Continents are drying up so fast, they’re now the biggest contributor to sea level rise, scientists say
Continents have lost so much water since 2002 that they have exceeded ice caps as the largest contributor to the rise in sea level, reveals a new study.
Almost 70% of this loss is due to an uncontrolled groundwater extraction, which eliminates water from deep aquifers and possibly transfers it in the ocean, researchers revealed. As well as the increase in evaporation rates due to climate changeThis caused a fusion of “hotspots” of drying quickly in four regions of “mega-scheing”, said scientists.
“There are very few places now that did not dry”, co-author of the study Jay FamigliettiA professor at the School of Sustainability of Arizona State University, told Live Science. “I have been looking at him for 20 years, and it has gotten worse, and worse, and worse.”
To measure continental drying, the researchers used satellite data that responds to small mass changes on earth. The gravitational traction leads to satellites when an area takes on water weight and releases them on their initial orbit when the water is lost. Resolution on the ground is around 15 miles (25 kilometers), which is enough to detect small changes on regional scales, said Famiglietti.
Hot drying points are generally regions with large aquifers that humans have been highly exploited for decades, which means that they have high water loss levels, said Famiglietti. These hot spots include places like the northern plain of China, northwestern India and the California central valley, which have lost huge amounts of water through human activities and evaporation. This water penetrates either in the rivers, which are found in the ocean or which cry from the atmosphere above the ocean – ultimately increasing the sea level.
The new conclusions, published on July 25 in the journal Scientific advancesShow that drying stitches develop quickly and that many of these areas join. “South Asia is an excellent example,” said Famiglietti. “Around the Himalayas, there were four or five hotspots. Now, it’s along the way.”
In relation: “ An existential threat affecting billions ”: three -quarters of the land of the earth have become drier permanently in the past 3 decades
The authors of the study called these regions of mega-sisters the size of a continent. They have identified three other regions of this type in the world, which are all in the northern hemisphere: one combining Alaska, northern Canada and northern Russia, another in Western Europe and a third overlap Southwest North America and Central America. Drying regions develop so quickly, “it’s a bit like a crawling mold or virus that spreads in the landscape,” said Famiglietti.
We do not know why the southern hemisphere has no regions of mega-drying, but the researchers think that it is somehow linked to a record El Niño event over 10 years ago. “There is this kind of change in the drying rate and the expansion of the extremes that occurred around 2014,” said Famiglietti.
The drying points of drying seemed to go from the southern hemisphere to the southern hemisphere to the northern hemisphere during a global transition of a very strong La Niña At the height El Niño, between 2011 and 2014, Famiglietti said, adding that his team always tries to understand why.
“The most important natural resource”
Drying in Alaska, Canada and Russia is mainly motivated by thaw and the melting of ice, while drying in Western Europe is caused by drought, Famiglietti said. The American Southwest was dry Before humans start to pump groundwater, but it has now propagate in Mexico and Central America.
Around the world, only the tropics become humid, which are also motivated by global warming. By breaking down the trend, researchers have found that 101 countries – which are home to 75% of the world’s population – have lost freshwater in the past 22 years.
“The groundwater becomes the most important natural resource of these world drying parts,” said Famiglietti.
The implications are deep, because continental drying affects food production, biodiversity, natural disasters, sea level and lifestyles. While we continue to cook the planet, more groundwater will be necessary to irrigate cultures and maintain the populations, Forcing people to unravel more and more deeply in the aquifersat great cost.
“The implications are so varied”, the main author of the study Hrishikesh ChandanpurkarA scientist of the land system on Arizona State University, told Live Science in an email. “Current water management efforts must be revisited on a war base.”
The exhaustion of groundwater cannot be reversed, but changes in the use of water, such as the end of irrigation against floods, can go very far, said Famiglietti. Everything we do to mitigate climate change will also help you, he said.
“We already see what is happening if we do not change,” said Famiglietti. For example, Forest fires have increased In Severity and frequencyWho is the direct result of water loss and warmer temperatures, he said. Many regions are also have a water stressand sea level has increased by 3.5 inches (9 centimeters) Over the past 25 years.
“We don’t have to stop doing everything,” said Famiglietti. “We just need to do things as effectively as possible.”
