Well, not just your PC. But according to Gartner, 40% of global carbon emissions from businesses originate from PCs and monitors. That's nearly double the contribution of data centers, which get more press as energy hogs. And although data centers and their associated cooling infrastructures do suck plenty of power (day and night), it's the thousands of installed PCs that do most of the carbon damage.
Read more directly from Gartner here.