(ORDO NEWS) — More than eight months after the eruption of an underwater volcano near Tonga on January 14, scientists are still analyzing the consequences of a large explosion and find out that it could lead to a warming of the planet.
Researchers recently calculated that the Hunga-Tonga-Hunga-Ha’apa volcanic eruption released a staggering 50 million tons (45 million metric tons) of water vapor into the atmosphere in addition to massive amounts of ash and volcanic gases.
This powerful release of steam increased the amount of moisture in the global stratosphere by about 5 percent and could have triggered a cycle of stratospheric cooling and surface warming – effects that could persist for months, according to a new study.
The eruption of Tonga, which began on January 13 and peaked two days later, was the most powerful in recent decades on Earth.
According to the National Oceanic and Atmospheric Administration (NOAA), the eruption stretched for 162 miles (260 km) and sent columns of ash, steam and gas into the air to a height of more than 12 miles (20 km).
Large volcanic eruptions typically cool the planet by expelling sulfur dioxide into the Earth’s upper atmosphere, which filters solar radiation.
Rock and ash particles can also temporarily cool the planet by blocking sunlight, according to the National Science Foundation’s University Corporation for Atmospheric Research.
Thus, widespread and violent volcanic activity in the distant past could have contributed to global climate change, causing mass extinctions millions of years ago.
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Recent eruptions have also demonstrated the ability of volcanoes to cool the planet. In 1991, when the Pinatubo volcano in the Philippines blew its top off, the aerosols spewed out by that massive volcanic explosion lowered global temperatures by about 0.9 degrees Fahrenheit (0.5 degrees Celsius) for at least one year.
Tonga emitted an estimated 441,000 tons (400,000 metric tons) of sulfur dioxide, about 2 percent of the amount erupted by Mount Pinatubo during the 1991 eruption.
But unlike Pinatubo (and most large volcanic eruptions that occur on land), the volcanic plumes of undersea Tonga have funneled “significant amounts of water” into the stratosphere, a zone that extends from 31 miles (50 km) above the Earth’s surface to 4 to 12 miles. (6-20 km), according to the National Weather Service (NWS).
In underwater volcanoes, “submarine eruptions can derive much of their explosive energy from the interaction of water and hot magma,” which pushes huge amounts of water and steam into the eruption column, the scientists write in a new study published Sept. 22 in the journal Science.
Within 24 hours of the eruption, the plume extended 17 miles (28 km) into the atmosphere.
The researchers analyzed the amount of water in the plumes by evaluating data collected by instruments called radiosondes that were attached to weather balloons and sent into volcanic plumes.
As these instruments ascend into the atmosphere, their sensors measure temperature, air pressure and relative humidity and relay this data to a ground receiver, NWS reports.
Atmospheric water vapor absorbs solar radiation and reradiates it as heat; tens of millions of tons of Tonga moisture now drifting in the stratosphere will warm the Earth’s surface – although it’s not yet clear how much, according to the study.
But because the vapor is lighter than other volcanic aerosols and less affected by gravitational pull, it will take longer for this warming effect to dissipate, and surface warming could continue “in the coming months,” the scientists say.
Previous studies of the eruption have shown that Tonga released enough water vapor to fill 58,000 Olympic-sized pools, and that such a huge amount of atmospheric moisture could potentially weaken the ozone layer.
In the new study, the scientists also determined that these huge volumes of water vapor may indeed change the chemical cycles that control stratospheric ozone, “however, detailed studies will be required to quantify the impact on ozone, as other chemical reactions may also play a role.”
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