Hardly a day passes without one being told that tropical deforestation is extinguishing roughly one species every hour, or maybe even one every minute. Such guesstimates are based on approximate species-area relations, along with assessments of current rates of deforestation and guesses at the global total number of species (which range from 5 to 80 million or more.) While such figures arguably have a purpose in capturing public attention, there is a clear and increasing need for better estimates of impending rates of extinction, based on a keener understanding of extinction rates in the recent and far past, and on the underlying ecological and evolutionary causes.The articles in the book are are:
1. Assessing extinction rates
2. Extinctions in the fossil record
3. Constancy and change of life in the sea
4. Insect faunas in ice age environments: why so little extinction?
5. Bird extinctions in the Central Pacific
6. Extinctions in Mediterranean areas.
7. Recent past and future extinctions in birds.
8. Rates and patterns of extinctions among British invertebrates.
9. Assessing the risk of plant extinctions due to pollinator and disperser failure.
10. Population dynamic principles.
11. Estimating extinctions from molecular phylogenies.
12. Biological models for monitoring species decline: the construction and use of databases.
13. Classification of threatened species and its role in conservation planning.
14. The scale of the human enterprise and biodiversity loss.
The last chapter is by Paul Ehrlich. It has his usual I = PAT.
A chapter I found particularly interesting is Chapter 6 on the extinction of plants in Mediterranean climates.
The author is Werner Greuter, Botanischer Garten und Botanisches Museum Berlin-Dahlem, Koenigin-Luise Strasse, 6-8, D-14191 Berlin Germany and is entitled "Extinctions in Mediterranean Areas". (I include the address in case anyone wishes to write for a reprint). Greuter is evidently as specialist in this matter, because he refers to several previous papers.
The total number of Mediterranean higher plants presumed to be extinct is thus 37, of which 35 were species and 2, subspecies. This compares to a total of about 23,300 Mediterranean plant species, or 29 000 taxa (species plus subspecies). The present Mediterranean extinction rate for vascular plants is therefore 0.15% at the species level, or a mere 0.13% of the taxa.He remarks that Mediterranean regions including the Mediterranean, California, central Chile, the Cape of Good Hope region and south-western Australia `total some 70 000 species and represent a major part of the higher plant diversity of the world, exceeding the combined floras of tropical Africa and Asia'. The reason for the large number of species is that many have very small ranges and the diversity in any given area is not so large. He also writes that the extinction rates are lowest in those areas where humanity has been active longest, e.g. the Mediterranean itself. I suppose that almost all the species incompatible with humanity died off long ago.
Let me refer to the chapter "Species Loss Revisited" by Julian Simon and Aaron Wildavsky in The State of Humanity edited by Julian Simon. They document the way species loss has been exaggerated by alarmist writers. I'll quote extensively from this article when I get around to it.
2003 September: The Specter of Species Extinction Will Global Warming Decimate Earth's Biosphere? by Sherwood, Keith and Craig Idso presents evidence against the widely believed theory that increases in temperature and CO2 will lead to widespread species extinctions. They discuss many studies that suggest the opposite - that increased temperature and CO2 will benefit most species of plants and extend their range. They discuss many articles offered as evidence by two groups of extinction advocates and show that the articles themselves lead to a different conclusion.
One interesting fact in the article concerns the effect of an increase in temperature on the north-south range of a plant species, especially of trees. It turns out that the northern limit of a species is determined by temperature. As that limit is approached the rate of growth goes to zero. However, the rate of growth of a species does not decline as it approaches the southern limit of its range but remains stable or even increases. What determines a species's southern boundary is competition from other species that require high temperatures. For this reason the southern boundary of a species is likely to change slowly as its territory is gradually invaded by species liking warm temperature. The invasion is likely to begin in gaps caused by logging and various kinds of die-off.
Scientists who worry about extinctions often agree that the world will reach a new equilibrium as temperature increases - assuming it does. However, they worry that the rate of increase of temperature is unprecedented and that species, especially of plants, will migrate northward too slowly and become extinct. None of the articles I have seen expressing this worry mention the possibility of replanting areas further north of the main present range of a species. It should work, because it's just agriculture. Failing to mention replanting is an example of the widespread inhibition against mentioning positive human activity to arrange the planet to obviate harmful changes or to make the planet more suitable for humanity.
Why do people believe these things? Explanations are offered about how ideology affects science in Ideology and sustainability, especially the section on Environmentalist ideology.
SLOGAN: The world is humanity's garden, to be arranged to suit humanity [Of course, it suits humanity to keep some part of the world wild.]
OPPOSITE SLOGAN: The world is a wild place, and humanity is an unwelcome intruder.
Up to: Sustainability FAQI welcome comments, and you can send them to jmc@cs.stanford.edu.
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