There are four main opinions on the subject of global warming:
1) It’s not happening.
2) It’s happening but has causes other than anthropogenic increases in the atmospheric carbon dioxide content, for instance the precession of the nodes of the earth’s orbit and cyclical variations in the sun’s radiation.
3) It is caused mainly by anthropogenic carbon dioxide emissions and we can and must reduce these emissions in time to arrest the increase in atmospheric carbon dioxide content and start to bring that content back to historical levels.
4) It is caused mainly by anthropogenic carbon dioxide emissions but it is too late, and not enough is being or will be done, to reduce these emissions in time to arrest the increase in atmospheric carbon dioxide content and start to bring that content back to historical levels. Our efforts should be directed to getting an accurate idea of what will happen to the planet as a result of global warming, and developing ways of coping with these changes.
I believe the first opinion has drifted to the fringes and there is no need to discuss it seriously. There is just too much strong evidence that global warming is happening.
The second opinion holds that global warming is a cause, not a consequence, of the increase in atmospheric carbon dioxide. The oceans warm more slowly than the atmosphere, there is a time lag of some centuries, and as it warms it releases dissolved carbon dioxide. Conversely, when the atmosphere cools, the ocean lags behind in cooling and continues to absorb carbon dioxide, reducing its content in the atmosphere, long after the atmospheric temperature has reached its minimum.
The fact is that the low level of carbon dioxide in the atmosphere, about 300 parts per million 50 years ago when I was at school, has a significant effect on the heat capacity of the atmosphere. In fact, if that small amount were not present, the earth might be barely habitable, due to the large drop in temperature that would occur during the night or during winter at any given spot on the earth’s surface.
So it is incontrovertible that raising the level of carbon dioxide in the atmosphere causes the atmosphere to retain more heat and raises global mean temperatures. A rise of only 200 parts per million, which has been achieved by anthropogenic carbon dioxide emissions, would be a rise of about 70 percent from the original. This would significantly affect the heat capacity of the atmosphere. It is just a scientific fact, which unfortunately flies in the face of the needs of the world economy, so it has become politically necessary to obscure and confuse it.
As for the third opinion, the process of limiting and reducing emissions should have started decades ago and the thrust behind increasing carbon dioxide emissions is just too strong for change to happen, great enough and timely enough.
I think everyone realises this, so in attempting to avoid the obvious, all sorts of nonsense is trotted out. We are encouraged not to leave our appliances on standby power, and to buy twirly light bulbs, while massive cars continue to roll off the production lines and rumble through the streets with one person in each.
We are told that cars can run on fuel from food crops or plants. This is supposed to be carbon neutral because the plants grow with energy from the sun and carbon dioxide from the atmosphere, and in burning the fuel the carbon dioxide is simply restored to the atmosphere to be re-used by growing a fresh crop of plants. This ignores the energy inputs of liquid and other fuels required to sow, harvest and transport the crops and to process them into liquid fuels.
Hydrogen is also touted as a fuel for vehicles. One person left a comment on this blog saying that ‘hydrogen is the most abundant resource in the universe’. I had to point out that hydrogen is the most abundant element, not the most abundant resource – not the same thing at all.
What are we supposed to do, send spaceships out to sweep intergalactic space for hydrogen and bring it back to earth so that huge American hummers can continue to rumble about with one person in each, as though that were important or even necessary? A resource must be available, not just exist. This matter of availability is covered in the posts already on this blog, in discussions about resources.
Oh yes, there is ‘unlimited’ (just kidding) hydrogen in the world’s oceans, but it is not in free form. It is combined with oxygen and can only be set free by the input of electrical energy. A certain minimum amount of energy is required to do this, it is set by the laws of thermodynamics, and no ‘breakthroughs’ or ‘new technology’ will reduce it.
Hydrogen used as fuel is often ridiculously described as ‘pollution free’, disregarding any waste products which might arise from the methods by which the hydrogen is produced. Certainly electrical energy can be produced by solar or wind farms, or hydro-electric dams, but these methods are in a minority and they can have environmental consequences of their own – indirect pollution. The great majority of electrical energy will continue to come from burning something or from nuclear fission. So these hydrogen-powered vehicles are in reality coal, oil, gas or nuclear powered.
The same problem applies to wholly or partly battery-powered vehicles. Actually more fuel is needed to produce the same ‘grunt’ from a battery-powered vehicle than if the fuel were burnt directly in the vehicle’s engine. This is because of losses entailed in the indirect process of burning the fuel in the electricity generator, transmitting it to sub-stations, transforming it down to household voltage and charging the battery, then running the battery’s current through an electric motor.
Underlying these schemes is the continuing assumption that we actually need two or three tons of powerful machinery to carry one person around. Apart from vague references to ‘improved fuel-efficiency’ no-one seems able or allowed to mention the possibility that individual powered transport could be available with only a fraction of the fuel consumption associated with the present system. Much smaller vehicles, much less powerful engines would still do the job. The human race evolved and became civilised and made great progress without the private car, until the unsustainable system we have now was developed in the 20th century. We developed it because we could. Cheap abundant liquid fuel made it possible. It is not something eternal and essential that we have to maintain regardless of the cost. But humanity is determined to maintain and increase it.
To the extent that global warming is due to anthropogenic carbon dioxide emissions, it will continue, and I think we all know that really.
I share the fourth opinion. All our efforts and money and ingenuity should be devoted to getting as accurate an estimate as possible of what is to happen, and when, and where, so that measures can be taken to cope with it. Shifting coastal populations. Changing the crop regimes on agricultural land that is shifting to a different climate regime. Developing a range of different seeds to allow people to grow similar crops in changing conditions.
Actually large areas of land that are at present sparsely habitable could be opened up to sustain larger populations and grow crops and forests, for example, Antarctica, Greenland, Northern Canada, Northern Russia and Siberia. This could go some way to compensate for a general loss of land area in coastal regions elsewhere, and for some areas becoming less able to support populations or grow crops.
The whole process will be arduous and disruptive and require a degree of world unity and cooperation currently lacking. There is much work to do.