Although carbon and hydrogen are plentiful, not all of it is suitable for fuel. The energy we get from burning comes not from the atoms, but from the bonds between the atoms. So, how the atoms are bonded matters.
Take seltzer water, for example: O=C=O dissolved in H-O-H. You have hydrogen bonded only to oxygen, and carbon bonded only to oxygen, and this remains true when the two combine to form carbonic acid, H-O-(C=O)-O-H. Breaking these bonds under ordinary conditions will use, not release energy. Try lighting seltzer water with a match, and you can confirm it's pretty useless as a fuel.
Carbon-hydrogen bonds, on the other hand, release a useful amount of net(*) energy when broken. But C and H compounds don't form C-H bonds spontaneously at ordinary temperatures and pressures. Conservation of energy tells us that someone or something had to put that energy into the C-H bond to form it in the first place. On Earth, we have plants to store energy in C-H bonds via photosynthesis. In space, though, discovery of extraterrestrial methane is always exciting to astronomers, because where there's methane, there's the possibility of life.
(*) Climate Realist explains this better.
Basically, because those hydrogen and carbon atoms are not on Earth in the form of fossil fuels.
There's probably enough water in the solar system to raise Earth's ocean levels enough to cover every mountain on the planet. Does that mean we're in danger of a Biblical-style flood? No, because that water *isn't here*. It's in the comets, on other planets, and so on. Similarly, there isn't enough hydrocarbon fuel on this planet to raise atmospheric CO2 to 5,000 ppm.
Hydrocarbons are formed by millions of years of decay of dead animaks and under temperature and pressure. This has nothing to do with abundance in the universe.
We're not going to run out, but trying to get oil out of tar and drilling in miles of ocean should tell you something
You must either like trolling or be incredibly ignorant.
We can't run out of hydrogen or carbon. What we can run out of is hydrocarbons produced when lifeforms are fossilized over millions of years under extreme heat and pressure that we can subsequently dig up and burn.
CO2 is not a poison at 5000 ppm, that is still just 1/2 of 1%.
Matt
Carbon-hydrogen bonds take energy to break. Just not as much energy as is released when carbon-oxygen and hydrogen-oxygen bonds form.
The inanity of your questions is unceasing. Have you read "The Rime of the Ancient Mariner"? Silly question, of course not. There is a relevant stanza in there:
Water, water, every where,
And all the boards did shrink;
Water, water, every where,
Nor any drop to drink
hydrocarbon fuels before CO2 rises to 5,000 ppm and poisons all people to death?
