This question has many parts to it. We know, for example, that eventually our star, the Sun, will die and in doing so will destroy the Earth. The very distant future, then mens the end of the Earth, but this will not occur for many millions of years and need not concern us here. It has also been suggested that our climate is changing and that we area at the beginning of another Ice Age, but opinion is divided. It is enough to say that large scale changes to the planet as a whole take place so slowly when compared to our short life span that they may go unnoticed, disguised by the much more rapid changes which man is causing to his own life and that of all other living creatures on Earth.
The usual way of attempting to ‘see’ into the future is to look at the way changes have occurred in the past up to the present day and then try to project into the future, but this is not easy because it is not always possible to anticipate the effects of a particulars set of circumstances. Try a simple experiment. Draw two lines on a piece of paper at right angles to one another to form the axes of graph. The graph could represent, say, the rate at which a hot water bottle cooled after it was placed in your bed. Suppose one axis represented temperature and the other time. Suppose also that you had measured the temperature on two occasions so that you could plot two points on your graph. These could be joined by a straight line, and if you wanted to know the temperature of the bottle sometime later, you would simply project that straight line to the required point in time. But if, in the meantime, someone removed the blankets from the bed, the bottle would cool much more quickly and your prediction would be wrong.
The subject of many science fiction stories deals with ideas of what conditions might be like in year to come. Some suggestions seem to be wildly far fetched, but a hundred years ago who would have believed in the possibility of supersonic flight or submarines that can stay under the Arctic ice for two years without surfacing, or even in satellites circling Venus? On the other hand in the heyday of the motor car a few years ago, most of us would have laughed at the idea of fuel shortage. How do we know what the world’s population might be in a hundred or even twenty years time? Can we predict whether science and technology will be able to find solutions to the problems of overcrowding, food shortage, and pollution choking our rivers and seas, or the ever decreasing numbers of wild animals and plants with the accompanying dangers to our own species. Will we be able to take a rocket to a distant planet as easily as we can now take a bus to the next town, or will we return to more rural living, each community growing its own food and making clothes by hand? Then there are the dangers of nuclear war. If man is to survive in peace and plenty, the watched word seems to be try to foresee the consequences of any action rather than wait and see, by which time it may be too late.