Oh, come on DA and RicS. Let's just confine this to discussion to Holocene fluctuations and little ice age and Medieval warm period. Interesting subjects in their own right. There has been a heap of work done on pollen profiles in NZ swamps. They don't directly tell us about the climate but do tell us what type of vegetation occurred nearby, thus giving us some idea of temperature and rainfall. Here's the first one i found:

http://geovoice.otago.ac.nz/issue001/mvandergoes.html

Of course humans had a huge influence on the vegetation when they arrived.