Vidqun, just because CO2 makes up only about 0.04% of Earth's atmosphere that doesn't mean it has an insignificant effect on the global air temperature. My study of science books and my own experiences with human made greenhouses makes that very clear.
If you have a car think of how hot the air in the car gets inside of the car (relative to the air outside of the car) on a sunny hot day when the windows are closed and sunlight is entering the car through the closed glass windows. The glass is much thinner (less than half an inch) than the several foot length of air in the car, but it is enough to let in UV waves (which are later converted into infrared waves) and to trap in infrared waves, and that results in the air within the car becoming considerably hotter than the air outside of the car. That is the greenhouse effect in work.
Likewise in greenhouses in which plants are grown, the length of air from the ground to the top of the greenhouse is even much greater than the length of air in a car, though the thickness of the glass is about the same as that of the car, yet the greenhouse effect is still produced. Some greenhouses used to grow plants, don't even use glass, using only plastic sheets (and thus much thinner than glass panes) yet a greenhouse effect is still produced, allowing the plants in the greenhouse to grow.
In my metropolitan area I have personally noticed that the summers and early portion of fall have become hotter over recent years, and that the winters have become warmer over recent years. I have also noticed that wildfires in my state have increased dramatically over recent years, resulting in the smoke from the distant wildfires getting into the air of my metro area on several days of each recent year. I don't remember such smoke every being in the air of my metro area prior to a few years ago, except on extremely rare occasions.That is extremely alarming to me. Furthermore, when I watch the televised news I see that such warming of the climate and increasing frequency of wildfires are happening across much of my nation and in many other nations.
I thus see the very clear evidence from my personal experiences. I also see the data presented in scientific sources about the Earth's climate. It is undeniable to me.
Whether global warming needs to be limited to 1 degree Celsius, 1.5 degrees Celsius, 2 degrees Celsius, 2.5 degrees Celsius, 3 degrees Celsius, or by some other amount, over pre-industrial levels, it is very clear to me that is needs to be limited in order for the human species (and numerous other species) on the planet to survive and in order for it (and them) to continue to thrive. [Life on Earth is interdependent. For example, the continued existence of our species is dependent upon the continued existence of numerous other species.] It also very clear to me that humans need to do more to reduce their CO2 emissions, in order to limit increases in the global temperature.
