The 15 red grains in the other bowl are the human contribution to the atmosphere.
So how do you parley a tiny increase in a tiny GHG into “dangerous” global warming?
Well, you claim it will cause the Earth’s real GHG, water vapour, to increase in a runaway warming. This never happens, normally. There is no natural instability in the GHG effect from small rises in global temperature, it is self regulating.
But lets not let facts get in way of a good doomsday story. “carbon emissions” are different because they are caused by the “evil multinationals” therefore the temperature rise that they cause will be different from the temperature rise from any other cause – yeah, right!