1.7 converts old cold taigas to warm ones

Read on here: http://www.minecraftwiki.net/wiki/Biome#Upcoming_Biomes

In snapshot 13w36a, Taiga biomes no longer have snow by default. The snow covered variant has been renamed Cold Taiga.

There is just one remaining problem: As shown in the duplicate MC-35151 existing Taiga biomes are snowy, but when upgrading to 1.7 they are updated to the snowless Taiga version, instead of the Cold Taiga. This will cause most of the snow in existing taiga Biomes to melt over time. It would be probably better to replace old Taiga Biomes with the new Cold Taiga when updating to 1.7, but I'm not sure how difficult that would be now.