I don't know how long it's been since we last had polar ice caps, but you mentioned dinosaurs..and that was 65 million years ago. And if you're saying that there's some kind of cycle, that indicates that there were ice caps before that period too. My knowledge of the earth's history, is that this isn't the case. The earth has been cooling since it's origins. If we are due for anything, it's probably another ice age, of which there have been many. Your post speaks of ice age in the singular.
There have been several known ice ages in the past. The last thing I remember reading is that we've only recently come out of a ice age (about 10000 years or so?)
As for the sun expanding, that will be just before she goes supernova on our arses. The whole process will pretty quickly make life a non-event in the whole solar system. But this is millions of years in the future. No doubt the human species is doomed eventually - as is the whole universe. But better in a few million years than within the next century.
ummm... no. Our sun will never go supernova. It is not massive enough for that. It will expand rather slowly, as its hydrogen stores start to thin, and other substances make up greater proportions of the fusion products (anything up to lead, you'll find that the centre of the sun will be a cloud of lead plasma).
In order to understand what's going on, you need to understand somethying about the time it takes for the light to escape from the sun. All of the energy is derived from within the sphere, not from the surface, as it tends to be too cold. What happens in the core takes an incredible amount of time to reach the surface. I think it may be in the order of years. The force exerted by all this energy, balanced by its gravitational force is what governs the size of the star.
Now, I can't remember exactly why, but the gravitational force of the sun weakens during this stage, and the force exerted by escaping energy from the core causes the sun to expand. At last, the fusion will halt, as the sun decreases its density and temperature [energy] enough. At this point, there will no longer be any of the energy holding the outer layers of the sun out, and it will all collapse inwards[implode] under the gravity, which has now become the stronger force. Hence, it will form a white dwarf (I think, from memory).
In a larger star, there is enough matter in the core after the inner layers have collapsed inwards (but not the outer layers) to continue fusion, and with the excess energy build up (remember how long it takes to reach the surface, in a really big star, that's a really big amount of energy) of energy, will literally all escape at once, creating a massive explosion, blowing the outer layers of the star away. At least, I'm fairly sure that's how it happens.
Anyway, point being that our star will not supernova.
And, as the universe ages, its energy is decreased, as is the natural order of things. Everything in the universe tends to fall to its state of lowest possible energy. And it will happen.
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