Impact of climate change on lakes

Climate change will have a different impact on lakes depending on the area with a warm or cold climate. This is the conclusion of Japanese and German researchers after studies of crater lakes in Japan.

Scientists from Hokkaido University, Hokkaido Institute of Environmental Sciences, Kagoshima University and Helmholtz Environmental Research Center (UFZ) compared the results obtained with data collected 70 years ago. This confirms that the temperature of deep water layers in the southern Japanese lakes increases, while the deep water temperature in the northern lakes remains the same. The rise in temperature can cause changes in nutrient exchange and rotation in the country.In some cases, rising temperatures and other climatic factors can seriously affect the winter cycle, causing oxygen supply to deep water to become deficient for many organisms, thereby leading to to the phenomenon of nutrient accumulation in deep water.

Calculations from 2005 and 2007 in Japanese crater lakes provide information about water-soluble nutrient distribution. There are two reasons why this type of tank is a suitable research object to provide information on the weather cycle under changing climatic conditions. Most, these lakes are located in a wide area of ​​weather extending from southern Japan to the northern Hokkaido island. Secondly, the temperature difference controls almost completely the exchange of oxygen and nutrients between the deep water layer and the surface of the studied lakes.

The researchers found that most of the lakes studied showed a fairly reasonable distribution of water-soluble nutrients, except for depths of up to 423 meters (Lake Tazawa, Honshu). These lakes can be divided into two deep-water circulation categories based on climatic conditions.

Toya Lake is a crater lake at Shikotsu-Toya National Park, Northern Japan, Hokkaido Island (Photo: Dr. Bertram Boehrer / UFZ).

Researchers say deep water temperatures in colder lakes (such as Lake Shikotsu, Hokkaido) remain the same in warmer winter weather, provided the temperature is not too high, while heat. Deep water in warmer lakes tends to increase. This is verified when compared to data from the 1930s. Scientists warn that if the winter temperature rise too high for many years, the water temperature will not be as low as in previous years. Domestic circulation will be stalled.In such a situation, the oxygen supply and nutrient distribution will be interrupted, affecting the life of the organisms.

Water quality in the lake is an important economic factor for tourism, water supply and fishing companies. Together with colleagues in Australia, Canada and Spain, UFZ scientists work on many lake environment simulation models designed to predict water quality when environmental conditions change.