avoiding 0.3?C of additional warming by mid-century, halving the expected warming under current policies. This could mean the difference between success and failure when it comes to avoiding dangerous climate change.

"The study also highlights the opportunities in lowering traffic pollution by encouraging low emissions vehicles, public transport and cycle lanes. The better air quality will immediately have important health effects - and it will immediately start cooling the climate."

Study co-author Harriet Forster, who has just completed her studies at Queen Margaret's School, said: "Our paper shows that the actual effect of lockdown on the climate is small. The important thing to recognise is that we've been given a massive opportunity to boost the economy by investing in green industries - and this can make a huge difference to our future climate.

"I'm going to London next month to study art but I also did chemistry at A-level so was glad to use what I learned in my chemistry classes to do something useful."

Study co-author Corinne Le Quéré from the University of East Anglia said: "The fall in emissions we experienced during COVID-19 is temporary and therefore it will do nothing to slow down climate change, but the Government responses could be a turning point if they focus on a green recovery, helping to avoid severe impacts from climate change."

Study co-author Joeri Rogelj from the Grantham Institute - Climate Change and the Environment at Imperial College London said: "Both sobering and hopeful, the flash crash in global emissions due to lockdown measures will have no measurable impact on global temperatures by 2030; but the decisions we make this year about how to recover from this crisis can put us on a solid track to meet the Paris Agreement. Out of this tragedy comes an opportunity, but unless it is seized a more polluting next decade is not excluded."

Study co-author Matthew Gidden from Climate Analytics, Berlin said: "The lasting effect of COVID-19 on climate will not depend on what happens during the crisis, but what comes after. "Stimulus focused on green recovery and low-carbon investment can provide the economic kick start needed while putting the world on track to meet climate pledges."

Study co-author Professor Mathew Evans. From Wolfson Atmospheric Chemistry Laboratories, University of York and the National Centre for Atmospheric Science said: "The analysis of air quality observations from around the world showed us that the emissions reductions captured by Google and Apple's mobility data were pretty close to those actually being experienced."

Study co-author Christoph Keller from Goddard Earth Sciences, Technology and Research (GESTAR) based in the Global Modeling and Assimilation Office (GMAO) at NASA GSFC said: "The decrease in human activity in the wake of the COVID-19 pandemic has created a unique opportunity to better quantify the human impact on atmospheric air pollution.

"Near real-time analysis of observations, mobility data, and NASA model simulations offers quantitative insights into the impact of COVID-19 containment measures on air pollution. This study demonstrates how such information can help to advance our understanding of the complicated interactions between air quality and climate."

Further information:

Link to media resources:

(Includes animation of fraction of usual NOx and SO2 emissions due to COVID-19)

Please credit all use of resources to CONSTRAIN

Page access password: CONSTRAIN

The paper Current and future global climate impacts resulting from COVID-19 is published in Nature Climate Change on 07 August 2020. (DOI: 10.1038/s41558-020-0883-0)

Once published the paper will be available at:

Christoph Keller is based in the Global Modeling and Assimilation Office (GMAO) at NASA GSFC, in Greenbelt, MD, just outside Washington, DC. He is employed by the Universities Space Research Association (USRA) in the institute "Goddard Earth Sciences, Technology and Research (GESTAR)" funded by GSFC.

Q&A Current and future global climate impacts resulting from COVID-19

What did the study do?

* The team used newly available mobility data from Apple and Google to estimate how emissions of 10 different greenhouse gases and air pollutants changed between February and June 2020, a time of unprecedented restrictions on work and travel due to COVID-19 lockdowns.

* The data, which covered a total of 123 countries responsible for 99% of global fossil fuel CO2 emissions, provided a unique opportunity to rapidly compare emissions trends consistently across countries and sectors.

* For each country, the team used the mobility data to establish changes in activity levels for six economic sectors (surface transport, residential, power, industry, public/commercial, and domestic aviation).

** For countries where access to Google data was not possible, such as China, Russia and Iran (all large emitters who imposed strict lockdowns), the methodology developed by Le Quéré et al.(2020) was used.

** The team also used Le Quéré et al. to provide estimates for international aviation and shipping.

* The changes in activity/mobility over time were used to estimate how emissions had changed during lockdown, compared to recent baseline emissions:

** For CO2 the baseline was taken from Le Quéré et al. (2019 levels).

** For all other emissions we used the EDGAR database (2015 levels).

* For CO2 alone, results are consistent with the study of Le Quéré et al. based on the analysis of confinement measures and activity data. The method used here makes use of mobility trends at the country level which is more direct than using confinement measures, but could be overestimating changes by around 20%.

* Observed concentration of nitrogen dioxide (NO2) from surface air-quality monitoring sites in 32 countries around the world were coupled to NASA's global air pollution model to predict what the concentration of NO2 would have been without the COVID-19 restrictions. Comparing the actual observed concentration during the restrictions to that predicted by the model allowed another way to estimate the change in the emissions of oxides of nitrogen.

* The team then developed a simple set of assumptions to estimate how lockdown emissions changes translated into temperature change - the direct effect of global lockdown on climate. In doing so, the team assumed some restrictions on activity due to COVID-19 (66% of the restrictions level seen in June 2020) will remain in place until the end of 2021, representing a "a "two-year blip".

* Using a simple climate model, the team also considered how choices made around economic recovery from the COVID-19 crisis will affect future emissions pathways and therefore global temperatures, from now until 2050.

* These choices included economic recoveries driven by green stimulus packages or increasing reliance on fossil fuels, which were compared to a baseline reflecting a direct return, post-lockdown, to pre-COVID-19 policies and associated emissions levels. In each case, the team included the "two-year blip" at the start.

** Our baseline represents emissions levels reflecting Nationally Determined Contributions (NDC) until 2030, with no significant strengthening of climate action thereafter.

** The fossil-fuelled recovery assumes strong support for fossil-fuels (an additional 1% of GDP invested). Emissions are 10% higher in 2030 compared to the baseline and continue to rise thereafter.

** The moderate green stimulus assumes that recovery packages target low-carbon energy supply and energy efficiency (an additional 0.8% of GDP invested), do not support bailouts for fossil firms, and begin to structurally change the carbon intensity of economic activity. Greenhouse gas emissions decrease by about 35% by 2030 relative to the baseline and reach global net-zero CO2 by 2060.

** The strong green stimulus invests an additional 1.2% of GDP in low carbon technologies and reduces investment in fossil fuels, leading to a 50% decrease in greenhouse gas emissions by 2030 and global net-zero CO2 by 2050.

What did the study find? (Only present central values. Full uncertainties ranges are reported in the paper.):

* The team's analysis shows that emissions reductions likely peaked in mid-April 2020, with carbon dioxide (CO2), nitrogen oxides (NOx) and other emissions falling by between 10-30% globally.

** Changes in surface transport were the biggest driver for most types of emission.

** Changes also occurred worldwide, with most countries contributing to the fall in emissions (mobility fell by 10% or more during April 2020 in all but one country, and by 80% in five or more countries).

** These findings are also reflected in satellite data and local ground-based observations, which show similar declines in air pollution.

** The reductions calculated by the mobility data were very similar to the reductions calculated from the air quality monitoring data.

* However, the direct temperature impact of the pandemic will be negligible: even with some lockdown measures staying in place to the end of 2021, global temperatures will only be around 0.01°C lower than expected by 2030 (compared to the current baseline).

** It will be difficult to see any effect of the pandemic on climate before 2030 because of temporary nature of the lockdown emission changes and also the short-term cancellation effects on climate from changes in NOx and SO2 described below.

** Falls in NOx emissions would normally lead to further cooling in the short-term, but this is offset by warming from a 20% reduction in SO2 emissions, which will balance out by 2030 (SO2 emissions lead to aerosol formation, which reflect sunlight back to space and cool the planet, so reducing SO2 reduces its cooling effect).

* Although it will be difficult to see the effects of lockdown on climate in the next decade, after 2030, differences begin to emerge depending on the choices made:

** If, after a two-year blip, economic recovery goes back to current investment levels, or we choose a recovery that strongly invests in fossil fuels, we are likely (>80% probability) to see warming of more than 1.5 °C above preindustrial levels by 2050.

** But if we choose a pathway with a strong green stimulus, investing around 1.2% of global GDP in low carbon technologies, and including climate policy measures, we could prevent around 0.3?C of additional warming by 2050.

** This would give us a good chance (~55%) of staying below the Paris Agreement's 1.5?C aspirational temperature goal.

What are the implications?

* As above, the direct effect of the COVID-19 pandemic on the climate will be negligible - a difference of only around 0.01°C by 2030.

* Lockdown's massive but temporary shifts in behaviour have therefore only had a tiny impact on the climate, and pollution levels across the world are already returning to near normal. This means we need structural change in the long-term in order to avoid dangerous climate change.

* The investment choices we make about economic recovery will strongly affect our climate trajectory to mid-century:

** A green recovery that invests in low carbon technologies, avoids fossil fuel lock-in, and cuts global emissions to net-zero by 2050, would mean we avoid around 0.3°C of warming by 2050, this is half of the expected 0.6C warming under current policies.

** This would also set the world on track for meeting the Paris Agreement's long-term temperature goal.

** This 0.3 degrees C could therefore represent the difference between us facing or avoiding dangerous climate change.

* In the short-term, policies that cut road transport emissions (NOx) will help to offset any temporary warming from cleaning up SO2 emissions from the power and industry.

** This will be especially important at a regional level where changes in aerosol concentration can lead to risks from extreme weather, such as heatwaves or rainfall, adding to the economic and health burden caused by the pandemic.

* Finally, rapid and easy access to big data can clearly contribute, in new and unexpected ways, to the evidence base scientific studies relating to COVID-19. We encourage Google, Apple and others to make their data freely available, and to promote its application.


University of Leeds

The University of Leeds is one of the largest higher education institutions in the UK, with more than 38,000 students from more than 150 different countries, and a member of the Russell Group of research-intensive universities. The University plays a significant role in the Turing, Rosalind Franklin and Royce Institutes.

We are a top ten university for research and impact power in the UK, according to the 2014 Research Excellence Framework, and are in the top 100 of the QS World University Rankings 2021.

The University was awarded a Gold rating by the Government's Teaching Excellence Framework in 2017, recognising its 'consistently outstanding' teaching and learning provision. Twenty-six of our academics have been awarded National Teaching Fellowships - more than any other institution in England, Northern Ireland and Wales - reflecting the excellence of our teaching.

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CONSTRAIN is an €8 million, 4 year programme of research and stakeholder engagement, funded by Horizon 2020.

Led by the University of Leeds, the CONSTRAIN consortium involves 14 partners and around 40 researchers from 9 countries across Europe and Israel.

CONSTRAIN focuses on developing a better understanding of global and regional climate projections for the next 20-50 years, as well as defining emissions pathways to limit warming. This requires a better understanding of how several human and natural factors will affect the climate in coming decades, such as how atmospheric aerosols influence the Earth's radiation budget, and the roles of clouds and oceans in driving climate change.

In doing so, CONSTRAIN is taking full advantage of results from the sixth Coupled Model Intercomparison Project (CMIP6), as well as other Horizon 2020 and European Research Council projects.

It is also translating this new scientific understanding into an improved evidence base aimed at informing international climate policy, and supporting decisions on climate mitigation and adaptation.

Follow CONSTRAIN or tag us in to coverage: @constrain_eu

Journal Link: Nature Climate Change