Australia: The Land Where Time Began

A biography of the Australian continent 

Climate Change Science – Attribution of Causes

In some cases it is possible to eliminate natural causes to leave only the human causes (anthropogenic) of global warming that explain the result.

In the recent past, variations in the output of energy from the Sun have to a large degree regulated the temperature of the Earth. It is known by scientists that the Sun is presently warmer than it was billions of years ago. It is suggested by some deniers and sceptics that the present warming is related to the effects of variations in solar radiation. This suggestion does not, however, explain why since the 1970s-2011, and into 2012, though the Sun has been in a deep stage of its solar minimum phase, a phase during which the solar output is diminished, the Earth has been warming. So the Earth has been warming while the Sun has been radiating less energy.

The solar activity and the temperature of the Earth were in fairly good sync until about 1980, then from that year until fairly recently, the energy transmitted by the Sun and the heating of the Earth have been diverging. This leads to the question of what has been causing the Earth to warm if it is not the Sun. What other factor is the cause of global warming? Some suggested possibilities are:

The Earth may be moving closer to the Sun in its orbit;

The Sun may be moving closer to the Earth;

The heat from the interior of the Earth may be causing the warming;

There may be another star, similar to the Sun, that is moving closer to the Earth;

The temperature readings may be unreliable;

There may be something in the atmosphere that is keeping the heat closer to the Earth instead of  radiating out into space.

Astronomers have found that the orbits of Earth and the other planets in the Solar System are very stable and have not deviated substantially over recorded history. So the Earth is not moving closer to the Sun and vice versa.

It has been found by geologists and geophysicists that the large amount of internal heat in the interior of the Earth is not expanding outwards. So this cannot be the means by which the surface of the Earth and the lower atmosphere are heating up.

There is no star that is moving closer to the Earth, and assuming there could be at distances too great to be detected it would be too far away to influence the temperature of the Earth.

The last option mentioned, could there be something in the atmosphere that is preventing energy radiated from the Earth being re-radiated back to the surface of the Earth instead of being radiated into space? The greenhouse effect is based on just such a “something”.

Sources & Further reading

1. Farmer, G. Thomas & Cook, John, 2013, Climate Change Science: A modern Synthesis, The Physical Climate Vol.1, Springer Dordrecht