《A The Conversation translated article (Note 1)》

When the World Health Organization (WHO) officially declared a pandemic on March 11, 2020, the planet was already about 1.2°C warmer than in pre-industrial times. Lockdowns were imposed across much of the world: factories shut down, car engines were switched off, and aircraft were left grounded, and human activity began to decline more sharply than ever before.

Since then, many notable changes have been observed, and as climate scientists we were also able to gain entirely new—and at times unexpected—insights during this period.

Here, we set out three of our findings.

Bangalore, India during lockdown (Photo: Nicolas Mirguet / Flickr [CC BY-NC 2.0])

Climate science is happening in real time

Prompted by the pandemic, we rapidly worked out how to tackle the challenge of monitoring greenhouse gas emissions, especially carbon dioxide (CO₂), in real time. In March 2020, when many lockdowns began, the next comprehensive Global Carbon Budget (Note 2) that determines that year’s emissions would not be finalized until the end of the year, so climate scientists began looking for alternative data that could show changes in CO₂.

Information about lockdowns was used as a mirror for global emissions. In other words, if we know by how much sectors of the economy or countries’ activities declined compared with pre-pandemic levels, we can assume a corresponding decline in their emissions.

A landmark study combining governments’ lockdown policies and activity data from around the world up to May 2020 projected a 7% decline in CO₂ emissions by the end of that year, a figure later confirmed by the Global Carbon Project. Building on that, my team used mobility data from Google and Apple to show changes in ten pollutants, and in a third study we again tracked CO₂ emissions using data on fossil fuel combustion and cement production.

According to the latest Google mobility data, daily activity has recovered to some extent, though it has not yet returned to pre-pandemic levels. This is reflected in the latest emissions estimates: after a limited rebound following the first lockdowns, global emissions rose fairly steadily through the second half of 2020. There was then a second slight dip from late 2020 into early 2021, emblematic of the second wave.

(Figure: Piers Forster)

Meanwhile, as the pandemic progressed, the near–real-time approach to tracking CO₂ emissions established by the Carbon Monitor project became a valuable new method for this kind of science.

No dramatic effect on climate change

In both the short and long term, the pandemic’s effect on climate action is not as great as many had hoped.

Although skies were exceptionally clear and quiet in spring 2020, related studies found a slight warming effect during lockdowns. As industry slowed, not only did air pollution decline, but the cooling role of aerosols—tiny particles produced by burning fossil fuels that reflect sunlight from the Earth’s surface—also weakened. The impact on global temperature was very small and short-lived (0.03°C), yet it was larger than the effects associated with ozone, CO₂, and the grounding of aircraft.

Looking ahead to 2030, simple climate models estimate that if countries had adhered to the emissions pledges already in place during the pandemic, as a result of COVID-19 global temperatures would fall by only about 0.01°C. This result was later supported by more sophisticated model simulations.

These national pledges have been updated and strengthened over the past year, but they are still not enough to avoid dangerous climate change, and as long as emissions continue, we will eat into the remaining carbon budget. The longer action is delayed, the steeper the required emissions cuts will become.

Passenger aircraft slated for dismantling during the COVID-19 pandemic (Photo: Clint Budd / Flickr [CC BY 2.0])

This is not a plan for climate action

Successive lockdowns temporarily halted the normal lives we had known, but that is neither sufficient to stop climate change nor sustainable. Like climate change, COVID-19 has hit the most vulnerable the hardest. We need to find ways to cut emissions without the economic and social impacts of lockdowns, and solutions that promote health, well-being, and equity. Broad enthusiasm and action on climate by individuals, institutions, and businesses remain essential, but they must be underpinned by structural changes in the economy.

My colleagues and I have projected that investing just 1.2% of global GDP in recovery packages could be the difference between keeping warming below 1.5°C and facing a future of more severe impacts and higher costs.

Unfortunately, green investment has come nowhere near the required level. However, more investment is likely over the coming months. It is essential that strong climate action be embedded in forthcoming investments. The spending may look high, but the potential returns are far greater.

Note 1 This article is a translation of an article by Piers Forster of The Conversation, a partner organization of “Covering Climate Now,” in which GNV also participates as a partner organization: “Piers Forster, I’m a climate scientist – here’s three key things I have learned over a year of COVID.” Covering Climate Now has designated the week of April 12–22, 2021 as a reporting week. We would like to take this opportunity to thank The Conversation and Piers Forster for providing the article.

Note 2 The carbon budget is the maximum amount of carbon that humanity can emit while keeping the rise in the global average temperature to 2°C or less. This goal of “keeping the rise in the global average temperature to 2°C or less” is the target set under the Paris Agreement of 2015, under the UN Framework Convention on Climate Change.

Writer: Piers Forster (University of Leeds)

Translation: Ayako Hirano

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