This repeats some buried comments but I think it's worthwhile: I'm not a climate scientist, but in my experience the absolute most reliable, most time-efficient way to learn about climate change is the IPCC reports. I wonder if there is anything written in any other field that compares:
http://www.ipcc.ch/
Specifically, if you are short on time, read the 'Summaries for Policymakers', written at the level and attention spans of non-technical politicians. They are quite readable and as I wrote in another post, if they can understand it, so can you. :) (The longer reports are fascinating, if you have an interest in science and want to get lost in something.)
As I understand it the reports are prepared by a global team of hundreds of scientists, and reviewed by thousands more.[1] (Seriously, has anything like that existed in any other field?) They are meant to cover the breath of climate science and the reports also are meticulous about the language of probabilities.
Spend a little time reading them and it will save you the time of reading 99% of what's written elsewhere, and you'll be much better informed.
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EDIT:
[1] Review process: http://www.ipcc.ch/activities/activities.shtml (scroll down to "The AR5 Writing and Review Process") -- for example, one report had over 50,000 comments on two drafts from >600 experts.
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EDIT 2: Website interface help.
Can you believe this needs to be written, and for HN readers? I had JavaScript off which makes the site usable (if not pretty). With JavaScript on, apparantly the UX concept is 'Easter eggs':
There are 4 images arranged horizontally at the top; these are report covers (with text too small to read even if you knew they were clickable). If you click a report cover then the section beneath it changes to display a description of and links to that report.
All that work making the reports accessible to the world, hamstrung by web design.