IPCC Climate Change Report - PowerPoint PPT Presentation

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IPCC Climate Change Report

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IPCC Climate Change Report. Moving Towards Consensus. Based on real world data ... Improved modeling of aerosols and their scattering properties ... – 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
Reinforced with 2D Representation
12
Winter Signal is Strongest
13
Central Europe Summer Signal
  • Huge statistical signal via baseline/area test

14
Record Events depend on wave form evolution
15
Global Aerosols leads to dimming
  • Mostly Industrial African Source is pyrogenic
    and biogenic in nature (drought related)

16
Convolution of positive and negative forcings are
what we observe.
  • GHG produces the net positive here

17
And all is superimposed on El Nino Cycle
18
Putting it altogether
19
Other indicators
  • Sea Ice
  • Glacial retreats and glacial mass balance
  • Permafrost
  • Droughts
  • Water vapor feedback
  • Cloud cover
  • Ocean wave heights
  • Sea surface temperature anamolies

20
Sea Ice opening of the NW Passage
2007
2006
21
Glacial Retreat and Mass Balance
1941 - 2005
22
Wholesale Change in Mass Balance
23
Permafrost indicators
24
Summary of the Cyrosphere (frozen land)
observations
25
Droughts
26
Water vapor increases?
27
Cloud Cover
  • Extremely difficult to really measure with any
    accuracy
  • Extant data are inconclusive and noisy

28
Wave height data shows something!
29
Ocean Sea Surface Temperature Response
  • Its important to realize that virtually all of
    the extra (heat) flux goes into the oceans

30
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!

31
Sea Level Rising
  • Sea Level measured at San Francisco

32
Known SST oscillations increasing in amplitude
  • North Atlantic Oscillation (notice the post 1995
    slope)

33
Future predictions remain uncertain
34
Physics of Atmospheric Energy Transport is
difficult
  • Potential energy
  • Internal energy
  • Kinetic energy
  • Latent heat
  • Latitude dependent vertical dependence

35
Complete Feedback Models too Difficult to
reliably construct
36
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37
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

38
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

39
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?
40
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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