Dramatic lockdown fossil fuel carbon dioxide decrease detected by citizen science supported radiocarbon observations

Dr Jocelyn Turnbull1, Dr Lucas Gatti Domngues1, Ms Nikita Turton1

1GNS Science, Lower Hutt, New Zealand


The travel and work restrictions imposed by COVID-19 lockdowns resulted in dramatic changes in fossil fuel CO₂ emissions around the world, most prominently in the transportation sector.  To date, most estimates of the change in CO₂ emissions have relied on proxy data.  In New Zealand, the lockdown requirements meant that travelling to measure emission changes was not possible, so we used a novel citizen science campaign to collect grass samples from which we measured the ¹⁴C content and calculated the local fossil fuel CO₂ contribution.  Our results from 17 sites in five cities around New Zealand demonstrate dramatic reductions in traffic emissions of 75 ± 3 % during the most severe lockdown restriction period.  This is consistent with sparse local traffic count information, and a much larger decrease in local traffic emissions than reported in global aggregate estimates of emission changes.  Our results demonstrate that despite nationally consistent rules on travel during lockdown, emission reductions varied by location, with inner city sites dominated by bus traffic showing smaller decreases in emissions than sites dominated by passenger vehicle traffic.


Dr Jocelyn Turnbull is the Radiocarbon Science Leader at the Rafter Radiocarbon Laboratory in New Zealand.  Her research interests are in the source and fate of fossil fuel  CO2 emissions, for which radiocarbon is a key tool.


Sep 09 2021


8:00 am - 6:00 pm