Is there any current research about the solar insolation that reaches Earth's atmosphere?

Question

With all the satelites we have is there any empirical data collected and available that would show if insolation has changed in the last 20-30 years?

Answer 1

Any large scale change in the amount of solar energy reaching Earth would be likely to take more than 20-30 years, however there are a number of satellites monitoring this. The data from one can be found here:
http://lasp.colorado.edu/sorce/data/tsi_data.htm
This data seems to show that since its launch in 2001 there has been a very small decrease in the energy reaching Earth from the sun. There has been a change in how much solar insolation reaches the Earth's surface over geologic time. The eccentricity of the Earth's orbit causes a difference in the amount of energy that reaches a given point on the Earth's surface, this has been thought to be a factor in the melting of the North American ice caps 12,000 years ago. The amount of solar insolation at that point was as high as 108% of today's surface values, it will likely reach its peak in another 9,000 years or so as it is thought to be cyclical.