Gamma rays from the atmosphere

“January 29, 2010: High-energy bursts of gamma rays typically occur far out in space, perhaps near black holes or other high-energy cosmic phenomena. So imagine scientists' surprise in the mid-1990s when they found these powerful gamma ray flashes happening right here on Earth, in the skies overhead.”

FROM:
http://science.nasa.gov/headlines/y2010/29jan_firefly.htm?list973507

As I understand it; gamma rays originate from the disintegration of atomic nuclei.
http://library.thinkquest.org/C006027/html-ver/es-gamma.html

I wonder if there are more “gamma ray flashes” in the upper atmosphere now than there was before our “atomic age” and if the climate change is somehow tied to such effects.

There are some interesting comments about climate change on this web site.
http://spectrum.ieee.org/energywise/energy/environment/three-cultures-of-climate-science