When you see people riding bicycles instead of driving a hydrocarbon-burning, molecular oxygen-consuming vehicle, we should be grateful that someone is contributing to the future survival of humans on planet Earth.
If everyone understood quantum physics and basis chemistry, we all would understand the process of global warming and the reduction of the surplus molecular oxygen that took 3.5 billion years to produce through photosynthesis.
Then, we all would understand that it's the molecular oxygen that absorbs the ultraviolet energy and becomes ozone. We also would understand that larger molecules such as nitrogen oxides, sulfur oxides, carbon dioxide and water vapor are great at absorbing the infrared (heat) portion of the energy spectrum.
When we drive our vehicles, we are reversing the process of photosynthesis at a very fast rate. For photosynthesis to catch up, it will take another few billion years.
A final thought: If everyone on Earth stopped burning fuel, the climate of the Earth would stay the same (plus or minus 1 degree). If we continue to burn at the current rate, we will face extinction in the next 60 years. So, at least bike if you can.