Breakthrough in estimating fossil fuel carbon dioxide emissions

Date:
April 22, 2022
Source:
University of East Anglia
Summary:
Scientists have made a major breakthrough in detecting changes in
fossil fuel carbon dioxide emissions more quickly and frequently.



FULL STORY ==========================================================================
A team of scientists led by the University of East Anglia (UEA) has made
a major breakthrough in detecting changes in fossil fuel carbon dioxide emissions more quickly and frequently.


==========================================================================
In a study published today they quantified regional fossil fuel CO2
emissions reductions during the Covid-19 lockdowns of 2020-2021, using atmospheric measurements of CO2 and oxygen (O2) from the Weybourne
Atmospheric Observatory, on the north Norfolk coast in the UK.

The estimate uses a new method for separating CO2 signals from land
plants and fossil fuels in the atmosphere. Previously it has not been
possible to quantify changes in regional-scale fossil fuel CO2 emissions
with high accuracy and in near real-time.

Existing atmospheric-based methods have largely been unsuccessful
at separating fossil fuel CO2 from large natural CO2 variability, so
that estimates of changes, such as those occurring in response to the lockdowns, must rely on indirect data sources, which can take months or
years to compile.

The atmospheric O2-based method, published in the journal Science
Advances, is in good agreement with three lower frequency UK emissions estimates produced during the pandemic by the Department for Business,
Energy and Industrial Strategy, the Global Carbon Budget and Carbon
Monitor, which used different methods and combinations of data, for
example those based on energy usage.

Crucially, as well as being completely independent of the other estimates,
this approach can be calculated much more quickly.



==========================================================================
The researchers are also able to detect changes in emissions with higher frequency, such as daily estimates, and can clearly see two periods
of reductions associated with two UK lockdown periods, separated by a
period of emissions recovery when Covid restrictions were eased, during
the summer of 2020.

Researchers at UEA -- home of the UK's only high-precision atmospheric O2 measurement laboratory -- worked with colleagues at Wageningen University
in the Netherlands and the Max Planck Institute for Biogeochemistry,
Germany.

The study's lead author, Dr Penelope Pickers, of UEA's Centre for Ocean
and Atmospheric Sciences, said: "If humans are to reduce our CO2 emissions
from fossil fuels and our impact on the climate, we first need to know
how much emissions are changing.

"Our study is a major achievement in atmospheric science. Several others,
based solely on CO2 data, have been unsuccessful, owing to large emissions
from land plants, which obscure fossil fuel CO2 signals in the atmosphere.

"Using atmospheric O2 combined with CO2 to isolate fossil fuel CO2 in the atmosphere has enabled us to detect and quantify these important signals
using a 'top-down' approach for the first time. Our findings indicate
that a network of continuous measurement sites has strong potential
for providing this evaluation of fossil fuel CO2 at regional levels." Currently, fossil fuel CO2 emissions are officially reported with a
'bottom-up' approach, using accounting methods that combine emission
factors with energy statistics to calculate emissions.



========================================================================== These are then compiled into national inventories of estimated
greenhouse gas (GHG) emissions to the atmosphere from anthropogenic
sources and activities, such as domestic buildings, vehicles, and
industrial processes.

However, inventories can be inaccurate, especially in less developed
countries, which makes it more difficult to meet climate targets.

It can also take years for the inventory assessments to be completed, and
at the regional scale, or on a monthly or weekly basis, the uncertainties
are much larger.

An alternative method of estimating GHG emissions is to use a 'top-down' approach, based on atmospheric measurements and modelling.

The UK emissions inventory is already successfully informed and supported
by independent top-down assessments for some key GHGs, such as methane
and nitrous oxide.

But for CO2, the most important GHG for climate change, this has never
before been feasible, because of the difficulties distinguishing between
CO2 emissions from fossil fuels and land plant sources in the atmosphere.

Dr Pickers said: "The time taken for inventories to be completed makes
it hard to characterise changes in emissions that happen suddenly,
such as the reductions associated with the Covid pandemic lockdowns.

"We need reliable fossil fuel CO2 emissions estimates quickly and at
finer scales, so that we can monitor and inform climate change policies
to prevent reaching 2DEGC of global warming.

"Our O2-based approach is cost-effective and provides high frequency information, with the potential to provide fossil fuel CO2 estimates
quickly and at finer spatial scales, such as for counties, states or
cities." The team used 10 years of high-precision, hourly measurements
of atmospheric O2 and CO2 from Weybourne Atmospheric Observatory, which
are supported by the UK's National Centre for Atmospheric Science. Having long-term measurements of these climatically important gases was crucial
to the success of the study.

To detect a Covid signal, they had to first remove the effects of
atmospheric transport on their O2 and CO2 datasets, using a machine
learning model.

They trained the machine learning model on pre-pandemic data, to estimate
the fossil fuel CO2 they would have expected to observe at Weybourne if
the pandemic had never occurred.

They then compared this estimate to the fossil fuel CO2 that was actually observed during 2020-2021, which revealed the relative reduction in
CO2 emissions.

'Novel quantification of regional fossil fuel CO2 reductions during
COVID-19 lockdowns using atmospheric oxygen measurements', Penelope
A. Pickers et al., is published in Science Advanceson Friday, April
22, 2022.


========================================================================== Story Source: Materials provided by University_of_East_Anglia. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Penelope A. Pickers, Andrew C. Manning, Corinne Le Que're', Grant L.

Forster, Ingrid T. Luijkx, Christoph Gerbig, Leigh S. Fleming,
William T.

Sturges. Novel quantification of regional fossil fuel CO2
reductions during COVID-19 lockdowns using atmospheric
oxygen measurements. Science Advances, 2022; 8 (16) DOI:
10.1126/sciadv.abl9250 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220422161529.htm

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