The sea and the kettle
FRIDAY OCTOBER 05, 2012
Water expansion is not uniform but exponential and greater closer to boiling, so height-rise of water is much less at lower temperatures. Salt water, being heavier, is slower to expand when heated, further reducing expanding of oceans at lower temperatures.
If seas were warmer, then more evaporation must occur, reversing sea-level increase. The very upper figure of net sea-level rise due to warming from above or below would be next to nothing.
‘Warming’ refers to thermal changes as measured by instruments.
We say we feel warmer if our body temperature raises a couple of degrees. The current figure for global warming of the planet is 0.3°C over the past century, about 1°C every 300 years. No one would feel that, even if they were to live for 300 years.
That amounts to 0.003°C per year, or 8 millionths of a degree per day.
Alarmists have been calling 0.3°C over a century a “tipping point for the planet”. It is hard to fathom how tipping-point can be applied here, as each day for most locations varies (maximum to minimum temperature) by around 10°C, a rather long way from 8 millionths of a degree, and yet each day is not called a tipping point.
A tipping point for a person would be an increase of about 30°C in a day, because one could not adapt quickly enough to such sudden rise.
Failure to adapt may define tipping point, but the planet has adapted successfully to all past weather anomalies and even greater temperature variations in our geological past.
Ice ages last 50-60,000 years and interglacials about 10,000 years. Monsoons and tropical cyclones are so regular you can set your season to them. Glaciers keep advancing and retreating such that polar ice has never expanded to cover the whole earth, nor have the poles ever become ice-free.
Sea-levels have never either risen up to cover all the land nor dropped to permanently dry ocean floors.
In short, everything in nature is at some stage of its recurring pattern as its cycle peaks and ebbs. There is no great calamity presenting itself. The only increase has been in the shrill warnings of approaching catastrophe by those receiving lucrative funds to study it.
The seas rise and fall every day. Tides vary constantly, caused by the daily rising and falling of land beneath the sea, called the Land or Earth Tide.
As the land pulls up and away from the sea it appears to us as a low sea tide. If sea-levels are gradually and relentlessly rising there are only two possibilities, either more water is being added (either by inflow or expansion), or the land is falling back down more.
Since the thawing of the last Ice Age, ocean levels are currently about the highest they will ever reach. Arctic ice is floating anyway, so is not in consideration. The Antarctic ice sheet is by volume about 10 million cu kms, and the total ocean volume about 1000 million cu kms.
If it all totally thawed, the Antarctic ice shelf would add, at most, 1% to world oceans. And even if a slight rising did take place, the amount of heat required would result in increased evaporation which would lower sea-level back down.
Global warming says we have a body of salt-water being heated from above, by a (supposedly) warmer atmosphere. What temperatures must we consider?
The lowest temperature ever recorded at the South Pole is almost -90°C at Vostok in 1983.
Thus, for the Pole to melt and stay melted all year around, Antarctica must heat by at least 90°C, which is almost the boiling point of water.
If water gets anywhere near boiling, it evaporates (as the sea would) well before rising.
The sea has, according to NASA a depth average of 1-2km deep. The IPCC’s figure for global warming is 2°C per century.
If a body of water 1-2 km deep raised 2°C could change its level by an additional 65 meters, which is Al Gore’s claim, then that is a factor of 65/1000-2000, about 4-5% due to a 2°C rise.
Then, for a cup of tea on a cold morning, raising our kettle temperature to boiling (100°C, which is 50x2) from 0°C would be 50x(4-5%), or an increase in depth of nearly 300%.
By this logic, as my quart tea kettle takes about 3 cups, allowing room at the top to prevent spillage, then one solitary cup poured into my empty kettle should be all the water required to result in my kettle being full at its boiling point.
If only. Our hot water bills could all be cut by half.
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