NASA study warns of freshwater decline in India
Washington, May 18: Availability of freshwater has declined in the northern and eastern parts of India, says a new study that combined an array of NASA satellite observations of Earth with data on human activities to map locations where freshwater is changing around the globe.
The study, published in the journal Nature, found that Earth's wetland areas are getting more wet and dry areas are getting drier due to a variety of factors, including human water management, climate change and natural cycles.
Areas in northern and eastern India, the Middle East, California and Australia are among the hotspots where overuse of water resources has caused a serious decline in the availability of freshwater, and without corrective actions by the governments to preserve water, the situation is likely to worsen in these areas, the Guardian reported this week citing the study.
The first-of-its-kind study used 14 years of observations from the US/German-led Gravity Recovery and Climate Experiment (GRACE) spacecraft mission to track global trends in freshwater in 34 regions around the world.
"This is the first time that we've used observations from multiple satellites in a thorough assessment of how freshwater availability is changing, everywhere on Earth," said Matt Rodell of NASA's Goddard Space Flight Center in Greenbelt, Maryland,
"A key goal was to distinguish shifts in terrestrial water storage caused by natural variability - wet periods and dry periods associated with El Nino and La Nina, for example - from trends related to climate change or human impacts, like pumping groundwater out of an aquifer faster than it is replenished," Rodell added.
Freshwater is found in lakes, rivers, soil, snow, groundwater and ice. Freshwater loss from the ice sheets at the poles - attributed to climate change - has implications for sea level rise.
On land, freshwater is one of the most essential of Earth's resources, for drinking water and agriculture.
The researchers found that while some regions' water supplies are relatively stable, others experienced increases or decreases.
"What we are witnessing is major hydrologic change," said co-author Jay Famiglietti of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
"We see a distinctive pattern of the wet land areas of the world getting wetter - those are the high latitudes and the tropics - and the dry areas in between getting dryer. Embedded within the dry areas we see multiple hotspots resulting from groundwater depletion," Famiglietti warned.
Famiglietti noted that while water loss in some regions, like the melting ice sheets and alpine glaciers, is clearly driven by warming climate, it will require more time and data to determine the driving forces behind other patterns of freshwater change.
However, the GRACE satellite observations alone couldn't tell the researchers what was causing the apparent trends.
"We examined information on precipitation, agriculture and groundwater pumping to find a possible explanation for the trends estimated from GRACE," said co-author Hiroko Beaudoing of Goddard and the University of Maryland in College Park.
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Groundwater depletion causes Earth's axis to shift by 31.5 inches: Study
A recent study has uncovered a significant impact of human activity on the planet: Earth's axis has shifted by 31.5 inches (nearly 80 centimeters) due to extensive groundwater extraction. Published in the journal Geophysical Research Letters, the research highlights how large-scale pumping of groundwater has changed the distribution of Earth's mass, affecting its rotation and contributing to sea-level rise. The shift in Earth's tilt is linked to a sea-level increase of 0.24 inches, according to Popular Mechanics.
Lead researcher Ki-Weon Seo, a geophysicist at Seoul National University, explained that among climate-related factors, the redistribution of groundwater has had the most significant effect on the movement of Earth's rotational pole. The planet's tilt, or axial precession, is influenced by changes in mass distribution. As glaciers and polar ice sheets in Greenland and Antarctica melt, water migrates towards the equator, shifting the planet's balance—a phenomenon comparable to how a figure skater’s spin changes when they alter their body position.
The study examined data from 1993 to 2010, revealing that approximately 2,150 gigatons of groundwater were pumped out during this time, largely for agricultural and human consumption. This large-scale extraction has contributed to a shift in Earth's axis of about 31.5 inches.
Groundwater, which is water stored underground in soil and rock, plays a crucial role in the hydrological cycle. It originates from precipitation that seeps into the earth, replenishing natural aquifers. These aquifers are vital freshwater resources, supporting drinking water supplies, agriculture, and industry. The availability and quality of groundwater depend on natural factors like recharge rates and human activity.
While the 31.5-inch shift in Earth's axis might seem minor, the consequences could be far-reaching over geological timescales. Changes in water distribution can lead to varying sea-level changes across regions, affecting coastal areas differently. Additionally, shifts in Earth's tilt can influence its internal systems, such as the magnetic field, which acts as a shield against harmful solar radiation.
