Yes it is. It's a by-product of burning fossil fuels, which release greenhouse gases, including Carbon Dioxide. It is also a side effect of deforestation and intensive livestock farming, which releases methane. In effect, our presence has resulted in a change in balance between the removal of greenhouse gases from the atmospehere and the production of greenhouse gases.
The science here is hardly settled. Many top scientists refute this idea of global warming. In fact, there have been times in the past, before the rise of industry, when the world was warmer than today.