Climate Science Update

107 Pages·2011·3.12 MB·English

The Centre for Australian Weather and Climate Research
A partnership between CSIRO and the Bureau of Meteorology
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Climate Science Update:
A Report to the 2011 Garnaut Review

Keenan, T.D. and Cleugh, H.A. (Editors)

CAWCR Technical Report No. 036

March 2011

Climate Science Update:
A Report to the 2011 Garnaut Review

Keenan, T.D. and Cleugh, H.A. (Editors)

The Centre for Australian Weather and Climate Research
- a partnership between CSIRO and the Bureau of Meteorology

CAWCR Technical Report No. 036

March 2011

ISSN: 1836-019X
National Library of Australia Cataloguing-in-Publication entry
Author: Keenan, T.D. and Cleugh, H.A. (Editors)

Title: Climate Science Update: A Report to the 2011 Garnaut Review

ISBN: 978-1-921826-22-1 (PDF)

Series: CAWCR technical report, TR036

Notes: Included bibliography references and index.

Subjects: Climatic changes--Australia.

Other Contributors - Technical Production: Andrew Hollis (BoM), Keith Day (BoM)
and Paul Holper (CSIRO).

Dewey Number: 551.6994
Enquiries should be addressed to:

H. Cleugh
CSIRO Marine and Atmospheric Research
Pye laboratory
GPO Box 3023
Canberra
ACT 2601

Copyright and Disclaimer
© 2011 CSIRO and the Bureau of Meteorology. To the extent permitted by law, all rights are
reserved and no part of this publication covered by copyright may be reproduced or copied in any
form or by any means except with the written permission of CSIRO and the Bureau of Meteorology.
CSIRO and the Bureau of Meteorology advise that the information contained in this publication
comprises general statements based on scientific research. The reader is advised and needs to be
aware that such information may be incomplete or unable to be used in any specific situation. No
reliance or actions must therefore be made on that information without seeking prior expert
professional, scientific and technical advice. To the extent permitted by law, CSIRO and the Bureau
of Meteorology (including each of its employees and consultants) excludes all liability to any person
for any consequences, including but not limited to all losses, damages, costs, expenses and any other
compensation, arising directly or indirectly from using this publication (in part or in whole) and any
information or material contained in it.

This document has been prepared by the Centre for Australian Weather and Climate Research
(CAWCR). CAWCR is a partnership between Australia's leading atmospheric and
oceanographic research agencies: the Bureau of Meteorology and CSIRO.
Contents

Introduction (Keenan and Cleugh)................................................................................1
1. Update on the state of the climate, long-term trends and associated causes
(Braganza, Power, Jones, Trewin, Arblaster, Timbal, Plummer, Hope,
Frederiksen and McBride)....................................................................................3
2. Hydrology (Chiew and Prosser)..........................................................................17
3. Building a national capability in climate and Earth system simulation (Hirst).......23
4. Oceans (Church, Hemer, Matear, Rintoul and Wijffels)....................................27
5. Palaeoclimate (Etheridge)....................................................................................41
6. Carbon and other biogeochemical cycles (Canadell and Raupach)...................47
7. Geoengineering – carbon cycle modification (Etheridge, Trull, and Krull).........51
8. Atmospheric constituents and radiative forcing (Fraser, Krummel and Steele)..61
9. Clouds and aerosols (Colman and Rotstayn).....................................................69
10. Projections (Whetton, Moise and Abbs).............................................................73
11. Impacts on Australia (Hennessy and Overton)...................................................81
12. Updates on significant national activities (Keenan, Power and Cleugh).............89

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i i CAWCR Climate Science Update for Garnaut Report
CAWCR Climate Science Update for Garnaut Report

INTRODUCTION

In November 2010, Professor Ross Garnaut was commissioned by the Australian Government
to provide an update of his 2008 Climate Change Review
(http://www.garnautreview.org.au/2008-review.html).
This review (see http://www.garnautreview.org.au/update-2011/terms-of-reference.html) was to
consider developments in climate change mitigation, climate change science, proposals to
develop a carbon price in Australia, trends in domestic and international emissions, changes in
low emission technology, the potential for abatement within the land sector and developments
in the Australian electricity market. A series of papers related to the above are being released
during the period November 2010 to March 2011 with the final report due May 2011.

The Centre for Australian Weather and Climate Research (CAWCR - see
http://www.cawcr.gov.au/) received a request from the Department of Climate Change and
Energy Efficiency (DCCEE) to provide input to this process. This technical report was
developed in response to the request. The rationale was to provide from CAWCR a summary of
the science of climate change, especially since the 2008 Garnaut Report, and associated national
developments in climate change programs.

This report was one part of the process that informed Professor Garnaut during the development
of his Climate Change Science Report. Essentially this science update is a rapid assessment of
material published from 2008 to 2010, designed specifically for consideration by Professor
Garnaut in his climate science update.

This technical report is based on scientific contributions from both CSIRO1 and the Bureau of
Meteorology. It is not intended to be comprehensive in terms of depth or breadth. Rather it is a
snapshot of the “state of the science” mainly from the perspective of CAWCR scientific
expertise based on peer-reviewed literature. The issues covered relate mainly (but not
exclusively) to the scope of Working Group One (WGI) of the Intergovernmental Panel on
Climate Change (http://www.ipcc.ch/); i.e. an assessment of the physical and scientific aspects
of the climate system and climate change. We are particularly grateful to these contributors for
undertaking this significant effort within a very tight timeline.

Thanks are also extended to the reviewers, who played important roles in assessing the content.
For the technical production we extend our thanks to others who assisted, especially Paul
Holper (CSIRO), Andrew Hollis (Bureau of Meteorology) and Keith Day (Bureau of
Meteorology).

Finally we would also like to thank DCCEE and the Garnaut Secretariat for the opportunity to
contribute to this important process.

Tom Keenan Helen Cleugh
Director Climate and Atmosphere Theme Leader
CAWCR CSIRO Marine and Atmospheric Research

1 Primarily from CSIRO Marine and Atmospheric Research Division (http://www.cmar.csiro.au/) with
additional contributions from the CSIRO National Research Flagships
(http://www.csiro.au/partnerships/NRF.html) including: Wealth from Oceans Flagship, Water for a Healthy
Country Flagship, and the Climate Adaptation Flagship.
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CAWCR Climate Science Update for Garnaut Report

1. UPDATE ON THE STATE OF THE CLIMATE, LONG-TERM
TRENDS AND ASSOCIATED CAUSES

Karl Braganza, Scott Power, Blair Trewin, Julie Arblaster, Bertrand Timbal, Pandora
Hope, Carsten Frederiksen and John McBride
The Centre for Australian Weather and Climate Research – A partnership between the Bureau
of Meteorology and CSIRO

David Jones and Neil Plummer
Bureau of Meteorology

This section provides a brief update on Australian climate variability and change since 2008.
We also discuss recent observations and longer-term changes in global temperature, and severe
tropical cyclones making land-fall over eastern Australia. The causes of the observed changes
are discussed in some cases.

Three appendices on popular questions are also provided: i) did global warming stop in 1998?
(Appendix A1), ii) was climate change responsible for Black Saturday? (Appendix A2), and iii)
how are the heavy rains in eastern Australia during late 2010 and early 2011 related to La Niña
and climate change? (Appendix A3).

1.1 Temperature

The decade ending in 2010 has easily been Australia’s warmest decade since record keeping
began and continues a trend of each decade being warmer than the previous that extends back
70 years (Figs 1.1 and 1.2). 2009 was the second warmest year on record based on the mean
annual temperature across Australia. 2010 was +0.19 °C above the 1961 to 1990 average of
21.81°C. This is milder than the previous eight years, underscoring the fact that individual
years can still be relatively cool even as the warming of Australia’s climate continues (see
Appendix A1 for further discussion of related issues).

Fig. 1.1 Annual (red line) and decadal mean (light grey bars) temperature deviations from the
1961 to 1990 average for Australia. This reference period is used throughout this Section unless
stated otherwise. The average for the last ten years is shown in the dark grey bar. Temperature
(and rainfall data appearing later) are quality controlled using multiple analyses to estimate the

robustness of broad-scale trends and variability. Such analyses show that changes in

Australia’s climate over the last 60 years are robust and unlikely to be greatly affected by issues
such as urbanisation, uncertainties, and occasional errors in the observational data. Source:
Australian Bureau of Meteorology.
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Fig. 1.2 Trends in annual mean temperature across Australia during 1910-2010. All regions
show a warming (positive) trend, with values up to approximately 0.2˚C/decade. Source:
Australian Bureau of Meteorology.

Global temperature data for the period 1950-2010 have been compiled by the UK Hadley
Centre and Climatic Research Unit, the National Aeronautics and Space Administration
(NASA), and the US National Climatic Data Centre. These observed data led the World
Meteorological Organization to conclude that “the year 2010 ranked as the warmest year on
record, together with 1998 and 2005. Data received by the WMO show no statistically
significant difference between global temperatures in 2010, 2005 and 1998” (see Fig. 1.3).
Globally, the current decade is the warmest on record.

Fig. 1.3 Global average annual surface temperature deviations from the 1961-1990 average for
the period 1850-2010. Data sources: UK Hadley Centre/Climatic Research Unit, NASA Goddard
Institute for Space Studies, US National Climatic Data Centre.
Reference: http://www.wmo.int/pages/mediacentre/press_releases/pr_906_en.html.

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