What skin cancer has to do with forest fires

Forest fires, polar air and the ozone hole

Corona has really brought little good. Such an exceptionally good effect was that a team of TROPOS researchers was unable to retrieve a container with measuring devices from Punta Arenas in Chile. The lidar system was only supposed to carry out its measurements in the small town in Patagonia from November 2019 to April 2020. Originally, the scientists had expected to find a particularly clean atmosphere here, since in these southern latitudes there is practically only ocean apart from a bit sparsely populated land at the southern tip of South America. But then the researchers saw in the stratosphere at an altitude of 12 to 30 kilometers the smoke from the gigantic fires that had ignited in the Australian outback around the turn of the year.

And because the pandemic eventually prevented the lidar from being retrieved, the scientists just kept measuring. And in the end they found out that the smoke particles from the fires had remained in the stratosphere for more than two years, while at the same time there was a huge hole in the ozone layer above them in both years. Was there a connection?

Already during the Mosaic expedition, during which TROPOS scientists traveled through the Arctic Ocean on board the German icebreaker Polarstern from 2019 to 2020 and measured the atmosphere over the North Pole, they noticed the layer of smoke caused by the forest fires in Siberia in the got there in the summer of 2019. Now they saw practically the same picture at the South Pole.

Researchers have long known from measurements after volcanic eruptions that particles can get stuck in the uppermost layers of the atmosphere for years. But that large forest fires can have a similar effect, is still a very recent discovery. According to Ansmann, researchers have so far observed this in three really large wildfires near the polar regions: In addition to the fires in Siberia (summer 2019) and Australia (beginning of the year 2019/2020), large wildfires in Canada also happened in August 2017.

Two mechanisms bring the smoke into the stratosphere, i.e. at altitudes of over 13 kilometers: On the one hand, fire clouds can form, technical term pyrocumulonimbus. Air heated above the fires rises and water condenses on the ash particles, causing clouds to form. A suction is created on the ground, whereby fresh wind flows to the seat of the fire and drives the fire further there. In the enormous clouds, water droplets and aerosols rub against each other and thunderstorms develop. In bad cases, lightning occurs that fuels new fires. In good cases, there is heavy rainfall that extinguishes the fires.

The second mechanism does not require firestorms, but is still being discussed among researchers. The hypothesis is that black soot particles are heated by solar radiation and thereby warm up the surrounding air, which is now rising. The Leipzig TROPOS researchers have made lidar measurements that are intended to prove this thesis and also simulated in detail how the process could take place. In both cases, the smoke reaches the very stable stratosphere, where there is little air exchange with the troposphere below. That’s why these particles stay there for years.

What’s the big problem with that? Forest fire smoke contains many organic chemicals, which are complex molecules made up of carbon, oxygen and hydrogen atoms. These molecules are sometimes very reactive and could be Bind ozone (consisting of three oxygen atoms). and decompose. This thesis is still under discussion. If true, that would be very bad news: the ozone layer protects us from UV radiation from the sun. When the gas is broken down, an ozone hole is created and the UV radiation that reaches the ground becomes more intense. We humans get sunburn more easily, animals and plants also suffer damage.

It has long been known that so-called chlorofluorocarbons (CFCs) damage the ozone layer, which is why these chemicals have been banned worldwide. If forest fires also enlarge such ozone holes, that would be another, previously unanticipated side effect of global warming. The chain of effects would be: people emit CO2, the climate is warming, there are longer droughts, huge forest areas are becoming drier and drier. If they do catch fire, massive wildfires will erupt, sending soot particles into the stratosphere where they attack the ozone layer. The UV radiation on the ground is increased through the ozone hole, which causes new damage to the health of humans, animals and plants. Or very briefly: The warmer it gets, the more forest fires occur, the larger the ozone holes become, and the more skin cancer people get.

Albert Ansmann therefore says that the discussion about the 1.5 degree target is deceptive. “We have to stop using fossil fuels immediately! If we think that we still have a few years until we reach the 1.5 degree mark and that everything will be under control by then, we have to realize: We have nothing under control !”

🗓 Climate dates

WEDNESDAY, JUNE 29, LEIPZIG

Slow fashion tour through the west of Leipzig: Cheap mass-produced goods in the online shop, fashion influencer marketing and the fast business with fashion did not only come under strong criticism in the times of Corona. The global effects of the fast fashion business model on people and the environment and the local alternatives for action are shown in an interactive city tour through the west of Leipzig. The tour is free. To register, click here.

THURSDAY, 30.06., ERFURT

Climate Pavilion: As part of the climate school, workshops and discussion events will take place on Thursday. How can areas of life such as food and agriculture, housing and energy develop in a climate-friendly way so that everyone can participate and live well? How can climate protection, business and more democracy go hand in hand? There are also practical offers on the topics. More info here.

THURSDAY, 06/30, POTSDAM

Is it possible to use the means of art to arouse desire and courage for changes that contribute to a more sustainable way of life? The Art For Futures Potsdam Fest is dedicated to this question. The children’s festival “Kids for Future” starts at 2 p.m. on the forecourt of the film museum. It is intended to give children a playful and imaginative introduction to a sustainable way of life. Event details here.

FRIDAY, 01.07., HALL

Long Night of Science: Numerous scientific institutions (the Martin Luther University, the Leopoldina and research institutions such as the Helmholtz Center for Environmental Research, UFZ) allow insights into laboratories throughout the city from 5 p.m. and offer lectures, readings and guided tours. All information about the program here.

📰 Climate research and humanity

Scientifically accurate reports convince even skeptics

Even Republican Americans can be persuaded that human-caused climate change is an enormous danger when they read scientifically accurate reports. These beliefs can be quickly shaken again by opinion pieces from climate change deniers. This is the result of an extensive online experiment with almost 3000 participants in autumn 2020, which a team led by Thomas Wood from Ohio State University is now reporting on in the renowned journal PNAS. The most important conclusion of the researchers: media should not only concentrate on new news but repeat scientifically correct facts over and over again so that the audience can orientate itself correctly.

Enormous traffic emissions from food transport

Avocados from Mexico, palm oil from Indonesia, mangoes and kiwis imported by plane – the transport of food is the largest source of greenhouse gases within the transport sector. Around 19 percent of global emissions from food production are caused by the transport of food alone. This is the conclusion of a new study by researchers at the University of Sydney, which appears in the journal “nature food”. Above all, consumers in wealthy countries have a key role to play in this development. In addition to a more plant-based diet, a focus on the regional production of food is therefore crucial.

Vanishing sea ice at the North Pole clears the way for shipping

Ice melt in the Arctic will assume enormous proportions in the coming decades. For shipping, however, this results in new routes outside of Russia’s territorial waters. These routes, which are 30 to 50 percent shorter, could significantly reduce the sector’s CO2 emissions. Researchers from Brown University in the USA have modeled various scenarios for this. They report on this in the journal PNAS.

UN Conference on Conservation of Endangered Species in Canada in December

The long-planned UN conference on stopping the mass extinction of animal and plant species is finally due to take place in December, two years late. The organizers of the COP-15 conference have now decided to move the location of the meeting from the Chinese metropolis of Kunming to Montreal, Canada, in order to prevent state representatives from being unable to travel to China due to possibly further tightened zero-Covid rules. China has approved the move and will continue to chair the conference’s Bureau. A global biodiversity framework is to be adopted at the meeting. The preservation of biodiversity is an urgent requirement for ecosystems to be able to adapt to the warming of the atmosphere.

📻 Climate in the MDR

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