A geophysiologist's thoughts on geoengineering - Philosophical Transactions A - 0 views
-
The Earth is now recognized as a self-regulating system that includes a reactive biosphere; the system maintains a long-term steady-state climate and surface chemical composition favourable for life. We are perturbing the steady state by changing the land surface from mainly forests to farm land and by adding greenhouse gases and aerosol pollutants to the air. We appear to have exceeded the natural capacity to counter our perturbation and consequently the system is changing to a new and as yet unknown but probably adverse state. I suggest here that we regard the Earth as a physiological system and consider amelioration techniques, geoengineering, as comparable to nineteenth century medicine.
-
Organisms change their world locally for purely personal selfish reasons; if the advantage conferred by the ‘engineering’ is sufficiently favourable, it allows them and their environment to expand until dominant on a planetary scale.
-
Our use of fires as a biocide to clear land of natural forests and replace them with farmland was our second act of geoengineering; together these acts have led the Earth to evolve to its current state. As a consequence, most of us are now urban and our environment is an artefact of engineering.
- ...7 more annotations...
-
Physical means of amelioration, such as changing the planetary albedo, are the subject of other papers of this theme issue and I thought it would be useful here to describe physiological methods for geoengineering. These include tree planting, the fertilization of ocean algal ecosystems with iron, the direct synthesis of food from inorganic raw materials and the production of biofuels.
-
Tree planting would seem to be a sensible way to remove CO2 naturally from the air, at least for the time it takes for the tree to reach maturity. But in practice the clearance of forests for farm land and biofuels is now proceeding so rapidly that there is little chance that tree planting could keep pace.
-
Oceans cover over 70 per cent of the Earth's surface and are uninhabited by humans. In addition, most of the ocean surface waters carry only a sparse population of photosynthetic organisms, mainly because the mineral and other nutrients in the water below the thermocline do not readily mix with the warmer surface layer. Some essential nutrients such as iron are present in suboptimal abundance even where other nutrients are present and this led to the suggestion by John Martin in a lecture in 1991 that fertilization with the trace nutrient iron would allow algal blooms to develop that would cool the Earth by removing CO2
-
The Earth system is dynamically stable but with strong feedbacks. Its behaviour resembles more the physiology of a living organism than that of the equilibrium box models of the last century
-
For almost all other ailments, there was nothing available but nostrums and comforting words. At that time, despite a well-founded science of physiology, we were still ignorant about the human body or the host–parasite relationship it had with other organisms. Wise physicians knew that letting nature take its course without intervention would often allow natural self-regulation to make the cure. They were not averse to claiming credit for their skill when this happened.
-
The alternative is the acceptance of a massive natural cull of humanity and a return to an Earth that freely regulates itself but in the hot state.
-
Global heating would not have happened but for the rapid expansion in numbers and wealth of humanity. Had we heeded Malthus's warning and kept the human population to less than one billion, we would not now be facing a torrid future. Whether or not we go for Bali or use geoengineering, the planet is likely, massively and cruelly, to cull us, in the same merciless way that we have eliminated so many species by changing their environment into one where survival is difficult.