Science Brief #1. Why It is So Cold Right Now!

Local weather can differ from global warming & climate change

Essay by S. Tom Bond, Resident Farmer & Retired Professor, Lewis County, WV

President Trump has famously joked from his Florida trip that much of he U. S. could “use a little global warming” right now. Like many of us he apparently doesn’t know the local Arctic blast is a part of global warming.

The weather broadcasts are very parochial – that is they are locally oriented. The contiguous U. S. comprises only two percent of the earth’s dry land. That’s where the population is and that is where our TV weather broadcasters devote most of their time.

In fact, even Alaska is warmer than usual, and permafrost is melting, with houses and roads breaking, and shorelines slumping and washing into the ocean. Much of the rest of the country is warmer than expected for this time of year.

The poles are warming about twice as fast as the tropics. In other words, the temperature difference between them is declining. The energy difference driving heat North (and South at the other end of the earth) is declining.

Somewhere between 90 and 95% of the additional heat produced by greenhouse gases goes into the ocean. The air is warmed and it is transferred to the surface of the ocean. There currents carry it away to the depths. Much of the ocean is not warmed yet, however. The heat storage capacity of the ocean is very large.

More heating of the air by greenhouse gases occurs where the surface of the earth is vertical to the incoming sunlight – that is, the tropics, and less is absorbed away from vertical. Heat leaves earth from the polar areas. Consequently, heat is constantly moving toward the poles to be lost into space. With global warming the difference is becoming less. Melting of Arctic ice is a big worry, because more heat can be absorbed there with a dark ocean than with reflective ice and there will be even less difference in temperature between the tropics and the poles.

The Jet Stream is a fast moving river of air at high altitude that is caused by the earth’s rotation. It is a boundary between the mid-latitudes and the more northerly area. It runs about the northern border between the U. S. and Canada. However, it is not a straight line, it has waves, and it’s position varies from time to time. The magnitude of these North-South waves depends on how much energy difference (temperature difference) there is between the tropics and the polar region.

Our thought must now rest on an analogy. The reader may have observed that a stream moving on a slope, a mountainside, goes downhill in a relatively straight line, moving rapidly. In contrast, a stream that is on a sight slope such as along the bottom of a valley or on a plain (as on a plane), the water moves slowly and the stream meanders.

The jet stream is affected the same way. Now that the energy difference between tropics and polar regions is less, it meanders more widely and the meanders move more slowly. Cold air from the North comes further South and stays longer. It is as if the far North has come south to visit new areas.

The result is more frequent cold spells further South than the past, and these are balanced by warm spells further North than in the past. In a few weeks it will be our turn for more unseasonably warm weather.