Excerpts from Roy Spencer's Climate Confusion (pg. 96)

We now know that the extra carbon dioxide and global warmth, no matter what their cause, are resulting in a gradual greening of the Earth.  There is some evidence that there has been a slight poleward shift in the habitats of some warm weather species, from the tropics where there is greater diversity of life, towards higher latitudes where many of these forms of life could not otherwise survive.  Global warming has made winters less severe, and cold weather is known to cause more deaths than hot weather.  So why is global warming necessarily a bad thing? 

I'm sure if mankind were accused of global cooling causing a destruction of carbon dioxide (which is food for vegetation) there would be howls of protest that we are strangling the biosphere!  So, why are we not hearing the environmentalists applauding humanity for helping to create more life?