Climate Change

Interview with Prof Stephen Schneider

As part of a recent textbook I wrote with Prof Navjot Sodhi and Assoc Prof Corey Bradshaw (Tropical Conservation Biology, Wiley-Blackwell, 2007), we interviewed some well known scientists for a ‘Spotlight’ series. Other interviews have been published on BNC’s sister blog, ConservationBytes.

For the chapter entitled “Climate Change: Turning up the tropical heat“, we put some questions to Prof Stephen Schneider. Steve is a good friend of mine who I first met at an extinction conference in Okazaki, Japan, in 2004 – the same conference, incidentally, that motivated Tim Flannery to write The Weather Makers). Steve was later a Thinker in Residence in Adelaide and produced an important public policy document for South Australia on government actions to combat climate change. We’ve also done a tag-team interview on carbon trading.

Anyway, here is the interview, the format for which includes a small biography, a list of major scientific publications and a Q & A on the person’s particular area of expertise.


I am the Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies, Professor of Biological Sciences, and Professor by Courtesy of Civil and Environmental Engineering at Stanford University. I am Co-Director of the Center for Environmental Science and Policy in the Freeman-Spogli Institute and a Senior Fellow in the Woods Institute for the Environment. I received my PhD in Mechanical Engineering and Plasma Physics from Columbia University, USA, in 1971. When considering research areas then, I became aware that anthropogenic dust can cool the climate and greenhouse gases can warm it, and thus decided to switch to studying climate science. Today, my global change interests include the ecological and economic implications of climatic change; integrated assessment of global change; climatic modeling of paleoclimates and human impacts on climate (e.g., carbon dioxide “greenhouse effect”); dangerous anthropogenic interference with the climate system; food/climate and other environmental science/public policy issues; and environmental consequences of nuclear war. I am also dedicated to advancing environmental literacy in all levels of education.

I co-founded the Climate Project at NCAR in 1972 and founded the interdisciplinary journal, Climatic Change, in 1975, which I continue to edit today. I was honoured in 1992 with a MacArthur Fellowship for my ability to integrate and interpret the results of global climate research through public lectures, seminars, classroom teaching, environmental assessment committees, media appearances, Congressional testimonies, and research collaboration with colleagues. I was elected to membership in the US National Academy of Sciences in 2002, and received both the National Conservation Achievement Award from the National Wildlife Federation and the Edward T. Law Roe Award from the Society of Conservation Biology in 2003, and the Banksia Foundation’s International Environmental Award in Australia in 2006. I have served as a Coordinating Lead Author in Working Group II of the Intergovernmental Panel on Climate Change (IPCC) from 1997 to the present. My recent work has centered on the identification and classification of ‘key vulnerabilities’ in the climate system and the role of risk management in climate policy decision-making. I continue to serve as an advisor to decision-makers and stakeholders in industry, government, and the nonprofit sectors. I am also engaged in improving public understanding of science and the environment through extensive media communication and public outreach.

5 most-relevant publications:

Schneider, S.H. and M.D. Mastrandrea, 2005:  “Probabilistic assessment of ‘dangerous’ climate change and emissions pathways,” Proceedings of the National Academy of Sciences 102, 15728-15735.

Root, Terry L., Dena MacMynowski, Michael D. Mastrandrea, and Stephen H. Schneider, 2005: “Human-modified temperatures induce species changes: Joint attribution,” Proceedings of the National Academy of Sciences, 102, 7465-7469.

Mastrandrea, M.D. and S.H. Schneider, 2004: “Probabilistic Integrated Assessment of: ‘Dangerous’ Climate Change,” Science 304, 571–575.

Schneider, S.H., and K. Kuntz-Duriseti, 2002: “Uncertainty and Climate Change Policy,” Chapter 2, in Schneider, S.H., A. Rosencranz, and J.-O. Niles, (eds.) Climate Change Policy: A Survey, Washington D.C.: Island Press, 53–88.

Schneider, S.H., 1990: Global Warming, Are We Entering the Greenhouse Century? Cambridge: The Lutterworth Press, 343 pp. (Japanese edition: Diamond, Tokyo; U.K. edition: Lutterworth, Cambridge; Italian edition: Armenia Editore, Milano; Paperback version (1990): New York: Vintage Books, New York, 343 pp.

Questions & Answers:

1. Climate has varied throughout earth’s history. Why is contemporary climate change particularly dangerous to biodiversity?

The current, much-faster-than-natural rate of temperature change, coupled with multiple stressors, makes contemporary climate change particularly threatening to biodiversity. The forecasted global average rate of temperature increase over this century (approximately 1–5oC/century) greatly exceeds by a rough order of magnitude rates typically sustained during the last 20,000 years. The balance of evidence from meta-analyses of species from many different taxa examined at disparate locations around the globe suggests that a significant impact from recent climatic warming is discernible in the form of long-term, large-scale alteration of animal and plant populations. This evidence takes the form of poleward or upward range shifts and changes in phenology such as dates of migration, breeding and flowering (making spring events for some species 10–15 days earlier over the past few decades). The IPCC has extended climate impact analyses to include such ‘environmental systems’ as sea- and lake-ice cover and mountain glaciers. Clearly, if such climatic and ecological signals are now being detected above the background of climatic and ecological noise for a twentieth-century warming of ‘only’ 0.6oC, it is likely that the combination of highly disturbed landscapes and temperature increases up to an order of magnitude larger by 2100 will have a dramatic impact on biodiversity and ecosystem functioning.

2. Will climate change have less impact in the tropics than at higher latitudes?

There are already signs of severe stress in high-latitude and alpine habitats and in coral reefs, showing that these ecosystems are experiencing significant impacts at present levels of climate change. Human-mediated climate change is or is projected to be affecting tropical biotas via range shifts (latitudinal and elevational), changes in phenology, increasing prevalence, distribution and severity of diseases and parasites, coral bleaching, drying of freshwater systems and sea level rise. The magnitude of temperature changes will be less in the tropics, but changes in the hydrological cycle may still be large. Some models suggest that above a few degrees more warming, tropical forests will switch from a sink to a source of CO2 emissions—a dramatic change if it were to occur as projected. The potential for forest fires under such conditions could become a major threat to forests both in Amazonia and in Southeast Asia because the forests in these regions are not adapted to fire. Species living at higher altitudes in the tropics are particularly vulnerable to climate change due to the disruption or loss of specific microclimates and the higher likelihood of invasive species influx from lower elevations.

3. How might climate change interact with other threats to tropical biodiversity, such as invasive species, fire, and land clearance for agriculture?

Adverse impacts on biodiversity caused by a synergistic suite of threats are already occurring and will continue to intensify climate impacts. It is expected that further warming could substantially rearrange the ranges and interactions of many species. However, because of human land uses such as agriculture, urban settlement and roads, most species no longer have a free range in responding (e.g. by freely migrating) to climatic shifts. The synergism or combined complex interactions of effects among climate changes, land use disturbances, the introduction of exotic species and artificial chemicals will most likely collectively impact on wildlife and terrestrial systems much more significantly than if each of these disturbances were simply considered separately.

4. Are there any benefits of a warmer world rich in atmospheric carbon for tropical ecosystems?

Undoubtedly some species—particularly those that are adaptable, such as crows or weeds—can flourish in disturbed conditions better than specialists such as warblers or orchids. Thus, although the populations of some well-adapted generalists may well expand, the slow rate of speciation and the major threat of endangerment to more vulnerable species have resulted in estimates of 10–50% of species becoming extinct in the next two centuries if warming of more than a few degrees occurs.

5. Based on current trends, how long will it be before the earth’s climate crosses an irreversible and potentially catastrophic tipping point?

It is very difficult to define precise tipping points given remaining uncertainties. Nevertheless, there are potential thresholds for events like ice sheet disintegration or coral reef bleaching, although most such estimates appear as ranges—for example, 1–3oC warming for major reef damages and 1.5–4oC warming for major ice sheet disintegrations.   The bottom line is that the harder and faster the system is disturbed, the more likely such catastrophic changes become.

(with thanks to Navjot Sodhi, Corey Bradshaw, Ward Cooper, Wiley-Blackwell and Stephen Schneider for permission to reproduce the text – buy your copy of Tropical Conservation Biology here)


By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

7 replies on “Interview with Prof Stephen Schneider”

> (approximately 1–5oC/century)

I’m not sure how that looks on your screen
and /View/Character Encoding suggests way too many possibilities.

Could you spell that out in words, to make it clear?


Thanks, thought so, I wasn’t sure it was clear that it stated a range (figured it out further down where other ranges are stated).


“The current, much-faster-than-natural rate of temperature change…”

Is there evidence for this statement? If I smooth (low pass filter) the instrumental temperature record and then examine the derivative, I see nothing unusual about the present rate of change, contrasted with earlier in the century.

“The forecasted global average rate…” The temperature record is diverging from the model forecasts. Every year this divergence continues, suggesting a lower than expected climate sensitivity to CO2. This results in more temperature variability attributable to other unknown factors. Perhaps, these factors also occurred in the past.

Then the alternate hypothesis is that the “…long-term, large-scale alteration of animal and plant populations” was a result of dramatically, but naturally occurring, temperature variations.

My question is, how do we know the temperatures at which these ‘population’ changes occurred? Also, how do we deconfound the environmental temperature with the adaptive, evolutionary change of the species between then and now – or is the time-scale too small for this effect?

many thanks for any response,


Dear Barry Brooks, Steve Schneider and Friends,

Perhaps all of us can agree that science is indisputably the finest source for gaining an adequate understanding of the way the world we inhabit actually works and for accurately enough grasping the “placement” of the human species within the order of living things on Earth. But, as others have noted with such clarity and coherence, too many world-class scientists have treated the human overpopulation of Earth as a taboo topic and, even worse, perniciously participated in the politicization of the science of climate change. Barack Obama cannot know whatsoever could somehow be true, in large part, because so many scientists have failed to reasonably assume their responsibilities to science as well as to sensibly fulfill their duties as scientists.

Rather than do what I have been doing over the past 7 years by extolling the virtues of good science, today I am going to try something different.

What follows is a brief artistic expression that is intended to convey a symbolic meaning parallel to but distinct from, and more significant than, the literal meaning.

Please consider an allegory: that a titanic struggle between human beings and the natural world is in the offing. It seems this struggle is fulminating now precisely because too many leaders of the 6.7 billion {soon to be 9+ billion} members of the human family generally do not share the distinctly scientific, evidence-based perspective of many within this community. Many too many of our brothers and sisters, especially those with great wealth and power, pompously and erroneously believe that human organisms are separate from, and somehow superior to, life as we know it on Earth.

At least to me, it appears that an epochal contest is taking shape on the far horizon between the ‘team’ of “mother culture and father profit” on one side and ‘Team’ Mother Nature on the other.

This could be the greatest show on Earth in 10,000 years.

The team of “mother culture and father profit” appears adamant in its willful intentionality to stay the same old business-as-usual course of recklessly overconsuming limited natural resources; relentlessly expanding large-scale production and distribution capabilities without regard to physical limitations of the natural world; and overpopulating our planetary home, come what may for children and coming generations, biodiversity, the environment and the Earth’s body.

Team Mother Nature simply is.

Which team will likely be seen by reasonable and sensible observers as winning the contest for success in 2012, 2020 and 2050, if the human community continues its idolatry of distinctly human overconsumption, overproduction and overpopulation activities by choosing forevermore unbridled overgrowth activities just as we are doing now?

If the leaders of the family of humanity do not choose change, do you have any ideas about which team will prevail and when will the outcome of the colossal contest no longer be in doubt?



Steven Earl Salmony
AWAREness Campaign on The Human Population,
established 2001


Interested_scientist @4: He is talking about this century and esp. the last 30 years vs the last 1000+ years. As to your other point, I suggest you read my follow-up post.

Steve @5: Well said. Indeed, this is why I prefer to refer to our current situation as the ‘Sustainability Emergency’, since it encompasses much more than just climate change – this is merely a severe symptom of a deeper malaise of living beyond the planet’s means. See the post on Hansen to Obama for a scientist who is fulfilling his duties.


Dear Barry Brooks (#6),

Thanks for your kind words.

Perhaps expressions of intellectual honesty and moral courage in our time are radical things to do because they are so rarely in evidence.

Is it not yet time careful and capable people in large numbers begin to behave honestly and courageously rather than remain silent and comfortable by choosing to follow misguided leaders who are irresponsibly pursuing the patently unsustainable business-as-usual expansion of the global political economy, an unbridled, rampant expansion of big-business activities that is resulting in the massive extirpation of biodiversity, the relentless degradation of our environs, the reckless ravage of Earth’s body and perhaps the endangerment of humanity?

Hurry up, please. Now is the moment for humane, civil action, is it not? If not now, then when?

Steven Earl Salmony
AWAREness Campaign on The Human Population,
established 2001


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