Though global sea levels are rising, lakes across the world are shrinking year after year, according to a latest IAEA study. The study published in Nature Communications revealed that several lakes are not able to compensate for water lost to evaporation and are at risk of disappearing over time.
Noting that global warming was a major threat to the lakes, First author of the study Yuliya Vystavna said that rising temperatures because of evaporation was one of the main reasons for this.
“Given the range of variables that shape the history and life of a lake, quantifying the extent of climate change impact on lakes worldwide is a complex task that can be simplified with the use of nuclear science,” the Isotope Hydrologist at IAEA said.
Lakes form majority of global unfrozen surface freshwater resources. They are an integral part of social and economic activities, as well as the ecosystem. The IAEA mentioned that isotope hydrology is a tell-tale tool for assessment of the impact of climate change on lakes. Isotopes reveal the history of lakes and provide a record of change, serving as a proxy of hydrological history.
WATER LOSS THROUGH EVAPORATION
The IAEA said that the isotope analysis revealed that about one-fifth of water inflow in lakes around the world is lost to evaporation. It also said that about ten per cent of Earth’s lakes show extreme evaporative losses. This was more than 40 per cent of total inflow. “Lakes sustain evaporation losses by inflow, but if a lake is losing more than 20 per cent of inflow, it is at risk of drying out,” Vystavna said.
“We used water balance models based on isotopes and estimated lakes’ sensitivity to evaporation to determine which lakes around the world may disappear because they are not able to compensate for evaporation losses.” the researcher said.
The team gathered information from databases, including the Global Network of Isotopes in Rivers, which includes data on rivers and lakes. In total, the stable isotope composition of 1257 lakes from 91 countries was analysed using artificial intelligence approaches developed by the IAEA. “We used artificial intelligence to determine what are the main evaporation drivers. Depending on climate type – tropical, arid, temperate, continental or cold – evaporation is driven by different factors,” Vystavna said. Regardless of the climate type, the amount of precipitation, wind speed, relative humidity and solar radiation affect the isotope composition of lakes and evaporation from them. The study showed that a combination of climatic and landscape variables, as well as lake size, need to be considered to predict lake evaporation processes.
Water and Cryosphere Coordination director at the World Meteorological Organization Johannes Cullmann opined that understanding future availability of water resources was key to resilience, sustainable development and peace. “Scientific isotope hydrological studies, as spearheaded by IAEA, are indispensable to underpin WMO’s development of operational water assessment and forecasting systems,” Cullmann said. The simple and affordable method of stable isotope monitoring creates potential for a global network of lake isotope data, “If you have a network dedicated to the collection and compilation of lake isotope information, you can provide explicit data and can compare and see climate change variations,” Vystavna said.