NB: Initially, the title of this column stated the figure 8%. Since this article was written, the 8% global CO2 emissions in 2020 has been re-evaluated at 7%.
Before the pandemic we were on a worst-case scenario trajectory in terms of greenhouse gas emissions. According to the Intergovernmental Panel on Climate Change (IPCC) 1, we need to prevent a global temperature rise of 2°C if we are to avert irreversible environmental changes. We are currently set to face an increase of twice that: 4°C. The pandemic and lockdown restrictions around the world represented a significant change in the interactions between humans and the environment. My team studies atmospheric composition and climate using observations from both ground stations and satellites, which explains why we were rapidly called upon when pandemic became global.
Depending on the type of gas or particle we are referring to, the observed effect of the pandemic is different. Anthropogenic greenhouse gases like carbon dioxide (CO2) and methane (CH4) stay in the atmosphere for around 100 and 10 years, respectively. So it is difficult to reliably measure changes over a relatively short time span. However, highly reactive species and pollutant particles found in the air have much shorter lifespans, and we did see big changes there. For example, we observed a 30% reduction in ultrafine particles around Paris in comparison to the same period over the last 10 years. Moreover, observations from the European satellite, Sentinel-5P, revealed a decrease of over 50% NO2 – an indicator of fossil fuel emissions – in European megacities during Spring.
However, to speak of a positive impact of the lockdown on climate is actually more complicated to answer than it would seem. If we look at the greenhouse gases present in the atmosphere, we actually don’t see much change. But this is not the best way to measure effects of human activity over short timeframes; atmospheric concentrations of CO2 can be masked by plant activity across the world. Instead, we measured emissions based on energy demand and in doing so we saw a significant decrease in CO2 released into the atmosphere. In April 2020, global CO2 emissions were 17% lower than last year – equivalent to 17 megatons of CO2 per day. And estimations for 2020 overall say that CO2 emissions were 8% less than in 2019.
This 8% reduction in CO2 emissions during the pandemic is great news for the planet. But it is worth noting that this only really takes us back to 2016 levels – carbon emissions drastically increased between 2016–2019. To respect the 2015 Paris Agreement, we need to reduce greenhouse gas emissions by 8% per year 2. The effect of the global pandemic and large-scale lockdown periods is proof that the climate goal is, in theory, achievable.
Nevertheless, the measures have been drastic. The economic and social constraints resulting from the pandemic are unsustainable over the long-term. ‚These results do, however, provide use with an indication of where we should focus our efforts. That is to say by pointing out the global sectors where the biggest changes can be made if we are to effectively reduce greenhouse gas emissions. We saw, for example, a 75% reduction in the aviation industry. But aviation is only responsible for 2–3% of global greenhouse gas emissions so it is not necessarily the industry that is likely to have the biggest overall impact.
If we turn our attention to the energy sector, we see that it is responsible for 44% of global greenhouse gas emissions. And during the first lockdown in 2020 we saw a 6% reduction in emissions due to lower energy demand. Another important sector is ground transport. Almost 50% of the reduction in emissions during the lockdown can be attributed to reduced surface traffic. So, the energy and road transport sectors are areas we should be paying attention to.
Nevertheless, there is a risk that political decisions involving environmental issues, or “green deals”, shift out of view whilst the world focuses on restarting the economy. But the climate crisis is not going away just because there is a health crisis. We should do everything to avoid turning our back on climate-related political decisions.
If we look at the evolution of CO2 emissions in relation to previous economic crises such as the ‘Credit Crunch’ in 2008 the pattern is unsettling. In every case we see that once the economy recovers, CO2 emissions return to their original trajectory – or more. This means that by 2021 or 2022, we are likely to have erased the environmental benefit of the pandemic. We must stay vigilant by focusing on new solutions globally and there are many options. We should be focusing on specific sectors such as energy and transport, but also invest in biomass energy, and carbon capture and storage by planting trees and developing more advance technological solutions. The next ten years really count.