August 9, 2022

Global Lake Evaporation Loss Is Larger than Previously Estimated Due to Climate Change

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Global lake evaporation loss is larger than previously estimated due to climate change

Near the Nevada-Arizona border, just east of Las Vegas, on the Colorado River, a white mineral ring as tall as the Statue of Liberty climbs along the rocky shores of Lake Mead. The biggest reservoir in the nation is fast evaporating.

Making informed decisions about water management is crucial given that a large portion of the country is experiencing above-average temperatures, below-average rainfall, and a changing environment.

Researchers developed the global lake evaporation volume (GLEV) dataset under the direction of Dr. Huilin Gao, an associate professor in the Zachry Department of Civil and Environmental Engineering at Texas A&M University. It makes use of modelling and remote sensing to offer the first long-term monthly time series for the 1.42 million unique natural lakes and artificial reservoirs globally.

Nature Communications is where the researchers reported their findings.

Lakes, both natural and manmade, hold about 87 per cent of fresh surface water in liquid form (i.e., reservoirs). The amount of water that evaporates from these global lakes is significant, but little is known about where it occurs and how it changes over time.

The amount of typical lake evaporation over the long term has increased by 3.12 cubic kilometres per year, according to research done between 1985 and 2018. Increased evaporation rates of 58 per cent, a 23 per cent drop in lake ice cover, and an increase of 19 per cent in lake surface area are all attributed to the trend.

Global lake evaporation loss is larger than previously estimated due to climate change

The study’s findings highlight the significance of utilising evaporation volume as the key criterion for determining how climate change affects lake systems (as opposed to evaporation rate).

According to the first author Dr. Gang Zhao, a former student of Texas A&M University who is currently a postdoctoral fellow in the Department of Global Ecology at the Carnegie Institute for Science, the long-term lake evaporation is 1500 plus or minus 150 cubic kilometres per year, which is 15.4% higher than earlier estimates.

This indicates that lake evaporation contributes more to the hydrological cycle than was previously believed,” the author writes.

6 715 reservoirs only make up 10% of all lakes’ surface area and 5% of the total water storage capacity, according to GLEV (both natural and artificial). But 16% of the volume of evaporation comes from reservoirs.

This reservoir evaporative loss amounts to 20% of the yearly water consumption used globally. Evaporative water loss from reservoirs has risen by 5.4 per cent annually during the past 33 years, surpassing the overall trend for all lakes, which is 2.1 per cent.

According to Gao, “researchers studying water resources and decision-makers will greatly benefit from our study with reference to evaporation loss.” The global evaporative loss will be accelerated and made worse in the future due to global warming, which has enormous repercussions for the environment, society, and the economy.

Global lake evaporation loss is larger than previously estimated due to climate change

The entire reservoir evaporation may, on a worldwide scale, exceed the sum of all home and industrial water demand. Only a small number of lakes/reservoirs, even in the United States, have accurate evaporation statistics.

Researchers claim that it is impossible to predict the availability of water and energy resources with any degree of accuracy without knowing the quantity and pattern of volumetric evaporation loss for each of the millions of global lakes. Both decision-makers and the larger scientific community can gain from this freely accessible resource.

In particular, Gao added, under conditions of increasing drought events and population growth, “GLEV can significantly help improve reservoir management decision-making worldwide.”

This dataset aids the scientific community in understanding the function of various water bodies in Earth systems, from global weather forecasting, flood and drought modelling, to Earth system modelling under climate change.”

In preparation for future work, Texas A&M researchers, the Desert Research Institute, and the U.S. Bureau of Reclamation recently began a nearly $1 million NASA Applied Science project that focuses on creating operational, daily reservoir evaporation monitoring and forecasts for the Western United States. A daily reservoir monitoring effort for Texas will be expanded by the team.Global lake evaporation loss is larger than previously estimated due to climate change

Dr. Yao Li, a postdoctoral research associate in the civil and environmental engineering division at Texas A&M, and Dr. Liming Zhou, a professor in the atmospheric and environmental sciences division at The State University of New York, are other authors of this study.

NASA, the Department of Energy, and the National Science Foundation are all contributing to the cost of this study.

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