Studying Global Lakes Surface Temperature Variability at the Basin-Level-Scale Using Remote Sensing Observations

Even though lakes make up a small percentage of the water bodies on the global land surface, natural lakes and impoundments provide critically important ecosystem services that include drinking water, fisheries, recreation, and irrigation. Unfortunately, several lake surface areas around the globe have been changing with many of them dying due to climate variability and local mismanagement at the basin-scale level. Lake Surface Water Temperature (LSWT) is recognized as a critical indicator of climate change in lakes. The changes in water and the surrounding land temperature could be an indicator of climate variability if there is consistency between changes in both temperatures. However, if the water temperature shows an increase accompanied with a reduction in the lake area while the surrounding basin doesn’t reflect similar increase in temperature, local water mismanagement could be blamed for such inconsistency and shrinkage of the lake. This project focuses on the application of remote sensing to investigate the changes in lake surface water temperatures and their relationship with their surrounding land cover type in a bid to identify the main driving factors of these changes. In this study, 394 global major lakes have been investigated. An analysis of temperature variation over these lakes has been conducted using daily observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) from year 2002 to 2019 over the lakes and their surrounding land areas. The rates of change of temperature for both the lakes’ water surface and their basins as well as the changes in the lakes’ surface areas were calculated. Preliminary results show that many of the lakes’ water temperatures are warming faster than their surrounding land temperatures approximately 43.22% of the studied lakes are warming, this percent includes 63.00% in the southern hemisphere and 34.70% in the northern hemisphere, and about 51.41% of them are cooling with 29.20% in the southern hemisphere and 61.30% in the northern hemisphere. Furthermore, 63.94% of the lakes are shrinking, specifically, 52.00% in the southern hemisphere and 69.37% in the northern hemisphere, while 29.67% of them are growing overall with 42.00% in the southern hemisphere and 24.40 % in the northern hemisphere. The relationship between the rates of LSWT change and other lake characteristics such as lake depth, salinity level, geographical location, and size were also investigated. A clear latitudinal relationship was discovered in temperature changes with increasing LSWT rates from north to south. This study, therefore, provides insights about LSWT variability on a global scale.