19 September 2016

Acidity in atmosphere minimised to preindustrial levels



The ice is drilled in Greenland and Antarctica and is transported back home to the laboratory where it is prepared and made ready the measurements. (Credit: Paul Vallelonga, NBI)


The ice is cut out and melted on a warm melting head. The new method measures the meltwater directly and the data can already be analysed a few seconds after melting the ice. (Credit: Ola Jakup Joensen, NBI)


Measures pollution from year to year

But the last 100 years are interesting for climate researchers as it is the period where we have had massive pollution of the atmosphere from industrialisation, vehicle use and people’s energy consuming lifestyles.

“We have therefore developed a new method that can directly measure the acidity of the ice using a spectrometer. We have an ice rod that is cut along the length of the ice core. This ice core rod is slowly melted and the meltwater runs into a laboratory where they take a lot of chemical measurements. With our new method you can also measure the acidity, that is to say, we measure the pH value and this is seen when the water changes colour after the addition of a pH dye. We can directly see the fluctuations from year to year,” explains Helle Astrid Kjær, postdoc in the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen.

The graph shows the acid content of the Greenland ice core NEGIS, measured using the new pH method. You see that the acid content in the atmosphere rose from the 1950s until the 1970s. The high acid content in the atmosphere in the 1970s affected the air quality in general and trees and fish died in forests and streams. In the 1970s, the United States and Europe therefore created the so-called "clean air act", which limited the emissions of acid and NOx. With the new measurements in the ice, you can see that this agreement has had a great effect and the acid content in the Arctic regions are now back to levels before the high emissions. (Credit: Helle Astrid Kjær, NBI)


Distinguishes between natural and manmade sources


Helle Astrid Kjær and Paul Vallelonga in the CFA (Continuous Flow Analysis) ice core laboratory, where they melt ice cores and study what the impurities tell us about past climate. (Credit: Ola Jakup Joensen, NBI)


The new pH method has already been used on ice cores from Greenland and Antarctica by research teams from New Zealand, the United States and Denmark.

Helle Astrid Kjær, postdoc at the Center for Ice and Climate, Niels Bohr Institute, Univesity of Copenhagen, +45 3532-0629, hellek@fys.ku.dk