Reply #8: I though Heinrich events... [View All]

[Odin2005]

only occured during, and just after (upper dryas event), glacials, and they don't cause as nearly as much warming as you say they did, they cause a warm-up to a temperature intemediate between full glacialand full interglacial. I've never heard of Heinrich events occuring in interglacials. The term "interstadial" is the short warm periods DURING a glacial, I think you are getting that term and interglacial mixed up. My understanding of the Upper Dryas (which lasted a few hundred years, not 2000, BTW) event was that it was caused by the partial draining of Lake Agassiz, sending all that fresh water into the north Atlantic, preventing the water near Iceland to sink, weakening the North Atlantic Drift. This is the reason I don't like these "Global Warming causes Upper Dryas repeat" hypothesis. Melting of glacial ice into the North Atlantc will weaken the sinkage near Iceland, but it is my understanding that only a rapid ourflow from a body of fresh water onto the Noth Atlantic will cause an Upper Dryas-like even, glacial melt from Greenland would not put enough fresh water fast enough to turn the Thermohaline circulation off completely.

Also, many climatologists think we are living in a Long Interglacial, an occurance that happens, IIRC, every 400,000 years. "normal" interglacials last about 10,000 years, while long interglacials last about 30,000. Long interglacials are caused when the tilt and precession parameters are right of a glacial to start, but it is delayed by one precession cycle because the earth's orbit is at it's most circular (like it is now). It needs to be slightly more eliptical for precession to have an effect on climate. So, no we are not at risk for our interglacil ending.