Swiss scientists: climate change raises CO2 emissions from alpine streams

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Swiss scientists: climate change raises CO2 emissions from alpine streams
Photo: EPFL

Scientists at Lausanne’s federal technology institute EPFL have discovered that alpine streams emit higher levels of carbon-dioxide (CO2) after a warmer than normal winter.


Alpine lakes and rivers emit a large amount of CO2 into the atmosphere as a naturally occurring phenomenon, said EPLF in a press release. But in a ‘normal’ winter, they absorb more than they emit.
However in a new study comparing CO2 levels over two consecutive winters, scientists discovered that after a warm winter with little snow, the streams release more CO2 than they absorb.
“After a normal winter, our study showed that during a 70-day ‘magic window’, the streams absorb more carbon dioxide through photosynthesis than they produce naturally,” explained Amber Ulseth, a researcher at the EPFL lab that carried out the research. 
“After a warm winter with very little snowfall, more production of CO2 takes place during the spring, which means that the streams release more carbon-dioxide than they absorb. There is no magic window, and the alpine streams become a net producer of CO2.”
To collect the data, researchers placed state-of-the-art environmental sensors in 12 streams in the Austrian foothills. 
Every five minutes the sensors measured the water ecosystem, including light intensity, temperature and oxygen levels. 
“By collecting data every five minutes we could really take each stream’s pulse and measure the metabolism of the entire ecosystem,” said Ulseth.
The study is the first of its kind to show the impact of climate change on the global carbon cycle in alpine streams, according to the lab’s director and co-author of the study Tom Battin. 
His team is now expanding the study in a three-year phase which in which researchers will monitor streams in the Swiss cantons of Valais and Vaud.
Lately winters in Switzerland have been warmer than ever with lower amounts of snow. Last December was the driest in Switzerland for 150 years
The Swiss parliament this week voted to ratify the Paris climate accord, which commits Switzerland to cutting its carbon emissions in half by 2030.



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