...ah once again Leon claims victory in the midst of defeat...kind of like running for a touchdown to the wrong end-zone and wondering why your teammates don't join in your victory dance! ) :

v

simple and plain

The ice core data link refutes your claim that Greenland was never lush. The core samples indicate Greenland was inhabited by a diverse array of conifer trees and insects within the past million years. The results provide direct evidence in support of a forested southern Greenland.

As for the "Vikings didn't eat fish" claim - Untrue. Here's a document from Radiocarbon concerning the Viking's average diet - http://64.233.179.104/scholar?num=30&hl=en&lr=&q=cache:B75LaHG-EWUJ:www.radiocarbon.org/PDF/v41n2/Arneborg.pdf+greenland+climate+norse

"...the average diet of the Norse people changed from 20% marine to 80% marine during the approximately 500 years that the settlement lasted..." 

"...Recently, Greenland ice-sheet temperature data have been used for a climatic reconstruction, which is specific for the high-latitude North Atlantic region (Dahl-Jensen et al. 1998). The results indicate a steady decrease from a temperature maximum around AD 1000 to a minimum around AD 1500, which may have gradually forced the Greenland Norse to change their subsistence pattern."

Or this concerning climate change during the Viking colonization - http://www.geus.dk/publications/review-greenland-98/gsb183p61-67.pdf

"From Mediaeval Icelandic sources we know that after the first period of colonisation, sea ice off south-eastern Greenland had significantly expanded, causing growing problems to Norse shipping between Iceland and Greenland. Numerous indications have been found in the northern hemisphere pointing to severe climate deterioration between about AD 1350 and AD 1850 (Little Ice Age), following the end of the Mediaeval Warm Period or Climatic Optimum (c. AD 900–1350)."

Here's another one from the National Science Foundation discussing climate changes - http://nsf.gov/pubs/2003/nsf03048/nsf03048_7.pdf

"The evidence indicates that warm conditions persisted during the early to mid-Holocene and that climate has become cooler and more variable during the past 4000 years. These variations permitted Norse settlement of Greenland during a warmer period, and forced abandonment when the climate cooled."

Please note that scientist do not know for a fact what caused the Vikings to abandon their settlements. They continue to study the evidence, and get closer to the truth each day. Please don't insult us by claiming you know more that the experts.