At this time, winters are getting milder in North America due to ice melting around the North Pole. There is also an increase in rainfall due to warmer oceans evaporating more moisture. With growing seasons getting longer, this all adds up to good agriculture. The corn belt has moved farther west into the plains over the past 25 years producing record corn and soybean harvests.

This trend should continue for a century or two, until a temperature reversal occurs. It may be a volcano which causes the temperature reversal, because there is no apparent reason why a cool-down would begin otherwise.

The reversal occurs when snow and ice increase in northern areas reflecting away more radiation from the sun. Precipitation stays high, because oceans stay warm at the beginning of the reversal. The precipitation creates more snow when the reversal begins, and since more snow reflects away more sunlight, the cool-down is very rapid and irreversible.

There is not enough precipitation at this time to cause snow to increase during the winters. But precipitation is increasing as oceans warm up. It will probably be another century or two before snowfall increases enough to cause the temperature reversal.

Sea level drops about 400 feet (130 meters) during an ice age. This is because moisture which evaporates from the oceans gets tied up over land as snow and ice. A small decline in sea level should begin any time, because snow and ice are already increasing over Antarctica and Greenland. A counteracting force is increased melting of mountainous glaciers. But those glaciers are disappearing rapidly. The ice which is melting over the oceans does not change seal level; only ice on land can influence sea level.

Once the reversal begins, much of North America and northern Europe will become uninhabitable. Roads will become impassible with rapidly accumulating snow. Only in the southern half of the United States will the snow melt during the summers. Agriculture will probably be possible only in California. Some vegetables which grow fast might be produced in southern states.

The ice accumulates for about 80 thousand years and then melts for about 20 thousand years. Scientists used to assume that ice ages were a natural result of ice accumulating and melting in a cyclic manner. But the timing is too precise for natural environmental effects, which vary a lot. I therefore theorize that the cause is hot spots rotating in the earth's center and heating the oceans. Rotations in the earth's molten center could cycle in a precise way. It cannot be a coincidence that the tilt of the earths orbit also cycles at the same interval of 100 thousand years. Perhaps the central core of the earth is pulled off center causing more heat to get to the surface where there are more oceans.

Since ice ages have been cycling at this interval for only one million years, a natural geological change is indicated. One of the changes which has been occurring is that continuous cool-down of the earth results in the outer mantle getting thicker and the earth's core differentiating from its cooler surroundings. This differentiation would promote convectional currents in the molten center of the earth.

Most critics of the carbon dioxide hype believe that increased energy from the sun is the cause of global warming. They may be right, if for some reason the air is not picking up that heat while the oceans are. But I think the increased heat is coming from the core of the earth rather than the sun, because solar energy would probably heat the atmosphere more and the oceans less than is occurring.