Why are a variety of instruments needed to measure change in the climate system?

The different types of weather measuring instruments are used to measure different parameters of the climate change. Some of these instruments include thermometers, barometer, rain gauge, anemometer and hygrometer.

OK wait.... um huh no. That dos not answer the question. I don't know what kind of dipsh!t answered it that way. I think the answer is so they know it's correct. Just like a science project. Do you do the experiment only once and know it;s 100% correct? No. Don't think so. But I'm only 3 so I don't know.