Hello year 13!
Sorry I have not been able to post onto the blog until now due to login issues. Here are some websites to help you with your research into the other factors that have changed global climate in the past:
Volcanic eruptions
http://sciencefocus.com/forum/can-increased-volcanism-trigger-the-onset-of-glaciations-t566.html
Ocean currents
Two strands to this
The author of this article is E. Linacre in October 1998. Linacre is suggesting that that the release of cold meltwater from the Laurentide Icesheet was responsible for cooling the Labrador Current, and shutting off theconveyor belt which brings warm water from the Gulf Stream. This happened at the end of the Pleistocene, about 12.9 - 11,000 years ago in a period known as The Younger Dryas i.e when climate cooled by -0.6 C. The end of the YD is the period we now live in which is known as the Holocene. The YD was therefore a STADIAL during which glacial ice advanced.
The impact of fresh water running into the Atlantic Ocean is also considered at the following web site: http://science.nasa.gov/science-news/science-at-nasa/2004/05mar_arctic/. Have a read of this and you’ll see the YD mentioned and the idea that the events of 11-13,000 yrs ago could return.
Robert Johnson from the University of Minnesota has put forward a theory which goes against the Milankovich cycles, and explains how a cold period 150-160,000 years ago was produced by ocean currents, despite there being maximum solar radiation reaching the Earth.
I would like to you answer the following questions as you read through the article, which will help you to get to grips with the theory.
· 160,000 to 150,000 years ago the Milankovich theory suggests that there was maximum radiation striking Earth, but a cold phase occurred. Why?
· What role does the salinity of the oceans play?
· What impact did large amounts of moisture over Siberia and Europe have?
· What link is there between salt water and pack ice formation over the Arctic Ocean?
· Why did water leaving the Med Sea become salty 160,000 years ago?
· What is happening to the salinity of water in the Med Sea today? Why?
· How may salty water sinking in Baffin Bay influence the CO2 content of the atmosphere?
I would suggest that everybody does the research, plans out their essays and writes their introduction before we go back (at least). That way we can discuss ideas in the first lesson back.
See you next week,
Miss Davey
