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Global Environmental Change
Climate Change, Global Warming…
…what’s going on?
What is Climate?• Climate = the average and variations of
weather over a long period of time (~30 years)
Above: Global average for atmospheric water vapor.
What is Weather?
• Weather = all natural phenonmena within the atmosphere at a given time (hours to days)
What is Science?
• Science is the search for knowledge
The lunar cycle
The extent of snowfall as the seasons progress from Summer into Winter and then back to Summer again.
How do these combine?• Used to understand
the physics, chemistry and biology of the Earth.
Science is the search for knowledge
The Nitrogen Cycle The Water Cycle
• The Earth has many different systems that interact with each other in different ways.
LandLand
OceansOceans AtmosphereAtmosphere
BiosphereBiosphere
IceIce
The Climate System
Modern Climate Systems
• Atmospheric circulation
Sunlight
Modern Climate Systems
• Atmospheric circulation
H.C.
F.C.P.C.
Modern Climate Systems
• Ocean circulation
The Great Ocean Conveyor
Sinking cool water, rising warm water and wind help to form global ocean current systems.
• Atmosphere and Greenhouse Effect– The Earth’s atmosphere keeps it around
30°C warmer than it would otherwise be.– This is the Greenhouse Effect
Modern Climate Systems
What is the Greenhouse Effect?
cc. Robert A. Rohde (Global Warming Art)
cc. Robert A. Rohde (Global Warming Art)
The temperature of the Earth depends on the amount of energy we receive from the sun versus the amount of energy lost back out to space.
Past Climate Systems
• How do we know about climate systems in the past?
Past Climate Systems
1. Early human record
Tourism NT http://www.travelnt.com
Rock paintings provide evidence of fertile Sahara region (now desert) 6,000 years ago.
cc. W.V. Bailey
Past Climate Systems
2. Geomorphology
Above: A “U” shaped valley shows that it was formed by a glacier.
River deltas show where rivers entered the ocean or a lake.
Past Climate Systems
3. Geological record
Drilling into the ground can recover rock layers that record what conditions were like when the rock was deposited.
Fossils preserve evidence of past life.
Past Climate Systems
4. Ice cores
GISP2 ice core at 1837m depth with clearly visible annual layers.
Ice cores can preserve seasonal layering. Studying the chemistry of each layer can give clues about climate change.
Practical Exercise
Climate Change: What can I do?
Is the Climate Changing?
What is Climate Change?
• Records change over decades to millions of years
What are the current climate trends?
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Instrumental_Temperature_Record_png
Global temperature for the last 150 years
What are the current climate trends?
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Global_Warming_Map_jpg
Looking further into the past…
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:1000_Year_Temperature_Comparison_png
Global temperature for the last 1000 years
Looking further into the past…
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Ice_Age_Temperature_Rev_png
Global temperature for the last 450,000 years
Looking further into the past…
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Phanerozoic_Climate_Change_Rev_png
Global temperature for the last 500 million years
Anthropogenic Influence
• Fossil fuel
• Aerosols
• Cement manufacture
• Land use
• Livestockcc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Carbon_Dioxide_400kyr.png
Future predictions…
• Based on no changes in emissions (“business as usual”)
• The UK would be 2-3.5°C hotter on average.
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Global_Warming_Predictions_Map_jpg
What does it all mean?
• Sea level rise
• More extreme weather
• Changes in precipitation
• Spread of disease
cc. Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Recent_Sea_Level_Rise_png
Questions to be answered…
• How fast will the sea level rise?
• How much warmer will it get?
• When will the Arctic Ocean be ice-free?
• Will the water cycle accelerate?
• Are climate extremes increasing?
• Will there be abrupt changes?
Science can provide knowledge…
…We all have to provide the solutions.
