The nearest star in the universe is the Sun. Climate change. Grand solar minimum. Magnetic reversals. Active Sun and Sun spots. Cosmic rays maximum. Earthquakes.
The amount of sunlight in the northern hemisphere has the greatest impact on the earth's climate. The reason is that there is more land mass there than in the southern hemisphere. The heat capacity of land is much lower than that of water. There is then a lot more snow and ice in the winter in the north. White ice reflects much more sunlight than dark earth. It then gets colder. When it gets colder, more ice settles, which must melt in the summer. If the amount of ice has increased by 15 percent, it could mean the start of a new ice age.
The earth orbits the sun. The Earth's axis forms approx. 23.5 degrees with the earth's orbit. Had the angle been 0 degrees, we would not have had seasons. The tilt varies between 22.1 degrees and 24.5 degrees with a period of 41 thousand years. (The variation is so smal due to the fact that the Earth has a large moon.) At 24.5 degrees, there will be more sunlight in the summer up in the north. If this was the only effect in the Earth-Sun mechanics, this would have resulted in a warmer climate.
How large a deviation the earth's orbit is from being a circle varies with a period of 100 thousand years. The eccentricity of the ellipse varies little, but enough that this effect alone can lead to 6 percent more sunlight in January in the northern hemisphere.
Polaris has not historically always been a pole star. The precision of the Earth's axis can be compared to what happens with a spinning top. The period is 26 thousand years. Today, the Earth's axis points approximately towards the North Star, but in approx. half a period, it will point to a point near the star Vega.
The solar system's largest planet, Jupiter, has most of the "credit" for these variations. Think of waves with different periods and amplitudes. Two waves in the same place will in certain places amplify or weaken each other and can be replaced by a more complicated single wave. It was the merging of the three cycles that Milutin Milanković discovered. The following video explains in a very good way how this contributes to affecting climate change on Earth. But there is more. For example, our galaxy rotates with a period of approx. 250 million years. Then the speed of the solar system is 250 km / s. The sun also goes in and out of galaxy arms several times.
Counting the number of sunspots. The beginning of a solar cycle is a solar minimum, when the Sun has the least sunspots. Over time the number of sunspots increases. The middle of the solar cycle the Sun has the most sunspots. It then fades back to the solar minimum. And it will be the start of the next cycle.
A Grand Solar Minimum occurs when several solar cycles exhibit lesser than average activity for decades or centuries. Solar cycles still occur, but are at a lower intensity than usual. Grand solar minima have shown some correlation with global and regional climate changes.
Cosmic high-energy particles can impact the Earth’s atmosphere. The decreasing solar magnetic field allows more cosmic rays to penetrate the solar system. The cosmic rays can have consequences on Earth’s cloud cover. This can happen despite the fact that the Earth has its own magnetic field. The mechanism is that sub-cooled water vapor needs some "pollution" to settle on to become ice. Electrically charged atomic particles help create white clouds.
Read also The Spaceship Earth is a myth
Volcanic activity may be attributed to the increase in Galactic Cosmic Rays penetrating deep into silica rich volcanoes. Several studies have shown this correlation along with historical evidence. But there is no general agreement on the physical mechanisms.
Scientific disagreements are resolved with more science. What about emergency preparedness in the northern hemisphere? Without good preparedness, volcanic eruptions can have greater consequences than today's pandemic. Historical data suggest that such eruptions have led to a fimbulwinter.