I HAVE received a number of emails from your readers on the subject of global warming and ocean temperatures.
Some even suggested I do not understand the science. So let me explain.
To simulate the influence of the Sun on the oceans, it is necessary to experiment with light whose peak wavelength is in the green sector of the visible spectrum: for it is this short-wave radiation that is capable of penetrating several feet beneath the surface and thus causing warming.
The surface tension of water does not act as a barrier against this short-wave radiation.
There is, after all, a good reason why swimming in the tropics is more comfortable than swimming in Bognor or Brighton.
Long-wave radiation from the Sun (accounting for around half of its incoming radiation) does not penetrate more than a fraction of an inch, and causes little oceanic warming.
Since the warming that occurs from greenhouse gas enrichment is in the long wave, that warming cannot in itself also warm the ocean. Instead, as the atmosphere warms, the altitude at which incoming and outgoing radiative fluxes balance, known as the “characteristic-emission altitude,” rises.
However, for well-understood reasons the temperature lapse-rate (the decline in atmospheric temperature with altitude) remains constant, so that the Earth’s surface - sea as well as land - warms up.
On this point the official theory seems to me to be correct. The true debate is not about whether CO2 and other greenhouse gases can warm the air, land and ocean, but about how much warming they will cause.
Here, the official theory that there will be substantial warming arises from the ingenious exaggeration of several distinct parameters whose product is final climate sensitivity - the warming to be expected from a given greenhouse-gas increase. Remove the exaggerations and it is at once apparent that we are in for 1 Celsius degree of warming, at most, in the whole of the present century.
I say “at most” because it is near-certain that the net effect of temperature feedbacks must be net-negative, so that the feedbacks attenuate the original warming rather than amplifying it. The IPCC’s notion of strongly net-positive feedbacks is not tenable.
You may care to repeat the experiment, but this time using thermocouples mounted at various points in the water within the bucket so as to get an accurate profile of the rather small but detectable changes in its temperature as you heat it from the surface.
For comparison, you could also stand the bucket out in the garden on a sunny day and measure how much the sunlight heats the water.
UKIP MEP for Yorkshire
and North Lincolnshire