| Most scientists believe that the current global | | | | Sun", those changes in temperature during past |
| warming is caused by man-made emissions of | | | | centuries are hard to explain if you don't include |
| greenhouse gases and that the most important of | | | | some other types of influence from the Sun. |
| these gases is Carbon Dioxide or CO2. | | | | It was not until the Danish scientist Henrik |
| They also believe that the Sun's influence for this | | | | Svensmark suggested that cosmic radiation could |
| warming is very small. We now know that the | | | | influence cloud cover that a plausible explains for |
| irradiance or "heat transfer" from the Sun to the | | | | this apparent correlation was given. |
| Earth has varied relative little during recent | | | | Here is this theory! |
| decades. Therefore the conclusion that most | | | | When the Sun is very active, as it is now, the |
| scientists have done is that the resent warming | | | | solar wind and the solar magnetic field are both |
| must be man-made, this is because they haven't | | | | strong. This in turn shields the Earth from high |
| found any other reasonable explanation. | | | | energy particles coming from the cosmos, usually |
| However what we know over how much a | | | | from particles which were once created in |
| specific increase of CO2 has on global | | | | supernova explosions. This affects low cloud |
| temperature is poor. The reason in that the | | | | cover formation as the radiation create ions which |
| knowledge of how greenhouse gases affect cloud | | | | seeds cloud forming water droplets. During times |
| formation is mostly down to speculations. Cloud | | | | when there are many high energy particles |
| formation physics is quite a complicated process | | | | reaching low altitudes there are more low cloud |
| to explain with many factors. | | | | cover and the Earth cools. When there are few |
| So, rather than having a solid theoretical and | | | | high energy particles penetrating to low altitudes |
| measured basis for how much man-made | | | | then less clouds form and the Earth warms. |
| greenhouse gases affect the climate, the made | | | | Usually clouds higher up in the atmosphere are |
| estimation is mostly down to deduction. | | | | almost always ionized from both low and high |
| They argue: We know how much the | | | | energy particles because both those types of |
| temperature has increased so therefore we can | | | | particles penetrate high altitudes at all time. |
| calculate how much a specific increase in | | | | The created variations are only in the low altitude |
| greenhouse gases will increase the global | | | | cloud cover which is affected by very high |
| temperature in the future. We have done this | | | | energy cosmic particles. |
| through deduction as we already have attributed | | | | Recently an experiment called SKY (Cloud in |
| the known increase to be greenhouse driven. | | | | Danish) was made by Svensmark which |
| However scientists who study the Sun have long | | | | conclusively confirmed this cloud forming |
| noted similarities between solar activity and | | | | mechanism experimentally and that this type of |
| terrestrial weather patterns. | | | | cosmic ionization has an important seed effect on |
| Also the weather changes the last century is not | | | | clouds. Links between low cloud cover variations |
| something unique. Given the relative small changes | | | | and high energy particles intensity have also now |
| in the observed irradiance "heat emitted from the | | | | been confirmed by satellite studies. |