How do scientist know climate change is happening is it a. they measure the amount of greenhouse gases in the atmosphere, and the temperature over many years b. they measure the amount of water in the ocean that covers the earth c. they measure the amount of clouds in the atmosphere over many years.

The answer would be A;They measure the amount of greenhouse gases in the atmosphere, and the temperature over many years.

Explanation: If scientists only went off of clouds, they'd only be able to tell if it is about to rain. If they only observed the oceans, they'd only be able to tell when a tornado or tsunami was about to occur.

the answer is 1 i believe