How does CO2 actually warm the planet?
Comment: 113 days ago
The CO2 that used to be in the atmosphere is still there, sort of. CO2 is "recycled" by life on Earth. Plants absorb CO2 from the air, use the C (carbon) to build themselves, and return the O (oxygen) back into the air. The process is photosynthesis. It's weird to think that trees grow out of the air and not the ground, but that's actually what happens.
The oxygen in the air is then absorbed by animals (we beathe oxygen) which oxidises our food providing us with energy, the waste from that process is CO2, which we breathe out back into the air - ready for plants to use again. And so the cycle continues. If plants absorb the same amount of CO2 as animals breathe out, then CO2 levels will remain the same.
There are plenty of other processes going on as well - oceans absorb CO2, volcanos emit CO2 - but overall, for the last 10,000 years, the level of greenhouse gases in the air has remained relatively constant and is just the right amount to provided humans the stable climate to develop. It's no coincident that human civilisation developed over this period. A stable climate meant humans could settle down and start farming rather than being nomadic and chasing food all the time.
When a plant dies, most of it decomposes and returns to the air in the form of CO2 and other gases, but some of the carbon in the plant stays in the ground. Over millions of years, this carbon, under the huge pressures of the rocks above, becomes oil and coal.
When we burn oil or coal, put that carbon back into the atmosphere again. So when you drive a petrol car, you are ADDING CO2 that was previously "locked up" underground, to the air. Before the Industrial Revolution, CO2 was about 280 ppm. Today it is 400 ppm.
We are adding about 40 billion tons of CO2 to the air every year. And it's still increasing a % or 2 each year. So that near perfect level of 280 ppm is shooting up, hence global warming. Also, when we cut down a tree, we are reducing the number of plants that can absorb CO2. It's a double whammy.
The detail is much more complicated than I have described or even understand, but that's the gist of it.
Can we do anything about it? Yes we can. If we stop adding greenhouse gases to the air, that would be a start, and over time (maybe hundreds of years), the composition of the atmosphere will return to something more suitable for human civilisation.
But there are massive problems looming. Under the permafrost, that's the ice in the northern hemisphere that remains frozen thoughout the year (Siberia, northern Canada etc.) there are huge amounts of partly decomposed organic material that hasn't fully decomposed becaused it has been frozen for thousands, probably millions of years. If the permafrost melts, it will expose this organic material to the air which will then decompose releasing CO2 and methane. These emissions will make our emissions look like baby food.
Unfortunately, the permafrost is melting and methane is already being released. There are many other huge related problems. The oceans have absorbed so much CO2 that they are acidifying (CO2 becomes carbonic acid in water), which is affecting the ecosystems in the oceans.
Basically, if we carry on business as usual, that's the end of human civilisation as we know it, and possibly the end of life on Earth. Scientists believe that's what happened on Venus - runaway global warming caused by natural processes resulting in an atmosphere 96% CO2 at over 400C.
What we need to do, is for the whole world to come together to "fight" global warming rather than fighting ourselves. The urgency cannot be underestimated. Every year we do nothing, or not enough, the higher chance Earth will end up like Venus. The cost of inaction is far higher than action. If you think immigration is a problem today, just wait until hundreds of millions of people start moving north because their countries are too hot to live in.
If only we could kickstart a global green revolution, with AI helping us make the right decisions...