Saving a Million Species: Extinction Risk from Climate Change - Softcover

Thomas E. Lovejoy

Softcover

ISBN 10: 1597265705 ISBN 13: 9781597265706

Publisher: Shearwater Books, 2012

Synopsis

The research paper 'Extinction Risk from Climate Change' published in the journal 'Nature' in January 2004 created front-page headlines around the world. The notion that climate change could drive more than a million species to extinction captured both the popular imagination and the attention of policymakers, and provoked an unprecedented round of scientific critique. 'Saving a Million Species' reconsiders the central question of that paper: How many species may perish as a result of climate change and associated threats? Leaders from a range of disciplines synthesize the literature, refine the original estimates, and elaborate the conservation and policy implications. This book examines the initial extinction risk estimates of the original paper, subsequent critiques, and the media and policy impact of this unique study. It presents evidence of extinctions from climate change from different time frames in the past. It explores extinctions documented in the contemporary record. It sets forth new risk estimates for future climate change. It considers the conservation and policy implications of the estimates. 'Saving a Million Species' offers a clear explanation of the science behind the headline-grabbing estimates for conservationists, researchers, teachers, students, and policymakers. It is a critical resource for helping those working to conserve biodiversity takes on the rapidly advancing and evolving global stressor of climate change - the most important issue in conservation biology today, and the one for which we are least prepared.

About this title

About the Author

Lee Hannah is Senior Researcher in Climate Change Biology at Conservation International and adjunct professor in the Bren School of Environmental Science and Management at the University of California, Santa Barbara.

Excerpt. © Reprinted by permission. All rights reserved.

Saving a Million Species

Extinction Risk From Climate Change

By Lee Hannah

ISLAND PRESS

Copyright © 2012 Island Press
All rights reserved.

ISBN: 978-1-59726-570-6

Contents

Title Page, 
Copyright Page, 
FOREWORD, 
PART I - Introduction, 
Chapter 1 - Are a Million Species at Risk?, 
Chapter 2 - First Estimates of Extinction Risk from Climate Change, 
Chapter 3 - Climate Change, Extinction Risk, and Public Policy, 
PART II - Refining First Estimates, 
Chapter 4 - Refining Risk Estimates Using Models, 
Chapter 5 - The Use and Misuse of Species-Area Relationships in Predicting Climate-Driven Extinction, 
PART III - Current Extinctions, 
Chapter 6 - First Extinctions on Land, 
Chapter 7 - Global Warming and Widespread Coral Mortality: Evidence of First Coral Reef Extinctions, 
Chapter 8 - Extinction Risk at High Latitudes, 
PART IV - Evidence from the Past, 
Chapter 9 - Extinctions in Deep Time, 
Chapter 10 - Terrestrial Ecosystem Response to Climate Change during the Paleogene, 
Chapter 11 - Quaternary Extinctions and Their Link to Climate Change, 
Chapter 12 - Quaternary Tropical Plant Extinction: A Paleoecological Perspective from the Neotropics, 
PART V - Predicting Future Extinctions, 
Chapter 13 - Every Species Is an Insect (or Nearly So): On Insects, Climate Change, Extinction, and the Biological Unknown, 
Chapter 14 - Extinction Risk from Climate Change in Tropical Forests, 
Chapter 15 - Coral Reefs, Climate Change, and Mass Extinction, 
Chapter 16 - Extinction Risk in a Changing Ocean, 
Chapter 17 - Climate Change and Freshwater Fauna Extinction Risk, 
Chapter 18 - Climate Change Impacts on Species Interactions: Assessing the Threat of Cascading Extinctions, 
PART VI - Conservation Implications, 
Chapter 19 - Strategies for Reducing Extinction Risk under a Changing Climate, 
Chapter 20 - Saving a Million Species, 
CONTRIBUTORS, 
INDEX, 

CHAPTER 1

Are a Million Species at Risk?

LEE HANNAH

The research paper "Extinction Risk from Climate Change" created front-page headlines around the world when it appeared as the cover story of Nature in January 2004 (Thomas et al., 2004). The notion that climate change could drive more than a million species to extinction captured popular imagination and the attention of policy makers. The story was covered by CNN, ABC News, NBC News, NPR, and major newspapers and magazines in Europe and the United States and was the subject of debate in the House of Commons and in the US Senate.

An unprecedented round of scientific critique quickly followed the huge popular interest in the story. Nature itself published three articles challenging fundamental points of the paper (Harte et al., 2004; Buckley and Roughgarden, 2004; Thuiller et al., 2004), while publications refining or debating the underlying science continue to appear in top research journals. This welter of publications makes for a diverse literature not easily synthesized or accessed, despite the critical policy implications of the research. Most important, the variety of critiques leaves unresolved the major question: What is the extinction risk associated with climate change, and how many species may perish?

Saving a Million Species addresses this important question by synthesizing the literature, by having leaders in the field refine the original estimates of extinction risk, and by drawing on these authors to elaborate the science, conservation, and policy implications of this research in an accessible format.

This book will speak to conservationists, researchers, teachers, undergraduate to graduate students, and policy makers interested in a clear explanation of the science behind the headline-grabbing estimates. Unpacking the research behind the headlines reveals complex chains of causation, with many taxa facing unique challenges. These stories reveal connections among climate change and many other alterations to the natural world, from rain forest destruction to overfishing. The chapters of the book are organized into six parts, each bringing to bear the insights of a relevant discipline. This multiplicity of perspectives breaks down the monolithic large numbers and reveals the complexity of the problem. It allows solutions to begin to take shape.

The six sections explore evidence from the past and present, estimates of future risk from modeling and taxonomic perspectives, and finally the conservation and policy implications. The chapters in part I introduce the original research and its critiques. Part II examines the research published since the 2004 article to refine estimation techniques. Part III explores extinctions documented in the contemporary record—the first of the extinctions due to human-induced climate change. Part IV examines extinctions from past natural climate change. New risk estimates from modeling of future climate change are presented in part V. The sixth and final section addresses the conservation and policy implications of the estimates: What does extinction risk imply for the future of biodiversity and global cooperation on action to curtail climate change?

Science behind the Hype

The saga of extinction risk from climate change began in London in 2002. The International Union for Conservation of Nature (IUCN) called a meeting of international climate change experts there to discuss the threat posed by climate change. The IUCN is a membership organization representing conservation groups from government agencies to nonprofit organizations. They assess and determine the global list of species threatened with extinction. IUCN officers were concerned about the threat climate change posed but didn't know what to do about it. They called in international researchers for advice.

The researchers at the IUCN meeting found a remarkable thing. They all were engaged in modeling of changes in species ranges in different parts of the world—locations as different as Australia and the Amazon. But all were finding high numbers of species losing suitable range, even in relatively mild midcentury (2050) scenarios. And all were finding significant numbers of species losing all of their suitable habitat. Climate change might be a much more serious threat to species' survival than anyone had previously imagined.

But they needed some way to compare their diverse results. The key question was how to estimate extinctions from models of shrinking range size. Chris Thomas, then of the University of Leeds (now at the University of York), had an idea. What if you used the well established species-area relationship (SAR) to estimate extinctions from range-size models? The SAR had previously been used to estimate extinctions based on decreasing forest size. Why not disaggregate that relationship and apply it to range loss in individual species? There were several ways to do that, and it turned out they all showed high levels of extinction risk— almost always in double digits, some estimates as high as 30 or 40 percent.

The London group agreed that these were important results and coalesced behind the leadership of Thomas to produce a research paper describing the results. Thomas had a strong track record with Nature, the most well respected journal in the field, so the manuscript was submitted there. After some hard review questions and revisions, Nature accepted the paper and scheduled it for publication in early 2004. Thomas developed a press release describing the research, in which he extrapolated the results of the paper to all species on Earth, to give the media a sense of the scale of the problem. The research results, and that extrapolation, created the widespread media and public interest in extinction risk from climate change.

Thomas's estimate was built on straightforward math. The extinction risk estimates in the research had a wide range of values, but midrange values showed 18–34 percent of species becoming extinct. There are a wide range of estimates of the number of species on the planet, but 10 million is a midrange value, with about half of those in the oceans. Because the areas modeled in the research were all terrestrial, Thomas excluded the marine species. The math was then simple—18–34 percent of 5 million terrestrial species is 900,000 to 1.7 million species extinctions. Thus, 1 million species is a lower-end estimate of the risk of extinction due to climate change, and it is likely that the total is more than 1 million. That's a large number in anyone's definition, and attracted worldwide attention as a result. Interestingly, despite catalyzing the 2002 meeting, the IUCN never fully bought into the results. The 2004 paper didn't follow the specific rules IUCN uses to create the Red List of species threatened with extinction. The IUCN rules were developed to flag species under immediate threat. The short-term time horizons in those rules are poorly suited to assessing threats such as climate change, which happen now but have effects years or decades in the future. IUCN Red List specialists have published a paper (Akçakaya et al., 2006) making it clear that the methods of Thomas et al. didn't meet the existing international criteria. The IUCN continues to struggle to incorporate climate change into their threat assessments.

Why Should We Care?

The public cared about the research results because extinction is a threat that ordinary people care about and relate to. Researchers often refer to biodiversity, which is a more abstract concept, less widely grasped by nonspecialists. The extinction risk paper translated results into terms to which everyone could relate.

Anyone concerned about conservation sees extinction as a critical yardstick, because it indicates irreversible loss. Biologists care because loss of a species is the loss of an entire evolutionary history and unique set of biological attributes—information that can't be replicated any other way. People of faith care because the creation is one of the great gifts of the Almighty, and extinctions slowly destroy that gift. Schoolchildren, students, and others see extinctions as a clear sign that we are not properly taking care of the planet.

Because of these concerns, extinctions have a more formal role in international policy. Governments care about preventing extinctions because their citizens care. National laws and international agreements have been created to prevent extinctions. The Convention on Biological Diversity is an international treaty designed to prevent the loss of biodiversity, which means preventing extinctions. Many nations have created legislation for national parks and protected areas to give nature safe haven and to guard against extinction.

Most important in the field of climate change, extinctions are embodied in the international treaty on climate change. "Allowing ecosystems to adapt naturally" is one of the three benchmarks of the United Nations Framework Convention on Climate Change (the others being agricultural growth and sustainable development). Ecosystem adaptation is a more sensitive indicator than climate change: it can be impaired at levels of biological disruption far less severe than extinction. But extinction is an exclamation point, a red flag in that context. If species are going extinct due to climate change, then clearly something is very wrong. So from points of view from everyday life to the political, extinctions from climate change matter. The huge press attention to the initial research proved this interest. Virtually every story on the impacts of climate change now references extinction risk. The polar bear is the poster child for these extinctions, but species from the tropics to the poles are affected.

Right for the Wrong Reasons?

The 2004 research was the first attempt to put numbers to climate change extinction risk. Did this first attempt to quantify this complex process get it right? Or was it simply a first straw man, to be torn down and replaced by more accurate estimates?

These questions are hotly debated. Many flaws have been found in the original research methods, some that could raise the estimate, some that could lower it. On the one hand, there is some evidence that the models used may overestimate range loss, and that there are substantial differences between modeling techniques. On the other hand, the climate scenarios used in Thomas et al. estimates were only for midcentury and didn't include interactions with habitat loss.

Climate models carry significant uncertainties, particularly with regard to precipitation. Precipitation change in one global climate model (GCM) will vary by region in ways very different from another GCM. Species distribution models rely on these GCM inputs to estimate changes in range sizes that can be used to estimate extinction risk. So where species range changes are sensitive to change in precipitation, very different results may emerge depending on what climate model is used. Species distribution models carry their own uncertainty, and it is not clear that the SAR can be used in the ways it was applied in the original research. The authors of this book explore these issues in part II.

Counterbalancing these possible sources of overestimation are climate change trajectories and land use interactions. The midcentury climate scenarios used in Thomas et al. are mild in comparison with likely overall change by the end of the century. Climate change is accelerating, and change in the latter half of the century is projected to be much greater than that in the first half century. Further, current emissions are above even the most extreme scenarios used by Thomas et al., so there is even more reason to think that change may be greater than that used to derive the million species estimate.

Conversion of land from natural habitat to human uses continues, and this wasn't factored into the original estimates. Because climate change causes species' ranges to shift, human land uses that block range shifts can dramatically increase likelihood of extinction. As ecosystems unravel and run into agricultural fields and expanding cities, critical interdependencies among species may begin to break down, ramping up extinction risk yet again.

Finally, marine species weren't considered at all in the million species estimate. Yet marine species are threatened not only by climate change, but by acidification caused when carbon dioxide dissolves in seawater. Thus, human CO2 pollution threatens the oceans in two ways—directly through acidification of seawater and indirectly through climate change. There is little reason to think that the species that inhabit the oceans are less vulnerable than those that inhabit terrestrial environments, so there is a large group of potential marine extinctions to consider. There are many reasons to think the million species number is too low, and many important research questions to be pursued to reach final answers. These issues are examined in part V.

So flaws in the early methods that favor overestimation may be more than compensated by strong bias toward underestimation. The purpose of this book is to elaborate these biases, contribute evidence from other lines of inquiry, and let readers decide for themselves. The early estimates may well turn out to be right for the wrong reasons, or to be too low.

How Can We Help?

The ultimate goal of this book is to suggest ways to stem a wave of extinctions due to climate change. By understanding the drivers and magnitude of change, policy makers and conservationists should gain critical insights into effective responses. It is certain that effective action will have two main foci: reduction of greenhouse gas emissions and improved conservation strategies.

Extinction risk helps identify acceptable and unacceptable levels of change relevant to global policy. Large numbers of extinctions are socially unacceptable, and make it impossible to achieve United Nations Framework Convention on Climate Change goal of allowing ecosystems to adapt naturally to climate change. We will need to understand extinction risk to help inform targets for limiting greenhouse gas pollution. The transition to a renewable energy economy is therefore the first ingredient in reducing the extinction risk from climate change.

But greenhouse gas levels are now unlikely to be tamed within the lower bounds safest for ecosystems and species. Thus, the second great challenge is to adapt our conservation strategies to cope with the stresses of climate change that can't be avoided. Given current emissions trajectories and the delays in international action, these stresses are likely to be large. Expanding protected areas, increasing connectivity, and creating ex situ safety nets for species will all be required. We hope that this book may also offer first insights into the magnitude and urgency of these needs.

The chapters that follow synthesize current research and suggest important avenues for advancing our understanding. They do not and cannot provide final answers. We hope that they speed the quest for answers and inform a wide range of readers deeply concerned about extinction risk from climate change.

CHAPTER 2

First Estimates of Extinction Risk from Climate Change

CHRIS D. THOMAS

This chapter reviews the first study that provided an international assessment of the risks to biodiversity associated with climate change. Rapid acceleration of information at the end of the twentieth century showed that the distributions of terrestrial species were responding to climate change (Parmesan et al., 1999; Pounds et al., 1999; Thomas and Lennon, 1999). Combined with the extreme El Niño event of 1998 that caused major bleaching damage to coral reefs, this work confirmed that climate variation and climate change were likely to have major impacts on biodiversity (Sala et al., 2000; IPCC, 2001; Walther et al., 2002; Parmesan and Yohe, 2003).

(Continues...)

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Edition details

• Publisher: Shearwater Books
• Publication date: 2012
• Language: English
• ISBN 10: 1597265705
• ISBN 13: 9781597265706
• Binding: Paperback
• Number of pages: 366
• Editor: Lee Hannah