Earth’s climate is changing rapidly.
In some areas, rising temperatures are increasing the frequency and likelihood of wildfires and droughts.
In others, it makes downpours and storms more intense or speeds up the rate of melting glaciers.
July 2023 is a clear illustration of exactly this.
Parts of Europe and Canada were devastated by forest fireswhile Beijing recorded its heaviest rainfall in at least 140 years.
Looking back, between 2000 and 2019, the glaciers The world lost about 267 gigatons of ice per year.
Melting glaciers contribute to sea level rise (currently rising by about 3.3 millimeters per year) and more coastal hazards such as flooding and erosion.
But research suggests that our changing climate may not just influence hazards on Earth’s surface.
He climate changeand specifically increased rainfall rates and melting glaciers, could also exacerbate hazards below the Earth’s surface, such as earthquakes and the Volcanic eruptions.
The drought in Europe and North America received a lot of recent media coverage.
But the sixth assessment report of the Intergovernmental Panel on Climate Change revealed in 2021 that average precipitation has actually increased in many regions of the world since 1950.
Getty Images Between 2000 and 2019, the world’s glaciers lost about 267 gigatons of ice per year.
A warmer atmosphere can hold more water vapor, which subsequently leads to higher levels of precipitation.
Interestingly, geologists have long identified a relationship between rainfall rates and seismic activity.
In the Himalayas, for example, the frequency of earthquakes is influenced by the annual rainfall cycle of the summer monsoon season.
Research reveals that 48% of Himalayan earthquakes occur during the driest pre-monsoon months – March, April and May – while only 16% occur in the monsoon season.
During the summer monsoon season, the weight of up to 4 meters of rain compresses the crust both vertically and horizontally, stabilizing it.
When this water disappears in winter, the effective “rebound” destabilizes the region and increases the number of earthquakes that occur.
Climate change could intensify this phenomenon.
Climate models project that the intensity of monsoon rainfall in South Asia will increase in the future as a result of climate change.
This could improve winter bounce and cause more seismic events.
The impact of the weight of water on the earth’s crust goes beyond simple precipitation; It also extends to glaciers.
When the last ice age came to an end about 10,000 years ago, the melting of large masses of ice caused parts of the Earth’s crust to rise.
This process, called isostatic reboundis evidenced by the elevated beaches of Scotland, some of which are up to 45 meters above present sea level.
Getty Images The beach of Loch Eriboll is one of those that registers elevation of the territory in Scotland.
Evidence from Scandinavia suggests that such uplift, along with the destabilization of the region’s tectonic plates, triggered numerous earthquakes between 11,000 and 7,000 years ago.
Some of these earthquakes even exceeded magnitude 8.0, indicating severe destruction and loss of life.
The concern is that the continued melting of glacial ice today could have similar effects elsewhere.
What happens to volcanic activity?
Research has also found a correlation between glacial charge changes in the earth’s crust and the occurrence of volcanic activity.
About 5,500-4,500 years ago, Earth’s climate cooled briefly and glaciers began to expand in Iceland.
Analysis of volcanic ash deposits spread across Europe suggests that volcanic activity in Iceland was markedly reduced during this period.
There was a further increase in volcanic activity after the end of this cold period, albeit with a lag of several hundred years.
This phenomenon can be explained by the weight of the glaciers that compress both the Earth’s crust and the underlying mantle (the most solid part of the Earth’s interior).
This kept the material that makes up the mantle under higher pressure, preventing it from melting and forming the magma needed for volcanic eruptions.
However, deglaciation and associated weight loss at the Earth’s surface allowed a process called decompression melting to occurwhere lower pressure facilitates melting in the mantle.
Such melting resulted in the formation of liquid magma that fueled subsequent volcanic activity in Iceland.
Getty Images The frequency of earthquakes is influenced by the annual rainfall cycle of the summer monsoon season.
Even today, this process is responsible for driving some volcanic activity in Iceland.
Eruptions at two volcanoes, Grímsvötn and Katla, occur constantly during the summer period, when the glaciers recede.
Therefore, it is feasible that ongoing glacial retreat due to global warming could increase volcanic activity in the future.
Still, the lag between the glacial changes and the volcanic response is reassuring for now.
The impacts of a changing climate are becoming more evident, and unusual weather events have become the norm rather than the exception.
However, the indirect impacts of climate change on the ground, under our feet, are not widely known or discussed.
This must change if we are to minimize the effects of the changing climate that are already firmly in place.
*Matthew Blackett is Professor of Physical Geography and Natural Hazards at Coventry University, England.
BBC
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2023-08-31 00:14:21
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