The past year saw global CO2 emissions drop by seven percent relative to 2019. The continued decrease at this rate would cause global emissions to reach net-zero by about 2035, giving us better than even odds of limiting global warming to 1.5C.
This will not occur without a global effort to change the trajectory of future emissions. The 2020 emissions drop was a side-effect of efforts to control COVID-19. If economic recovery efforts were targeted to try to bring emissions down further this could keep the 1.5C target within reach. At the peak of global lockdowns in April 2020, daily CO2 emissions decreased by almost 20 percent relative to the same period in 2019.
These insights can inform how COVID-19 recovery investments could be used to drive emissions further downward. The largest relative decreases in emissions came from reductions in road transport, such as commuting by car, and air travel.
Although we are all suffering from the loss of in-person interactions, we have also learned a lot about how to convene meetings, presentations and collaborations online. While individual mobility will rebound as lockdowns ease, our crash course in remote working and learning means that we may not need to return to pre-COVID-19 travel levels. Emissions from industry and power generation did not decrease as much, in relative terms.
This points to the need for systemic changes in technological infrastructure to unlock the potential for lower-carbon economic activity. Similar technological advances are also needed to support low-carbon travel in circumstances where online platforms are not up to the task. The combination of sustained individual behavioural change, with a rapid expansion of low-carbon infrastructure, has the potential to have a substantial effect on the trajectory of future CO2 emissions.
An increasing number of countries, cities and companies are committing to net-zero emissions targets, where CO2 emissions are decreased to zero or to a level that is matched by the intentional removal of CO2 from the atmosphere. These targets are essential to any effort to stay within the remaining carbon budget.
Countries that have adopted or promised net-zero emissions targets include the European Union, United Kingdom, China, Canada and the United States under the new Biden administration. Currently, most of these targets are set for 2050 (or 2060 in the case of China).
According to our estimate of the remaining carbon budget, these commitments are insufficient to limit warming to 1.5C. They may, however, limit warming to the higher temperature goal of the Paris Agreement: well below 2C.
The climate effects of other greenhouse gases, as well as of aerosols emitted from fossil fuel use, remain one of the largest sources of uncertainty in estimates of the remaining carbon budget. Our effectiveness in mitigating these other emissions could expand or contract the size of the remaining carbon budget.
This year will be key in our efforts to decrease emissions. COVID-19 has opened a window of opportunity to meet ambitious climate targets that might otherwise have been out of reach. Governments around the world are spending unprecedented amounts to support and reinvigorate national economies. We must actively pursue this opportunity for a green recovery and avoid investing in infrastructure and industries that will lock in future CO2 emissions.
Yet the COVID-19 stimulus packages announced so far are “missing the opportunity,” according to the UN Environment Program’s adaptation report released last week.
There are no emergency lockdown measures that will slow the rate of climate warming. Instead, we need targeting, substantial and sustained effort and investments to continue to decrease and eventually eliminate global CO2 emissions. This window is open now, and we must not miss the opportunity.