Sir John Houghton

¡¡Jf Cambridge fejP UNIVERSITY PRESS


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Information on this title: © J. T. Houghton 1994, 1997, 2004, 2009

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First published in print format 2009

ISBN-13 978-0-511-53365-5 ISBN-13 978-0-521-88256-9 ISBN-13 978-0-521-70916-3

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To my grandchildren, Daniel, Hannah, Esther, Max, Jonathan, Jemima and Sam and their generation


Preface page xvii

1 Global warming and climate change 1 Is the climate changing? 2 The last 30 years 2 El Niño events 7 The effect of volcanic eruptions on temperature extremes 10 Vulnerability to change 10 What is global warming? 13 Adaptation and mitigation 14 Uncertainty and response 15 Questions 16 Further reading and reference 17

2 The greenhouse effect 18 How the Earth keeps warm 19 The greenhouse effect 20

Pioneers of the science of the greenhouse effect 23

Mars and Venus 27

The 'runaway' greenhouse effect 28

The enhanced greenhouse effect 29

Summary 31

Questions 32

Further reading and reference 32

3 The greenhouse gases 34 Which are the most important greenhouse gases? 35 Radiative forcing 35 Carbon dioxide and the carbon cycle 35

The biological pump in the oceans 43

What we can learn from carbon isotopes 44

Future emissions of carbon dioxide 46

Feedbacks in the biosphere 48

Other greenhouse gases 50

Gases with an indirect greenhouse effect 57

Particles in the atmosphere 57

Global warming potentials 63

Estimates of radiative forcing 63

Summary 64

Questions 65

Further reading and reference 67

4 Climates of the past 69 The last hundred years 70

Atmospheric temperature observed by satellites 72

The last thousand years 79

The past million years 82

Palaeoclimate reconstruction from isotope data 84

How stable has past climate been? 87

Summary 90

Questions 91

Further reading and reference 92

5 Modelling the climate 93 Modelling the weather 94

Setting up a numerical atmospheric model 97

Data to initialise the model 98

Seasonal forecasting 101

Weather forecasting and chaos 102

A simple model of the El Niño 105

The climate system 106

Forecasting for the African Sahel region 107

Feedbacks in the climate system 108

Cloud radiative forcing 112

Climate feedback comparisons 115

Models for climate prediction 116

Validation of the model 119

The ocean's deep circulation 120

Modelling of tracers in the ocean 124

Comparison with observations 124

Is the climate chaotic? 128

Regional climate modelling 130

The future of climate modelling 131

Summary 132

Questions 133

Further reading and reference 134

6 Climate change in the twenty-first century and beyond 137 Emission scenarios 138

The emission scenarios of the Special Report on Emission

Scenarios (SRES) 140

Model projections 141

Projections of global average temperature 143

Simple climate models 144

Equivalent carbon dioxide (CO2e) 147

Regional patterns of climate change 149

Changes in climate extremes 154

Regional climate models 161

Longer-term climate change 163

Changes in the ocean thermohaline circulation 164

Other factors that might influence climate change 165

Does the Sun's output change? 166

Summary 167

Questions 168

Further reading and reference 169

7 The impacts of climate change 172 A complex network of changes 173

Sensitivity, adaptive capacity and vulnerability:

some definitions 173

How much will sea level rise? 176

Thermal expansion of the oceans 177

Impacts in coastal areas 181

Increasing human use of fresh water resources 187

The impact of climate change on fresh water resources 190

Impact on agriculture and food supply 196

Desertification 197

The carbon dioxide 'fertilisation' effect 199

Modelling the impact of climate change on world food supply 200

The impact on ecosystems 203

Forest-climate interactions and feedbacks 208

The impact on human health 213

Heatwaves in Europe and India, 2003 215

Impacts on Africa 216

Adaptation to climate change 217

Costing the impacts: extreme events 219

The insurance industry and climate change 222

Costing the total impacts 223 Estimates of impacts costs under business-as-usual (BAU)

from the Stern Review 227

Summary 232

Questions 233

Further reading and reference 234

8 Why should we be concerned? 239 Earth in the balance 240 Exploitation 240 'Back to nature' 241 The technical fix 242 The unity of the Earth 243

Daisyworld and life on the early Earth 246

Environmental values 247

Stewards of the Earth 250

Equity - intergenerational and international 252

The will to act 253

Summary 254

Questions 255

Further reading and reference 257

9 Weighing the uncertainty 260 The scientific uncertainty 261

The reasons for scientific uncertainty 262

The IPCC Assessments 263

Narrowing the uncertainty 267

Space observations of the climate system 268

Sustainable development 270

Sustainable development: how is it defined? 272

Why not wait and see? 273

The Precautionary Principle 274

Principles for international action 276

Some global economics 276

The Rio Declaration 1992 278

Integrated Assessment and Evaluation 280

Summary 285

Questions 286

Further reading and reference 287

10 A strategy for action to slow and stabilise climate change 290

The Climate Convention 291

Extracts from the UN Framework Convention on

Climate Change 291

Stabilisation of emissions 293

The Montreal Protocol 294

The Kyoto Protocol 294

The Kyoto mechanisms 298

Carbon trading 299

Forests 300

The world's forests and deforestation 301 Reduction in sources of greenhouse gases other than carbon dioxide 305

Stabilisation of carbon dioxide concentrations 307

The choice of stabilisation level 311

Realising the Climate Convention Objective 315

Summary 319

Questions 320

Further reading and reference 322

11 Energy and transport for the future 325 World energy demand and supply 326 Future energy projections 330

Energy intensity and carbon intensity 331

Socolow and Pascala's Wedges 335

A long-term energy strategy 336

Buildings: energy conservation and efficiency 336

Where are we heading? Components of energy strategy 338

Thermodynamic efficiencies 339

Efficiency of appliances 340

Insulation of buildings 341

Example of a ZED (Zero Emission Development) 343

Energy and carbon dioxide savings in transport 343

Technologies for reducing carbon dioxide emissions from motor vehicles 346

Energy and carbon dioxide savings in industry 346

Carbon-free electricity supply 347

Hydropower 351

Biomass energy 353

Biomass projects in rural areas in the developing world 354

Biofuels 357

Wind energy 358

Wind power on Fair Isle 360

Energy from the Sun: Solar Heating 360

Solar water heating 361

Solar energy in building design 362

The photovoltaic solar cell 364

Local energy provision in Bangladesh 366

Other renewable energies 367

The support and financing of carbon-free energy 369

Policy instruments 370

Mitigation technologies and potential in 2030 375

Technology for the longer term 375

Fuel cell technology 376

Power from nuclear fusion 377

A Zero carbon future 378

IEA World Energy Outlook 2008 381

Energy policy in the UK 382

Summary 383

Questions 385

Further reading and reference 387

12 The global village 391

Global warming - global pollution 392

Sustainability - also a global challenge 393

Not the only global problem 394

Poverty and population growth 396

The challenge to all sections of community 397

The conception and conduct of environmental research 400

What the individual can do 401

The goal of environmental stewardship 402

Questions 404

Further reading and reference 406

Appendix 1 408

Sl unit prefixes 408

Chemical symbols 408

Appendix 2: Acknowledgements for figures, photos and tables 409

Figures 409

Photos 415

Tables 417

Glossary Index

418 426


Global Warming is a topic that increasingly occupies the attention of the world. Is it really happening? If so, how much of it is due to human activities? How far will it be possible to adapt to changes of climate? What action to combat it can or should we take? How much will it cost? Or is it already too late for useful action? This book sets out to provide answers to all these questions by providing the best and latest information available.

I was privileged to chair or co-chair the Scientific Assessments for the Intergovernmental Panel on Climate Change (IPCC) from its inception in 1988 until 2002. During this period the IPCC published three major comprehensive reports - in 1990, 1995 and 2001 - that have influenced and informed those involved in climate change research and those concerned with the impacts of climate change. In 2007, a fourth assessment report was published. It is the extensive new material in this latest report that has provided the basis for the substantial revision necessary to update this fourth edition.

The IPCC reports have been widely recognised as the most authoritative and comprehensive assessments on a complex scientific subject ever produced by the world's scientific community. On the completion of the first assessment in 1990, I was asked to present it to Prime Minister Margaret Thatcher's cabinet - the first time an overhead projector had been used in the Cabinet Room in Number 10 Downing Street. In 2005, the work of the IPCC was cited in a joint statement urging action on climate change presented to the G8 meeting in that year by the Academies of Science of all G8 countries plus China, India and Brazil. The world's top scientists could not have provided stronger approval of the IPCC's work. An even wider endorsement came in 2007 when the IPCC was awarded a Nobel Peace Prize.

Many books have been published on global warming. My choice of material has been much influenced by the many lectures I have given in recent years to professional, student and general audiences. The strengths of this book are that it is:

• up-to-date with the latest reliable, accurate and understandable information about all aspects of the global warming problem for students, professionals and interested or concerned citizens.

• accessible to both scientists and non-scientists. Although there are many numbers in the book - I believe quantification to be essential - there are no mathematical equations. Some important technical material is included in boxes.

• comprehensive, as it moves through the basic science of global warming, impacts on human communities and ecosystems, economic, technological and ethical considerations and policy options for action both national and international.

• appropriate as a general text for students, from high-school level up to university graduate. Questions and problems for students to consider and to test their understanding of the material are included in each chapter.

• Its simple and effective visual presentation of the vast quantities of data available on climate change ensures that readers can see how conclusions are made, without being overwhelmed. Illustrations are available online.

Over the 20 years since the inception of the IPCC, our understanding of climate change has much increased and significant changes in climate due to human activities have been experienced. Further, studies of the feedbacks that determine the climate response have shown an increasing likelihood of enhanced response, so leading over these years to greater concern about the future impact of climate change on both human populations and ecosystems. Can much be done to alleviate the impact or mitigate future climate change? Later chapters of the book address this question and demonstrate that the technology is largely available to support urgent and affordable action. They also point to the many other benefits that will accrue to all sectors of society as the necessary action is taken. However, what seems lacking as yet is the will to take that action.

As I complete this revised edition I want to express my gratitude, first to those who inspired me and helped with the preparation of the earlier editions, with many of whom I was also involved in the work of the IPCC or of the Hadley Centre. I also acknowledge those who have assisted with the material for this edition or who have read and helpfully commented on my drafts, in particular, Fiona Carroll, Jim Coakley, Peter Cox, Simon Desjardin, Michael Hambery, Marc Humphreys, Chris Jones, Linda Livingstone, Jason Lowe, Tim Palmer, Martin Parry, Ralph Sims, Susan Solomon, Peter Smith, Chris West, Sue Whitehouse and Richard Wood. My thanks are also due to Catherine Flack, Matt Lloyd, Anna-Marie Lovett and Jo Endell-Cooper of Cambridge University Press for their competence and courtesy as they steered the book through its gestation and production.

Finally, I owe an especial debt to my wife, Sheila, who gave me strong encouragement to write the book in the first place, and who has continued her encouragement and support through the long hours of its production.

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