Floods and droughts, pouring rain, hellish fires, extreme temperatures, extinction of species.
Many of the effects of climate change caused by human activity are visible in the four corners of the planet. However, some are not that obvious.
Research published in March in the American Geophysical Union (AGU) showed that climate change has been behind a series of shifts on the Earth’s axis of rotation since the 1990s.
Over the past 30 years, the planet’s axis – the imaginary line around which the earth rotates as it moves on itself – has accelerated. Since 1980, the position of the poles (i.e. the points where the Earth’s axis of rotation crosses the surface) has changed by about four meters in an easterly direction, the paper says.
The evaluation of the so-called polar drift, which is referred to as the movement of the poles, shows that the current completely changed direction in 1995 and the speed of movement of the poles increased about 17 times between that year and 2020 compared to between 1981 and 1995 observed.
According to experts, the shift in the earth’s axis is normal.
Changes in the distribution of the planet’s mass cause the axis and, consequently, the poles to move.
This movement usually occurs naturally, either through changes in the atmosphere, in the oceans or in the solid part of the earth.
However, research shows that human action is one of the drivers of the acceleration observed since 1990.
To understand why there is a need to rethink some of the concepts of physics we learned in high school.
The rotation of an object is influenced by the distribution of its mass.
The distribution of the earth’s weight, in turn, is constantly changing as the planet’s molten intestine trembles and its surface changes.
But water, which makes up almost three quarters of the planet, also has a fundamental “weight” in this process.
Therefore, the researchers decided to make observations on the waters, measurements of ice loss and the volume of groundwater pumped for human consumption to check their effects on the displacement of the axis.
The research found that water is a key factor: water loss from the polar regions – the ice that melted and flowed into the oceans – would be “the main driver of rapid polar drift after the 1990s”.
Melting glacier ice is a direct result of human-made climate change.
It is estimated that more than a third of the world’s remaining glaciers will melt in less than a century before 2100. At the sea ice banks, 95% of the oldest and thickest glaciers in the Arctic have already disappeared.
Scientists estimate that the Arctic could no longer have any ice in the summer from 2040 if harmful gas emissions continue to increase in an uncontrolled manner.
Water for human consumption
The study also reveals how, to a lesser extent, the effect of pumping water for agriculture or human consumption also affected polar drift.
This is because the water in the groundwater table that was previously stored underground tends to flow into the sea and redistribute its weight across the planet.
Experts estimate that over the past 50 years, humans have extracted 18 trillion tons of water from deep underground reservoirs that have never been replaced.
“The results provide an indication of the study of climate-related polar movement in the past,” said Suxia Liu, a hydrologist at the Chinese Academy of Sciences and lead author of the study, in a statement.
Science had already linked the melting of glaciers to the movements at the poles between 2005 and 2012 with data collected by the Grace mission (short for Gravity Recovery and Climate Experiment), which launched a satellite into space in 2002.
However, this is the first survey to demonstrate the effects of climate change on the Earth’s axis of rotation in the decade prior to the launch of this monitoring system.