The Covid-19 global lockdown has had an “extreme” effect in cutting daily carbon emissions, but the trend is unlikely to last, according to analysis by an international team of leading climate scientists.
The study shows daily emissions decreased by 17 per cent – or 17 million tonnes of CO2 – during the peak of confinement measures in early April compared to mean daily levels in 2019.
The effect, dropping to levels last observed in 2006, is greater than previous published estimates.
Emissions from surface transport, such as car journeys, account for almost half (43 per cent) of the decrease in global emissions during peak confinement on April 7th. Emissions from industry and from power combined account for a further 43 per cent of the decrease in daily global emissions.
Aviation, the sector most impacted by lockdown, saw a 10 per cent decrease in emissions – it accounts for 3 per cent of global emissions outside of the pandemic.
Increased use of residential buildings by people working at home only marginally offset the drop in emissions from other sectors.
In individual countries, emissions decreased by 26 per cent on average at the peak of their confinement. Separate analysis by the MaREI centre in UCC also published on Tuesday suggests carbon emissions in Ireland are set to reduce by 5 per cent this year (2 million tonnes of CO2), excluding aviation, which is counted under the EU emissions trading system.
The global analysis published in Nature Climate Change shows social responses alone, without increases in wellbeing and/or supporting infrastructure, “will not drive the deep and sustained reductions needed to reach net-zero emissions”, as committed to by many countries including Ireland.
“Population confinement has led to drastic changes in energy use and CO2 emissions. These extreme decreases are likely to be temporary though, as they do not reflect structural changes in the economic, transport, or energy systems,” said Prof Corinne Le Quéré of the University of East Anglia who led the analysis.
The extent to which world leaders consider climate change when planning their economic responses post Covid-19 will influence the global CO2 emissions paths for decades to come, she pointed out.
“Opportunities exist to make real, durable, changes and be more resilient to future crises, by implementing economic stimulus packages that also help meet climate targets, especially for mobility, which accounts for half the decrease in emissions during confinement,” she added.
Cities and suburbs supporting walking and cycling and uptake of electric bikes, was far cheaper and better for wellbeing and air quality than building roads and preserved social distancing, Prof Le Quéré pointed out.
The team analysed government policies on confinement for 69 countries including Ireland responsible for 97 per cent of global emissions. At peak of confinement, regions responsible for 89 per cent of global emissions were under some level of restriction.
Data on activities indicative of how much each economic sector was affected by the pandemic was then used to estimate change in CO2 emissions from fossil fuels for each day and country from January to April 2020.
The estimated total change in emissions from the pandemic amounts to 1,048 million tonnes of carbon dioxide (MtCO2) until the end of April. Of this, changes were largest in China where the confinement started, with a decrease of 242 MtCO2, then in the US (207 MtCO2), Europe (123 MtCO2), and India (98 MtCO2).
The impact of confinement on 2020 annual emissions is projected to be around 4 to 7 per cent compared to 2019, depending on the duration of the lockdown and the extent of the recovery.
“If pre-pandemic conditions of mobility and economic activity return by mid-June, the decline would be around 4 per cent. If some restrictions remain worldwide until the end of the year, it would be around 7 per cent,” they predict.
This annual drop is comparable to the amount of annual emission reductions needed year-on-year across decades to achieve the climate objectives of UN Paris Agreement.
Co-author Prof Rob Jackson of Stanford University added: "The drop in emissions is substantial but illustrates the challenge of reaching our Paris climate commitments. We need systemic change through green energy and electric cars, not temporary reductions from enforced behaviour."
The rush for economic stimulus packages “must not make future emissions higher by delaying new green deals or weakening emissions standards”, the authors warn.