How Do We Know Climate Change Is Real? There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause.How Do We Know Climate Change Is Real? There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause.

How Do We Know Climate Change Is Real? There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause. https://climate.nasa.gov/evidence/