Geoscience Reference
In-Depth Information
drilling of coral atolls in the South Pacific Ocean in the late nineteenth and mid-twentieth
centuries. His theory was again validated by drilling coral atolls in the Bahamas.
Elsewhere in the Pacific (e.g. Vanuatu), a local land level rise has elevated coral reefs
above sea level and dead modern coral reefs occur well above sea level. If Pacific island
nation states enjoyed a sea level rise, their land area would increase. This was suggested
by Darwin and has been confirmed by recent satellite measurements. Compaction, use of
coral forcement manufacture, roads and construction, and extraction ofgroundwater from
unconsolidated coralline sand all lead to a relative sea level rise in the Pacific islands, as
does polar ice cap melting.
Extinctions
Extinction is normal. Highly adapted terrestrial species (such as humans) have a short
life whereas some basic highly adaptable species can survive for billions of years (e.g.
bacteria).Thereisagreatdiversityofreasonsforextinctionandclimatechangeisonlyone
oftheminorcauses.Atanytimeinthehistoryoftheplanet,thereareextinctions,andhence
it is no surprise that we live in a period of extinction. Dominant species, such as humans,
killotherspeciesforfoodandchangehabitats.Ithashappenedmanytimesbefore.Vacated
ecologies are quickly filled and life goes on.
Global warming may create a few extinctions although most species (including plants)
havetheabilitytomovetotheiridealclimate.Thehistoryoftheplanetshowsthatthereisa
hugeincreaseinbiodiversityduringwarmtimesandthatextinctionsareuniversalincolder
times, when ecosystems are reduced or changed. For example, during the last glaciation,
the Amazonian rainforests did not exist and there were copses of trees and grasslands.
Inland Australia was devegetated and covered by shifting sand dunes.
The Australian Great Barrier Reef, the poster child of the Greens, disappeared during
glacialeventsmorethan60timesoverthelastthreemillionyears.Itreappearedafterevery
oneoftheseevents.TheGreatBarrierReeffirstformedabout50millionyearsagoandhas
survivedhundredsofcoolingsandwarmingsandmassiveraineventsthatdepositsediment
on the Reef. The sea levels fall and lower temperatures during glacial events kill higher
latitude coral reefs and they continue to thrive at lower latitudes. The geological record
shows that coral reefs love it warm, especially when there is more CO
2
in the atmosphere.
During glacial events, tropical vegetation is reduced from rainforest to grasslands with
copses of trees, somewhat similar to the modern dry tropics inland from the Great Barrier
Reef.
