Oceans and coastal zones, the things I know best, have been far warmer and colder than is projected in the present scenarios of climate change. Marine life has been in the oceans nearly since when they were formed. During the millennia they endured and responded to CO2 levels well beyond anything projected. Prior temperature changes put tropical plants and coral reefs near the poles or had much of our land covered by ice more than a mile thick – and during the time of the “Ice Ball Earth”, the ocean was frozen to the equator.. The memory of these events is built into the genetic plasticity of the species on this planet. IPCC forecasts are for warming to occur faster than evolution is considered to occur, so impacts will be determined by this plasticity and the resiliency of affected organisms to find suitable habitats. Species mixes and distributions will change, just as they always have. Some species will be so disadvantaged they will go extinct and ecological niches will develop that offer opportunities for new species to arise.
The chart is of the Paleo Record. Northern Hemisphere Annual Temperatures from Low- and High-Resolution Proxy Data over the last 2000 Years. The red signifies only the use of the instrumented record, since about 1860.(From NOAA/NCDC).
In the oceans, major climate warming and cooling is a fact of life, whether it is over a few years as in an El Niño or over decades as in the Pacific Decadal Oscillation or the North Atlantic Oscillation. Currents, temperatures, salinity, and biology change rapidly to the new state in months or a couple years. These changes far exceed the changes expected with global warming and occur much faster. The one degree F. rise since about 1860, indeed since the year 1000, has brought the global average temperature from 56.6 to 57.4 degrees F. This is at the level of noise in this rapidly changing system. Sea level has been inexorably rising since the last glaciation lost its grip, and temperatures rose by 10-20 degrees, a mere 8,000 years ago for the final gasp of the last glaciation. It is only some few thousand years since Georges Bank was part of the mainland. It is now 60 miles offshore of Provincetown on Cape Cod. Its trees and the shells of its oysters that flourished on its shores still come up in dredges and trawls in now deep water, with the oysters looking like they were shucked yesterday. In the face of all these natural changes, and those we are here to consider, some species flourish while others diminish. These considerations were well understood in all the IPCC groups in which I participated. I have some concerns about some few species near the margins of their suitable habitat range. These include corals near the equator and perhaps polar bears. But I would much rather have the present warm climate, and even with the IPCC’s warming, than the next ice age that will likely last over 80,000 years and bring temperatures much colder than even today, and according to my IPCC briefers, ice that is 2 miles thick in Chicgo. The NOAA PaleoClimate Program shows us that when the dinosaurs roamed the earth, the earth was much warmer, the CO2 levels were 2 to 4 times higher, and coral reefs were much more expansive. The earth was so productive then that we are still using the oil, coal, and gas it generated. In contrast, the last ice age maximum, at just 20,000 years ago saw temperatures 4-7 deg. C (7.6-13.6 F) cooler than present. The one deg. F rise since the 1850s is a relatively small component. (Photo of frozen North Cove, Fairhaven Mass. in March 2007; courtesy of OceansArt.us)
