What does the Earth's magnetic field do on Earth?

Answer 1

One does not necessarily think of the Earth's magnetic field every day, but it does some important things.

First, everyone knows, the Earth's magnetic field influences all magnets on Earth and the compass is the most famous. The Earth's magnetic field allows you to use a compass. Even without a compass some birds are able to detect the Earth's magnetic field and get a sense of direction.

Second, the Earth's magnetic field protects us from the solar wind which is a high energy stream of charged particles coming out of the Sun. Occasionally, there is a great burst of these particles associated with a solar flare. Without the Earth's magnetic field these particles would hit Earth's atmosphere and create additional radiation. Though that radiation would not threaten life on Earth, it may be quite harmful. Satellites are a different matter and the assault of the charged particles has important consequences on GPS and communications and without the magnetic field

The solar wind and the Earth's magnetic field together form the Aurora Borealis, the Northern Lights, so they would be gone without the Earth's magnetic field.

The solar wind and the Earth's magnetic field are the main ingredients to what is now called solar weather. There is a complex interplay between the Earth, its atmosphere and the magnetic field which is currently the subject of much study.

Oddly, the Earth's magnetic field helps hold on the the air. One way the Earth loses air is that the highest air particles are hit by the solar wind and knocked off the Earth. That is very much decreased because the Earth's magnetic field deflects most of the solar wind. There is some reason to believe that Mars lost its atmosphere

after it lost its magnetic field and that is why Mars has only 1% as much atmosphere as Earth.

Sometimes the Earth's magnetic field disappears or reverses or just gets all jumbled up when the currents that cause it in the Earth's core become erratic. This hasn't happened for about 10,000 years, but the geologic record shows that it has happened dozens of times and the length of calm periods like now can be a few thousand or a few million years long.

A reversal of the Earth's magnetic field takes a few hundred years to settle down again, and so during that time your compass won't work, birds may be confused, Northern Lights become a vague glow and GPS and cell phones may be replaced by maps and wires. And, of course, it will be good to have stock in companies that sell sun screen.