not anymore, see Antartica is shrinkng with the loss of the water.. the ice is flowing north to fill in the lost sea and melting, but not fast enough, and the Sahara is growing, with lack of rain.. so… :P

Your point is valid for this world, but this is steampunk, and is therefore set in the past. We are in an age where the world is steam and clockwork, and therefore the very idea of global warming has not even been concieved.