Quakes vs global warming: Seismic activity found to reduce greenhouse gases, combat acidification in oceans
Chinese team believe movement of earth’s tectonic plates can offset some of the impact of climate change, but say more research required to test hypothesis.
Rather than just being something to fear, earthquakes may be a secret ally in man’s fight against global warming, according to an international study led by Chinese scientists.
Quakes can release chemicals like silicates that not just trap greenhouse gas but also help prevent ecological disasters induced by global warming such as ocean acidification, according to their paper published in the journal Geology, run by the Geological Society of America.
Climate change jumped to the top of the agenda this month as Chinese President Xi Jinping and his US counterpart Barack Obama joined a host of world leaders and 40,000 delegates in France earlier this week for the formal opening of UN Climate Change Conference in Paris.
Quakes, and the silicates they release, are just the latest area of exploration.
Silicates - or alkaline salts that contain silicon and oxygen, among other elements - can absorb large amounts of carbon dioxide from the atmosphere.
Moreover, because these are a major component of the rocks that make up much of the earth’s crust, scientists were curious to find out whether - and if so, to what extent - they can help offset the impact of global warming.
Seven years ago, a magnitude 7.9 earthquake hit the southwestern Chinese province of Sichuan and caused the death of more than 80,000 people. It also released an enormous amount of silicate into the rivers in the ensuing years.
The temblor shredded the rugged mountainous landscape, exposing silicate-rich minerals and underground water sources as a result of over 56,000 landslides and long, deep fractures.
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The discharges of groundwater increased the number of silicate solute fluxes while rocks were ground to fine sediment, creating a sound environment for a number of chemical reactions to occur, according to the research team. The team featured people from China, the United Kingdom, the United States and Australia.
By comparing the chemical composition of water in the Minjiang River, which flows through the quake zone, before and after the earthquake, the scientists observed that the river’s ability to absorb CO2 was four times higher due to the influence of the silicate solute.
This also made the river water more alkaline. As the river bleeds into the sea, and about a third of CO2 produced by man is dissolved in the world’s oceans, thus making them more acidic, the effect of the alkaline in combatting the problem of acidification was also highlighted.
This is important as overly acidic seawater threatens the existence of various species, especially those like shrimp and coral that use calcium to fortify their exteriors.
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“Our study provided the first direct evidence of a big hypothesis that has been tantalising scientists for decades,” said Professor Jin Zhangdong, lead scientist of the study. Jin works at the Institute of Earth Environment under the Chinese Academy of Sciences in Xi’an in northern Shaanxi province.
There has been much speculation in the past as to whether activity in the earth’s tectonic plate can change the chemical composition of surface water, which could have a bearing on the climate, but no concrete data has until now been forthcoming.
Jin said the team were fortunate because Chinese authorities kept a detailed record of the Minjiang’s chemical make-up before the quake.
The amount of silicate solute released by one earthquake would be insufficiently large to have any notable impact on global warming, Jin said.
However a series of quakes over an extended period may make a difference and also challenge our understanding of the global carbon cycle, Jin added.
According to the US Geological Survey, the earth experiences over 1.4 million quakes a year, averaging 4,000 a day. Most occur in remote areas or are too small to make news headlines, yet when lumped together they could be quietly manipulating the world’s climate system.
The latest findings do not mark the end of the debate on climate change, but they do throw up interesting new avenues for exploration, Jin said
Another research team led by scientists from the UK has been studying the impact of this year’s devastating earthquake in Nepal, which killed over 9,000 people in April. Jin said it would be interesting if their results match the findings of the Chinese team.
But more detailed issues must be resolved before a general model assessing quakes’ impact on climate change can be said to hold water. Temblors that occur on flat plains, for example, release much lower levels of silicate solute than those that tear up mountain ranges.
To calculate all the possible variations to come up with a feasible mathematic model could take years, Jin said.
