Hunting weapon 10,000 years old found in melting ice patch

"We didn't realize until the early 2000s [why not?] that there was a potential to find archaeological materials in association with melting permanent snow and ice in many areas of the globe," Lee said.
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Over the past decade, Lee has worked with other researchers to develop a geographic information system, or GIS, model to identify glaciers and ice fields in Alaska and elsewhere that are likely to hold artifacts. They pulled together biological and physical data to find ice fields that may have been used by prehistoric hunters to kill animals seeking refuge from heat and insect swarms in the summer months.

Why was it so warm 10,000 years ago that animals had to seek refuge from the heat?  If the Medieval Warm Period was allegedly just a local event, no big deal, how does this one weapon prove anything about global temperatures?