Global WarmingGlobal Warming

Or Climate Hysteria?Or Climate Hysteria?

The Long ViewThe Long View

• The Earth has The Earth has repeatedly repeatedly experienced climate experienced climate change throughout change throughout its long historyits long history

• The Phanerozoic Eon The Phanerozoic Eon is characterized by is characterized by fluctuations between fluctuations between “Greenhouse” and “Greenhouse” and “Icehouse” climates.“Icehouse” climates.

Greenhouse WorldGreenhouse World• Cretaceous Cretaceous

Period was one Period was one of significant of significant warmth.warmth.

• Tropical Tropical temperatures temperatures not much not much different.different.

• Much warmer at Much warmer at poles – no ice!poles – no ice!

• Current models Current models cannot duplicate cannot duplicate these conditions.these conditions.

The Great CoolingThe Great Cooling• The The

bottom bottom water of water of the ocean the ocean has cooled has cooled gradually – gradually – but but dramaticaldramatically over the ly over the past 100 past 100 million million years.years.

The Eocene Climatic Optimum

The Eocene Climatic The Eocene Climatic OptimumOptimum

• Tropical fossils found Tropical fossils found at high latitude.at high latitude.

• Fossil forest sites on Fossil forest sites on Axel Heiberg Island, Axel Heiberg Island, NWT, CanadaNWT, Canada

• Turtles, Crocodiles Turtles, Crocodiles and other fauna and other fauna excavated from excavated from nearby Ellesmere nearby Ellesmere IslandIsland

The Eocene Climatic The Eocene Climatic OptimumOptimum

• Tropical fossils found Tropical fossils found at high latitude.at high latitude.

• Fossil forest sites on Fossil forest sites on Axel Heiberg Island, Axel Heiberg Island, NWT, CanadaNWT, Canada

• Turtles, Crocodiles Turtles, Crocodiles and other fauna and other fauna excavated from excavated from nearby Ellesmere nearby Ellesmere IslandIsland

The Eocene Climatic The Eocene Climatic OptimumOptimum

• Birches, laurels, tulip trees, metasequoia, Birches, laurels, tulip trees, metasequoia, and other deciduous tree species lived and other deciduous tree species lived happily at 83happily at 83N, where six months of N, where six months of darkness prevailed!darkness prevailed!

Ocean CirculationOcean Circulation

• Some researchers Some researchers believe that ocean believe that ocean circulation holds circulation holds key to long-term key to long-term changeschanges

• Continental drift Continental drift allowed allowed circumpolar flow circumpolar flow around Antarctica around Antarctica in the Miocenein the Miocene

• Renewed glaciers Renewed glaciers in Antarcticain Antarctica

Sea Level ChangesSea Level Changes

• Sea level Sea level has also has also been been much much higher higher throughouthroughout “recent” t “recent” Earth Earth historyhistory

Our most recent ice ages

Rapid Changes Can Also Rapid Changes Can Also Happen!Happen!

• Paleocene-Eocene Thermal Maximum (PETM)Paleocene-Eocene Thermal Maximum (PETM)

Paleocene-Eocene Thermal Paleocene-Eocene Thermal MaximumMaximum

• Ocean Ocean responded responded within 10,000 within 10,000 years.years.

• Caused by Caused by sudden release sudden release of methane(?) of methane(?) from the from the continental continental shelf (??)shelf (??)

• Back to Back to “normal” “normal” within 100,000 within 100,000 yearsyears

Earth Today: The Ice AgesEarth Today: The Ice Ages

• We live in an We live in an “icehouse” period “icehouse” period that has been that has been around for the around for the last ~1 million last ~1 million years.years.

• Typified by short Typified by short warm interglacials warm interglacials and then long and then long declines into declines into glacial episodes. glacial episodes.

What causes these cycles?What causes these cycles?• Changes in the Changes in the

Earth’s orbital Earth’s orbital parameters parameters (Milankovitch (Milankovitch cycles).cycles).– Distance to the sunDistance to the sun– Precession of the Precession of the

Earth’s axisEarth’s axis– Changing of angle of Changing of angle of

inclinationinclination

• These don’t work all These don’t work all that well, but no one that well, but no one has a better idea!has a better idea!