Black Summer’s effect on the atmosphere and more climate news

Welcome to our regular segment on breaking climate news you may have missed. The title refers to the global average daily concentration of carbon dioxide in the Earth’s atmosphere in parts per million (ppm). This means that for every million air particles, currently about 418.08 of them are CO2.

Black summer bushfires have changed the chemistry of our atmosphere

The 2019-2020 Black Summer bushfires had a dramatic effect on the chemistry of our upper atmosphere and could destroy ozone, according to a study by US and Canadian researchers.

The study published in Sciencefinds “unexpected and extreme perturbations in stratospheric gases beyond anything observed in the 15 years of previous measurements”.

The researchers used satellite data to make these observations. The stratospheric gases they found include formaldehyde, chlorine nitrate, chlorine monoxide, and hypochlorous acid.

Many of these chemicals could affect or destroy ozone.

The document also reports a decrease in ozone, nitrogen dioxide and hydrochloric acid in the stratosphere.

River carbon does not always go to sea

What could be more complicated than modeling the storage of carbon or the movement of water? Model both at the same time! An international team of researchers has come up with a more detailed analysis of how carbon moves through streams, rivers and oceans, and found that stored carbon doesn’t always end up where you think it should.

The researchers published their description of the land-ocean aquatic continuum, or DCA, of carbon in Nature.

“The complexity of the DCA, which includes rivers, groundwater, lakes, reservoirs, estuaries, littoral marshes, mangroves, seagrasses and waters above continental shelves, has made it difficult to assess its influence on the global carbon cycle,” says co-author Professor Pierre Regnier, researcher at the University of Brussels, Belgium.

Modelers often assume that there is a direct carbon pipeline from rivers to oceans and that most of the carbon that is transported there is natural. But this study found that DCA also carries a substantial amount of anthropogenic carbon. This means that the ocean probably absorbs more of our carbon, and the land less, than other models might suggest.

Fast methane action could save the Arctic

According to current trajectories, the Arctic could be ice-free in summer by the end of the century. But with a sharp turnaround in methane emissions, things could remain frosty until well after 2100, according to an article in Environmental Research Letters.

Methane is a much more powerful gas than carbon dioxide at absorbing heat, so reducing methane emissions can have a big impact. To date, little research has focused on the specific effects of methane attenuation.

The article finds that, if “all currently available solutions” for methane reductions were introduced, along with a reduction of CO2 emissions, there is an 80% chance that the Arctic will still have permafrost by the end of the century.

“Reducing current methane emissions represents a huge opportunity to help curb global warming,” says lead author Tianyi Sun, a researcher at the Environmental Defense Fund, US.

“Quickly cut methane with CO2 is our best chance of preserving the Arctic summer sea ice in our lifetime and for future generations. We have to do both.

Maybe you don’t suppress fires in the savannahs

Bushfires and forest fires generally increase carbon emissions because they literally burn carbon. This has led to proposals that we try to suppress natural fires, especially in areas that burn every year or so like the African savannahs, and plant more trees for carbon storage.

But a study published in Nature questioned this, finding that the benefits of fire suppression in a South African savanna resulted in only a marginal increase in carbon storage.

The researchers looked at 68 years of data from a long-term experiment in Kruger National Park, South Africa, where some plots are burned every year and others every three years.

They found that the three-year-old plots improved carbon storage by 0.35 tonnes of carbon per hectare per year, almost 30 times less than other estimates.

The researchers point out that while combustion releases carbon into the atmosphere, it can also help improve carbon storage in plants and soil. They caution against fire suppression as a tool to reduce carbon emissions.

Respite for Australia’s environment in 2021

Last year was kinder to Australia’s general environment, according to a study by researchers at the Australian National University.

ANU researchers produce an annual Environment Report, which tracks everything from field measurements to satellite data, and produces an overall score on the state of Australia’s environment.

After the devastation of the Black Summer bushfires in 2019-2020, researchers found that 2021 was a much better year overall. The total environmental score was 6.9 out of 10, down from a score of 3 in 2020.

Although there have been biodiversity losses and an increase in emissions, researchers say the two La Niña summers have given the environment some time to recover with more rainfall and fewer extreme temperature days.

“We have seen strong signs of recovery in all states and territories thanks to low fire activity, easing drought conditions and good rainfall which has replenished parched soils, improved vegetation and led to better conditions. growth,” says the report’s lead author, Professor Albert. van Dijk.

It points out, however, that this increase in rainfall has now led to devastating floods in Queensland and New South Wales – which fell outside the period covered by this report.

Although there were fewer very hot days, 2021 was still the sixth hottest year on record.

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