Lecture 15

Lecture 15 - SIO 40 Life and Climate on Earth Nov. 4 th ,...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: SIO 40 Life and Climate on Earth Nov. 4 th , 2009 Lecture 15 Recent climate variations Can climate change be rapid? Lecture Outline- The Younger Dryas event- Climate tipping points?- The Little Ice Age Influence of volcanoes and sun spots on climate- Present day climate variability Ocean-atmosphere oscillations - ENSO Temperature reconstruction for Central Greenland, based on ice core data. Very large, rapid temperature fluctuations were common during the last glaciation, and during the transition to interglacial conditions at the start of the Holocene, About 10,000 years ago. Alley, Scientific American 2004 Ice core temperature records from Greenland show major climatic reversals (the Younger Dryas) as well as smaller but significant climate oscillations during the Holocene. More detailed high resolution analysis of Greenland ice core records has indicated that the Younger Dryas event happened very rapidly, on the time scale of decades. Alley, Scientific American 2004 What contributes to climate variability? 2. Thermohaline circulation Was the Younger Dryas caused by a shutdown of the North Atlantic conveyor? Alley, Scientific American 2004 In the case of the Younger Dryas, it is believed that a conveyor shutdown was caused as a result of massive freshwater influx to the North Atlantic during the most recent deglaciation period. Conveyor reductions or shutdowns may also be caused by changed in the hydrological cycle, or melting of the Greenland Ice Sheet. Is there a climate tipping point? Evidence for the role of the North Atlantic Conveyor circulation in the Younger Dryas event has resulted in some alarmist climate-related scenarios in the popular media (eg. the movie The Day After Tomorrow). More realistically it seems that there are likely to be a variety of tipping points operative on different scales within Earths climate system, and interaction of these thresholds with positive feedback loops is likely to determine the ultimate outcome of global-scale climate change. For more on this topic see Runaway Tipping Points of No Return" on Realclimate.org . The Little Ice Age Hunters in the Snow by Bruegel the Elder, 1565 The Little Ice Age was a period of cold climate (between 0.5-1 C cooler relative to modern times), particularly in the North Atlantic and Europe, although varying signals of this cooling are observed in different locations around the world. Experts disagree as to when the LIA officially began, but it is generally thought that a globally significant cooling began in the late 1500s....
View Full Document

This note was uploaded on 10/23/2010 for the course SIO SIO 40 taught by Professor Barbeau during the Fall '10 term at UCSD.

Page1 / 20

Lecture 15 - SIO 40 Life and Climate on Earth Nov. 4 th ,...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online