The sea level used to be 300 feet lower than where it is today. The planet changes, deal with it. Why is whatever the temperature was in 1700 the ideal temperat

The sea level used to be 300 feet lower than where it is today. The planet changes, deal with it. Why is whatever the temperature was in 1700 the ideal temperature? If we have the power to change the temperature of the earth we should be thinking what the ideal temperature we'd like it to be is and do that instead of picking the day we started burning coal.