The Discovery of Global Warming Spencer Weart |
June
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Timeline of Milestones
Here are gathered in chronological sequence the most important events in the history of climate change science. (For a narrative see the Introduction: summary history.) This list of milestones includes major influences external to the science itself. Following it is a list of other external influences. 1800-1870 First Industrial Revolution. Coal, railroads, and land clearing speed up greenhouse gas emission, while better agriculture and sanitation speed up population growth. 1896 1897 1870-1910 1914-1918 1920-1925 1930s Milankovitch proposes orbital changes as the cause of ice ages.=>Climate cycles 1938 1939-1945 1945 1956 Phillips produces a somewhat realistic computer model of the global atmosphere.=>Models (GCMs) Plass calculates that adding CO2 to the atmosphere will have a significant effect on the radiation balance.=>Radiation math 1957 Revelle finds that CO2 produced by humans will not be readily absorbed by the oceans.=>CO2 greenhouse 1958 1960 Keeling accurately measures CO2 in the Earth's atmosphere and detects an annual rise.=>CO2 greenhouse The level is 315 ppm. 1962 1963 1965 1966 1967 Manabe and Wetherald make a convincing calculation that doubling CO2 would raise world temperatures a couple of degrees.=>Radiation math 1968 1969 Budyko and Sellers present models of catastrophic ice-albedo feedbacks.=>Simple models Nimbus III satellite begins to provide comprehensive global atmospheric temperature measurements.=>Government 1970 Creation of U.S. National Oceanic and Atmospheric Administration, the world's leading funder of climate research.=>Government Aerosols from human activity are shown to be increasing swiftly. Bryson claims they counteract global warming and may bring serious cooling.=>Aerosols 1971 Mariner 9 spacecraft finds a great dust storm warming the atmosphere of Mars, plus indications of a radically different climate in the past.=>Venus & Mars 1972 1973 1974 1975 Manabe and collaborators produce complex but plausible computer models which show a temperature rise of several degrees for doubled CO2=>Models (GCMs) 1976 Deforestation and other ecosystem changes are recognized as major factors in the future of the climate.=>Biosphere Eddy shows that there were prolonged periods without sunspots in past centuries, corresponding to cold periods.=>Solar variation 1977 1978 1979 U.S. National Academy of Sciences report finds it highly credible that doubling CO2 will bring 1.5-4.5°C global warming.=>Models (GCMs) World Climate Research Programme launched to coordinate international research.=>International Election of Reagan brings backlash against environmental movement. Political conservatism is linked to skepticism about global warming.=>Government 1981 Hansen and others show that sulfate aerosols can significantly cool the climate, raising confidence in models showing future greenhouse warming. =>Aerosols Some scientists predict greenhouse warming “signal” should be visible by about the year 2000. =>Modern temp's 1982 Strong global warming since mid-1970s is reported, with 1981 the warmest year on record.=>Modern temp's 1983 1985 Antarctic ice cores show that CO2 and temperature went up and down together through past ice ages. =>CO2 Broecker speculates that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change.=>The oceans 1987 1988 Toronto conference calls for strict, specific limits on greenhouse gas emissions.=>International Ice-core and biology studies confirm living ecosystems make climate feedback by way of methane, which could accelerate global warming.=>Other gases Intergovernmental Panel on Climate Change (IPCC) is established.=>International Level of CO2 in the atmosphere reaches 350 ppm After 1988 it is difficult to identify historical milestones. Not only do we lack perspective (as discussed in a separate note), but the effort was so large that progress on a given topic, even more than before, came through a variety of results spread over several groups and several years. A TENTATIVE LIST: 1989 1990 1991 Global warming skeptics emphasize studies indicating that a significant part of 20th-century temperature changes were due to solar influences. (The correlation would fail in the following decade.) =>Solar variation Studies from 55 million years ago show possibility of eruption of methane from the seabed with enormous self-sustained warming. =>Rapid change 1992 Study of ancient climates reveals climate sensitivity in same range as predicted independently by computer models. =>Models (GCMs) 1993 1995 Reports of the breaking up of Antarctic ice sheets and other signs of actual current warming in polar regions begin affecting public opinion.=>Public opinion 1997 International conference produces Kyoto Protocol, setting targets to reduce greenhouse gas emissions if enough nations sign onto a treaty. =>International 1998 Qualms about arbitrariness in computer models diminish as teams model ice-age climate and dispense with special adjustments to reproduce current climate. =>Models (GCMs) 1999 Ramanathan detects massive "brown cloud" of aerosols from South Asia. =>Aerosols 2000 Variety of studies emphasize variability and importance of biological feedbacks in carbon cycle, liable to accelerate warming.=>Biosphere 2001 Bonn meeting, with participation of most countries but not US, develops mechanisms for working towards Kyoto targets.=>International National Academy panel sees a "paradigm shift" in scientific recognition of the risk of abrupt climate change (decade-scale). =>Rapid change Warming observed in ocean basins; match with computer models gives a clear signature of greenhouse effect warming. =>Models (GCMs) 2002 2003 Deadly summer heat wave in Europe accelerates divergence between European and US public opinion. =>Public opinion 2004 First major book, movie and art work featuring global warming appear. =>Public opinion 2005 Hurricane Katrina and other major tropical storms spur debate over impact of global warming on storm intensity. =>Sea rise & ice |
Additional External Influences 1950-1980 |
This is a reference list of miscellaneous significant developments that don't fit into any of the other essays: scientific-technical matters that arose altogether independently of the scientific fields covered, and are not included above in the list of major "milestones," but that did have a significant influence on climate change studies. Before the 1950s there were practically no global warming studies as such, and all the important discoveries (the ice ages, the infrared absorption of carbon dioxide, etc.) were effectively "external." 1950s:
1960s:
1970s: After about 1980, efforts that would be relevent to global warming were
generally undertaken with an awareness of potential connections. copyright© 2003-2005 Spencer Weart & American Institute of Physics |