Question

9. How do we know whether or not global warming is caused by humans?

		From experiments in which a small experimental plot of forest is subjected to excess carbon, and the growth of the trees along with the temperature are then measured.
		From experiments in which excess carbon is injected into a laboratory-created Earth-like atmosphere, and the resulting temperature is measured.
		From computer calculations that "predict" 20th-century temperatures based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show that only natural variations are important.
		From computer calculations that "predict" 20th-century temperatures, based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show the importance of human variations.
		Actually, scientists have been unable to determine this.

Answer 1

9. How do we know whether or not global warming is caused by humans?

Answer : (d) option

From computer calculations that "predict" 20th-century temperatures, based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show the importance of human variations.

explanation :

Atmosphere researchers likewise realize that convergences of ozone harming substances in the air have developed altogether since the Industrial Revolution. Carbon dioxide has risen 45 percent. Methane has risen in excess of 200 percent. Through some moderately direct science and material science, researchers can follow these increments to human exercises like consuming oil, gas, and coal.

There are other human fingerprints that recommend expanded ozone depleting substances are warming the planet. For example, thinking back to the 1960s, basic atmosphere models anticipated that an Earth-wide temperature boost brought about by more carbon dioxide would prompt cooling in the upper air (on the grounds that the warmth is getting caught at the surface). Later satellite estimations affirmed precisely that. Here are a couple of other comparable expectations that have additionally been affirmed.