After the exhaustion of oil resources, what materials should human beings use instead of plastics?

First of all, as an energy source and raw materials for many chemical industries, if oil is greatly reduced, there will be no substitute, which is a pessimistic possibility.

The global economic crisis must have come first. First of all, there is a shortage of oil, and the producing countries will definitely cut production and raise prices. The whole related oil industry in the world will definitely have a high price, and then the demanding countries, especially the owners of international currencies such as the US imperialists, will definitely print money at full capacity or the domestic economy will collapse instantly.

The result of printing money is to spread the crisis, and people around the world pay for oil prices.

Then the credit collapse of the US dollar, then the credit collapse of other international currencies, and finally the complete collapse of the modern financial system, returning to the precious metal currency era.

In the whole process, there will be widespread famine, resource wars and plagues, the global population will drop sharply, science and technology will go backwards, civilization will go backwards, and then it will gradually move towards another primitive balance that does not need oil.

Let's look at an optimistic possibility. The speed of scientific and technological development has solved the energy problem. Clean energy solar energy has replaced oil, other chemical products have been replaced by biopolymer materials, and biological cloning and soilless culture have replaced traditional agriculture.

Then, in the process of oil being constantly replaced, science and technology and economy have further developed, industry has been further enriched, global famine has been solved, and human civilization has reached a new level. In fact, many energy sources are replaced in this way. For example, whale oil was used for lighting before, and some people asked what we would do if whales became extinct.

To sum up, from the perspective of the whole human system, there are always more solutions than problems, and I am personally optimistic.

Finally, insert a little question that I find interesting. Is solar energy a clean energy source? Won't solar energy pollute?

I don't think so, because the temperature of our earth is maintained by the fact that sunlight radiation is not converted into other energy by the ground during the day, and there is thermal radiation on the ground at night, which is scattered in the air, so that the temperature difference between day and night will not be too great.

If solar energy is widely used and the energy conversion efficiency of solar energy is high, the radiation on the ground will be greatly reduced, the temperature difference between day and night will change first, then the global climate will change, and then many species will not survive.