Transcript Climate change, the IPCC, and the media

Climate change: the science,
the IPCC, and the media
Neville Nicholls
School of Geography & Environmental Science
Monash University
Unprecedented droughts
• In each of the last 13 years, Melbourne annual
total rainfall has been below average. Prior to this
dry period, the longest period of below average
rainfall was six years.
• In the last nine years, annual rainfall in the
Murray Darling Basin (the “breadbowl” of
Australia) the rainfall has been below 500mm.
Prior to the current dry period, the longest period
of below 500mm was six years.
Unprecedented hot temperatures:
a few examples
• Adelaide (March, 2008): 15 consecutive days above 35C – seven days
more than the previous record heatwave duration.
• The Melbourne temperature on three successive days at the end of
January 2009 exceeded 43C; never previously seen three days in a row
reach 42C, let alone 43C.
• Black Saturday (2009) set a new Melbourne record temperature of
46.4C, more than 3C hotter than the previous February record.
• The seven hottest August days ever recorded at Windorah in western
Queensland all occurred in 2009. The new record August maximum
temperature for Windorah is 38C; the record prior to 2009 was 34.2C.
• Mean monthly NSW temperature in November 2009 was 4.61C higher
than normal.
• Murray Bridge (near Adelaide) had 6 days in a row >40C in November
2009; never previously had more than a single day >40C.
• Melbourne has had 110 days in a row reaching over 20C, December
2009-March 2010 (previous record was 78 days – set in 2000)
Melbourne record mean daily temperature
(average of max and min)
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Data since 1855
15 December 1876: 34.2˚C
21 January 1997: 34.25˚C
22 January 2006: 34.55˚C
29 January 2009: 35.0˚C
30 January 2009: 35.4˚C
Record broken 4 times in 12 years; now 1.2˚C
warmer than record prior to 1997.
Melbourne, 1979-2001
27-30 January 2009: 42.3˚C
Mean annual temperature has
been increasing everywhere
Global September-February near surface
temperatures
John Tyndall, 1861
“…a slight change in its [the atmosphere’s] variable
constituents…may have produced all the mutations
of climate which the researches of geologists
reveal.” Tyndall (1861)
Greenhouse effect: history
• John Tyndall (1861): shows CO2, water vapour are
“greenhouse gases”
• Guy Callendar (1930s): atmospheric CO2 concentration
increasing, leading to warming
• Gilbert Plass (1950s): Predicted warming of about 2C
by 2000.
• 1972: John Sawyer “The increase of 25% in CO2
expected by the end of the century therefore
corresponds to an increase of 0.6ºC in world
temperature”
• 1988: Intergovernmental Panel on Climate Change
(IPCC) established
The IPCC is a “remarkable example” of
mobilizing expert analysis to inform
policymakers
Jeffrey Sachs (Nature, 12 August 2004)
The IPCC assessments are
“dull as dishwater”
Tim Flannery, The Weather Makers
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Role of the IPCC
- to assess…the scientific, technical and socio-economic
information relevant to understanding the scientific basis
of risk of human-induced climate change, its potential
impacts and options for adaptation and mitigation
- IPCC reports should be neutral with respect to policy
- Review is an essential part of the IPCC process
- Membership open to any member country of UNEP and
WMO
- Four small (5-10 staff) Technical Support Units. Other
participation (by scientists) is pro bono
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Annual numbers of peer-reviewed journal papers on “climate
change”, or “greenhouse effect” or “global warming”
Evolution of the IPCC
Working
Group I
Working
Group II
Working
Group III
FAR (1990)
Science
Impacts
Response
SAR (1996)
Science
Impacts,
Adaptation and
Mitigation
Economic and
Social
Dimensions
TAR (2001)
The Scientific
Basis
Impacts,
Adaptation and
Vulnerability
Mitigation
AR4 (2007)
The Physical
Science Basis
Impacts,
Adaptation and
Vulnerability
Mitigation
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Structure of IPCC AR4 Assessment
• 3 Working Group Reports:
– Full Reports
• Each ~1000 pages
• Extensive expert and government review
• “Accepted” by IPCC Working Group Plenary
– Summaries for Policy Makers
• Typically 20 pages
• Detailed expert & government review
• “Approved” line-by-line by Working Group Plenary
• Synthesis Report
– Synthesizes the 3 WG reports
– About 30 pages, with 5 page Summary for Policy Makers
– SPM “approved” line-by-line by IPCC Panel, November 2007
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AR4 WGI: The Physical Science Basis
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Historical overview of climate change science
Changes in atmospheric constituents and in radiative forcing
Observations: Surface and atmospheric climate change
Observations: Changes in snow, ice and frozen ground
Observations: Oceanic climate change and sea level
Paleoclimate
Couplings between changes in the climate system and
biogeochemistry
8. Climate models and their evaluation
9. Understanding and attributing climate change
10. Global climate projections
11. Regional climate projections
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WGI: Chapter 9 “Understanding and attributing
climate change”
• Coordinating Lead Authors
– Gabriele Hegerl (USA)
– Francis Zwiers (Canada)
• Lead authors
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Pascale Braconnot (France)
Nathan Gillett (Canada)
Yong Luo (China)
Jose Antonio Marengo (Brazil)
Neville Nicholls (Australia)
Joyce Penner (USA)
Peter Stott (United Kingdom)
• Review editors
– David Karoly (USA)
– Laban Ogallo (Kenya)
– Serge Planton (France)
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WGI AR4 Schedule
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May 2004: Author teams selected
September 2004: 1st Lead Author meeting, Trieste
February 2005: Informal review of preliminary draft
May 2005: 2nd LA meeting, Beijing
September 2005: External review of 1st draft begins
December 2005: 3rd LA meeting, Christchurch
April 2006: External and government review of 2nd draft
June 2006: 4th LA meeting, Bergen
October 2006: Final draft to governments - SPM review
February 2007: WGI plenary (Paris) approves/accepts
documents
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WGI: The Physical Science Basis
>30,000 reviewer comments
>6,000 references cited
>900 pages
154 Lead Authors
11 chapters
5 meetings
>3 years
We need to include human action in climate models, to simulate recent warming
Projected changes in extremes (global)
The Australian misrepresents IPCC
The Australian
IPCC AR4
• Research by hurricane scientists
may force the UN climate panel
to retract its claims that
greenhouse gas emissions have
caused an increase in the number
of tropical storms
• There is no clear trend in the
annual numbers of tropical
cyclones.
• The benchmark 2007 report by
the Intergovernmental Panel on
Climate Change said an increase
in cyclone force storms since
1970 was probably caused by
climate change
• It is more likely than not that
anthropogenic influence has
contributed to increases in the
frequency of the most intense
tropical cyclones. Stronger
attribution is not possible at the
moment because…
The Australian misrepresents Knutson et al
The Australian
• Cyclone climate link
rejected
Knutson et al
• …future projections based on
theory and high-resolution
dynamical models consistently
indicate that greenhouse
warming will cause the
globally averaged intensity of
tropical cyclones to shift
towards stronger storms, with
intensity increases of 2-11% by
2100
• …high resolution modelling
studies typically project
substantial increases in the
frequency of the most intense
cyclones
The Australian exaggerates differences between
IPCC (2007) & Knutson et al (2010)
Knutson et al (2010)
• Some increase in the mean
maximum wind speed of tropical
cyclones is likely ✓
• It is likely that the global frequency
of tropical cyclones will either
decrease or remain essentially
unchanged ✓
• Rainfall rates are likely to increase
✓
• …despite some suggestive
observational studies, we cannot at
this time conclusively identify
anthropogenic signals in past
tropical cyclone data
IPCC AR4 (2007)
• It is likely that future tropical
cyclones…will become more intense,
with larger peak wind speeds ✓
• less confidence in projections of a
global decrease in numbers of tropical
cyclones ✓
• Likely that future tropical cyclones will
[have]…more heavy precipitation ✓
• It is more likely than not that
anthropogenic influence has
contributed to increases in the
frequency of the most intense tropical
cyclones [but….]
UK Government advertisements
Comparison to IPCC (2007)
Advertisement
IPCC (2007)
• “Extreme weather events
such as storms, floods and
heatwaves will become
more frequent and intense.”
• “very likely increase in
frequency of hot extremes,
heat waves and heavy
precipitation”
• “very likely” means “>90%
chance”
On-line climate information resources
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http://www.realclimate.org/
http://www.climatedata.info/index.html
http://scienceblogs.com/deltoid/
http://tamino.wordpress.com/
http://www.youtube.com/user/greenman361
0#p/u
• http://www.skepticalscience.com/
• http://www.ipcc.ch
Wiley Interdisciplinary Reviews: Climate Change