Is research on the greenhouse effect itself. Right now the theory is that greenhouse gases absorb IR radiation in the upper atmosphere that would normally escape to space, and reradiate that in all directions, including back to earth, thus forming a greenhouse effect.
This part needs more confirmation. Has anyone done more empirical tests on this effect itself? You know, actually measure controlled IR emissions from earth to space to analyze absorption?
I think the research is heading towards more of the secondary effects - CO2 is a greenhouse gas, but so is, water. Will increase CO2 cause reduced H2O in the air? that sort of effect..
Another thing i'm curious about is just energy production causing global temperatures to rise.. Do all the carbon & nuclear production of energy, do they cause global temperatures to increase directly? (and not just via a greenhouse effect) All that heat production has to end up somewhere, and all the power plants just end up dissipating the heat into the atmosphere (or convert to electricity, which eventually gets turned to heat somewhere else..) Is that enough energy to cause global temperatures to rise?
Lots of research still left to be done.