Not only are melting glaciers, most of which are concentrated in Greenland and Antarctica, but also the depletion of groundwater reserves contributing to the rising level of the world’s seas and oceans. By constantly pumping groundwater from the depths of the world around the world, this reserve is no longer able to remake the required amount of fresh water. As a result, water levels in the world’s seas and oceans are constantly rising.
How Much Groundwater Do We Consume?
The amount of groundwater consumed is increasing every year: it irrigates the fields of drier regions, it is used in industry, and a large amount of it is on the consumer’s table in the form of drinking water. Wherever and how we use it, it eventually escapes somewhere in the form of streams and streams of water, part of it evaporates and somewhere in the form of precipitation, and the very last place it eventually finds itself is the ocean.
To determine the extent to which such use of groundwater resources responds to sea level, a team of Dutch scientists led by Yoshihide Wada, PhD in Hydrogeology at Utrecht University, divided the entire land surface into a grid of 50 km by 50 km and calculated the current area for each of these squares. the amount of groundwater consumed and expected to be consumed in the future.
To make the calculations as accurate as possible, they used not only the groundwater consumption statistics provided by each country, but also the economic growth forecasts of these countries. They also considered the impact of climate change on regional water needs by assessing all key factors. Because the groundwater reservoir can fill up over time, scientists in each of the regions used climate, rainfall, and hydrological models to estimate this fill rate. After assessing all possible factors, they obtained the total extent of groundwater depletion.
The loss of groundwater resources could be offset by new surface water reservoirs. Such a solution could prevent water from entering the ocean. Until the 1990s, groundwater resources were still able to recover, so the United Nations Intergovernmental Panel on Climate Change never considered the problem of groundwater depletion when predicting global ocean levels in the twenty-first century. At present, groundwater is no longer able to recover as it used to.
Due to groundwater depletion, the world’s ocean level is rising by 6 mm every year. By 2050, this rate will increase to 0.82 millimeters per year due to the growing population of the Earth, global economic growth, and the increased need to irrigate arable land due to global warming. Such speeds will be enough to increase the level of the world’s oceans by 40 mm by 2050 compared to 1990 levels. According to some projections, it will rise even faster between 2050 and 2100.
Of all the factors contributing to sea level rise, declining groundwater contributes 25% to the overall increase in global ocean levels. This is more than the influence of the melting ice of Greenland and Antarctica. Even the melting water of glaciers covering the highest mountain tops does not raise the overall sea level as much as pumped groundwater does.