Is Global Warming Caused By Greenhouse Gases Or By The Sun?
Most scientists believe that current global warming is caused by man-made greenhouse gas emissions and that the most important of these gases is carbon dioxide, or CO2.
They also believe that the influence of the Sun for this heating is very small. We now know that the irradiance or “heat transfer” from the Sun to the Earth has changed relatively little over the last few decades. Therefore, the conclusion most scientists have come to is that the warming must be man-made, because they have found no other reasonable explanation.
However, what we know about how much a specific rise in CO2 has on global temperature is poor. The reason that knowledge of how greenhouse gases affect cloud formation is largely due to speculation. The physics of cloud formation is quite a complicated process to explain with many factors.
Therefore, instead of having a solid theoretical and measured basis on the amount of human-produced greenhouse gases that affect the climate, the estimation made is mainly reduced to inference.
They argue: we know how much the temperature has risen, so we can calculate how much a specific increase in greenhouse gases will raise global temperatures in the future. We have done this through deduction, as we have already attributed the known increase as being driven by the greenhouse effect.
However, scientists who study the Sun have long noted similarities between solar activity and Earth’s weather patterns.
Also the climatic changes of the last century are not something unique. Given the relatively small changes in the observed “heat emitted by the Sun” irradiance, those changes in temperature over the last few centuries are difficult to explain if some other types of influence from the Sun are not included.
It was not until the Danish scientist Henrik Svensmark suggested that cosmic radiation might influence cloud cover that a plausible explanation was given for this apparent correlation.
Here is this theory!
When the Sun is very active, like now, the solar wind and the solar magnetic field are strong. This, in turn, protects Earth from high-energy particles from the cosmos, usually from particles once created in supernova explosions. This affects the formation of a low cloud layer as the radiation creates ions that generate clouds that form water droplets. During times when there are many high-energy particles reaching low altitudes, there are more low-lying clouds and the Earth cools. When few high-energy particles penetrate low altitudes, fewer clouds form and the Earth warms.
Clouds higher in the atmosphere are almost always ionized by low and high energy particles because both types of particles penetrate high altitudes at all times.
The variations created are only in the low altitude cloud layer which is affected by very high energy cosmic particles.
Recently, Svensmark conducted an experiment called SKY (Cloud in Danish) which conclusively confirmed this cloud formation mechanism experimentally and that this type of cosmic ionization has an important seed effect on clouds. Satellite studies have also now confirmed the links between variations in low cloud cover and the intensity of high-energy particles.