Are we tilting at windmills....
Let's look at a couple of indisputable facts:
1) The Global Mean Surface temperature has increased by about 0.8°C since the beginning of the 20th. century. (NASA GISS data).
2) The percentage of CO2 in the atmosphere has increased to approximately 400 parts per million, (or to put it another way, 0.04%). This level of CO2 is c. 24 times less than the noble gas argon in the atmosphere.
As I understand it the problem with current climate theory is that there is no reliable science that links 0.04% of CO2 in the earth's atmosphere to a significant affect on radiative forcing. (This could explain the failure of the infamous 'hockey stick' projection).
Is human activity still responsible for that increase of the above mentioned 0.8°C in the global mean surface temperature? Possibly, but perhaps the situation may not be as simplistic as a simple link between CO2 levels affecting radiative forcing which seems to get all of the world's attention at great cost.
Consider for instance that every single fossil fuelled family sized automobile travelling down the motorway/freeway/autobahn at say 75mph has to dissipate c. 15Kw* (15x 1Kw, 1-bar electric fires...), worth of waste energy due to the inefficiencies of the internal combustion engine without even considering trucks, coaches, trains, planes etc. This could go a long way to explain the c. 2°C temperature difference between urban and rural areas. This is just one small example of the possible influence of Direct Energy Wastage on climate change. (There is a better correlation between the rise of the automobile than the industrial revolution on the increase in global mean surface temperature).
In the end, of course, everything comes down to population growth, (7 billion and counting towards doom), and the associated demands for food, goods, services, mobility and energy usage.
*Say 30bhp to maintain 75 mph @ 30% engine efficiency = (0.746x30)Kw = c.22Kwx70%=15Kw wasted power dissipated to atmosphere as thermal energy.