What is Happening to the Arctic Forests Due to Pollution?

We have discussed in previous articles the devastating action of man on the exploitation of Amazon forest and on the exploitation of timber in forests of Romania but now we find it interesting to propose an article published in Science which informs about the situation of Russian arctic forests due to pollution caused by human industrial activities.

Rampant air pollution in northern Siberia is blocking sunlight and slowing the growth of boreal forests, suggests new research

Largest study on tree rings in Norilsk , the most polluted city in Russia and the northernmost city in the world, found that air pollution from local mines and smelters is alme not partly responsible for a phenomenon known as "Arctic darkening".

Similar to `` global dimming '', this more regional effect occurs when tiny particles - from air pollution, volcanic eruptions and dust - collect in the atmosphere, where they absorb or partially disperse energy solar, interfering with the availability of light, evaporation and hydrology. the terrain.

Long-term observations and satellite measurements have shown that the amount of solar radiation reaching the Arctic surface has decreased since the middle of the century, but it was unclear whether this was due to human pollution in the region .

Today, after nearly a century of heavy and unregulated mining, the death of trees near Norilsk has extended up to 100 kilometers, but this is one of the first studies to link that dwindling forest with reduced sunlight.

"Although the problem of sulfur emissions and forest dieback has been successfully addressed in much of Europe, for Siberia we have not been able to see what the impact has been, to a great extent. partly due to a lack of long-term monitoring data, "says Ulf Büntgen, an environmental systems analyst at the University of Cambridge.

Yet this region is one of the most heavily polluted in the world. Then, by reading thousands of living and dead coniferous tree rings surrounding the city of Norilsk, researchers tried to piece together what happened to this once pristine forest.

Using wood and soil chemistry, they mapped the extent of Norilsk's uncontrolled environmental devastation over the course of nine decades.

"We can see that trees near Norilsk started dying massively in the 1960s due to rising pollution levels," says Büntgen.

Using solar radiation reaching the surface as a proxy for air pollution, the team's models provide "strong evidence" that Arctic darkening has substantially reduced tree growth since the 1970s.

Today, the authors say, even the boreal forests in Eurasia and northern North America have largely become a "landfill for large concentrations of anthropogenic air pollutants", and hence the effects of darkening Arctic could be felt much more broadly outside the Norilsk region studied here.

Unfortunately, due to large-scale circulation patterns, we know that pollutants tend to accumulate in the Arctic atmosphere, which means that ecosystems to the north can be particularly vulnerable to global pollution as a whole. .

Even knowing this, the authors were not prepared for the scale of the problem they had discovered.

"What surprised us is how widespread the effects of industrial pollution are: the extent of the damage shows how vulnerable and sensitive the boreal forest is," says Büntgen.

"Given the ecological importance of this biome, pollution levels in the northern high latitudes could have a huge impact on the entire global carbon cycle."

Nor is pollution the only threat to these precious ecosystems, sometimes described as "lungs" for our planet. It appears that climate change is also altering the diversity of boreal forests, as more intense and frequent fires are wiping out huge swaths of Siberia every year, contributing to further regional air pollution.

While some models of global warming suggest that tree growth will increase with climate change, new research highlights that air pollution could overcome this, meaning trees in the Arctic north will grow more slowly and weaker than before.

Further research should examine how air pollution could lead to a reduction in solar radiation by absorbing solar radiation directly or indirectly through its effects on clouds.

Given the importance of these boreal forests as a carbon sink and how vulnerable they appear to be, the authors ask for more information on the long-term effects of industrial emissions on the world's northernmost forests.

"This study appears particularly timely in light of the unprecedented release in Norilsk of more than 20,000 tons of diesel in 2020," they write, "an environmental disaster that underscores the threat of Norilsk's industrial sector under rapid Arctic warming and thawing of permafrost, and also underlines the ecological vulnerability of the high northern latitudes. "

Carly Cassella, Science

Automatic translation from English. We apologize for any linguistic inaccuracies.