How Climate Change will effect Baikal

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As you travel west on the Trans-Siberian railway from Ulan Ude the train runs down the bank of the Selenge, a river that feeds water from the heart of Mongolia into Lake Baikal. Mountains rise to the south, thrown up by the same tectonic plate movements that split the earth, giving rise to Lake Baikal.

And then all of a sudden you see a great expanse of grey water opening before you. In summer it can be blue, but for us, travelling in November, the lake and sky met in the middle distance in a haze of grey, almost concealing the cliffs on the far side. To the north east the lake carries on to the horizon and beyond for over 600 kilometers.

We left the main railway, changing to travel around the lakes edge on a small train following the original route of the Trans-Siberian. We change station at Sludyanka, near to wood processing factories that used to spew untreated waste into the lake. Later we were to learn from a journalist in Irkutsk that there is pressure to re-open the factories. The factories were originally shut down after a successful environmental campaign a few years ago, but it looks like this was a case of winning a battle, not a war.

The next day we crossed the River Angara, the only river leaving a lake that receives water from over 300 tributaries. The Angara is so huge that it draws water from the depths of the lake and never freezes, even when the temperature is minus 40 and the lake itself is covered in clear ice two meters thick.

This also makes the Angara the only open water in Siberia during the winter and so it acts as home an overwintering wildfowl population – the only such population in Siberia.

Once across the river we visit a scientific institute devoted to the study of the lake. The staff here co-wrote a recent report in Bioscience outlining the risks climate change brings to Baikal.

We’re shown around the museum and aquarium before our meeting. Our guide fires facts and statistics at us as she shows us the exhibits.

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Lake Baikal is the world’s largest, oldest, and most biotically diverse lake. It’s surface area is larger than Denmark, and because it reaches oceanic depths of up to 1640 m, it contains 20% of the worlds fresh-water, more than that of the American great lakes combined.

The extreme cold results in the water containing high concentrations of oxygen. This means there is sufficient oxygen at the bottom of the deepest parts of the lake for bottom dwelling fish – typically species of goby – and many invertebrates. In comparison lake Tanganika, a lake of comparable size and depth, is anoxic below 200m, with toxic levels of hydrogen sulphide.

We were told that if local people disappear the police don’t bother looking for their bodies in Baikal because they will be picked clean in three days by this vigorous benthic community, “leaving just polished bones.”

UNESCO declared Lake Baikal a World Heritage site in 1996 because of its biodiversity and endemism. The lake is approximately 25 million years old and this and its size has given space and time for a great many endemic species to evolve. The most famous of these is the Baikal seal but there are thousands of other endemic animals and plants.

To understand the risks climate change present to Lake Baikal you need to understand something of its unique eco-system which is dependent on the ice-cover. The life in Lake Baikal is fuelled by a double algal bloom. The winter ice is swept clear of snow by strong winds. The ice is also very clear so consequently there is sufficient light to fuel the growth of large endemic diatoms that live in, on and just under the ice. These grow to form the May bloom. The ice is also crucial to seal reproduction as the seals pup on the ice. Then a second bloom occurs in late summer when the upper water layer is warm, promoting the growth of bacteria-sized diatoms.

There is clear evidence for warming in the Baikal region. Annual air temperatures increased 1.2°C over the last century. The surface waters of Lake Baikal warmed significantly to a depth of 25 m during the last 60 years. This has had an impact on the duration ad thickness of icce-cover>In addition, the ice-free season lengthened 18 days from 1869 to 2000, and ice thickness decreased 12 centimeters (cm) between 1949 and 2000 in the southern basin (Shi- maraev et al. 2002). As air temperatures warmed, annual precipitation and snow depth increased 0.59 mm per year (83 to 130 mm) and 0.135 cm per year (24 to 30 cm), respectively, over northern Eurasia between 1936 and 1995 (Kitaev et al.

Climate warming has made an impact on the duration of ice-cover on the lake. The ice is forming around a week later than a century ago and melting 10-14 days earlier. The ice has also become 12 cm thinner beween 1949 and 2000. As the region is also getting wetter, so the ice is covered in snow more frequently than before – cutting off the light. This will diminish the first bloom with consequences for the rest of the food chain. It might also have consequences for the seal population.

At present there are around 100,000 seals. This figure is revised annually because the breathing holes seals make and maintain in the ice become visible as the ice melts in May.

Permafrost is found on the mountains and highlands that form the Baikal watershed. This permafrost is melting rapidly and so once frozen soil is being washed into the lake, increasing turbidity and nutrient load. There has also been industrial pollution from cellulose works in the past that eutrophied areas on the lake margin and there is pressure to re-open these works.

So climate change is likely to modify the food web in the worlds oldest and most biodiverse lake. From the freshwater seals – unique to Baikal - to some of the largest diatoms on the planet, all will be affected.

For more information, please read:
Climate Change and the World’s “Sacred Sea”—Lake Baikal, Siberia,
MARIANNE V. MOORE, STEPHANIE E. HAMPTON, LYUBOV R. IZMEST’EVA, EUGENE A. SILOW, EKATERINA V. PESHKOVA, AND BORIS K. PAVLOV

www.biosciencemag.org May 2009 / Vol. 59 No.5