This series on ConservationBytes.com takes a page out of our book Tropical Conservation Biology (Sodhi, Brook & Bradshaw) – therein we produced a series of ‘Spotlights’ describing the contributions of great thinkers to conservation science. Each highlight of a Conservation Scholar includes a small biography, a list of major scientific publications and a Q & A on the person’s particular area of expertise.
Our eighth Conservation Scholar is Stephen Schneider…
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.
- Schneider, S.H. and M.D. Mastrandrea (2005) Probabilistic assessment of ‘dangerous’ climate change and emissions pathways. Proceedings of the National Academy of Sciences of the USA 102, 15728-15735
- Root, T. L., D. MacMynowski, M. D. Mastrandrea, and S. H. Schneider. (2005) Human-modified temperatures induce species changes: Joint attribution. Proceedings of the National Academy of Sciences of the USA, 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, Lutterworth, Cambridge
Questions and 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.