and a few other greenhouse gases, such as methane, that are causing the overall warming of the atmosphere and oceans. Carbon dioxide absorbs some infra-red frequencies that would otherwise escape straight to space. The increase of carbon dioxide in the atmosphere (nearly a third more than pre-industrial levels) is universally acknowledged. This increases the insulation the atmosphere provides, which means that surface level temperatures go up. The most advanced models have shown that, on top of natural variations we would expect to see, we have seen this insulating effect increasing during the past century (see
http://www.grida.no/climate/ipcc_tar/wg1/figts-15.htm).
The only thing that could stop global warming is some as-yet unknown negative feedback machanism (eg global warming sceptics have suggest cloud formation, but have been unable to come up with a decent model of how it would work).
There is no reason to think it has anything to do with nuclear weapons, or the military. It's the amount of oil, coal and gas that we all burn.