Paleoclimates

The Greenland ice sheet is likely to be eliminated [within 50 years] unless much more substantial reductions in emissions are made than those envisaged [and changes will] probably be irreversible, this side of a new ice age.

Kofi Annan, Past Secretary General of the United Nations (2004)

Box 4.5 Occupation of ecospace through time

Life through time has increased in taxonomic diversity, but have the number of life modes also increased? One way to investigate this is by mapping the increase in Bambachian megaguilds (Bambach 1983) across the three great evolutionary faunas. The trend is one of not only increasing numbers of megaguilds through time but also one of increased urbanization as more taxa are squeezed into each category (Fig. 4.21a-c). But in order to sustain the increased membership there must have been some fine-tuning and splitting within the megaguilds as new guilds and niches were developed within the Bambachian structure. Can this be tested with new data and why should the number and importance of various life modes change through time? Richard Bambach and his colleagues (Bambach et al. 2007) have reported an increase from about one, in the Late Ediacaran, to over 90 lifestyles in Recent and Neogene faunas (Fig. 4.21d). Between the Paleozoic and Neogene faunas, there has been an increase in motility, infaunalization and predation. Thus the expansion of predation and increased bioturbation may have forced organisms to adjust to new challenges and participate in ever more complex ecosystems.

Continued

Suspension Herbivore

Carnivore

Suspension Herbivore

Carnivore

Suspension

Deposit

Herbivore

Cambrian evolutionary fauna

Suspension

Mobile

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