As the Earth’s landmasses continue to lose water at an alarming rate, scientists are sounding the alarm about the devastating consequences of this phenomenon. The study reveals that terrestrial water storage has declined by trillions of metric tons since the turn of the century.
The Shrinking Water Storage: A Growing Concern
As the Earth’s landmasses continue to lose water at an alarming rate, scientists are sounding the alarm about the devastating consequences of this phenomenon. The study, published in Science Magazine, reveals that terrestrial water storage has declined by trillions of metric tons since the turn of the century.
According to NASA, approximately 1% of the world's freshwater is lost every year due to human activities such as deforestation and climate change.
This translates to about 400 billion gallons of water per day.
The main culprit behind this loss is evaporation from oceans, lakes, and rivers, which accounts for around 90% of global water loss.
Additionally, human consumption, agriculture, and industrial processes also contribute significantly to the depletion of Earth's water resources.
The Main Culprit: Rising Temperatures
Rising global temperatures are the primary driver behind the decline in freshwater stores. As ‘the planet warms,’ it leads to changes in precipitation patterns, intensifying evaporation and transpiration – the process by which water vapor is released into the atmosphere from plants. This increased evaporation results in brief bouts of intense rainfall, but most of this water does not infiltrate the soil; instead, it becomes runoff that flows overland to the sea.
According to NASA, global temperatures have risen by about 1°C since the late 19th century.
The past four years (2016-2019) were the warmest on record, with 2020 being the hottest year globally.
The Arctic is warming at a rate twice as fast as the rest of the planet.
Sea levels are rising due to melting ice and thermal expansion, contributing to coastal erosion and more frequent flooding.
Soil Moisture Loss: A Worrisome Trend
The loss of soil moisture is particularly stark and worrisome due to its link to drought. Satellite data show that water stored in soils dropped by about 1.6 trillion tons from 2000 to 2002, leading to a global sea level rise of almost two millimeters in those years. This rate of decline continued throughout the period for which the data are available.
Greenland‘s Melting Ice Sheets: A Comparative Perspective
In contrast, Greenland’s melting ice sheets contributed about 900 billion tons, or about 0.8 millimeters a year, to sea level rise from 2002 to 2006 – less than half as much as the decline in soil moisture. This highlights the significant impact of terrestrial water loss on global sea levels.
The Connection Between Groundwater and Sea Level Rise
Environmental scientist Katharine Jacobs notes that increasing demand for groundwater is also contributing to this trend. ‘It is fair to say that most people who work on water issues are unaware of the connections between groundwater pumping and sea level rise,’ she adds. Using multiple data sets, including satellite gravity observations and measurements of global sea level rise, researchers can better understand these complex relationships.
A Critical Time for Climate Action
The study’s findings underscore the urgent need for climate action. As geophysicist Ki-Weon Seo of Seoul National University states, ‘Everything needs water. If you don’t have enough, you’re in trouble.’ The loss of terrestrial water storage is a critical indicator of the planet’s changing hydrological regime, and its consequences will be felt for generations to come.
The Future of Water Storage
Given future projections for the planet’s temperatures, it’s likely that the total amount of water in Earth’s soils won’t replenish. This raises significant concerns about the long-term sustainability of our planet’s ecosystems. As climate modeler Benjamin Cook of the NASA Goddard Institute for Space Studies notes, ‘We’re facing a permanent hydrological regime change in the 21st century.
- sciencenews.org | Earth’s landmasses lost trillions of tons of water this century
