Is there global warming, yes, possibly followed by global cooling. Planet earth is going through one of its Millennial cycles. Is this cause man made by pollutants and hydrocarbons, e.g. CO2? We don't really know, as most of the science appears to be a politically motivated career opportunity.
Here is my theory, which is as good as some of the others being postulated by people really devoid of science/engineering training and knowledge.
The sun's rays heat the earth to produce global warming and also transmit billions and billions of photons each day. The environmentalists want to use these photons to produce green energy by employing solar collectors and solar panels. However, currently the falling photons are unused and just lay on the ground! Once we started tapping these photons for their energy content we create depleted photons, which don't just lay on the ground anymore, but stick to all organic and inorganic matter. This enormous depleted photon problem or global swarming is constantly overlooked or swept under the rug by the environmentalists. The additional earth warming effect is caused by this photon clinging action, which insulates and warms up all things on the planet. These billions and billions of depleted photons must be safely gathered and then stored some place until they can be properly disposed of, to alleviate the issue.
The depleted photon problem is similar to not putting child safety caps on your unused electrical outlets, such that the electricity leaks out onto the carpet. Hence, you get an electrical shock when walking across the carpet and then touching a doorknob.