1. Studying Clues to Past Climate
Climate Change
Lesson #4

2. Learning Goal
To find out more information about how scientists are able to learn more about our changing climate and signs of global warming
To better understand the ways we can monitor and model climate change

3. How Do We Know Today’s Changes Aren’t Natural?
Scientists are more than 90 % certain current changes in climate are due to human emissions of greenhouse gases.
How do scientists know that today’s changes are human-caused, and not natural?

4. How Do We Know Today’s Changes Aren’t Natural?
They develop complex computer models to test the effects of different factors on the climate system.
They compare current changes to changes in the past.
Let’s take a look at these changes!

5. 9.6 How Do We Know Today’s Changes Aren’t Natural?
(1) They develop complex computer models to test the effects of different factors on the climate system.
(2) They compare current changes to changes in the past.

6. Studying Clues to Past Climates
There is over 200 years of documented temperature and climate
Informal records before that kept in journals, oral histories etc.
Paleoclimatology: is the study of climate change taken on the scale of the entire history of the Earth

7. Studying Clues to Past Climates
Natural materials such as rock and ice preserve clues to discovering the climate of the past
Investigations are one by using proxy records
which are stores of natural information that we can measure today that tell us what the climate was like in the distant past.

8. Studying Clues to Past Climates
Proxy records are indirect records of climate
They are not quantitative measurements of temperature or precipitation
Scientists compare proxy records with quantitative records to determine proxy observations present

9. Studying Clues to Past Climates
Proxy records can include:
Fossils
Tree rings
Ice cores
Coral reefs
Rock
Ocean sediments

10. a) Ice Cores
Ice cores drilled in Antarctica and Greenland contain trapped air bubbles.
Studying these air bubbles gives information about concentrations of greenhouse gases and air temperature at the time the bubbles formed.
Ice cores provide records going back years.

11. a) Ice Cores
Scientists have learned the following information from ice cores:
Concentrations of greenhouse gases have changed dramatically over Earth’s history
Temperature and greenhouse gas concentrations increase and decrease at the same time
Earth has gone through many changes in climate, from ice ages to interglacial periods, and back to ice ages.

12. a) Ice Cores
Also tested for different types of oxygen: different types of atoms exist, some with are heavier than others
The ratio between the lighter and heavier atoms can obtain information about the air temperature
Also give information about precipitation and volcanic eruptions through preserving layers of dust
During warm periods, levels of greenhouse gases were higher; when it was cooler, levers were lower

13. a) Ice Cores
Video (2)
(6)

14. b) Tree Rings Trees create one growth ring per year
Thickest in years with good growing conditions (warm & wet environment)
Thinnest in bad growing conditions (cold & dry environment)

15. c) Coral Reefs Coral reefs also add layers of growth each season
Scientists drill cylinders of coral and study layers
Help determine the temperature of the surface ocean when each layer of coral grew

16. d) Rock
Layers of rock contain clues, such as plant pollen or fossils, to the climate at the time and place where the rock formed.

17. e) Ocean Sediment
Scientists drill sediment cores from the ocean floor.
The layers in sediment cores contain fossils and other clues that provide evidence of different climates over time.  

18. f) Caves
In caves, rock formations grow as the minerals dissolved in dripping water solidify into rock.
Scientists can measure and date rock layers in caves to obtain information on how much precipitation occurred at different times in the past

19. Modeling & Monitoring Climate Change

20. Introduction Are oceans getting warmer?
Are sea levels actually rising?
I tell you yes … but how do we know for sure?
Well, scientists collect accurate information over long periods of time based on observations and measurements
This is what we call monitoring

21. Monitoring
Is the only way to identify climate trends, like increases in average global temperatures
There are many different ways and instruments that can be used to collect this data

22. Improving Technology & Data
While many different tools and techniques are used to measure atmospheric temperature, humidity, precipitation for over 200 years now
We are looking for ways to jump forward with the invention of various technologies that can measure atmospheric changes above the earth!

23. Radar and the Weather
Meteorologists and climate scientists use radar data to forecast the weather and other climate factors around the world
Radar systems take measurements by emitting short pulses of microwaves
These microwaves travel by being reflected off of water and ice in the atmosphere

24. Climate Data from Satellites
Today hundreds of satellites orbit Earth to measure different components of climate
There are two main ones used:
Geostationary Satellites
Orbit the earth at the same speed as the earth rotates
lets them stay at the same point on Earth (positioned at Markham – still records there 24/7)
This allows the satellite to constantly monitor changes over one specific area of the planet

25. Climate Data from Satellites
Polar Orbiting Satellites
These satellites move over the North and South poles as Earth turns over them
One complete orbit takes just over 2 hours and only 6 hours for the whole planet

26. Earth Orbiting Systems
In 1997 Canada, USA, and Japan combined resources to launch the first of a series of satellites to monitor the Earth’s changing satellite
Today there are more than 50 specialized satellites that work to perform 1 of 4 basic functions

27. Earth Orbiting Systems
The Quick Scatterometer (QuickSCAT)
Measures the speed and direction of winds near the surface of oceans
For example, this satellite can be used to see how winds and water interact to produce El Nińo
Also used to monitor changes in rainforest vegetation and changes in ice coverage in the north and south pole

28. Earth Orbiting Systems
Terra
Works by carrying 5 remote sensors to monitor
heat emissions
Reflections from earth
Cloud coverage
Amount of Pollution in the troposphere

29. Earth Orbiting Systems
Aura
Carries 4 instruments to monitor atmospheric chemistry and concentrations of greenhouse gases
Measures:
Ozone
Water vapour
CFC’s
Methane
Carbon monoxide
Nitrogen compounds
Used to monitor the ozone hole in the Antarctic

30. Earth Orbiting Systems
Aqua
Carries 6 instruments designed to study:
Precipitation
Evaporation
Cycling of water
Uses the Atmospheric Infrared Sounder (AIRS) to accurately measure the amounts of water vapour and greenhouse gases in the atmosphere

32. Modeling Climate Change
Gathering accurate data is only the first step in understanding climate change
But it is also important to interpret this information correctly using tools such as maps, math formulas, or computer programs
Often scientists use observations of past climate data and compare this to what they are seeing to better identify climate features currently

33. Modeling Climate Change
For example, when comparing current weather systems over Texas to previous ones, meteorologist are able to predict weather and expected damages

34. Modeling Climate Change
Climate Models are computer programs designed to analyze climate data and project how climate may change in the future
Able to do this through software that describes, stimulates, and predicts the interactions of the atmosphere, oceans, land surfaces, and ice of Earth to simulate past, present and future climate conditions

35. Modeling Climate Change
Climate models used today connect data about the atmosphere and oceans together into General Circulation Models
GCMs is a complex computer program that uses math equations to describe the physical processes of the atmosphere and to manipulate the variables that affect how the natural climate system works

37. Uncertainty in Climate Models
Sometimes computer systems don’t add up data the same way, and can lead to discrepancies in results
Thus, improvements in data processing and models has lead to the advancements of “virtual climates”
These virtual climates help reduce discrepancies, but does not remove them completely

38. Uncertainty in Climate Models
Three other sources of uncertainty in climate models include :
Sophistication of the model
Quality / Quantity of data available
Complexity of variables

39. Uncertainty in Climate Models
Thus, the predictions of climate models are not 100 % accurate because of inaccuracies in the data and difficulties in the calculations
In the end, the major climate models agree on approximately how much some factors like greenhouse gases contribute to climate change – which are still on the rise