One of the most popular topics for “head in the sand” thinking is global warming. Never mind the evidence; only too many assert that the models are wrong, so there is no need to worry. What I find annoying about this is there is no evidence supplied to support the assertion, although you can usually see a quote in some “scientific” journal. You will see some claims about “peer review” but that is irrelevant. Some time I shall post about peer review, but for the present that does not matter because who asserts something is irrelevant to deciding truth; it is what is said that matters, and specifically, what the evidence is to support it.
Very recently we have heard more on this topic, and the climate change models have been shown to be almost certainly wrong. Not that the deniers can take any bows; the models were wrong in the other direction. Up until now, the modellers have argued that by the end of the century sea levels would rise a meter, mainly due to thermal expansion of the oceans and the loss of minor glaciers, with a small effect due to fragmentation of ice sheets in Greenland and Antarctica due to “bottom-warming”, i.e. ice melted by contact with warmer ocean currents, together with a little “top-warming” from sunlight.
Now they have become aware that the major ice sheets are undergoing top-warming from contact with moist warm air. The net result is that the ice sheets are thinning for major distances from the sea, and the end-position if this net heating is left to go on unchanged is now considered to be a sea level rise of up to sixty meters. In New Zealand, where I live, the cost assigned to the loss of houses due to a 1.5 meter sea level rise was assessed as about $20 billion. That does not include commercial buildings, and worse, it does not include required changes to infrastructure because here quite a number of roads run along beside the sea. This helps the view for tourists and holiday-makers, but only too many of the low bits of those roads will have to be moved. Worse, the high bits through tortured hilly regions will have to be rebuilt. Certainly, these roads are high enough but they have to connect with something. It only takes a small section to be submerged, and if the low-lying land is flat enough, then there may be real problems connecting a new fragment with existing sections that climb up steep hills. Worse than that, the reason these roads run alongside the sea is that often this is the only flat land, and a new coastline will have the sea smashing into mountainous land. A road-building nightmare.
The next thing we see is that we have numerous exhortations that society must as a priority reduce emissions of greenhouse gases. Sorry, but this won’t work, although it will reduce the rate at which the problem gets worse. The reason is this. At present we have net melting of ice. The polar bear habitat is shrinking rapidly, and this can only happen by the heat input melting more ice than can be laid down through winter snow. This is clear evidence the planet is receiving net heat input.
For the planet to heat, there has to be net power input, which is the difference between the solar input and the radiated output from the planet. If the heat input is constant, that can only arise through something keeping in more than it did previously. The agent that is doing that is the blanket of greenhouse gases covering the planet.
My point is, if we totally stopped producing greenhouse gases tomorrow, the current rate or heat retention, and hence the current rate of melting, would continue. The usual way of returning to balance between heat in and heat out would be that the planet warms until at the new temperature it radiates enough out. However, ice melts with the water being at the same temperature as the ice so the overall warming only partially occurs.
The problem is, there is a constant heat input from the sun, and the temperature is determined by the rate at which the planet radiates out excess energy. While it is a grey body, the rate at which it radiates heat from surface is proportional to the fourth power of the temperature. Accordingly the temperature rises until heat out equals heat in, and the system is at equilibrium. (Of course, this only happens on an overall average, because the planet does not get uniform heating, and there are weather events and ocean currents that move heat around.)
Think of yourself in summer lying in bed, and you are quite comfortable. Now someone throws three blankets over the bed. Are you going to stay comfortable? Not likely. Even if we stopped greenhouse gas emissions completely, in this example it is no better than that someone stopping throwing extra blankets on the bed. We cannot make further headway until someone starts to remove the extra blankets. That is what has to happen. The trouble is, so far governments cannot even stop the throwing on of extra blankets.