Wild Cards of Global Warming — Parts 3 thru 5
By S. Tom Bond, Resident Farmer, Lewis County, WV
III The global heat conveyor
In the tropical Atlantic Ocean, surface water warms and some of it evaporates so the water becomes saltier. It moves north through the Gulf Stream along the East coast of the United States and into the North Atlantic. There it cools, giving up it heat to warm the cooler air that comes from the Arctic area. On cooling, the salty seawater becomes more dense and descends to the bottom.
This occurs over a large area. As more seawater arrives above, this bottom deep water moves southward, past the equator, around South Africa and all the way to the Central Pacific. Here it warms, picks up freshwater from rain, becoming both less salty and less dense, and returns via the surface, back around South Africa, out into the Atlantic and back up to the Equator.
The pace is slow, but the quantity of water is huge, and very much heat is acquired and carried with it from the tropics to the North Atlantic. The heat given up there gives Western Europe a much more temperate climate than it would be without the global heat conveyer. This is nicely diagrammed here.
Because of the great mass, the system is quite robust from year to year. There are indications it has stopped in the past, however, due to injection of fresh water into the North Atlantic. Normally the water is very salty, and cooling it makes it more dense and causes it to sink. If fresh water mixes with the salt water from the tropics, it becomes less dense, and even with cooling cannot sink into the surrounding salty ocean, stopping the conveyer. So Western Europe becomes very cold, as much as 15 to 20 Fahrenheit degrees colder in winter.
This in believed to have happened in the past, as the continental glaciers were melting. A vast lake kept in place by the glacier in the great plains broke through and caused what is called the “Younger Dryas Event,” causing a return to glacial conditions in Europe for 1500 years, about 7000 years ago, until the fresh water was mixed into the ocean.
When ice forms crystals, the salt is excluded, so the ice pack is pure water. Many scientists consider the possibility of the warming of the Arctic with melting of the ice pack and mountain glaciers there might cause the global heat conveyer to slow or stop again.
Melting of the Arctic ice is readily observed by satellite. You can follow this whenever you wish at Arctic Sea Ice New & Analysis.
At present, movement of global heat conveyer currents is a major area of investigation by scientists. They track the speed and volume of the Arctic and North Atlantic currents with surface floats and other floats designed to stay a fixed distance below the surface. This apparatus is capable of measuring temperature and salinity, and then broadcasting this information and position.
A related unknown is what will happen when the Article Ocean is ice-free, which is likely to happen in a decade or so. Snow surfaces reflect both light and infrared radiation back into space. The ocean is relatively dark and will absorb much of the incident solar radiation in summer, and will retain much that it absorbs through the winter. (Companies are gearing up to sail directly across the Arctic Ocean rather than take more circuitous routes between Europe and Asia.)
But what will the increased temperatures and increased evaporation from this vast area do to the weather?
IV Other uncertainties
1. Clouds. How will cloud patterns change? Clouds reflect the sun’s radiant energy back into space. Increased evaporation leads to more clouds. Will this be a negative feedback? In other words, will more clouds mean less sunlight gets to the earth’s surface? How will this affect the upper atmosphere?
2. How much carbon dioxide will ultimately dissolve in the oceans? How will this affect sea life? It is now given credit for bleaching tropical corral that forms reefs, the area of the oceans with most abundant life and making it difficult for shelled invertebrates to form their shells.
3. How will global warming affect the distribution of rainfall? It seems likely that some areas will receive less, such as the drought in the Western U. S., due to the strong el niño shifting of the jet stream North. It is also likely that weather extremes will be greater, mostly hotter, but colder in some places at some times, as well as more floods, snow storms, droughts with wildfires, and so on.
4. Effects on hurricanes. Increasing temperatures will cause greater evaporation from the surface of the ocean. Evaporated water provides the energy for hurricanes. Heavy rainfall and greater storm surges will affect costal residents?
5. How much will the sea rise? It certainly will rise, as a result of ice melting on land. Also, the melting of beached glaciers that are not completely floating is occurring. The melting of floating Arctic sea ice will not increase sea level, because it floats and will occupy the same volume as it displaces.
6. Changes in distribution of plants and animals. What about the northern shift of Africanized bees and fire ants that now plague the U. S. South? What about the birds adapted to raising their young in the Arctic? Tropical diseases such as malaria?
7. Worsening air quality due to increased use of fossil fuels in summer? More asthma, allergies from dust and pollen? Drinking water shortages because of reduced snow mass and disappearing mountain glaciers?
8. What about effects on recreation? Hunting and fishing? Seaside resorts? Camping? Boating? Hiking? Bird watching? Watching TV will be a winner!
9. Effects on agriculture? No levity here! This is the basic industry. Empty bellies cause riots! Shifted growing seasons, shifted and reduced crop regions, new directions in livestock breeding. Greater year to year production variability. Grapes in Denmark? Dates in Italy? Pineapple in Alabama? Wheat on Greenland?
!0. Building. Both cement and steel production are major emitters of carbon dioxide, as is glass. These are the standard materials of construction of large buildings everywhere, and smaller buildings in warm climates. Wood is used elsewhere. The forests of the Western U. S. and Canada are now being destroyed by the pine bark beetle, because it doesn’t get cold enough to kill them in winter.
V. Concluding remarks . . .
We could go on, but lets stop here. Contrary to what the climate warming deniers say, the future being built now promises to be quite a “hassle” as we get older and for our children and theirs.
The climate denier says, “If there is so much uncertainty, don’t worry about it.” Ah! But every one of these possibilities is bad. When you really analyze the effects presented above, there are no good possibilities from global warming. It only takes one or a few major changes to drastically reduce the carrying capacity of the earth. Anybody want to volunteer to go first? Seems to me many regions of the earth are already experiencing the effects of global warming!