Global warming affects the seasons

http://www.panda.org/about_our_earth/aboutcc/problems/impacts/
The source is WWF.
Some credentials are WWF is an independent foundation registered under Swiss law, governed by a Board of Trustees under an International President.
This source is very credible because they get funded to do this research.
They said Rapid temperature changes affect the seasons, causing variations in season length. Changes such as shorter winters can lead to mismatches between key elements in an ecosystem. I believe what they say because they showed lots of graphs and pictures.
http://www.globalwarming.org.in/effects-of-global-warming.php
The source is fight global warming.com
Some credentials are against Global warming and help spread awareness of the issues at hand.
This source is very credible because they want every one to know the truth about global warming.
They say the effect of global warming can be felt on seasons too. There is shift in season cycle, as the summers are getting longer than the winters.
I believe what they say because they they want everyone to know the truth even though they dont get paid.
http://science.howstuffworks.com/global-warming-hunting-season.htm
The source is Julia Layton.
Some credentials are Julia Layton holds a B.A. in English literature from Duke University and a M.F.A. in creative writing from the University of Miami.
This source is somewhat credible because they dont give a lot of details.
They say these gasses trap heat in a sort of bubble around the planet, causing increased temperatures and accompanying weather changes.
I dont believe what they say because they were basiclly talking about hunting season.