In 1968, I began scientific research on the possible ecological effects of global warming, and published my first scientific paper about this subject in 1973. During the same period, I developed a computer model of forest growth. Called JABOWA, it became one of the major methods in the 1980s and 1990s to forecast possible effects of global warming on forests and some endangered forest species. When I first became concerned about global warming, there was a relatively small group of scientists - ecologists, climatologists, and meteorologists mostly - who were thinking about it. In the years since, I have continued to do research and publish articles, both scientific and for lay people, about global warming. I devoted a chapter and more to this subject in my first major trade book, Discordant Harmonies: A New Ecology for the 21st Century(Oxford University Press, New York: 1990).
In all of this work, my goal was to do an objective scientific analysis and new research, following traditional scientific principles of disprovability. This research includes observations (empirical studies) and theory. Wherever possible, theoretical models have been tested and validated.
Now that global warming has become a major public issue, a great many people are speaking and writing about global warming , regardless of their knowledge, experience, research, and study of the subject. As a result, people have been asking me a variety of questions about the scientific basis of what we are being told.
Ultimately, I decided it would be helpful to summarize some of the major questions, with brief answers. To assure the reader that I have done years of research on this subject, I have also listed my major papers that deal directly with ecological effects of global warming or provide some scientific results essential to assessing some of its possible ecological effects. That list follows the 21 questions and answers.
One of the reasons that debates over global warming become confused is that the subject raises a number of scientific questions and as a result people often talk at cross-purposes. Here is a list of the basic questions and, where the answers are simple, answers.
Questions about Global Warming Itself
1. Is there a greenhouse effect?
Yes, some gases and liquids transmit visible light and absorb infrared light.
2. What are the major greenhouse gases in our atmosphere?
Water vapor, carbon dioxide, methane, nitrogen oxides, and CFCs (Freon). Strictly speaking, water vapor is the major greenhouse gas by concentration; the rest are minor constituents of the atmosphere.
3. If carbon dioxide is only 0.03% of the atmosphere, and water vapor is one of the atmosphere's major components, how can carbon dioxide play a greenhouse role?
The answer has to do with the infrared wavelengths carbon dioxide absorbs uniquely and the fact that it liquefies and freezes at a lower temperature than water does and therefore can act as a greenhouse gas much higher in the atmosphere than water can.
4. Has the climate changed in the past prior to the industrial age and prior to any human effects on the atmosphere? If so, at rates and degrees that are forecast by current climate models to happen in the near future for us?
Yes, recent scientific evidence indicates that climate has always been changing, and prior to human influences, temperature has changed as rapidly and to as great a degree as is forecast to occur in the future from the global warming computer models.
5. Is carbon dioxide increasing?
Yes. There are solid data for this.
6. Are any of the other greenhouse gases increasing?
Data support that this is happening for methane, nitrogen oxides, and CFCs. It is worth noting that rate of increase in methane, CFC-11, and CFC-12 slowed (or even decreased) recently, for reasons that are not well explained or understood.
7. Has the temperature been rising steadily in recent years?
There have been decades in the 20th century when the temperature rose and decades when it fell. Up through the end of the 1990s, there had been a recent warming trend. So far, it is unclear whether this is continuing in the 21st century. A warming trend began around 1850, lasting until the1940s, when temperatures began to cool again, followed by a leveling off of temperature in the 1950s, and a further drop during the 1960s. After that, the average surface temperature rose.
8. What is the source of the major beliefs that global warming will occur and will have severe and undesirable effects?
Large computer models of Earth's climate, called general circulation models (GCMs). There are at least 30 of these in use worldwide.
9. Have these climate models been proved to be true?
Scientists refer to such proof as model validation. The GCMs have not been validated with standard scientific methods.
10. Are there any legitimate questions about the forecasts from these climate models?
Yes. In particular: Climate modelers and their critics agree that the models do not do a very good job with water in the atmosphere. As the climate warms, more water is evaporated from Earth's surface. A key question is: Does most of this water remain vapor (a greenhouse gas) or condense into clouds (that cool the climate)?
- The models are steady-state, requiring and assuming that a specific change in the concentration of a greenhouse gas always has the same effect, regardless of past changes and total concentration. In fact, however, climate is always changing and is not in a steady state.
- The effect on climate of carbon dioxide and other greenhouse gases is not linear. As the concentration of carbon dioxide goes up, an increase in a ton of CO2 has less and less effect on climate.
- The relative effects of greenhouse gases compared to other factors that influence the Earth's temperature are still open to debate. Among these other factors are the following:
- variations in the sun's energy output;
- internal dynamics of the atmosphere, ocean, and life, which can modulate the direct greenhouse effects.
- One of the main causes of variation in sunlight reaching the Earth is long-term variations in our planet's path around the sun and its tilt and wobble as it spins like a top. Known as the Milankovitch cycles, these produce variations over 20,000, 40,000, and 100,000 years and are believed to be the primary drivers of the glacial and interglacial cycles.
- The models are weak in their handling of the dynamics of land vegetation and ocean dynamics, and the coupling among these and the dynamics of the atmosphere. Since both oceans and land vegetation --- especially forests, wetlands, and grasslands --- can have major effects on atmospheric chemistry and physics, these aspects of the global models need considerable attention.
Questions about Possible Effects of Global Warming
11. The UN IPCC report states that up to 30% of animal and plant species will be threatened with extinction in the next few decades from global warming. Is this realistic?
In the past 2½ million years, under climate change as great and as fast, very few animal and plant species went extinct, far less than 30%. Most forecasting methods suggest that extinctions will be fewer than the IPCC asserts. Methods that suggest high rates of extinction assume that the world is in steady state and must be in steady state for species to persist; that species have little or no ability to adjust and adapt to climate change, contrary to well-established biological and ecological knowledge.
12. Will tropical epidemic diseases spread widely and rapidly?
Some excellent scientific papers show that temperature is not a good basis to forecast the spread of malaria and encephalitis. In fact, until the second half of the 20th century, malaria was endemic and widespread in many temperate regions and there were epidemics north to the Arctic Circle.
13. Will all the ice in the arctic melt?
Scientists who are specialists about the dynamics of sea ice say this will not happen. What might happen is that the Northwest Passage could open up - could become ice-free - for a few months in the summer; large areas of sea ice in the arctic might melt back, but these would be renewed each year. Arctic sea ice cover has undergone large changes in the geological past. For example, studies of deposits of fossil plankton indicate that sea ice in the Chukchi Sea was significantly less between 6,000 and 2,500 years ago. (These organisms respond rapidly to climate change.)
14. Will many arctic mammals go extinct from this change in ice cover?
Today's arctic mammals evolved long enough ago for the species to have experienced past climate changes of equal rate and amount, and survived these. Experts on arctic mammals are concerned about a few that have very specific requirements and narrow, highly specialized ecological niches.
15. What about polar bears?
There are between 17,000 and 27,000 polar bears worldwide, and some of the populations have increased recently. Polar bears evolved several hundred thousand years ago and survived past climate changes equal in rate and amount to what is forecast to happen in the future. Ecologists and geneticists have in the past said that a species is not likely to be threatened with extinction until its number gets below 500 individuals.
16. Are all mountain glaciers melting because of present warming?
No. A prime example is Mt. Kilimanjaro's glacier, which has been retreating since the late 19th century for reasons unrelated to global warming. Some mountain glaciers may retreat from global warming, but this can happen only when the temperature at the elevation of the glaciers is above freezing, or if global warming greatly reduces snowfall in those mountains.
17. Is Greenland's ice melting? If so, will it disappear?
Current scientific papers disagree about the extent to which Greenland has lost its glacial ice in recent years and about how much the glaciers will change in the future. But the most thorough recent study by Greenland scientists suggests that Greenland's glaciers have oscillated and are not in general decreasing.
18. Is the sea level rising rapidly because of global warming?
The sea level has been rising at about a 18 cm (7 inches) a century since the end of the last ice age. Between 1993 and 2003, the sea level rose about 3.1mm/year, or a rate of 31 cm (about 1 foot) a century. There is much disagreement about what may happen to the sea level in the future, even among climatologists and oceanographers, and even if global warming happens as forecast by the global climate models.
19. Will some island nations disappear due to sea-level rise?
Yes, even from the background rate (the rate at which the sea level has been rising without global warming). But the jury is still out as to whether the sea level is rising more rapidly than that, and therefore might be causing accelerated problems of this kind. (Of course, healthy coral reefs grow and in the past have kept pace with sea level rise.)
20. Will global warming affect world food production?
If global warming occurs, it will change where the best areas for agriculture will be. Present forecasting methods are not good enough to tell us much more than that. The result will be that some countries will benefit and others will lose agriculture production.
21. Are there any fundamental underlying issues we have not addressed?
One of the most important is whether, globally, life and its life-supporting systems have been, must be, and are best in a steady state, one that is unchanging over time. The most extreme concerns about global warming assume that life and its environment must remain as they were around 1960. This assumption is common among climatologists who argue that global warming is happening and will be disastrous. In contrast, ecologists have established that ecological systems are not steady-state and that species not only have evolved and adapted to change, but in fact many, perhaps most, require change.
Global warming Publications by Daniel B. Botkin
Botkin, D.B., and E.A. Keller, 1987, Environmental Studies: Earth as a Living Planet (Columbus, Ohio: Charles E. Merrill), 500 pp. (2nd edition; 1st edition published 1982).
Botkin, D.B., M. Caswell, J.E. Estes, and A. Orio, eds., 1989, Changing the Global Environment: Perspectives on Human Involvement (New York: Academic Press).
Botkin, D.B., 1990, Discordant Harmonies: A New Ecology for the 21st Century (New York: Oxford University Press).
Botkin, D.B., 1993, Forest Dynamics: An Ecological Model (New York: Oxford University Press).
Skinner, B., S. Porter, and D.B. Botkin, 1999, The Blue Planet (New York: John Wiley & Sons).
Botkin, D. B., and E.A. Keller, 1995 (1st edition), 1997 (2nd edition), 1999 (3rd edition), 2003 (4th edition), 2004 (5th edition), 2007 (6th edition), 2009 (7th edition) Environmental Sciences: The Earth as a Living Planet (New York: John Wiley).
Keller, E.A., and D.B. Botkin, 2007, Essential Environmental Science (New York: John Wiley).
Global Warming Articles and Reports by Daniel B. Botkin
Botkin, D.B., J.F. Janak, and J.R. Wallis, 1973, Estimating the effects of carbon fertilization on forest composition by ecosystem simulation, pp. 328-344, In G.M. Woodwell and E.V. Pecan, eds., Carbon and the Biosphere, Brookhaven National Laboratory Symposium No. 24, Technical Information Center, U.S.A.E.C., Oak Ridge, TN.
Botkin, D.B., 1977, Forests, lakes, and the anthropogenic production of carbon dioxide, BioScience 27: 325-33
Woodwell, G.M., R.H. Whittaker, W.A. Reiners, G.E. Likens, C.A.S. Hall, C.C. Delwiche, and D.B. Botkin, 1978, The biota and the world carbon budget, Science 199: 141-146.
Ralston, Charles W., G.M. Woodwell, R.H. Whittaker, W.A. Reiners, G.E. Likens, C.C. Delwiche, D.B. Botkin, 1979, Where Has All the Carbon Gone? Science, New Series, Vol. 204, No. 4399. (Jun. 22, 1979), pp. 1345-1346.
Botkin, D.B.,ed., 1980, Life from a Planetary Perspective: Fundamental Issues in Global Ecology. Final report NASA Grant NASW-3392. 49 pp.
Botkin, D.B., 1982, Can there be a theory of global ecology? Journal of Theoretical Biology, 96: 95-98.
Botkin, D.B., 1984, The Biosphere: The New Aerospace Engineering Challenge. Aerospace America, July 1984, pp. 73-75.
Botkin, D.B., J.E. Estes, R.M. MacDonald, M.V. Wilson, 1984, Studying the Earth's Vegetation from Space, BioScience 34(8):508-514.
Botkin, D.B., and S.W. Running, 1984, Role of Vegetation in the Biosphere, Purdue University Machine Processing of Remotely Sensed Data (Symposium), pp. 326-332.
Davis, M.B., and D.B. Botkin, 1985, Sensitivity of the Cool-Temperate Forests and Their Fossil Pollen to Rapid Climatic Change, Quaternary Research 23:327-340.
Botkin, D.B., 1985, The Need for a Science of the Biosphere, Interdisciplinary Science Reviews,10(3):267-278.
Botkin, D.B., 1985, The Science of the Biosphere, Origin of Life, 15:319-325.
Orio, A.A., and D.B. Botkin, eds.,1986, Man's Role in Changing the Global Environment, Proceedings of International Conference, Venice, Italy, 21-26 October 1985; The Science of the Total Environment 55: 1-399 and 56:1-415.
Bretherton, F.P., D.J. Baker, D.B.Botkin, K.C.A. Burke, M. Chahine, J.A. Dutton, L.A. Fisk, N.W.Hinners, D.A. Landgrebe, J.J. McCarthy, B. Moore, R.G. Prinn, C.B. Raleight, WV.H.Reis, W.F. Wee,s, P.J. Zinke, 1986, Earth Systems Science: A Program for Global Change, NASA Earth Systems Science Committee of the NASA Advisory Council, Washington, DC. 48pp + supplements.
Botkin, D.B. 1986, ed., Remote Sensing of the Biosphere, National Academy of Sciences, Washington, DC.
Botkin, D.B., 1989, "Science and The Global Environment," pp. 3-14 (Chapter 1) in Botkin, D.B., M. Caswell, J.E.Estes, A.Orio, eds., Man's Role in Changing the Global Environment: Perspectives on Human Involvement (Boston: Academic Press).
Stolz, J.F., D.B. Botkin, and M.N.Dastoor, 1989, "The Integral Biosphere", pp. 31-49 (Chapter 3) in M.B. Rambler and L. Margulis, eds., Global Ecology:Towards a Science of the Biosphere (Boston: Academic Press).
Botkin, D.B., R.A. Nisbet, and T.E. Reynales, 1989, "Effects of Climate Change on Forests of the Great Lake States, pp.22-31 in The Potential Effects of Global Climate Change on the United States, J.B. Smith and D.A. Tirpak, eds. U.S. Environmental Protection Agency, Washington, DC, EPA -203-05-89-0.
Rosenfeld, A.H., and D.B. Botkin, 1990, Trees Can Sequester Carbon, Or Die, Decay, and Amplify Global Warming: Possible Positive Feedback Between Rising Temperature, Stressed Forests, and CO2, Physics and Society 19:4pp.
Botkin, D.B., and L. Simpson, 1990, Biomass of the North American Boreal Forest: A step Toward Accurate Global Measures: Biogeochemistry 9:161-174.
Botkin, D.B., and L.G. Simpson, 1990, Distribution of Biomass in the North American Boreal Forest, pp. 1036-1045 in G. Lund, ed. Proceedings of the International Conference on Global Natural Resource Monitoring and Assessments: Preparing for the 21st Century, American Society for Photogrammetry and Remote Sensing.
Botkin, D.B., and R.A. Nisbet, 1990, Response of Forests to Global Warming and CO2 Fertilization, Report to EPA.
Botkin, D.B., D.A. Woodby, and R.A. Nisbet, 1991, Kirtland's Warbler Habitats: A Possible Early Indicator of Climatic Warming, Biological Conservation 56 (1): 63-78.
Botkin, D.B., 1991, Global Warming and Forests of the Great Lakes States: An Example of the Use of Quantitative Projections in Policy Analysis. An Essay submitted for the George and Cynthia Mitchell International Prize Competition, 1991, which won first prize and was published by the Mitchell Foundation, Houston, TX.
Botkin, D. B., 1991, Global Warming: What it is, What is Controversial About it, and What We Might Do In Response To It, UCLA J. of Environmental Law and Policy, 9: 119-142.
Botkin, D.B., R.A. Nisbet, S. Bicknell, C. Woodhouse, B. Bentley, and W. Ferren, 1991, Global Climate Change and California's Natural Ecosystems, pp. 123-149 in J.B. Knox, ed., Global Climate Change and California: Potential Impacts and Responses (Berkeley: University of California Press).
Botkin, D.B., and R.A. Nisbet, 1992, Forest response to climatic change: effects of parameter estimation and choice of weather patterns on the reliability of projections, Climatic Change20: 87-111.
Botkin, D.B., R.A. Nisbet, and L.G. Simpson, 1992, Forests and Global Climate Change, Chapter 19, pp. 274- 290 in S.K. Majumdar, L.S. Kalkstein, B.M. Yarnal, E.W. Miller, and L.M. Rosenfeld, eds., Global Climate Change: Implications, Challenges and Mitigation Measures, (Philadelphia: Pennsylvania Academy of Sciences).
Botkin, D.B., L.G. Simpson, and H.J. Schenk, 1992, Estimating Biomass, Science Letters.
Botkin, D.B., and R.A. Nisbet, 1992, Projecting the effects of climate change on biological diversity in forests, pp. 277-293 in R. Peters and T. Lovejoy, eds., Consequences of the Greenhouse Effect for Biological Diversity, (New Haven: Yale University Press).
Botkin, D.B., L.G. Simpson, and R.A. Nisbet, 1993, Biomass and Carbon Storage of the North American Deciduous Forest, Biogeochemistry 20: 1-17.
Simpson, L.G., D.B. Botkin, R.A. Nisbet, 1993, The Potential Aboveground Carbon Storage of North American Forests, Water, Air, and Soil Pollution 70:197-205.
Nisbet, R.A., and D.B. Botkin, 1993, Integrating a Forest Growth Model with a Geographic Information System, pp.265-269 in Goodchild, M.S., B.O. Parks, L.T. Steyaert, eds., Environmental Modeling with GIS (New York: Oxford University Press).
Hunsaker, C.T., R.A. Nisbet, D.C.L. Lam, J.A. Browder, W.L. Baker, M.G. Turner, D.B. Botkin, 1993, pp.248-264 in Goodchild, M.S., B.O. Parks, L.T. Steyaert, eds. Environmental Modeling with GIS (New York: Oxford University Press).
Guggenheim, D., and D.B. Botkin, 1996, CO2 Offset Opportunities in Siberian Forests, Report to the Electric Power Research Institute, Center for the Study of the Environment, Santa Barbara, CA, EPRI report # TR-106059.
Botkin, D.B., 2001, "Energy and the Quality of Life," Los Angeles Times, Sunday, June 10, 2001.
Botkin, D.B., Henrik Saxe, Miguel B. Araújo, Richard Betts, Richard H.W. Bradshaw, Tomas Cedhagen, Peter Chesson, Terry P. Dawson, Julie Etterson, Daniel P. Faith, Simon Ferrier, Antoine Guisan, Anja Skjoldborg Hansen, David W. Hilbert, Craig Loehle, Chris Margules, Mark New, Matthew J. Sobel, and David R.B. Stockwell, 2007, "Forecasting Effects of Global Warming on Biodiversity," BioScience57(3): 227-236.
Bockstoce, J.R., D.B. Botkin, A. Philp, B.W. Collins, and J.C. George, 2007, "The Geographic Distribution of Bowhead Whales in the Bering, Chukchi, and Beaufort Seas: Evidence from Whaleship Records, 1849-1914,"2007 Marine Fisheries Review 67 (3) 1-43.
- Botkin, D.B., 2007, The Future of Ecology and the Ecology of the Future, pp. 409-414 in Larry L. Rockwood, Ronald E. Stewart, and Thomas Dietz, eds., Foundations of Environmental Sustainability: The Co-Evolution of Science and Policy (New York: Oxford University Press).
- Botkin, D.B., M.J. Sobel, L.G. Simpson, K. Cummins, and L.M. Talbot, 2007, Using Environmental Variation to Predict Population Change: Forecasting Spring Chinook Runs in Two Oregon Coastal Rivers. Report from The Center for the Study of the Environment available at www.naturestudy.org as a pdf file.