GEO130 – OCEANOGRAPHY

The Role of The Isthmus of Panama


500 Million Years of Climate Change

By Glen Fergus via Wikipedia


500 Million Years of Climate Change
Using a variety of proxy temperature data climate scientists
have re-constructed Earth's temperature history.




Large Version of the Graph






5 Million Years of Climate Change

By Robert A. Rohde via Wikipedia


5 Million Years of Climate Change

Prior to 3.5 MYBP Earth was warmer than today and climate was stable, meaning only small variations
in global average temperature. Earth then cooled and the variations became large as global
climate de-stabilized. This was partially caused by the formation of the Isthmus of Panama
and the formation of the strong Gulf Stream, the western boundary current of today's North Atlantic ocean.
Warm water transported into the far North Atlantic increased evaporation and therefore snowfall.
This increased the influence of the ice-albedo feedback mechanism and ultimately the importance of the Milankovitch Mechanism.






800 Thousand Years of Climate Change


800,000 Years of Climate Change

Ice cores contain bubbles of ancient atmosphere so climate scientists can reconstruct the concentration of CO2 as far back as the ice cores go. In this case it is 800,000 years. Ice core records now go back 1 million years. Notice how warm periods coincide with high concentrations of CO2. Also Notice how CO2 peaks occur a short time later than temperature peaks. CO2 concentrations are therefore a positive (amplifying) feedback - a reaction to a warming world that amplifies the warming taking place. On a warmer Earth there is more decay and less CO2 uptake by the oceans. As CO2 levels increase the greenhouse effect increases and warming accelerates.




800,000 Years of Climate Change




800,000 Years of Global Ice Volume






100 Thousand Years of Climate Change


100,000 Years of Climate Change
Johan Rockström et al (2009) Ecology and Society Vol 14. No. 2
http://www.ecologyandsociety.org/vol14/iss2/art32/






20 Thousand Years of Climate Change


20,000 Years of Climate Change
http://www.globalwarmingart.com/wiki/File:Holocene_Temperature_Variations_Rev_png






2000 Years of Climate Change


2000 Years of Climate Change
http://www.globalwarmingart.com/wiki/File:2000_Year_Temperature_Comparison_png



The Carribean Sea and Central America


The Caribbean Sea and Central America



The Carribean Sea and Central America 3 Million Years Ago


The Caribbean Sea and Central America 3 Million Years Ago



Ocean Current Changes
Carribbean Sea and Central America
As the Isthmus of Panama Formed


Warm water from the Atlantic flowed into the Pacific as part of a global current. When the Isthmus of Panama was formed because of plate tectonics the warm Atlantic water was diverted and formed the strong Gulf Stream. The Gulf Stream transported warm water to the north shores of Europe. Evaporation increased from the North Atlantic ocean increasing precipitation in the polar regions. Especially imprortant was the amount of snow. This change made Earth's climate more sensitive to the Milankovitch Mechanism through the ice-albedo feedback.