When Will Earths Magnetic Field Flip Again

Globe is surrounded by a organization of magnetic fields, called the magnetosphere. The magnetosphere shields our habitation planet from harmful solar and cosmic particle radiations, but information technology can change shape in response to incoming space weather from the Sun. Credit: NASA'due south Scientific Visualization Studio

A constant outflow of solar material streams out from the Sunday, depicted here in an creative person's rendering. This solar wind is ever passing by Earth. Credit: NASA Goddard'south Conceptual Image Lab/Greg Shirah

Globe is surrounded by an immense magnetic field, chosen the magnetosphere. Generated by powerful, dynamic forces at the center of our world, our magnetosphere shields usa from erosion of our atmosphere by the solar wind, particle radiation from coronal mass ejections (eruptions of large clouds of energetic, magnetized plasma from the Sun's corona into space), and from cosmic rays from deep space. Our magnetosphere plays the role of gatekeeper, repelling these forms of energy that are harmful to life, trapping about of information technology safely away from Globe's surface. You can learn more about Globe's magnetosphere here.

Since the forces that generate our magnetic field are constantly changing, the field itself is as well in continual flux, its strength waxing and waning over time. This causes the location of Earth'southward magnetic northward and south poles to gradually shift, and to fifty-fifty completely flip locations every 300,000 years or so. That might be somewhat important if you lot use a compass, or for certain animals similar birds, fish and sea turtles, whose internal compasses use the magnetic field to navigate.

Some people accept claimed that variations in Earth's magnetic field are contributing to current global warming and can cause catastrophic climate change. Notwithstanding, the science doesn't back up that argument. In this weblog, we'll examine a number of proposed hypotheses regarding the furnishings of changes in Globe's magnetic field on climate. We'll as well hash out physics-based reasons why changes in the magnetic field can't impact climate.

Launched in November 2013 by the European Space Agency (ESA), the three-satellite Swarm constellation is providing new insights into the workings of Earth'southward global magnetic field. Generated by the motion of molten iron in World's cadre, the magnetic field protects our planet from catholic radiation and from the charged particles emitted by our Sun. It also provides the ground for navigation with a compass.

Based on information from Swarm, the top image shows the average strength of Earth's magnetic field at the surface (measured in nanotesla) between January 1 and June 30, 2014. The 2nd prototype shows changes in that field over the aforementioned period. Though the colors in the second prototype are only as bright as the beginning, notation that the greatest changes were plus or minus 100 nanotesla in a field that reaches threescore,000 nanotesla. Credit: European Space Agency/Technical University of Denmark (ESA/DTU Space)

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Hypotheses:

1. Shifts in Magnetic Pole Locations

The position of Earth's magnetic north pole was first precisely located in 1831. Since then, it's gradually drifted due north-northwest by more than 600 miles (1,100 kilometers), and its forward speed has increased from about 10 miles (16 kilometers) per year to about 34 miles (55 kilometers) per yr. This gradual shift impacts navigation and must be regularly accounted for. However, there is little scientific evidence of any significant links between Earth's drifting magnetic poles and climate.

2. Magnetic Pole Reversals

Supercomputer models of Earth's magnetic field. On the left is a normal dipolar magnetic field, typical of the long years betwixt polarity reversals. On the correct is the sort of complicated magnetic field World has during the upheaval of a reversal. Credit: University of California, Santa Cruz/Gary Glatzmaier

During a pole reversal, World's magnetic due north and south poles swap locations. While that may sound like a big deal, pole reversals are mutual in Globe's geologic history. Paleomagnetic records tell us Earth's magnetic poles have reversed 183 times in the terminal 83 million years, and at least several hundred times in the past 160 million years. The time intervals between reversals have fluctuated widely, simply boilerplate about 300,000 years, with the terminal one taking identify almost 780,000 years ago.

Geomagnetic polarity over the past 169 million years, trailing off into the Jurassic Quiet Zone. Dark areas denote periods of normal polarity, light areas denote reverse polarity. Credit: Public domain

During a pole reversal, the magnetic field weakens, but it doesn't completely disappear. The magnetosphere, together with Globe's atmosphere, continue protecting World from cosmic rays and charged solar particles, though there may exist a small amount of particulate radiations that makes it downward to Earth's surface. The magnetic field becomes jumbled, and multiple magnetic poles can emerge in unexpected places.

No one knows exactly when the next pole reversal may occur, only scientists know they don't happen overnight: they take place over hundreds to thousands of years.

In the past 200 years, Earth's magnetic field has weakened about nine percent on a global boilerplate. Some people cite this as "evidence" a pole reversal is imminent, but scientists have no reason to believe so. In fact, paleomagnetic studies show the field is about as strong as information technology'due south been in the past 100,000 years, and is twice equally intense as its million-twelvemonth average. While some scientists estimate the field's strength might completely decay in about ane,300 years, the current weakening could end at any fourth dimension.

The Dominicus expels a constant outflow of particles and magnetic fields known equally the solar air current and vast clouds of hot plasma and radiations called coronal mass ejections. This solar material streams across infinite and strikes Earth's magnetosphere, the infinite occupied by Earth'southward magnetic field, which acts similar a protective shield around the planet. Credit: NASA Goddard/Bailee DesRocher

Found and creature fossils from the menstruation of the concluding major pole reversal don't show any large changes. Deep ocean sediment samples point glacial activity was stable. In fact, geologic and fossil records from previous reversals show nothing remarkable, such as doomsday events or major extinctions.

three. Geomagnetic Excursions

Recently, in that location have been questions and discussion about "geomagnetic excursions:" shorter-lived only significant changes in the magnetic field'south intensity that terminal from a few centuries to a few tens of thousands of years. During the last major excursion, chosen the Laschamps consequence, radiocarbon evidence shows that about 41,500 years ago, the magnetic field weakened significantly and the poles reversed, merely to flip back once again about 500 years later.

Globe's magnetic field. Credit: NASA

While at that place is some evidence of regional climate changes during the Laschamps event timeframe, ice cores from Antarctica and Greenland don't bear witness any major changes. Moreover, when viewed within the context of climate variability during the last ice age, whatever changes in climate observed at Earth's surface were subtle.

Bottom line: In that location's no prove that World's climate has been significantly impacted past the concluding three magnetic field excursions, nor by any circuit outcome within at least the last ii.eight million years.

Concrete Principles

1. Insufficient Free energy in Earth'southward Upper Atmosphere

Electromagnetic currents exist within Globe's upper atmosphere. But the energy driving the climate system in the upper atmosphere is, on global average, a minute fraction of the energy that drives the climate system at Earth's surface. Its magnitude is typically less than one to a few milliwatts per square meter. To put that into context, the energy upkeep at Globe's surface is about 250 to 300 watts per square meter. In the long run, the energy that governs Earth'due south upper temper is about 100,000 times less than the amount of energy driving the climate organisation at Earth'south surface. There is simply not plenty free energy aloft to take an influence on climate downward where we live.

ii. Air Isn't Ferrous

Finally, changes and shifts in Earth's magnetic field polarity don't impact weather condition and climate for a fundamental reason: air isn't ferrous.

Ferrous? Say what?? Bueller? Bueller?

Ferrous means "containing or consisting of atomic number 26." While iron in volcanic ash is transported in the atmosphere, and small quantities of atomic number 26 and iron compounds generated by homo activities are a source of air pollution in some urban areas, iron isn't a significant component of Globe's atmosphere. There's no known physical machinery capable of connecting atmospheric condition weather at Earth'south surface with electromagnetic currents in space.

Thermal and compositional structure of the atmosphere. The upper temper, comprising the mesosphere, thermosphere, and embedded ionosphere, absorbs all incident solar radiation at wavelengths less than 200 nanometers (nm). Most of that captivated radiation is ultimately returned to infinite via infrared emissionsfrom carbon dioxide (CO₂) and nitric oxide (NO) molecules. The stratospheric ozone layer absorbs radiation between 200 and 300 nm.

The plot on the left shows the typical global-boilerplate thermal construction of the atmosphere when the flux of solar radiation is at the minimum and maximum values of its eleven-year cycle. The plot on the correct shows the density of nitrogen (N2), oxygen (O2), and atomic oxygen (O), the three major neutral species in the upper atmosphere, along with the gratis electron (e−) density, which is equal to the combined density of the diverse ion species. The F, E, and D regions of the ionosphere are also indicated, as is the troposphere, the atmosphere's lowest region. Credit: Naval Research Laboratory/J. Emmert

Solar storms and their electromagnetic interactions just touch on Earth's ionosphere, which extends from the lowest border of the mesosphere (nigh 31 miles or 50 kilometers in a higher place Earth'south surface) to space, around 600 miles (965 kilometers) above the surface. They have no affect on Earth's troposphere or lower stratosphere, where World's surface weather, and subsequently its climate, originate.

In brusk, when it comes to climate, variations in Earth'southward magnetic field are zippo to get charged up about.

Related Feature

Earth'south Magnetosphere: Protecting Our Planet from Harmful Space Energy

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Source: https://climate.nasa.gov/ask-nasa-climate/3104/flip-flop-why-variations-in-earths-magnetic-field-arent-causing-todays-climate-change/

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