[ad_1]
The Earth is teetering on its axis as a result of climate change of human origin, according to a study funded by NASA. Over the last 100 years, the rotation of the planet on its axis of rotation has drifted more than 11 meters and researchers have discovered that this change results from mantle convection, glacial bounce and loss of mass in Greenland . to human activities.
The study, published in Scientific letters of the Earth and planets, is the first to use observational data and model-based data to discover what is happening in Earth's movements.
We know that the Earth is not a perfect sphere and when it turns on its axis of rotation, it oscillates and drifts. This is normally called the "polar movement". Scientists thought that the rebound of glaciers was the only process that had an impact on polar movement.
The glacial bounce is where the heavy glaciers that once depressed the Earth's surface began to melt. At the peak of the last glacial maximum, the last time the ice cap was the largest, about 26,500 years ago. At this point, ice covered almost all of North America, Europe and Asia.
When the ice melts, the ground rises to its original position, creating a slight movement of the polar movement. However, previous research has indicated that the rebound of glaciers was responsible for only about a third of the drifts and oscillations recorded during the 20th century.
"The traditional explanation is that a process, the glacial rebound, is responsible for this movement of the axis of rotation of the Earth." But recently, many researchers have assumed that others process could have significant effects on it, "said Surendra Adhikari. NASA Jet Propulsion Laboratory.
See all best photos of the week in these slideshows
The team has assembled models for different processes that may be involved. In general, anything that changes the distribution of the mass around the planet will affect the rotation of the Earth.
"We have identified not one but three sets of processes that are crucial," said Surendra, "and the melting of the global cryosphere (especially Greenland) during the twentieth century is one of them".
The results showed that ice loss in Greenland was a major factor. In total, about 7,500 gigatonnes melted in the ocean between 1900 and 2000. As a result, the melting of Greenland ice has been identified as an important factor contributing to changes in the Earth's axis of rotation. . Its global position has also made it particularly important for mass transfer around the world.
"There is a geometric effect that if you have a 45 degree mass in relation to the North Pole – which is Greenland – or the South Pole (like the Patagonian glaciers), it will have a greater impact on the rotation of Earth "is close to the pole," said co-author Eric Ivins, also of the JPL.
Greenland ice melts because global temperatures rise because of anthropogenic greenhouse gas emissions. So climate change, at least in part, is causing the Earth to falter.
The third cause is the convection of the mantle. This concerns the movement of tectonic plates – the circulation of matter in the mantle as a result of the heat of the Earth's core. It is a natural process unrelated to human activities.
However, understanding the processes at the origin of the polar movement over which we have some control is important for the future. The authors conclude: "For the first time, a suite of environmental geophysical (eg, cryospheric, hydrological, oceanic) and solid Earth processes are combined to explain secular polar motion (SPM). These processes operate over a wide range of time scales, but each transports the mass and disrupts the Earth's inertial tensor in an entirely quantifiable manner.
"The question of how future modeling will progress to achieve a more robust reconciliation is an open question … we assume that the path to a less uncertain reconciliation of GPS should involve simultaneous reversals of mantle convection and fit. glacial isostatic. internal mass transport components treated in a strictly coherent manner.
[ad_2]
Source link
