Thread by @SteB777

@Cedders68 @djspratt I've never spoken to or corresponded with Roger Hallam, so I have no idea of precisely what he meant. However, I think it is a straw man argument to imply that he was referring to specific scientific research which makes these predictions. I will explain in a series of tweets.

@Cedders68 @djspratt 1) We are referring to 2 entirely different things.

a) The whole body of scientific understanding and research, and what is tacit in this understanding.

b) Hugely simplified models trying to predict future scenarios.

@Cedders68 @djspratt 2) It is impossible to incorporate the whole body of scientific knowledge and understanding into a model trying to predict future events. In fact it's impossible to incorporate even a tiny fraction of that knowledge, because of the nature of models.

@Cedders68 @djspratt 3) Most modelling of future scenarios is based on a few simple physical parameters, because this is the most reliable parts to model. However, we must never take these models as an accurate forecast of what is going to happen, because these models exclude major factors.

@Cedders68 @djspratt 4) There are 2 critical factors excluded from all modelling due to the complexity.

I) Ecosystems and ecological processes.

II) The stability of our present civilization, society and economy.

@Cedders68 @djspratt 5) The ability of human society to feed and sustain itself in it's current form relies on a globally organized economy. This is held together by financial institutions, and currently the pursuit of economic growth. History shows that civilizations are apt to sudden collapse.

@Cedders68 @djspratt 6) Even though we don't understand it, our economies and societies are sustained through myriad ecosystem services provided by natural ecosystems. These are systems, and will not function in the same way if the climate substantially changes.

@Cedders68 @djspratt 7) Without an organized global economy and food production system, and one powered by high energy dependent farming, we would be able to feed far less.

@Cedders68 @djspratt 8) Prior to the Industrial Revolution and Agricultural Revolution, our food supply could only sustain a population of well under 1 billion.

@Cedders68 @djspratt 9) It is almost certain if our civilization collapsed, and remember every previous civilization in history has collapsed, we'd be able to feed i.e. sustain a population, much, much smaller than present.

@Cedders68 @djspratt 10) Previously when civilizations collapsed, the basic unit of our society was the peasant farmer, and the majority were peasant farmers. Peasant farming economies can carry on unhindered if central power collapses i.e. the food supply remains similar.

@Cedders68 @djspratt 11) However, if our civilization collapsed, our farming system would not be able to continue feeding the population. Unlike all previous civilizations the majority of our population are not subsistence farmers, and have no ability to grow food themselves.

@Cedders68 @djspratt 12) What is more our farms rely on a regularly supply of power (electricity), fuel, agro-chemicals, and a transport system, global and nationally to distribute that food. All would disappear if our civilization collapsed.

@Cedders68 @djspratt 13) This is why nearly all the responses on the Climate Feedback page you link to are deeply unrealistic, because none even considered the collapse of our organized economy, and bizarrely assume it will just continue no matter what.

@Cedders68 @djspratt 14) Only the response of @ClimateHuman is at all realistic in that he makes the key point, that there is no scientific evidence to rule out the possible death of 6 billion people, a fact all other responses overlook.