As to the real environmental problems, this is primarily due to toxicity and poor resource management.

As to the toxicity, most of it is avoidable and much of it is actually intentional. By unavoidable, I mean to say that for example, cars can and already do run on nothing but water, leaving no traces other than water vapor. But such clean technologies have been suppressed by big financial interests, who are the worst polluters and the people themselves have no choice but to follow and participate in that.

As to being intentional, it is a proven fact that the elite are engaged in a global agenda of eugenics using a variety of means to dumb-down and otherwise weaken the general population who are being controlled so that these elites can establish their New World Order system with minimal resistance while at the same time culling the population down to a more managaeble level. They believe that THEY have the right to do that by virtue of their “superior genes”. All this is borne out through reading the leading elite expositors of eugenics like Russell, CG Darwin and others.

So our water supplies are contaminated with all sorts of deadly toxins, many of which were put there intentionally in full view of the public, including fluoride. They have ramped up the use of vaccinations and drugging of both adults and children by factors of hundreds of per cent over the last several decades and we have seen autism, mental illness, alzheimers etc exploding. We also see cancers exploding related to industrial pollutants, pesticides and other sources. Big Agribiz and “food science” have taken over the food supply and made us dependent on toxic foods where most people buy them in the supermarkets. A lot of our food is also cominng from places like China. It is ridiculous, but Californians are eating foods grown thousands of miles away, when the same foods are grown in abundance in that state. In addition, it is estimated that two thirds or more of the produce in the supermarkets is genetically modified which is bad for the environment, bad for farming and bad for health.

Fortunately there has been an organic backlash in recent years and more people are supporting the idea of natural foods, farmers markets and smaller organic farms, so that part is hopeful. Just turning back, boycotting big Agribiz and supporting or even engaging in organic farming and gardening alone will dramatically limit pollution and increase health.

Driving water cars is a good start for clearing up air pollution. That isn’t to say that we should immediately stop driving gas-powered cars because that is just not possible at the present time, but luckily, there is economic incentive to switch over to water (ie cracked hydrogen) cars. So unless the elite try to stop their production, we should see more cars running on water in the near future. And maybe more exotic free energy, which would be even better. See:

FREE ENERGY Home Generator -Zero Point Energy – Off the Grid
http://www.youtube.com/watch?v=efCelx7qe_M

Getting off the grid as far as possible makes the most sense for the environment, for health and for economics. We don’t have to sacrifice in order to do this, only live more intelligently, more freely and independently. In other words, it isn’t a matter of overpopulation, but one of education.

Point 1:
I think that it is easy to see humans can do great damage via pollution, even if you don’t think global warming is happening (and I feel odds are that it is these days) there is still the toxic pollution that has been added to rivers, lakes, and some pieces of land that has a detrimental effect of plant and animal life in that area. So we do cause pollution and it does cause harm.
Does that last point mean that life/from Earth would be better without us? I argue no. Not only are we part of life on/from Earth but if we are able to limit the damage we do to various ecosystems around the world so they do not collapse then we provide means by which life on Earth will become life from Earth and those have the potential to survive past the point (in about 5 billion years from now-so keep paying your mortgage) when the sun expands and most things remaining on Earth get cooked. While humanity should learn how not to damage other forms of life on Earth and should actively work to avoid harm now, we are the only species likely to currently enable space travel and thus create the ability to evacuate the planet when such an evacuate becomes necessary to sustaining most of the life on/from Earth (not just us).
Thus calling for human extinction actually removes a potential boon to the survival of Earth’s various life-forms.

Point 2:

I would argue the harm via pollution that humans cause is mainly not do to the number of humans but to the manner we go about economic development. Global Warming is caused by greenhouse gasses. This are released by the burning of fossil fuels. If not for the latter the former would not be a problem. Also look at China, it has a great deal of problems relating to both air and water quality because of the many emissions (some of which are quite toxic) put into each. China’s emissions problem (touching on fossil fuels again) has grown worse after it started its population control program. This is because of the fact that there is no stable ratio between the amount of humans and amount of emissions, factories, cars, coal powers plants, and so on. China jumped ahead of the USA in CO2 emissions not by a population boost but through rapid and reckless economic development in which consideration of the environment was not an issue. Thus focusing on economic systems systems to be the logical way to prevent pollution and environmental damage.

Note: Population control does not involve counting and limiting the amount of emissions-only the number of humans. This is why it actually fails to serve as effective protection for the environment.