1. Changes in Climate and Feedback Loops
Climate Change Lesson #3

2. Learning Goal To better understand the indicators of climate change
To better understand and learn the causes of short term and long term changes in our climate

3. Global Warming
The biggest indicator of climate change is global warming
The increase in the average temperature of the atmosphere and oceans has been accelerating since the 1960s
The amount and rate of warming is felt around the whole planet, where some areas “warm” more than others
Why do you think this is?

4. Impacts of Melting Ice
In addition to rising sea levels, melting ice affects the habitat of animals like polar bears
Polar bears depend on large areas of ice to hunt their prey
When it warms up and the ice melts, polar bears stop hunting and start to starve

5. Toronto Zoo: Ice Bear
The Ice Bear unit uses off-peak electricity, in the middle of the night, to make a big block of ice.
The ice then slowly melts through-out the next day and is used to cool the air!
If this type of technology is used in cooling systems around the city, our daytime peak demand will be lower, and the need to build more power stations, to cope with peak demand, will be reduced

6. Sea levels & Ocean Acidity
Oceans are a part of Earth’s climate system - so changes in the water effects the whole system
Climate scientists are especially concerned about sea level and ocean acidity (pH)

8. Sea levels & Ocean Acidity
As parts of the world’s oceans get warmer, changes in pH have dropped due to the excess carbon dioxide in the atmosphere
This negatively effects many ecosystems around the world
For example, coral reefs that form naturally are now not as stable than they once were

9. What trends / observations do
Ocean Acidity
What trends / observations do
you notice?

10. Climate & Health
Climate is related to our health, not only with the risk of disease and infections, but also injury due to the extreme HOT or COLD temperatures
For example, heat waves, floods, tornadoes, lightning strikes and snowstorms can occur more frequently with such extremes
Increasing temperatures also affects the amount of dust in the air, mould, and pollen – which trigger asthma attacks

11. Changing Winds & Precipitation
Changes in heat distribution over Earth’s surface have lead to changing wind patterns
The speed, frequency, and direction of winds over the earth’s surface have changed unpredictably for several years
Researchers believe that unusual wind patterns have increased further the melting of ice in the artic

12. Changing Winds & Precipitation
The high temperatures increase the rate of evaporation
When warm, moist air rises and cools, it adds to the precipitation in the atmosphere
In a span of 65 years annual temperatures have increased, and don’t seem to be dropping any time soon

13. Changes in the Earth’s Climate
Short Term & Long Term Effects

14. Natural Changes in Climate
Earth’s climate goes through natural changes
Long-term changes over hundreds of thousands or millions of years due to changes in Earth’s orbit
Short-term variations caused by natural events such as volcanic eruptions

15. Natural Changes in Climate
Plate Tectonics
Is the theory that Earth's outer shell is divided into several plates that glide over the rocky inner layer above the core
The plates act like a hard shell compared to Earth's core
This strong outer layer is called the lithosphere
Thus, researchers believe that continents have moved over the surface of the globe for hundreds of millions of years

16. Natural Changes in Climate
Continental Drift
Is the movement of the Earth’s continents closer to one another, as they “drift” across the ocean
This theory was first coined by Abraham Ortelius in 1596
Where we see changes in land mass distribution
Result: changes air and ocean currents, large effects on climate

17. Natural Changes in Climate

18. Long-Term Cycles in Climate
For the last years or more, Earth’s climate has cycled between freezing ice ages and warmer interglacial periods

19. Long-Term Cycles in Climate

20. Long-Term Cycles in Climate
Milankovitch theory:
Describes the many effects of changes in the Earth's movements that affects its  climate
We see that the Earth cycles are triggered by three changes in Earth’s orbit:
Eccentricity: shape of orbit varies in year cycle
Tilt: Earth tilts back and forth over a year cycle
Precession Cycle (wobble): axis slowly wobbles in a year cycle

21. Long-Term Cycles in Climate
The Eccentricity Cycle 
The earth's orbit around the sun is elliptical
We see how the shape of the ellipse (eccentricity) varies from less elliptical to more elliptical and back in a 100,000 year cycle
Currently, we are in an orbit of low eccentricity (near circular).

22. Long-Term Cycles in Climate
The Precession Cycle
The earth is wobbling about it's axis of rotation like a spinning top
To make one complete cycle takes about 23,000 years
In 11,000 years, the seasons will switch times during year and will be more severe

24. Long-Term Cycles in Climate
The Tilt Cycle / Obliquity
The Earth’s axis of rotation is tilted at 23.5°
However, this value changes from a minimum of 22.5° to a maximum of 24.5° and takes 41,000 years to complete one cycle
Where:
at 22.5° the seasonal variation will be _______________than current?
at 24.5° the seasonal variation will be _______________than current?
SMALLER / LARGER

25. Short-Term Cycles in Climate
Reflect small variations in climate over 10’s to 100’s of years (much smaller than millions of years ago!)
Causes:
volcanic eruptions
small changes in solar output
changes in air and ocean currents

26. Short-Term Cycles in Climate
Volcanoes: dust/gases go high into atmosphere,
blocks solar radiation, Earth temporarily cools
Solar radiation drops slightly, Earth’s climate cools
Solar radiation slightly increases, Earth’s climate warms
Ocean current changes may cause abrupt climate changes: not fully understood
Some changes in air and ocean currents occur regularly, such as El Niño

27. Short-Term Cycles in Climate

28. Feedback Loops and Climate
Small changes are sometimes made larger by feedback loops
Feedback loops can also work the opposite way and make changes smaller

29. Feedback Loops and Climate
Water Vapour Feedback Loop:
More water vapour enters atmosphere when climate warms
Water vapour = greenhouse gas, its presence causes climate to warm even more
If climate cools, less water vapour forms and climate cools further

30. Feedback Loops and Climate
Low Cloud Feedback Loop:
Low clouds trap thermal energy near Earth’s surface and reflect more sunlight
Result: as Earth warms, more clouds form

31. Feedback Loops and Climate
High Cloud Feedback Loop:
High clouds reflect solar radiation back into space
Result: cooler temperatures and fewer clouds

32. Albedo Effect
Looks at how well the Earth’s surfaces reflect the sun’s energy
Ice has high albedo: reflects back most solar radiation
Water has lower albedo: absorbs more solar radiation

33. Albedo Effect

34. The albedo effect is a feedback loop between ice on Earth’s surface and Earth’s average temperature.

35. The albedo effect is a feedback loop between ice on Earth’s surface and Earth’s average temperature.