What are some natural global or cosmic catastrophes which could actually happen -- probably with enough forewarning to cause a season of panic / terror / dread before they occur?

Solar flares destroying power grids
yes

and pelting the Earth with city-sized fireballs?
no

Massive meteor showers?
theoretically possible, has happened but none scheduled any time soon

One huge meteor as big as Texas?
there are asteroids approaching that size, but no

Could there be a change in the composition of the sun resulting in massive overheating / supernovae or cooling off to a dim red?
not within any even comprehensible amount of time (5 billion years)

Rouge planet entering our solar system in near collision with the Earth?
no. (Not only is rouge a color and not the word rogue, but there are almost certainly no wandering planets anywhere nearby, if there were, we’d see it coming for a ridiculous amount of time, and the odds of it coming near Earth are ridiculously low.

What if the Earth’s core stops spinning and the Earth’s magnetic field disappears. When that happens, compasses will stop pointing north, birds will not know where to fly when they migrate, and the Earth’s atmosphere will disappear.
LOL no. There is no reason why the planet would stop spinning suddenly enough to matter. It is slowing down, such that there were 40 more days per year… about 400 million years ago.

Or, maybe humans lose the ability to reproduce
Sure, maybe. We keep adding radiation, industrial food, water treatments, GMO foods laced with the pesticides they enable, microbeads and other industrial crap. Or maybe we get a pandemic that sterilizes us. That could help with our overpopulation and overexploitation problems.

or some other animal or insect becomes the dominate species.
(domi-nant) That could be a good thing, since we’re driving ourselves and way too many other species to extinction. But unless you mean a species of disease and/or insect, or after we mostly die off due to our utterly foolish environmental abuses, this seems very unlikely without an imaginative SF cause.

Or some horrific pandemic kills large amounts of life.
Quite possible.

It’s ironic that you think of all of these causes, but don’t mention the actual ones that are happening and may wipe out life on our planet as we know it, including ourselves:

catastrophic climate change

rapid human-caused extinctions leading to ecosystem collapse

food supply failures due to risks from excessive industrial food production and GMO monocultures, dying bee populations, etc

food supply failures due to catastrophic overfishing, ocean acidification, pollution, climate change, etc

modern warfare including nuclear, biological, chemical, space-based kinetic weapons, automated weapon systems, etc

I have to agree with Zaku on this one that many of us dread.

But it doesn’t seem like many are panicking or that many care in the slightest, since we continue to pollute everything we come in contact with with no regard to the warnings. :(

But those are things that we ourselves do, and could be remedied before it’s too late.

What about those things that we couldn’t do anything about?

I think extreme panic happens for most people when they feel like they can do something to avoid the catastrophe. Like when a Hurricane is coming some people get panicked and try to go to a safer place. They get a boost of nervous energy to prepare and do whatever they decide needs to be done.

If an asteroid was coming and was going to kill everything on earth I think we would have a season of people trying to do bucket list things and seeing loved ones and trying to do enjoyable things in their last days. They would be in a mode of hoping it’s not true, that some miracle might happen, and acceptance.

Another animal becoming more dominant than humans and maybe making us prey I guess some people would try to fight and others would try to hide. Some people might commit suicide.

In almost all the scenarios I think people would hope scientists would be able to fix the problem.

@Yellowdog “But those are things that we ourselves do, and could be remedied before it’s too late.”
– Some of those might be too late, either for disastrous problems, end-of-the-world-as-we-know-it problems, or game-over-for-humanity problems.

The other ones mentioned aren’t enough? You want more inevitable dooms of high likelihood? Most of those are going to involve human activity one way or another, because the world doesn’t seem to have natural mass extinction events on average more often than 50 to 150 million years apart, evidently typically it’s been a massive eruption caused by a huge asteroid or comet impact

I was thinking of the Earth’s magnetic poles swapping place. The last time it happened the magnetic field dropped to something like only 6% of what we consider normal. Neanderthals were wiped out.
Also you might consider a Yellowstone eruption. It has happened before and is about due again. It is being monitored all the time.

A tectonic event or meteor strike that disrupts the global food supply chain. I’m thinking about the recent blockage of the Suez Canal, and I’m wondering what effect an event like a large meteor strike, or an earthquake might have if it would block or destroy part of either the Suez or Panama Canal. The week-long jam in the Suez has created a ripple effect that will likely be felt in some form or other until the end of the year, according to this NBC article. Just imagine if there is an event that causes a longer term blockage.