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Current Program: Series 14 - Fall 2018

Climate Change, Catastrophe and the Tides of History
Sept. 13 - Nov. 1, 2018

The nearly four billion years of geologic record tell us that the Earth’s climate has fluctuated from tropical hothouse to icehouse (Snowball Earth). The record provides perspective for our current focus on global warming. For most of Earth history, climate has been much warmer than today. Ice ages, like the one in which we are presently embedded are rare. In essence, the world that we regard as normal is unusual. It’s cool and has biomes (tundra, boreal forest, grasslands, etc.) that are young and fleeting.

Climate change has driven evolution, the emergence of humans and their movement around the world. It has determined where and when civilization emerged. In the last two thousand years it has regulated the rise and fall of many societies, and continues to exert huge control over how we occupy the Earth and our very survival.

Art Gallery of Burlington     (Map)

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Third Age Learning Burlington reserves the right to substitute speakers as necessary.

Series #14: Schedule

This series will be presented by a single speaker, Dr. Anthony Davis

Tony Davis is an Emeritus Professor in the Department of Geography, University of Toronto. He is a biogeographer. His research focussed on the reconstruction of past environments using pollen analysis. His passion is teaching. Although he has been officially retired for over a decade, he continued to teach a large introductory course on human-environment interactions until three years ago.  He has become very active with lifelong learning groups in Mississauga and Etobicoke.

Date Details
September 13
Earth history and changing climate

What is climate and how do we measure it? Information on past climate spans nearly four billion years, but it’s plentiful only for the last half billion. What is the nature of the record?  What does it tell us? How do past climates compare to what we have today?

September 20
Understanding Earth climate

The Earth is located in our solar system’s Goldilocks Zone (not too hot, not too cold, etc.). That suggests that the critical control on our climate is distance from the sun, but the internal processes of our planet (plate tectonics) also play a major role. They control the carbon cycle and atmospheric chemistry and thus the processing of solar radiation.

September 27
Climate and evolution

Over the last half billion years, life has become more diverse and complex. Although there seems to have been an increase in diversity through that time, the record is marked by several episodes of mass extinction. Five major events are recognized. The largest, at the end of the Permian, may have eliminated 70-90% of species. Each extinction provides opportunities for survivors. The biological modernization of our world comes after the extinction event at the Cretaceous-Tertiary boundary, about sixty five million years ago. Climate change appears to have been heavily involved in all of these events.

October 4
Quaternary Ice Advances and Retreats, the Human Diaspora and Plant and Animal Domestication

From about twenty five million years ago Earth’s climate cooled and became more seasonal. This culminated in the series of pulse-like ice advances and retreats that have marked the last two million years. Cooling climate constrained the evolution of hominids and their spread around the world. Plant and animal domestication appears to be a feature of the present interglacial, the Holocene. Did people develop agriculture as a response to the pronounced climate change at the end of the Pleistocene or were other influences involved? What were the consequences?

October 11
Climate Change and the Rise and Fall of Civilizations: El Nino (ENSO) and its Effects on the Asian Monsoon and the Early Civilizations of the Americas

El Nino is a periodic climatic phenomenon initiated by the reversal of oceanic and atmospheric circulations in the equatorial Pacific, but its effects are global. Severe ENSO events may have catastrophic consequences. Several major famines in India and China have been attributed to ENSO. It is likely that multiple ENSO events were responsible for the demise of the Maya in Central America, the Moche, Chimu and Nazca in South America and the Anasazi in the Chaco Canyon area of the US southwest

October 18
Holocene Climatic Shifts and Their Consequences ;The Medieval Warm Epoch and the Little Ice Age

The time since the last ice retreat, the Holocene, is marked by a series of climatic shifts that lasted for decades to centuries. Some appear to be global, while others are largely regional phenomena. One of these was the Medieval Warm Epoch, between 950 and 1350 AD. It’s marked by an expansion of agriculture into higher latitudes and altitudes, but is best remembered for its coincidence with Norse expansion across Europe and the North Atlantic.The period of cooling after the Medieval Warm Epoch known as the Little Ice Age lasted from about 1350 AD to 1850 AD. It was marked by an expansion of glaciers, retrenchment of agriculture and widespread famine in Europe, depopulation in Iceland, and the demise of the Greenland settlements. It was also a time of cultural and economic shifts – the rapid expansion of European influence across the globe, for example. Were the French Revolution and the Irish potato famine products of the LIA?

October 25
Contemporary climate change (‘global warming’); causes.

Our activities have radically altered the Earth’s surface and the chemistry and behaviour of its atmosphere. The major culprit, the burning of fossil fuels, has increased the concentration of greenhouse gasses, notably carbon and methane. Although we focus on rising temperature, the package is complex and may include increasing climatic variability, increased storminess, higher intensity ENSO events and rising sea-levels.

November 1
Contemporary climatic change; consequences

Increasing temperature is likely to be accompanied by increasingly unpredictable weather, water shortages and less productive and less secure agriculture and political and economic instability. One immediate impact is rising sea-level. Some project that perhaps a billion people will be displaced. Many of the small island nations in the Pacific and Indian Oceans are likely to disappear within a few decades. What can/will we do about it?