Oddly enough, the study, obtained by this blogger, does not state what the total emissions were before the reduction, but it assigns most of the credit for the reduction to efforts by the hardware vendors (responding to pressure from the CSCI) to make more efficient power supply units.
The report also said that process in CO2 reductions has been hampered by the low market penetration of power management system in laptops and desktops. (If people went back to junking their systems every three years, that would change-as would a lot of other things.)
The world woke up to the surprising impact of IT on the environment in 2007 when it was famously reported that servers in the US consumed more electrical power, on aggregate, than the state of Mississippi. Power consumption for servers had doubled between 2000 and 2005, this was 1.2 percent of US and 0.8 percent of total consumption of electrical power. Consumption was expected to grow by another 75 percent by 2010
The only recent figures I have found that might throw some light on the CompTIA's figures are in this recent study from the Pacific Institute of Climate Solutions, a collaboration of four universities in British Columbia. It says that CO2 emissions from data centers has reached 157 million metric tons annually. This is roughly 2 percent of the global total and is comparable to the emissions generated by the aviation industry.