“We would expect from a 100% switchover from fossil fuels to zero-emission renewables…net radiative heating would increase drastically.” – Nair et al., 2023
Using observational data gleaned from COVID-19 lockdowns in South Asia, scientists publishing in a Nature journal (Nair et al., 2023) have now determined the ongoing switch to zero greenhouse gas (GHG) emissions renewables will subsequently lead to a dramatic reduction in climate-cooling aerosol (pollution) emissions. Because aerosol emissions have a relatively greater climate impact by reflecting shortwave radiation, the net effect of transitioning to renewables will be to “drastically” increase Earth’s temperatures over the coming decades.
“Mitigation strategies focusing on the phase-out of fossil fuels will lead to quick removal of the short-lived aerosols while the longer-lived major greenhouse gases decrease much more slowly, likely resulting in undesired net warming of the climate during a decades-long transition period.”
Image Source: Nair et al., 2023
The curtailment of industrial and transport energy use in South Asia during COVID lockdowns (March-May 2020) not only reduced fossil fuel (GHG) emissions, but also the associated aerosol (pollution) emissions that serve to cool the climate by reflecting shortwave radiation.
Scientists have assessed a ~7% reduction in aerosol emissions during the initial lockdown months induced a ~20 W/m² increase in downwelling solar radiation forcing.
The magnitude of this reduced-aerosol-emissions climate forcing (~20 W/m² within just a few months) is characterized as a “major surprise.”
To put this into perspective using the conclusions found in Feldman et al., 2015, this aerosol forcing is about 100 times larger than the clear-sky surface forcing (0.2 W/m²) associated with 10 years of CO2 increases (22 ppm).
The switch to 100% renewables, or the phasing out of fossil fuel energy sources, has the (unintended) net effect of causing decades of warming. This is the opposite of mitigation policy intentions.