Presented at this week’s Living Planet Symposium, new results from the constellation of Swarm satellites show where our protective field is weakening and strengthening, and importantly how fast these changes are taking place.
The Earth’s magnetic north pole is drifting from northern Canada towards Siberia with a presently accelerating rate of 10 kilometers (6.2 mi) per year at the beginning of the 20th century, up to 40 kilometers (25 mi) per year in 2003 – and since then has only accelerated. “At this rate it will exit North America and reach Siberia in a few decades, says scientist Larry Newitt of the Geological Survey of Canada.
In addition, the magnetic north pole is wandering east, towards Asia. The current rate of change (since 1840) is about 0.07 degrees per year. But between 1225 and about 1550 AD, rates averaged closer to 0.12 degrees per year – significantly faster than expected.
VIDEO: Changes in Strength
of Earth’s Magnetic Field
Based on results from ESA’s Swarm mission, the animation shows how the strength of Earth’s magnetic field has changed between 1999 and mid-2016. Blue depicts where the field is weak and red shows regions where the field is strong. The field has weakened by about 3.5% at high latitudes over North America, while it has grown about 2% stronger over Asia. The region where the field is at its weakest field – the South Atlantic Anomaly – has moved steadily westward and further weakened by about 2%. In addition, the magnetic north pole is wandering east.
With more than two years of measurements by ESA’s Swarm satellite trio, changes in the strength of Earth’s magnetic field are being mapped in detail. It is clear that ESA’s innovative Swarm mission is providing new insights into our changing magnetic field. Further results are expected to lead to new information on many natural processes, from those occurring deep inside the planet to weather in space caused by solar activity.
Launched at the end of 2013, Swarm is measuring and untangling the different magnetic signals from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere – an undertaking that will take several years to complete.
Although invisible, the magnetic field and electric currents in and around Earth generate complex forces that have immeasurable effects on our everyday lives.
The field can be thought of as a huge bubble, protecting us from cosmic radiation and electrically charged atomic particles that bombard Earth in solar winds. However, it is in a permanent state of flux.
The magnetic field is thought to be produced largely by an ocean of molten, swirling liquid iron that makes up our planet’s outer core, 3000 km under our feet. Acting like the spinning conductor in a bicycle dynamo, it generates electrical currents and thus the continuously changing electromagnetic field.
It is thought that accelerations in field strength are related to changes in how this liquid iron flows and oscillates in the outer core.
Chris Finlay, senior scientist at DTU Space in Denmark, said, “Unexpectedly, we are finding rapid localized field changes that seem to be a result of accelerations of liquid metal flowing within the core.”
Rune Floberghagen, ESA’s Swarm mission manager, added, “Two and a half years after the mission was launched it is great to see that Swarm is mapping the magnetic field and its variations with phenomenal precision.
“The quality of the data is truly excellent, and this paves the way for a profusion of scientific applications as the data continue to be exploited.”
In turn, this information will certainly yield a better understanding of why the magnetic field is weakening in some places, and globally.