Be smart with global warming solution

It is amazing to me that no one has brought up one of the most significant facts in regard to global warming. Thousands of years ago a gigantic glacier covered North America to somewhere south of Champaign-Urbana. At that time there was no industry and very few humans on earth, compared to now. Yet that glacier melted clear back to northern Canada. What caused that melting that was far greater than anything than is happening now?

Some scientists say it was caused by changes in the sun's activity. Some scientists today are saying that most of the present global warming has a similar cause. Some scientists even say that our human part in the global warming is between 1 and 5 percent. If that is true all of our human efforts will have very little effect on global warming.