Interview with Dr Debbie Rosen, Science and Policy Manager for the EU Horizon 2020 CONSTRAIN project, based at the University of Leeds, UK, and Prof Piers Forster, professor of climate physics at the University of Leeds, the founding Director of the Priestley International Centre for Climate and PI for the CONSTRAIN project
Global economic activity dramatically ramped down as a result of measures to combat the coronavirus pandemic. Could you tell us what this has meant for the levels of carbon dioxide and other greenhouse gases and air pollutants?
For several reasons, CO2 emissions are difficult to monitor in real time, but proxy data (e.g. changes in transport, industry and power generation, as well as satellite and ground observations of other gases) can be used to estimate what has happened to CO2 emissions during the lockdown.
The first peer-reviewed study on CO2 (Le Quere et al.) indicates that daily global CO2 emissions had decreased by 17% by early April 2020 (the peak of the lockdown) compared with 2019, with the peak in emissions reductions hitting 26% on average in individual countries.
Forster et al. (pre-print soon) build on this approach to look at a larger number of countries (123 in total, responsible for 99% of global CO2 emissions) and a range of additional pollutants (9 in total) that can affect climate as well as air quality. These include nitrogen oxides, NOx, (mainly from transport emissions) and sulphur dioxide, SO2 (mainly from power generation). Although there were falls in both during lockdown (NOx falling by about 25% globally), the cooling we can expect from a fall in NOx is cancelled out by the warming from a similar fall in SO2 and aerosol emissions. There were also smaller changes in other pollutants (such as an increase in organic carbon from the residential sector as everyone is at home more), but overall this means that any temperature change is basically the result of what happens to CO2.
Will this be significant at all in reaching the goals of the Paris Agreement?
The temperature change from CO2 reductions during even a prolonged lockdown will be very small – in the grand scheme of things, lockdown is so far a temporary blip in our overall post-industrial emissions trajectory. But – and this is the key – studying what has happened during lockdown gives us insights into what we need to do to meet the Paris Agreement goals.
Forster et al. estimate that even if some lockdown measures stay in place until the end of 2021 (as a rapid return to the “old normal” seems very unlikely), this will only result in temperatures that are 0.01°C lower than if we carried on with current national plans and strategies.
However, we have choices about what happens after that two-year blip. We could aim for an economic recovery that is powered by fossil fuels, resulting in emissions that are 10% higher by 2030 and pushing the Paris goals even further out of sight. Alternatively – and preferably – we could support even a moderate green recovery, with investment in green stimulus having potential to reduce emissions by 36% over the same time period.
Although the effect on temperature from these different choices is difficult to distinguish before 2030, due to natural variability in the climate system, as we reach mid-century, choosing a green stimulus could reduce warming by about 0.2°C, and keep the Paris goals in sight.
The coronavirus pandemic and climate change are both global threats to human life, yet the responses to them have been very different. Post-pandemic, are there lessons we can take from the coronavirus response to tackle climate change?
Many articles have been written about the lessons learned for climate change. We discuss some of them in this blog, which, importantly, acknowledges that the crises are very different. Nonetheless, we would emphasise that both are compound risks, and that justice, fairness and equity are clearly central to both.
Globally, we will be evaluating the coronavirus response for years to come. But in the immediate future we should look at things like how the science has been presented to the public, our global and national levels of preparedness, and the impacts of delaying action (in terms of both risk and the economic and societal costs). One of the main challenges will be how to maintain any positive behaviour changes resulting from coronavirus (e.g. less car travel) in a way that is safe and equitable for all.
The COP26, scheduled to take place in Glasgow, Scotland, in November, has been postponed. Are you concerned that the pandemic might delay vital international talks and action on climate?
Among the research community, work is ongoing to prepare for COP – for example, we are using this time to increase our preparedness, factor in what we have learned from coronavirus, and raise awareness of the upcoming talks through webinars and workshops. We also aim to participate in lead-up events such as the UNFCCC’s June Momentum series, as well as the scientific and technical discussions at SBSTA 52, which will hopefully still take place in October. In some ways, the fact that COP26 has had to be postponed may have actually drawn more attention to it, and highlighted the need to tackle global (and compound) risks as a global community.
As countries and their economies start up again, is it possible that the climate and environment become secondary priorities to catch up on lost economic growth?
This is, of course, a possibility. But coronavirus has also led us to focus on what is possible for the environment if we can make different, but sustainable choices. As scientists, we can provide the evidence, but we need to work closely with policy makers, and also engage better with the public, to ensure that we are all aware of the implications of returning to “normal” compared to the unexpected option we now have of changing trajectories.
As above, Forster et al. show that we only need to make a relatively modest investment in a green recovery to make the Paris Agreement goals attainable. If we don’t make better choices now – for example, tapping in to the opportunities presented by the European Green Deal, not only to cut emissions but create a better society for all – then when will we?