Very Long Term (109 Years or More)
Jan Veizer and Nir Shaviv have proposed the interaction of cosmic rays, solar wind and the various magnetic fields to explain the long term evolution of earth's climate. According to Shaviv, the early sun had emitted a stronger solar wind with a protective effect against cosmic rays. In that early age, a moderate greenhouse effect comparable to today's would have been sufficient to explain an ice free earth and the faint young sun paradox. The solar minimum around 2.4 billion years ago is consistent with an established cosmic ray flux modulation by a variable star formation rate in the Milky Way and there is also a hint of an extinction event at this time. Within the last billion years the solar wind has significantly diminished. It is only within this more recent time that passages of the heliosphere through the spiral arms of the galaxy have been able to gain a strong and regularly modulating influence as described above.
Over the very long term the energy output of the sun has gradually increased, on the order of 5% per billion (109) years, and will continue to do so until it reaches the end of its current phase of stellar evolution.
Read more about this topic: Paleoclimatologists, Controlling Factors
Famous quotes containing the words long and/or term:
“It is long ere we discover how rich we are. Our history, we are sure, is quite tame: we have nothing to write, nothing to infer. But our wiser years still run back to the despised recollections of childhood, and always we are fishing up some wonderful article out of that pond; until, by and by, we begin to suspect that the biography of the one foolish person we know is, in reality, nothing less than the miniature paraphrase of the hundred volumes of the Universal History.”
—Ralph Waldo Emerson (1803–1882)
“We now demand the light artillery of the intellect; we need the curt, the condensed, the pointed, the readily diffused—in place of the verbose, the detailed, the voluminous, the inaccessible. On the other hand, the lightness of the artillery should not degenerate into pop-gunnery—by which term we may designate the character of the greater portion of the newspaper press—their sole legitimate object being the discussion of ephemeral matters in an ephemeral manner.”
—Edgar Allan Poe (1809–1845)