Climate science, risks and solutions

More than 99 % climatologists attributed to the increase in global temperature over the last 30-40 years greenhouse gas , which people added to the atmosphere from the beginning  industrial revolution in the 18th century. The vast majority of these scientists agree with the fact that if this warming continues,  poses a significant risk to humanity and all life on Earth: for our cities and towns, our water and food supplies and our health.  How do we know this warming is happening? and that it is caused by humans? How strong is the evidence? What risks can we expect and what can we do with them? (More on climateprimer.mit.edu)