Here's a bunch of imminent threats we know can happen or are happening that will or could have a major impact on very short timelines:

1. The global debt levels are reaching civilization threatening levels.

2. The population bomb is going to go off, leading to mass suffering as in some countries there will be 2 retirees for every working person. The fact that populations are increasing in Africa isn't relevant to all the other continents.

3. The end of the Pax Americana is arguably occurring right now and that's going to have major global civilizational ramifications since global trade relies on the American Empire, and high technology depends on global trade. During the COVID-19 Pandemic, fields full of automobiles were stuck at the factory solely because we couldn't get electronic parts from Asia. Imagine if a conflict were to cut that supply line. Now imagine for all the supply chains that are relying on globalized materials.

4. Loss of biodiversity not directly related to climate change is at crisis levels due to things like plastic pollution in the waterways and overuse of fertilizer causing massive dead zones in large bodies of water. We could kill off the global ecosystem before climate change has a chance to harm us.

5. The era of antibiotics is ending. Overuse of antibiotics partially in hospitals but more importantly in commercial farming is leading to mass antibiotic resistance which will set humanity back 150 years in terms of dealing with common diseases caused by bacteria.

6. The post cold-war era of relative peace is ending. While the risk level is presently low, global tensions are rising between nuclear powers, and it's possible we see a nuclear war in our lifetimes.

7. Before climate change becomes an issue, the problems with global trade could put oil and gas as a major problem for many nations because for the most part where oil and gas live is not where the people who use the most oil and gas live. Witness Europe being cut off from Russian oil & gas. A few strategic strikes and Russia could be totally cut off from global energy markets, and that's just one example. We don't have enough renewables to make up for even a small amount of the energy we use from these fuels today.

8. Critical infrastructure is extremely fragile in most developed nations. A relatively small number of agents with relatively low-tech means could cripple key infrastructure and there wouldn't even be anyone around to see it. That's fine for one event, but it doesn't take a lot of events to completely shut down an economy because there's no power and limited telecommunications. Many major manufacturers and systems such as water treatment, power, manufacturing are far behind in cybersecurity and highly susceptible to focused cyberattacks. Systems that would have been air gapped 20 years ago are now often connected to the Internet to provide operational intelligence, providing a vector for problems

9. Silviculture and engineered forests are highly dangerous to some of the massive forests we rely on. The British Columbia pine beetle epidemic has massively damaged that province's massive forests and part of the reason is monoculture from forests replanted with a monoculture after being harvested.

10. At any moment, a major solar flare hitting earth could destroy most of our technology in a way that might not be recoverable in a generation. There was a major solar event early on in the electrical age that caused fires. Today we rely on electricity so much and in such precision devices that a similar spike might destroy too much technology to replace. A much smaller event about 10-20 years ago took out the power grid in Quebec, and that's without the trouble of the same event causing global issues. Right now new major transformers are on a queue years deep.

11. Genetic engineering of microbes is a relatively mature science at this point, bad actors today could potentially engineer a supervirus that is more dangerous than COVID. Given how much COVID harmed civilization, a real threat that's more like airborne ebola could end global civilization, and if it was spread clandestinely all at once it could be killing people before the government even realizes it's here.

12. Genetic engineering of humans is in its infancy, but is already possible. Unwise genetic tinkering will have knock-on effects that could end civilization. For example, if everyone were to jump on a bandwagon to implement the mighty-mouse gene in human populations, we'd have strong, long lived humans who eat more food and are much more aggressive. Alternatively, if we commonly cured things we considered genetic defects that were actually prophylaxis against something (the same as sickle-cell trait is protection against Malaria in Africa), we could leave our species defenseless against some situation we didn't recognise but was mitigated in some people's DNA.

13. The degradation of soil and land due to unsustainable agricultural practices, deforestation, and urbanization is threatening food security and ecosystem services. Soil is a vital resource that supports life on Earth, but it is being eroded and depleted at an alarming rate. According to the Food and Agriculture Organization, 95% of our food comes from soil, but 33% of global soils are already degraded. Soil degradation reduces crop yields, increases greenhouse gas emissions, and affects water quality and availability. If not prevented and restored, soil degradation could lead to famine and environmental collapse. This is one of the things believed to have led to the collapse of the Indus Valley civilization.

14. The drive towards bureaucratic authoritarianism even in liberal democracies is a dangerous trend. In eras like the bronze age collapse, such authoritarian regimes has led to civilizational collapse. Our need to control everything has a massive danger of causing the end of our civilization.

15. Freshwater resources are strained for reasons other than climate change, such as pure mismanagement. We built cities in the middle of deserts, and that has meant that the limited water resources have been stretched more and more thin. In addition, you have situations like Nestle bottling water from one water shed where it's purchased and drank in another water shed, further displacing fresh water supplies. The Nile river is being dammed by Ethiopia, and that's going to cause full-scale war in Egypt, with Sudan stuck in the middle. That megaproject is being constructed right now, and it's just one example of freshwater resources being a potential flashpoint for a world war.