https://phys.org/news/2020-01-emissions-potent-greenhouse-gas-contradicting.html
anuary 21, 2020
Emissions of potent greenhouse gas rises, contradicting reports of huge
reductions
by University of Bristol
Despite reports that global emissions of the potent greenhouse gas
hydrofluorocarbon (HFC) were almost eliminated in 2017, an international
team of scientists, led by the University of Bristol, has found
atmospheric levels growing at record values.
Over the last two decades, scientists have been keeping a close eye on
the atmospheric concentration of a hydrofluorocarbon (HFC) gas, known as
HFC-23. This gas has very few industrial applications. However, levels
have been soaring because it is vented to the atmosphere during the
production of another chemical widely used in cooling systems in
developing countries.
Scientists are concerned, because HFC-23 is a very potent greenhouse
gas, with one tonne of its emissions being equivalent to the release of
more than 12,000 tonnes of carbon dioxide. Starting in 2015, India and
China, thought to be the main emitters of HFC-23, announced ambitious
plans to abate emissions in factories that produce the gas. As a result,
they reported that they had almost completely eliminated HFC-23
emissions by 2017.
In response to these measures, scientists were expecting to see global
emissions drop by almost 90 percent between 2015 and 2017, which should
have seen growth in atmospheric levels grind to a halt. Now, an
international team of researchers has shown that concentrations
increased, setting an all-time record in 2018. The paper is published
today in Nature Communications.
Dr. Matt Rigby, who co-authored the study, is a reader in atmospheric
chemistry at the University of Bristol and a member of the Advanced
Global Atmospheric Gases Experiment (AGAGE), which measures the
concentration of greenhouse gases around the world. He said, "When we
saw the reports of enormous emissions reductions from India and China,
we were excited to take a close look at the atmospheric data. This
potent greenhouse gas has been growing rapidly in the atmosphere for
decades now, and these reports suggested that the rise should have
almost completely stopped in the space of two or three years. This would
have been a big win for climate."
The fact that this reduction has not materialized, and that, instead,
global emissions have actually risen, is a puzzle that may have
implications for the Montreal Protocol, the international treaty that
was designed to protect the stratospheric ozone layer. In 2016, Parties
to the Montreal Protocol signed the Kigali Amendment, aiming to reduce
the climate impact of HFCs, whose emissions have grown in response to
their use as replacements to ozone depleting substances.
Dr. Kieran Stanley, the lead author of the study, visiting research
fellow in the University of Bristol's School of Chemistry and a
post-doctoral researcher at the Goethe University Frankfurt, added, "To
be compliant with the Kigali Amendment to the Montreal Protocol,
countries who have ratified the agreement are required to destroy HFC-23
as far as possible. Although China and India are not yet bound by the
amendment, their reported abatement would have put them on course to be
consistent with Kigali. However, it looks like there is still work to
do. Our study finds that it is very likely that China has not been as
successful in reducing HFC-23 emissions as reported. However, without
additional measurements, we can't be sure whether India has been able to
implement its abatement program."
Had these HFC-23 emissions reductions been as large as reported, the
researchers estimate that the equivalent of a whole year of Spain's CO2
emissions could have been avoided between 2015 and 2017.
Dr. Rigby added, "The magnitude of the CO2-equivalent emissions shows
just how potent this greenhouse gas is. We now hope to work with other
international groups to better quantify India and China's individual
emissions using regional, rather than global, data and models."
Dr. Stanley added: "This is not the first time that HFC-23 reduction
measures attracted controversy. Previous studies found that HFC-23
emissions declined between 2005 and 2010, as developed countries funded
abatement in developing countries through the purchase of credits under
the United Nations Framework Convention on Climate Change Clean
Development Mechanism. However, while in that case, the atmospheric data
showed that emissions reductions matched the reports very well, the
scheme was thought to create a perverse incentives for manufacturers to
increase the amount of waste gas they generated in order to sell more
credits."
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