Our sun gives us energy. What happens to that energy after we’re done using it? Does it stay here on earth? If it does, won’t it accumulate over time and harm our planet?
In: Earth Science
A large chunk of it just bounces back into space. The earth isn’t black.
Of what is absorbed, the vast majority directly heats the ground, heats the oceans, and heats the atmosphere. This raises the temperature of the earth, and thankfully so or we’d freeze to death.
Now, the sun gives us sunlight because it’s hot (about 5400°C to be specific). The earth is also hot, about say 15°C. Doesn’t seem that hot to us, but it is still 288°C hotter than absolute zero. This means the earth (and everything on it) also glows, just like the sun. We just can’t see it, but a thermal camera can. Tskes about 525°C before we can start to see it as a giant red glow. A light bulb noticably glows at 2400°C. This earth infrared glow all gets sent off into space. It happens day and night, but at night the effect is really noticable without the sunlight heating. Meaning, at night it gets colder, because heat is thrown off into space without any incoming heat.
The warmer the earth gets, the more heat it sends off to space as it glows. 15°C, the current average temperature of the earth, is just the balance. The earth absords sunlight and heats up until it starts to throw off as much heat as it is taking on from the sun. And hotter and the earth would throw more off into space and cool. Any colder and the earth would absorb more from the sun and heat up. It would reach ~15°C eventually.
Now enter global warming. The sun sends us mostly visible light. CO2, methane, and water vapour are transparent to visible light, goes right through. The earth sends off infrared to space. CO2, methane, and water vapour are not transparent to all infrared, the atmosphere isn’t clear to some infrared. This means heat the earth tries to send back out might be blocked by greenhouse gases. This heat the greenhouses gases up, and then they go and emit their own infrared light. But half of that goes into space, the other half goes back down to earth. Greenhouse gases are a one way blanket for the earth. Visible light heat from the sun can come in easily, infrared heat can’t leave as easily. So the earth warms the more CO2 or methane we out in the atmosphere.
A tiny fraction of the heat from the sun does something before becoming general heat that raises the temperature of the earth. Some of the heat drives large scale atmospheric movement, aka wind, due to the temperature imbalances it causes. Same for ocean currents. This motion, wind or currents, eventually just becomes heat though through friction. Plants make sugar with some of the light, and it’s stored as the chemical energy in sugar. As soon as the sugar is burnt, it’s heat. And by brunt I mean a plants own metabolism, the metabolism of an animal (like us) that ate the plant, the plant rots and the bacteria and fungi metabolisms’ use it, or its literally burnt like in a forest fire. As for us, solar panels push some electrons first, before whatever device uses the electricity turns it all into heat. Computer, light bulb, motor, these all eventually make heat.
So it all ends up heat. Unless the chemical energy (sugar) gets buried before it can be burnt. That’s how we have oil, coal, and natural gas. The energy was trapped as chemical energy underground, never burnt. Well, until we dug it up and burnt it. Fossil fuels are using solar light energy from millions of years ago. This would be a miniscule faction of the sunlight coming in though.
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