What is karma!

Well this is a good definition:
http://en.wikipedia.org/wiki/Karma

but I prefer the following poem that explains it well:
"Each thought, each word and each deed
has to be accounted and compensated for in Nature.
Every cause has an effect and every action brings about a reaction.
Uproot the cause and the effect disappears.
This has been done by the Masters
who have transcended these laws..."
- Sant Kirpal Singh

I think the idea of having a balance in Nature and everything we do,
is central to much of the research life scientist do. They try to
understand why species are kept in check and how ecosystems stay
stable. Critically, in this time of change where humans have had and
are still having a huge impact on the environment, life scientist are
trying to understand how the balance in Nature could return and
stabilise before we go extinct. "Every action brings about a
reaction". We know that we are the cause of climate change but for its
effect to disappear we really need to start changing our behaviour.