I am optimistic about our future in this planet and also for our existence in general. Technology is going to find a solution really soon but its a race against time. We have already witnessed glaciers melting and the increasing volatile weather around the world . The Balkans have recorded their worst floods in 130 years minimum and north America is facing droughts etc . But as time passes we are going to find a solution for global warming.As for the population. Well earth is big place and my guess is that earth will be able to sustain 30 billion people If we are really orderly. But then its comes down to industries and carbon emissions. That would really be disastrous on that scale.
The Population Clock indicates that there 7.2 billion people in the world. 10 billion, on that scale, simply is not that much more. It sounds like a lot, but the planet is large, to us anyways. I think the population will bypass 10 billion quite easily, we're almost three quarters of the way there.
It is possible for the planet to sustain 10 billion people on it at one time. I think that this planet is getting crowded and that the more people you put on it the pollution and troubl ewill become of it. I do beleive that the planet could probably hold that much but at what cost.
Yes, it is possible for the planet to sustain 10 billion people, because most of the planet is still undeveloped. So much of the planet is undeveloped that we cannot even find one airplane in the middle of Asia. We would find better ways to farm and we would modify crops to meet our needs.
Before the current energy anomaly, You know, The anomaly caused by the exploitation of liquid fossil fuels which released large amounts of almost free energy upon the world, The planet sustained about a billion people tops. The world (and it's ecosystem) had been supporting only this number (and generally much less) for thousands of years. That is the long term sustainable population of Earth.
Apparently we aren't supposed to think of what is going to happen when the oil runs out (or technically it won't actually "run out", But when the cost of extraction exceeds it's value to civilization it has effectively "run out"). What will happen of course is that the population anomaly which is only being supported by the cheap energy anomaly will suffer a massive correction.
The more people we keep adding to the planet, And why would we even consider ten billion! , The more calamitous will be the plunge down to truly sustainable levels, Which are about a tenth what we have today.
The planet earth cannot sustain 10 billion people at the current levels of world consumption of resources. Energy, food and water resources would not be available to all ten billion people for basic sustenance. Water and food resources are critical for all life. Too much of the planet's resources are being utilized for the production of unnecessary consumer goods.