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IPCC Climate Change Report

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IPCC Climate Change Report Moving Towards Consensus Based on real world data – PowerPoint PPT presentation

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Title: IPCC Climate Change Report


1
IPCC Climate Change Report
  • Moving Towards Consensus
  • Based on real world data

2
IPCC Consensus process is Conservative by Nature
3
IPCC Consensus Evolution
  • FAR 1990 The unequivocal detection of the
    enhanced greenhouse gas effect from observations
    is not likely for a decade or more
  • SAR 1995 The balance of evidence suggestions a
    discernible human influence on global climate

4
Getting Stronger
  • TAR 2001 There is new and stronger evidence
    that most of the warming observed over the last
    50 years is attributable to human activities
  • AT4 2007 Most of the observed increase in
    globally averaged temperatures since the mid-20th
    century is very likely due to the increase in
    anthropogenic greenhouse gas concentrations.

5
Climate Modeling Evolution
6
Better Grid Resolution
7
Basic Approach
  • Coefficient of doubling CO2

8
Leads to CO2 Stabilization Scenarios
9
Basic Future Predictions
  • A 2C rise from today's temperatures produces 30
    species extinction
  • A 3C warming will lead to widespread coral
    deaths
  • Water availability in the moist tropics and in
    the high latitudes will increase, but will drop
    in the semi-arid low latitudes
  • A 1C warming will decrease agricultural yields
    in the low-latitudes 2C increases yields at
    high latitudes

10
Preponderance of Evidence
  • Want to find indicators of climate change
  • Requires a) a robust definition and measure of
    what constitutes climate and b) an instrumental
    precision sufficient to measure change
  • No one indicator (e.g. smoking gun) exists
    aggregate of all data then forms the preponderance

11
Many Hockey Sticks
  • This is most peoples view of Global Warming
  • It is perhaps the worse indicator to use
  • Average global temperature has no physical
    meaning
  • How do you measure it?
  • Reliability of Measurements in question
  • Effects of urbanization difficult to factor in
  • What do you use as your baseline?

12
Weather is a Seasonal Event
  • Yet Hockey stick only plots annual index.
  • Bothun/Ostrander Monthly Treatment

13
La Nina/El Nino
14
Reinforced with 2D Representation
15
Winter Signal is Strongest
16
Amplification of Polar Warming
Note the significant slop change at 2005
Methane Feedback signature?
17
Methane
  • Potential role of methane is larger than CO2
  • GWP 21
  • Scales with population growth
  • Released from permafrost
  • Released from hydrate deposits
  • Emissions now rising again due to global wetlands
    returning from prolonged drought

18
Ocean sink capacity no longer scales with
increasing emissions
19
Record Events depend on wave form evolution
20
Global Aerosols leads to dimming
  • Mostly Industrial African Source is pyrogenic
    and biogenic in nature (drought related)

21
Convolution of positive and negative forcings are
what we observe.
  • GHG produces the net positive here

22
And all is superimposed on El Nino Cycle
23
Other indicators
  • Sea Ice
  • Glacial retreats and glacial mass balance
  • Permafrost
  • Droughts
  • Water vapor feedback
  • Cloud cover
  • Ocean wave heights
  • Sea surface temperature anamolies

24
Glacial Retreat and Mass Balance
1941 - 2005
25
Wholesale Change in Mass Balance
26
Arctic Ice Loss Rapidly Escalating
27
Waveform of Concern
An Ecosystem Literally Melts Away
28
Global Sea Level Rise Greenland Melting at an
unexpectedly higher rate
29
But 2009 did not continue this catastrophic trend
  • And 2009 point is consistent with long term trend

30
Total Ice Sheet Melting
31
Droughts
32
Water vapor increases?
33
Cloud Cover
  • Extremely difficult to really measure with any
    accuracy
  • Extant data are inconclusive and noisy

34
Wave height data shows something!
35
Ocean Sea Surface Temperature Response
  • Its important to realize that virtually all of
    the extra (heat) flux goes into the oceans

36
Big reservoir of heat
  • 0.1 degree C increase transferred (instantly) to
    the atmosphere produces 100 degree C increase.
  • Ocean circulation and redistribution of excess
    heat is (fortunately) a slow process
  • But that is where the pipeline warming is even
    if CO2 was stablized today!

37
Sea Level Rising
  • Sea Level measured at San Francisco

38
Known SST oscillations increasing in amplitude
  • North Atlantic Oscillation (notice the post 1995
    slope)

39
Complete Feedback Models too Difficult to
reliably construct
40
(No Transcript)
41
Source of Uncertainties
  • Roles of clouds and aerosols in radiative
    transfer models? (e.g. scattering!)
  • Role of tropical convection and the water vapor
    feedback loop?
  • How well do observations constrain the input
    climate parameters?
  • How to weight the inputs for best fit statistical
    model?
  • Contributions of other greenhouse gases
    specifically methane from permafrost release

42
Uncertain Futures
BAD
Manageable
Humanity Blew It
43
Global Warming Potential
  • TH Time Horizon (20 or 100 years)
  • Ax increased forcing from X (Watts m2 kg)
  • x(t) decay following some hypothetical
    instantaneous release of X
  • Denominator is relevant quantities for CO2
  • Nominal value for Methane is 21

44
Do Tipping Points Exist in Climate?
  • Does the system have critical phenomena?

Or do the various and somewhat unknown feedback
mechanisms serve to counter this?
45
The Next Level of Physics in Climate Science
  • More strongly incorporates the role of various
    feedbacks particularly water vapor
  • Identifying critical points (or lack thereof) is
    essential in future models
  • Improved modeling of aerosols and their
    scattering properties
  • Improved modeling of tropical convection to
    better understand ocean/atmosphere heat exchange
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