Today: all about clouds. Clouds are some of the most important, yet least understood, parts of the feedback mechanism involved in climate change. Do they increase global warming or not? All over the world or not. The short answer is: it depends. The longer answer(s) will follow soon as this is one the most intense and exciting areas of climate research today.

The mandatory primers on clouds and aerosols:

http://isccp.giss.nasa.gov/role.html

http://en.wikipedia.org/wiki/Cloud#Tropospheric_class

http://en.wikipedia.org/wiki/Aerosol

A good intro to cloud feedbacks in climate change:

http://www.skepticalscience.com/clouds-negative-feedback.htm

Why cloud feedbacks are likely to be positive, or amplify global warming, in the tropics:

http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3666.1

http://www.sciencemag.org/content/325/5939/460.full

But there is a lot of uncertainty left, and this is where the climate skeptics are pointing their big guns:

http://news.nationalgeographic.com/news/2013/12/131231-climate-sensitivity-doubling-carbon-warmer/

http://www.nytimes.com/2012/05/01/science/earth/clouds-effect-on-climate-change-is-last-bastion-for-dissenters.html?pagewanted=all

Including solving (or at least slowing) global warming by increasing the pollution levels:

http://www.ucsusa.org/global_warming/science_and_impacts/science/aerosols-and-global-warming-faq.html#.VCfX5WeSySp

http://en.wikipedia.org/wiki/Stratospheric_sulfate_aerosols_(geoengineering)#Arguments_for_the_technique