http://www.realclimate.org/index.php/archives/2007/05/start-here/

“We’ve often been asked to provide a one stop link for resources that people can use to get up to speed on the issue of climate change, and so here is a first cut. Unlike our other postings, we’ll amend this as we discover or are pointed to new resources. Different people have different needs and so we will group resources according to the level people start at.

For complete beginners:

NCAR: Weather and climate basics
Oxford University: The basics of climate prediction
Pew Center: Global Warming basics
Wikipedia: Global Warming
NASA: Global Warming update
National Academy of Science: Understanding and Responding to Climate Change
Encyclopedia of Earth: Climate Change Collection
Global Warming FAQ (Tom Rees)
Global Warming: Man or Myth? (Scott Mandia, SUNY Suffolk)

There is a new booklet on Climate Literacy from multiple agencies (NOAA, NSF, AAAS) available here (pdf).

The UK Govt. has a good site on The Science of Climate Change (added Sep 2010).

The portal for climate and climate change of the ZAMG (Zentralaanstalt für Meteorologie und Geodynamik, Vienna, Austria). (In German) (added Jan 2011)

Those with some knowledge:

The IPCC AR4 Frequently Asked Questions (here (pdf)) are an excellent start. These cover:

• What Factors Determine Earth’s Climate?
• What is the Relationship between Climate Change and Weather?
• What is the Greenhouse Effect?
• How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences?
• How are Temperatures on Earth Changing?
• How is Precipitation Changing?
• Has there been a Change in Extreme Events like Heat Waves, Droughts, Floods and Hurricanes?
• Is the Amount of Snow and Ice on the Earth Decreasing?
• Is Sea Level Rising?
• What Caused the Ice Ages and Other Important Climate Changes Before the Industrial Era?
• Is the Current Climate Change Unusual Compared to Earlier Changes in Earth’s History?
• Are the Increases in Atmospheric Carbon Dioxide and Other Greenhouse Gases During the Industrial Era Caused by Human Activities?
• How Reliable Are the Models Used to Make Projections of Future Climate Change?
• Can Individual Extreme Events be Explained by Greenhouse Warming?
• Can the Warming of the 20th Century be Explained by Natural Variability?
• Are Extreme Events, Like Heat Waves, Droughts or Floods, Expected to Change as the Earth’s Climate Changes?
• How Likely are Major or Abrupt Climate Changes, such as Loss of Ice Sheets or Changes in Global Ocean Circulation?
• If Emissions of Greenhouse Gases are Reduced, How Quickly do Their Concentrations in the Atmosphere Decrease?
• Do Projected Changes in Climate Vary from Region to Region?

RealClimate: Start with our index

Informed, but in need of more detail:

Science: You can’t do better than the IPCC reports themselves (AR4 2007, TAR 2001).

History: Spencer Weart’s “Discovery of Global Warming” (AIP)

Art: Robert Rohde’s “Global Warming Art‘

Informed, but seeking serious discussion of common contrarian talking points:

All of the below links have indexed debunks of most of the common points of confusion:

• Coby Beck’s How to talk to Global Warming Skeptic
• New Scientist: Climate Change: A guide for the perplexed
• RealClimate: Response to common contrarian arguments
• NERC (UK): Climate change debate summary
• UK Met Office: Climate Change Myths
• Brian Angliss A Thorough Debunking
• John Cook Skeptical Science
• The Global Warming Debate (slides)

Please feel free to suggest other suitable resources, particularly in different languages, and we’ll try to keep this list up to date.”