Earths Climate Future and Past

1
Earths Climate Future and Past

• Chapter 8
• Orbital-Scale Climate Change
• 8-7 through 8-10

2
Insolation Changes According to Caloric Season

• Chapter 8
• Section 8-7

3
Reminder of what Insolation is

• Insolation is the amount of radiation received at
  the top of the Earth's atmosphere.
• This is different than what we have been taking
  about, which is the amount of radiation received
  at the Earths surface.

4
Caloric Season

• What is a Caloric season?
• It is basically the year divided into the what
  we call summer and winter
• the caloric summer has 182.5 days out of the
  year where there is more insolation than the
  other 182.5, known as the caloric winter.

5
The seasons
6
Caloric seasons can add a new perspective on how
the earth is affected by its tilt

• When looking at the big picture the insolation
  changes only at a mean of 5
• While the monthly insolation changes can be as
  great as 15

7
Caloric Season Insolation Anomalies
8
Looking for orbital-scale changes in climate
records

• Differentiating these cycles can be quite tricky.
  The cycles can be distinguished when the time
  period is more spread out, but when the time
  periods are close together, they tend to cancel
  each-other out or visa versa.
• The earth can have up to three different
  orbital-scale cycles
• It might take more than the human brain to
  differentiate the complicated cycles.

9
Complications from overlapping cycles
10
Time Series Analysis

• Chapter 8
• Section8-8

11
Time Series Analysis

• So instead of trying to separate the cycles
  scientists use something called Series Analysis
• A primary goal of time series analysis is to
  examine the complicated climatic signals and
  extract any rhythmic embedded within them.
• There are several steps to take for this process.

12
Steps Series Analysis

• A time scale can be formed by dating the
  sediment.
• 3. The time scale converts the climactic
  measurements to the time framework need for the
  series analysis.

• Convert measures of climactic indicators to time
  frameworks.
• Use the different dating techniques to properly
  name the different ages between the different
  levels of sedimant.

13
An example of what time series analysis might
look like
14
Spectral Analysis

• Spectral analysis is one of the dating techniques
  for dating the levels of sediment.
• imagine taking a time record and plotting it on
  time axis and gradually sliding a sine wave of
  different periods across itthe correlation
  between each sine wave is used and the full
  climactic signal is measured.

15
Example of spectrum analysis
16
Filtering

• Filtering can be another useful tool to use for
  series analysis. Filtering can pull out a
  specific cycle by the time period from the total
  signal.

17

• When the three sin-wave cycles are separated by
  spectral analysis they can be put on a plot that
  is called power spectrum
• These are some methods of figuring out the
  different cycles in long-term time periods, but
  when the series analysis is done on short-period
  cycles there becomes a small problem known as
  Aliasing.

18
Aliasing of Climate Records

• Chapter 8
• Section8-9

19
Aliasing

• - is the false movement in records, this is
  created by under sampling the climactic signal.
• If sampling is only taken when the signal was at
  its maximum then the record will only show the
  maximum data, and same goes for the minimum
  signal sampling
• This can become a big problem in screwing up the
  records for climate cycles.

20
Aliasing
21
Tectonic-scale Changes in Earths Orbit

• Chapter 8
• Section 8-10

22
Tectonic-scale Changes in Earths Orbit

• The earth orbit is greatly affected by the
  tectonic plates.
• Coral holds good evidence of these changes.
  Because the environmental changes affecte the
  CaCO3 in coral and this creates a record of
  seasonal changes in sunlight and water
  temperature.

23
The Earth over 440 MYA

• Coral samples from 440 million years ago show a
  much high number of tidal cycles per year than
  compared to current tidal cycles.
• this means that the earth spun up to 11 more
  time each year, which added 11 more days each
  year.
• But as the sun and moon created more tide it
  slowly put a drag on the earths rotation.

24
Tides