It is neither feasible nor desirable to cut greenhouse gases by substantially cutting consumption. The size of the reduction would be so great that it would lead to a deep and continual recession, the like of which the world has rarely seen. Falling incomes, mass unemployment and widespread social upheaval would be a price that few would be willing to pay.
Thankfully the existence of energy efficient technology, and the promising outlook for future breakthroughs, means that it will be possible to cut greenhouse gas emissions while still maintaining the lifestyles to which we have become accustomed. Rather than cutting how much we consume, we can simply slightly alter what we consume, by using the new and better technologies as they become available.
These developments are not, however, inevitable. It must be in the best interests of the private sector companies to invest in these more efficient technologies, which will be so only if there is a demand for these new and modified products. In this both us as individuals, by embracing the new technologies, and governments, by providing appropriate tax relief, can play a part in driving forward innovation in low CO2 technologies.
The generation of electricity is the single biggest contributor to CO2 emissions in the world, responsible for almost 40% of the total. Innovation in consumer appliances will go some way to reducing the demand for energy, but potentially more significant advances can be made in tackling how electricity is supplied.
The worst offender in this area is coal-powered generators. They are widely used as coal has traditionally been very cheap and is abundantly available. The problem is that they are also very dirty, emitting substantially higher greenhouse gases than other available technologies.
A number of alternatives are currently available but each has its own particular drawback. Natural gas has grown in popularity over the past couple of decades as the price of generation has been low while CO2 emissions are about half what would be expected from a similar coal-based system. However, as its popularity has grown the price of the natural gas has risen, removing the cost incentive, and there has been growing concerns about its political security as Russia, one of its biggest suppliers, has begun using it as a tool of foreign policy.
Another possibility is the use of nuclear power stations. With zero CO2 emissions the nuclear option cannot be dismissed without serious consideration. Against this benefit stands formidable problems of high costs, the safety and security of nuclear materials, and the problem of disposing of radioactive waste.
The alternative which is favoured by environmental organisations is the use of renewable energy. Wind, solar and hydro power can be utilised for electricity generation on an ongoing basis without emitting any CO2. However the cost of such systems remains high, and are unlikely to be able to provide more than a fraction of energy needs in the short term. They also have their own environmental drawbacks as they will often need to be setup in the most scenic areas of natural beauty.
A promising new approach is carbon capture and sequestration whereby CO2 emissions are reduced by capturing them before they enter the atmosphere. The captured CO2 can then be stored underground in natural sinks, preventing it from ever contributing to the greenhouse effect. Such a technology could allow coal to still play a part in electricty generation while still achieving the desired reductions in greenhouse gas emissions.
As one of the major contributors to CO2 emissions the scope for improvements in the electricity generation sector are considerable. For reasons of cost, national security and climate change considerations it is probably preferable that most nations pursue a diversified approach, selecting a mix of technologies. The key is that whatever selection is made, CO2 emissions are substantially reduced.
The transportation industry is also responsible for a substantial share of the world emissions of CO2. The use of oil to fuel road vehicles and aeroplanes is responsible for almost a third of world emissions, and this figure could grow considerably in the coming decades as developing nations expand. There are already several technologies available which can improve the CO2 efficiency of engines by reducing the amount of oil required to power them.
Hybrid vehicles improve fuel efficiency by storing energy which is normally lost when cars brake. By improving the miles per gallon ratio, the amount of fuel required to travel a given distance is also reduced, and consequently CO2 emissions fall as well.
An alternative to oil which is becoming increasing popular in developing nations is ethanol. This alcohol based fuel can be combined with traditional gasoline to produce a mixture known as E85. Vehicles can have their engines modified to become flex-fuel compatible, at relatively low cost and use this new mixture. Although a higher volume of fuel is required overall, only 15% is made up of fossil fuel based oil, so CO2 emissions will be reduced. As ethanol is produced from agricultural crops it can be regarded as a renewable energy source which will have economic benefits for farming communities.
Despite these advantages it is unlikely that ethanol will be able to be produced in sufficient quantities to power the world's transport and it would require a massive investment to replace all petrol stations and engines to make them capable of supplying and using the ethanol respectively.
The great hope for the future is that some day hydrogen will be a practical alternative to oil based fuel. When hydrogen reacts with oxygen it releases energy, with the only waste emission being water (H20). Hydrogen could be stored in fuel cells and allowed to react with air when energy is required. Although the promise of CO2 free transportation is seductive, many problems stand in the way.
Firstly, hydrogen is not often found in its natural state in the environment, it must either be released from fossil fuels or separated from oxygen by applying electrolysis to water. Either of these sources require energy to release the hydrogen, meaning that a low CO2 solution, such as nuclear, renewable or carbon sequestration would be necessary if the goal is to reduce CO2 emissions.
Secondly, there are concerns about how the hydrogen could be stored and used in vehicles. The fuel cell technology required is currently prohibitively expensive so substantial advances are required before it would be feasible.
Finally, the cost of creating a hydrogen distribution system would be massive. For consumers to buy a hydrogen based car they must be confident they will be able to refuel it no matter where they are, just as they can with petrol or diesel cars. On the other hand distributors will only invest in the distribution system if there is already enough hydrogen based cars on the road to make it profitable, a classic chicken and egg situation.
In conclusion, advances in technology hold the promise of radically reduced CO2 emissions while maintaining the low cost and flexible solutions which are currently available. However, the long term path of research and development is, almost by definition, unpredictable and surprising. The key is to make CO2 reduction a primary goal, while allowing flexibility in how this goal will be achieved. For consumers there is little more they can do than assuring the producers that there will be a demand for their environmentally friendly technologies.