1. Earth Science Notes
Climate Change

2. Objectives I can… Explain climate change and describe its causes.
Explain why we believe the climate has changed and is changing.
Cite data and infer conclusions

3. Things to Remember about Climate Change.
Climate change is occurring. We will discuss the data supporting this claim.
Climate change is natural and has been happening for most of Earth’s history.
Humans play a role in climate change.
The degree of involvement is debated.
Climate change is a political issue. Its always best to put politics aside an conclude things from data (i.e. be scientific).

4. What is Climate Change?
Climate change is a long-term shift in weather conditions identified by changes in temperature, precipitation, winds, and other indicators.

5. Where do we get our data for Climate Change?
Each day multiple organizations measure and record data on the weather.
NOAA (National Oceanic and Atmosphere Administration).
NASA (National Aeronautics and Space Administration).
The National Weather Service.
Over time these records tell us something about our climate.
Unfortunately accurate direct measurements only go back 130 years or so.

6. Where do we get our data for Climate Change?
Climate data before the 1880’s has to be measured indirectly.
People who research Earth’s past climates are called paleo-climatologists.
Source of Climate Data in Earth Past include:
Ice Cores
Tree Rings
Fossils

7. Sources of Paleoclimate Data
Ice Cores
We can determine the amount of gases in the atmosphere at specific times based on the concentration of CO2 found in ice cores.
Very specific amounts of gas stay dissolved at specific temperatures.

8. Sources of Paleoclimate Data
Tree Rings
Trees live for hundreds of years and the “collect” information about climate.
We can infer what years are more wet and what the duration and intensity of drought.

9. Sources of Paleoclimate Data
Fossils
Fossils like Foraminifera give us information about sea level and temperature
These organisms form their CaCO3 shells from the minerals available to them.
The availability of these minerals depend on the degree of weathering and photosynthesis occurring which is based on temperature and sea level.

10. Sources of Paleoclimate Data
Fossils
There have been a number of fossils discovered in places that no longer support those organisms.
Ex:
Whale bones found in the Chilean Dessert and the Sahara Dessert.
Plant Fossils found on Antarctica
Sea Shells found in Himalayas

11. Data for Climate Change
What conclusion do we draw from this graph?

12. Data for Climate Change
What conclusion do we draw from this graph?

13. Data for Climate Change
What conclusion do we draw from this graph?

14. Data for Climate Change
What conclusion do we draw from this graph?

15. Data for Climate Change
What conclusion do we draw from these graphs?

16. Summarize the Data
_______________________________________

17. Causes of Climate Change
Seasons
El Nino / La Nina
Solar Output
Volcanic Eruptions
Variations in CO2 concentrations in the atmosphere (human impacts).
Variations in Earth Orbit and Earth’s Axis of Rotation.

18. Causes of Climate Change
Seasons – periods of climate change caused by the amount of solar radiation an area receives
Caused by the Earth's tilt toward the sun
Tilted toward = summer
Tilted away = winter
Tropics experience little change
High altitudes near pole experience great change.
Earth’s tilt can vary from 22.1° to 24.5°.
More of a tilt means more of a temperature difference between summer and winter temperatures.

20. Causes of Climate Change
El Nino – is the weakening or reversal of wind in the Southern Pacific.
What should happen is the upwelling you see the top picture.
What happens during El Nino, is a down welling effect that creates higher than normal ocean temperatures

21. Causes of Climate Change
Effects of El Nino
Jet stream is altered, changing wind and precipitation patterns around the world.
For the US, during El Nino is the Jet Stream is pulled farther south and that is where we will find more severe weather.
Africa and Australia may experience droughts.
California will experience more storms and possible flooding.

22. Causes of Climate Change
Wobble – the earth wobbles as it spins on its axis.
Currently our North Star is Polaris. Due to this wobble over time our North Star will be Vega.
Earth’s wobble affects the timing of the seasons (summer happens in June, etc.).

23. Causes of Climate Change
The Wobble Earth experiences will cause climate change because the winters will become milder and summers will become cooler.
We will eventually be tilted toward the sun in December and that would then be our summer.

24. Causes of Climate Change
Orbital Variation - The shape of Earth's Orbit changes every 100,000 years from being elliptical to being nearly circular and then back.

25. Causes of Climate Change
Changes in the eccentricity of Earth’s orbit will cause changes in climate
The more elliptical the orbit, the greater the difference in temperature we experience as Earth distance from the sun changes.
Temperature increases when we are close and decreases as we get farther from the sun
If Earth had a circular orbit, it would always be equidistant from the sun, therefore, the orbital position would not affect Earth’s climate.

26. Causes of Climate Change
Volcanic Eruptions
Climatologists have noticed a connection between large explosive volcanic eruptions and short term climatic change.
For example, one of the coldest years in the last two centuries occurred the year following the Tambora volcanic eruption in 1815.
Accounts of very cold weather were documented in the year following this eruption in a number of regions across the planet.
Several other major volcanic events also show a pattern of cooler global temperatures lasting 1 to 3 years after their eruption.

27. Causes of Climate Change
Explosive volcanic eruptions also eject large quantities of SO2 gas
The gas remains in the atmosphere for as long as 3 years.
SO2 gas reacts with water vapor commonly found in the stratosphere
This forms a dense haze layer that reduces the radiation from the sun.

28. Causes of Climate Change
Blocking of Solar Radiation (minimal effect)
Volcanic Eruptions
Picture is a volcanic eruption viewed from space
Pollution / Forrest Fires

29. Causes of Climate Change
Solar Output
Some evidence suggest that sunspots affect global climate patterns.
Sunspots are huge magnetic storms that are seen as dark (cooler) areas on the Sun's surface.
Cooler because they have emitted heat that the Earth will receive.

30. Variations in Solar Output

31. Causes of Climate Change
Climate Studies have discovered a connection between the concentration of CO2 in the atmosphere and average global temperature.
Point of clarification  this demonstrates a correlation – not causation. This is not the sole cause of climate change but one of its factors.

32. Causes of Climate Change
Carbon dioxide is one of the more important gases responsible for the Greenhouse Effect.
Greenhouse Effect – natural process that occurs when certain gases (CO2, CH4, and water vapor) trap heat
This effect can be magnified by human activities like the burning of fossil fuels.

33. Atmospheric CO2 variations
Measurements indicated that atmospheric CO2 levels were about 30% lower during colder glacial periods.
It is theorized that the oceans were a major store of CO2. The warmer the temperature the less CO2 can be stored in the ocean.
CO2 is released from oceans when global temperatures become warmer and diffuses into the ocean when temperatures are cooler.
Initial changes in global temperature were triggered by changes in received solar radiation by the Earth.
The increase in CO2 then amplified the global warming by enhancing the greenhouse effect.

36. Assessment Can I … Explain climate change and describe its causes.
Explain why we believe the climate has changed and is changing.
Cite data and infer conclusions