Talk:Orbital forcing

From Wikipedia, the free encyclopedia

[edit] Hemispheric Chauvinism?

The article does not make clear if the seasons referred to are Northern or worldwide. Does the lengthened summer season occur only in the north or does the southern hemisphere experience a lengthened summer as well? Hu 06:50, 1 October 2006 (UTC)

Surely the amount of insolation on the Pacific ocean, a major driving force on climate variation, must change due to the various "Milankovitch"cycles.Currently the Pacific ocean, 50% of the earths surface, takes the full brunt of the sun's energy at some stage during the day. At other times due to the numerous orbital variations , the insolaton on the the Pacific ocean will be considerably less, surely this must influence the world's climate

The significance given to northern hemisphere insolation is not (entirely) chauvinism: the glacial- interglacial cycles reflected in the marine isotope record (and elsewhere) much more closely resemble northern than southern hemisphere insolation, and they are most readily understood and modelled as a response to northern hemisphere insolation. The cause of the asymetry is not entirely clear but is presumably linked to continental and oceanographic configuration; oceanic convection systems (such as that creating the "Gulf Stream", and carbon cycling (for example by land plants) are probably involved. Note that insolation over an entire year is globally averaged, except for the effects of eccentricity.

This does not, however, mean that the southern hemisphere does not play a role. In particular, the precise timing of deglaciations may well be connected with events in the southern hemisphere. Further back in the geological record (some tens of millions of years ago) the effects of southern hemisphere insolation may have been dominant over northern hemisphere insolation. Orbitalforam 17:29, 25 January 2007 (UTC)