We all know that an average temperature rise of even 5°C would have catastrophic effects on our planet. Then wouldn’t the Sun changing temperature by 5°C have a similar effect?
In: Earth Science
We’re far away from the Sun. Heat radiating outwards is subject to the inverse-square law. Because the surface area of a sphere is a function of r², the intensity of radiation from the Sun at a distance r is proportional to 1/r². This means that at a distance of 2 solar radii from the centre of the Sun, the amount of radiation you get is 1/4 of what’s leaving the surface. We are so far away that the proportional amount we receive on Earth is tiny compared to the output of the Sun.
Now, the Sun is at millions of degrees. If the temperature went up by 5°C, that 5°C worth of extra heat gets spread out as it moves away from the Sun. By the time it reaches us, the difference is tiny. Another way to think about it is that that’s 5°C out of millions of degrees. That tiny fractional increase is like the fractional increase we’d get. Except we’re sitting at a cool 300K-ish (only a physicist deals in absolutes). So that tiny percentage increase amounts to much less than a degree in Earth.
The outer shell of the sun is about 5 million degrees C. Dropping that by 5C won’t do much to the amount of energy it emits, so we most likely wouldn’t notice or be impacted.
The Sun does get periodically hotter (sunspots) and it does have an effect on Earth. Eventually the Sun will get a lot hotter when it runs out of hydrogen and will expand to approximately where Earth currently orbits.
5°C on the suns surface would be a change of roughly 0.1%. Since radiation energy rises with the 4th power of the temperature, it would rise by about 0.4%, or by about 5 W/m².
For comparison, a doubling of the CO2 consentration in the atmosphere is the equivalent of an extra 3.7 W/m².
So yes, a long-lasting rise of 5°C on the suns surface would have significant consequences.
Latest Answers