Is there anything man can do to change the planets weather? NO
That seems naive. Even global warming "skeptics" like Bob Carter say that man has increased the temperature.
The types of buildings we build effect heat. The way we irrigate areas. When we burn gas in cars, it creates heat. Do you think kinetic energy just disappears? Stand in an elevator packed with a dozen people for an hour. Stand in that same elevator by yourself for an hour. Temperature difference? Of course. Run a motor in there you get an increase in temperature too.
Our presence and the things we build and do have an effect. We do have choices in our behavior.
Man certainly has the capability to change the ecosystem. If we cut down all the trees, we deplete our oxygen. If we pollute our oceans and destroy all the fish, we lose food sources and if we kill the marine plant life, we lose another source of oxygen.
On the other hand, if we are responsible with these resources, we don't face the results.
Whether our effect on global climate is large or small, it is still an effect.