Climate Change and COVID-19
The worldwide disruption caused by the COVID-19 pandemic has resulted in numerous effects on the environment and climate. The global reduction in modern human activity such as the considerable decline in planned travel was coined anthropause and has caused a large drop in air pollution and water pollution in many regions.
Up to 2020, increase in the amount of greenhouse gases produced since the beginning of the industrialization era caused average global temperatures on the Earth to rise, causing effects including the melting of glaciers and rising sea levels. Prior to the COVID-19 pandemic, measures that were expected to be recommended to health authorities in the case of a pandemic included quarantines and social distancing.
In a study published in August 2020, scientists estimated that global NOx emissions declined by as much as 30% in April but were offset by ~20% reduction in global SO₂ emissions that weakens the cooling effect and conclude that the direct effect of the response to the pandemic on global warming will likely be negligible, with an estimated cooling of around 0.01 ±0.005 °C by 2030 compared to a baseline scenario but that indirect effects due to an economic recovery tailored towards stimulating a green economy, such as by reducing fossil fuel investments, could avoid future warming of 0.3 °C by 2050. The study indicates that systemic change in how humanity powers and feeds itself is required for a substantial impact on global warming.
In October 2020 scientists reported, based on near-real-time activity data, an 'unprecedented' abrupt 8.8% decrease in global CO₂ emissions in the first half of 2020 compared to the same period in 2019, larger than during previous economic downturns and World War II. Authors note that such decreases of human activities "cannot be the answer" and that structural and transformational changes in human economic management and behaviour systems are needed.
In January 2021 scientists reported that reductions in air due to worldwide COVID-19 lockdowns in 2020 were larger than previously estimated and conclude that, because of that, the impact of the COVID-19 pandemic on the climate during that year was a slight warming of Earth's climate of the year, instead of a slight cooling. They used climate models to identify small impacts that could not be discerned with observations. The study's lead author noted that aerosol emissions have major health ramifications and that they can't be part of a viable approach for mitigating global warming.