The challenge our industry faces is that we are judged based on calculations of emissions that are incorrectly compared to other transportation modes. Specifically, we see total emission values for a trip from A to b regularly quoted or the hourly emissions of an aircraft in cruise compared to other sources. This is an apples to oranges comparison. If you "normalize" the data by comparing the emissions of transporting 1 passenger or 100 kg of cargo for 100 km, the results are very interesting - lower than the most efficient cars and certainly far less than those people travelling alone in their SUV's.
It is also worth noting that aviation has made great strides in improving efficiency, far better than other modes.
The last point is that in many cases the constraints that preclude us from achieving further efficiencies are beyond the control of the aircraft operators; they are the result of ineeficient airspace structures and air traffic systems that are further constrained by local airport noise and traffic restrictions.