NEW DELHI: Global warming has resulted in evaporation of water that could have been used by 27 million people, a new study published in Nature has found
The study based on satellite imagery of quantified evaporative water loss for 1.42 million lakes and reservoirs globally for the past 30 years warns that global warming can impose a hefty strain on water resources as demand for agriculture, industrial and domestic water continues to increase in future.
The paper finds that the long-term trend attributions include an increased evaporation rate (58%), decreasing lake ice coverage (23%), and increasing lake surface area (19%). In total, the annual evaporation of global lakes from 1985 to 2018 is found to be 15.4 percent higher than the previous model-based estimate.
For most of the nine thermal regions in the world, the lake evaporation volume has increased during the past 34 years due to both an increased evaporation rate and an increasing lake area. Evaporation rate can be altered by warming temperatures and by elevated solar radiation.
Compared to natural lakes, the evaporative water losses and their associated trends from reservoirs are more pronounced. This quantity of reservoir evaporative loss is equivalent to 20% of the global annual consumptive water use, it said.
From 1985 to 2018, evaporative water loss from reservoirs has been increasing at a rate of 5.4% per decade, which largely outpaces the global trend for all 1.42 million lakes (2.1% per decade).
The study attributed climate change as one of the factors to the long-term trend of lake evaporation volume.
"An increase of global air temperature can elevate evaporation of lakes and reduce ice. There are 1.09 million lakes (77%) that belong to this category. The climatic effect is especially notable in the high-latitude (e.g., Canada and northern Eurasia) and high-altitude (e.g., Tibetan Plateau) regions. Given the amplification effect of climate change in these regions, we expect an accelerated increase of evaporation in the future," it noted.
The authors said that the findings have significant environmental, societal, and economic implications, as the global evaporative loss will be accelerated in the future under global warming.
"Given the large increase of temperature in the high-latitude and high-altitude regions, the loss of lake ice can result in greater heat uptake and larger open surface areas to evaporate," it added.