Anthropogenic Global Warming - Two Scientists Speak

Here is a link to a very good presentation by prominent US climate scientists on different viewpoints on climate sensitivity (to forcing mechanisms) and the consequences of increasing CO2 emissions. It's quite short, interesting and enjoyable.

Dr Roy Spencer believes there are natural mechanisms (such as the cooling influence of clouds) which are not well accounted for in present climate modelling and which will prove to be more important in determining global temperatures than human production of CO2. Dr Scott Denning stresses the effects of increases of non-CO2 greenhouse gases (i.e. water vapour) that arise once the earth starts warming that will intensify warming n a process of positive feedback. Dr Denning is already persuaded that global warming is being strongly affected by human activities and that large-scale impacts will come about. Dr Spencer is not.

 

Dr Denning's viewpoint is based on an established correlation between the amount of CO2 in the atmosphere and the amount of energy trapped by and radiated back the ground by CO2 molecules (rather than radiated out into space). According to this correlation a doubling of CO2 in the atmosphere results in an extra 4 Watts (i.e. four Joules of energy per second, i.e. four Newton-metres per second, i.e. four kilogramme-metres-squared per second per second) of power striking every square metre of the earth's surface every day, all day for as long as the CO2 remains in the atmosphere. This extra power causes (according to some predictions) the durable temperature increase that is being called anthropogenic global warming. Dr Denning draws attention to the transition to developed world living standard in India and China, and the construction of many new fossil-fuel burning power stations in those countries, which he projects will result in a quadrupling of pre-industrial atmospheric CO2 in the coming century. (We are nearing a point at which atmospheric CO2 levels - at 385 parts per million - will be double the quantity present in the atmosphere before the onset of industrialisation). Dr Denning is optimistic that enterprise and scientific development in a free market will produce technologies that will enable a transition away from fossil-fuel-based energy production in the coming century or centuries. But he points out that the CO2 that is produced in the meantime will stay in the atmosphre for a very long time, and certainly long enough for the slow-responding oceans to warm up along with the land surface. He projects that the climate in the USA will be radically altered, and he draws attention “your $410k” (which I think refers to the average property value in the US) and what it will mean when “your” home loses value because the climate is no longer pleasant or even hospitable. (“Forget polar bears”, he says, “what about your $401k”).

The dispute between these two scientists is simply over the degree to which the climate is sensitive to the forcings imposed by human activity. The warming effect of adding CO2 to the atmosphere is not disputed, only its relative importance to climate compared to other factors.

These two men were making presentations of their work to a scientists'  conference on global climate change.

They both take opportunities to show their primary concern for human, rather than non-human, life (to set them apart from environmentalists who often come across as simply misanthropic).

This is important.

Where peole express concern about human population, Dr Roy Spencer reminds us that population growth rates are highest in parts of the world which have not industrialised. We will do well, therefore, he says, to encourage as-rapid-as-possible industrialisation of un-developed nations. His view is that there should be the maximum possible acceleration of the extraction and burning of fossil fuels to generate the wealth (for him the link is direct, which may be a big gloss) to raise as quickly as possible the global industrial-technological capability of humans which, stimulated by global free-market competition, will enable the soonest-possible emergence of the non-fossil-based technology of energy production that will enable us to move out of fossil-fuel dependency. I think there is much to agree with in this viewpoint. Of course, it depends on a belief, a faith, that there will be a technological breakthrough in energy production which is less likely to happen without a free-market global economy.

Of course, I certainly would reject any kind of poltical solution that enforced upper limits on the number of children people can have, or any other coercive method.

But I am disquieted by facets of the presentations of these two scientists.

Dr Spencer, I think, glosses pretty heavily over what will surely be massive harmful impacts of his desired accelerated extraction and burining of fossil fuels (to generate wealth). The Iraq War (2003 -) was surely as much an oil-grab on the part of the US, as an opportunity to depose a WMD-wielding secular dictator and “spread democracy”? More of the same (by which-ever nation) is likely to be accompanied by enormous conflicts, blighting millions of lives. And what is Dr Spencer’s response to Dr Denning’s point about the fact that CO2 will remain in the atmosphere long after the hoped-for and anticipated technological breakthrough comes about? One feels he’s not too concerned. (Just move north, where the new, cool jobs will be). He conceded that he would re-consider his “What’s the problem?” stance if the global warming trend seen between c.1970-1998 re-starts and continues to 2050-ish.

Dr Denning has more concern that significant humanly-disruptive climatic changes will occur. But he too seems to gloss over the impact of climate change on bio-diversity, for example. At some level our way of being on earth depends on non-human life. If Polar Bears go, maybe we go too? Eco-systems are present. We seem to have our place at the top of every food-chain, but I think we are wrong to assume we don't need a bio-sphere of greatest diversity. (On the other hand, the bio-sphere certainly does not need us). Eco-systems and species are lost with our population growth and the giving over of available land to cultivation to produce our food. Apparently, land in Africa is being leased or purchased today by industrialised nations in order to produce foods which can no longer be produced in enough quantities within their territories. I personally find this kind of thing troubling, even though it may be part of the industrialisation of African nations which the citizens of those countries want.

I couldn’t help feeling that the sheer scale of open space in the US was a factor in the “I’m ok” quality of the two scientists’ presentations. They have their product (climate science) and it's doing ok. Good for them. One can imagine that climate changes of the kind Dr Denning supposes may happen in the US post-China and India development (if Chicago gets the climate of Tallahasee, for example, what will Tallahasee be like?) will involve big migrations of people. In the US perhsp this doesn;t look too bas, because migration is all within the bounds of one nation. What if migrations cross national boundaries? It's significant that Dr Denning made his point to this conference showing only the map of the US. What about the populations of the central- and south-American states?

But there we go again. That recent and ongoing climatic warming is being forced more by human activity than natural processes is not currently proven. The projections can be too alarming to comprehend. It is a one-way experiment. We are probably heading for a stable hot state, and natural climatic processes will take over what our activities are probably forcing. As James Lovelock put it recently “We just pulled the trigger”.