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James Hansen: Earth's Temperature Tracker
Washington, November 5 2007 -
NASA scientist James Hansen has tracked Earth's temperature for decades, and he is confident the global warming trend of 0.9 degrees Celsius observed since 1880 is mainly the result of human-produced greenhouse gases.
earthobservatory.nasa.gov: Earth's Temperature Tracker
Hansen’s 1988 projections
Climate: Sawyer predicted rate of warming in 1972
London, September 6 2007 -
Thirty-five years ago this week, Nature published a paper titled "Man-made carbon dioxide and the 'greenhouse' effect" by the eminent atmospheric scientist J.S. Sawyer (Nature 239, 23-26; 1972).
In four pages, Sawyer summarized what was known about the role of carbon dioxide in enhancing the natural greenhouse effect, and made a remarkable prediction of the warming expected at the end of the twentieth century. He concluded that the 25% increase in atmospheric carbon dioxide predicted to occur by 2000 corresponded to an increase of 0.6 °C in world temperature.
gristmill.grist.org: Climate: Sawyer predicted rate of warming in 1972
Hansen’s 1988 projections
Washington / London, May 15 2007 -
At Jim Hansen's now famous congressional testimony given in the hot summer of 1988, he showed GISS model projections of continued global warming assuming further increases in human produced greenhouse gases. This was one of the earliest transient climate model experiments and so rightly gets a fair bit of attention when the reliability of model projections are discussed. There have however been an awful lot of mis-statements over the years - some based on pure dishonesty, some based on simple confusion. Hansen himself (and, for full disclosure, my boss), revisited those simulations in a paper last year, where he showed a rather impressive match between the recently observed data and the model projections. But how impressive is this really? and what can be concluded from the subsequent years of observations?
www.realclimate.org: Hansen’s 1988 projections
Hansen et al.: "Greater than average warming in the southeastern United States and much of Europe"
The Long Consensus On Climate Change
Paris, February 1, 2007 -
With the release of the new report by the Intergovernmental Panel on Climate Change tomorrow, the fourth since the organization's founding in 1988, many will be looking for what's new. How have estimates of sea-level rise changed? How soon will we achieve a doubling of carbon dioxide levels?
Scientists and journalists focus on novelty, because both are largely about discovery. But from a policy perspective, what matters is not what's new but what's old.
www.washingtonpost.com: The Long Consensus On Climate Change
Hansen et al.: "Greater than average warming in the southeastern United States and much of Europe"
Washington, 1988 - (....)
Pricipal results from the experiments are as follows:
(1) Global warming to the level attained at the peak of the current interglacial and the previous interglacial occurs in all three scenarios (see full abstract); however, there are dramatic differences in the levels of future warming, depending on trace gas growth.
(2) The greenhouse warming should be clearly identifiable in the 1990s; the global warming within the next several years is predicted to reach and maintain a level at least three standard deviations above the climatology of the 1950s.
(3) Regions where an unambiguous warming appears earliest are low-latitude oceans, China and interior areas in Asia, and ocean areas near Antarctica and the north pole; aspects of the spatial and temporal distribution of predicted warming are clearly model-dependent, implying the possibility of model discrimination by the 1990s and thus improved predictions, if appropriate observations are acquired.
(4) The temperature changes are sufficiently large to have major impacts on people and other parts of the biosphere, as shown by computed changes in the frequency of extreme events and comparison with previous climate trends.
(5) The model results suggest that some near-term regional climate variations, despite the fixed ocean heat transport which suppresses many possible regional climate fluctuation; for example, during the late 1980s and the 1990s there is a tendency for greater than average warming in the southeastern United States and much of Europe.
(.....)
pubs.giss.nasa.gov / Hansen et al. 1988: Global climate changes as forecast by Goddard Institute for Space Studies three-dimensional mode
nytimes.com: Global Warming Has Begun, Expert Tells Senate (June 24 1988)
Jim Hansen's 1988 testimony before the US Congress
The 1981 predictions of the impact of carbon dioxide emissions
The Last Ice Age....?
(Kurt Covey / February 1984)
Will there be more ice ages in the future? The fluctuations in the isotope record show no sign of abating, but the planet may nonetheless have seen its last ice age because of the effect of human activities on climate. As industrialisation continues and more fossil fuel is burned the concentration of carbon dioxide and other trace atmospheric gases increases. By the end of the century these gases may cause an appreciable warming of the earth, an increase in average temperatures large enough, if it were to continue, to overwhelm any cooling due to orbital variation.
(Source: Kurt Covey / The Earth's Orbit and the Ice Ages; Scientific American, Volume 250, Nr 2, February 1984.)
The 1981 predictions of the impact of carbon dioxide emissions
In 1981, NASA scientists predicted the impact of carbon dioxide emissions on global temperatures between 1950 and 2100 based on different scenarios for energy growth rates and energy source.
If energy use stayed constant at 1980 levels (scenario 3, bottom lines), temperatures were predicted to rise just over 1°C.
If energy use grew moderately (scenario 2, middle lines), warming would be 1–2.5 °C.
Fast growth (scenario 1, top lines) would cause 3–4°C of warming.
In each scenario, the warming was predicted to be less if some of the energy was supplied by non-fossil (renewable) fuels instead of coal-based, synthetic fuels (synfuels).
earthobservatory.nasa.gov: Graph from Hansen et al., 1981, page 9
The Carbon Dioxide Question
(George M Woodwell / January 1978)
The potential hazards associated with a steady increase in the carbon dioxide content of the atmosphere will loom large in the coming decades and will doubtless bear heavenly on such decisions as wether to accelarate the development of power plants based on nuclear fuel instead of those based on coal and whether to preserve forest areas instead of encroaching on them (and, if the forests are to be preserved, how to provide the new lands that are allmost certain tot be needed for agriculture).
There is allmost no aspect of national and international policy that can remain unaffected by the prospect of global climate change. Carbon dioxide, until now an apperently innocuous trace gas in the atmosphere, may be moving rapidly toward a central role as a major threat to the present world order.
(Source: George M Woodwell / The Carbon Dioxide Question; Scientific American, Volume 238, Nr 1, January 1978.)
Man-made Carbon Dioxide and the "Greenhouse" Effect
(J. S. SAWYER / September 1972)
In spite of the enormous mass of the atmosphere and the very large energies involved in the weather systems which produce our climate, it is being realized that human activities are approaching a scale at which they cannot be completely ignored as possible contributors to climate and climatic change.
J. S. SAWYER / Man-made Carbon Dioxide and the "Greenhouse" Effect, Nature, Volume 239, 23- 26, 1 September 1972
gristmill.grist.org: A must-read 1972 climate prediction: Rate of global warming predicted 35 years ago in Nature
Large scale geophysical experiment...
(Source: Revelle and Suess 1957)
"Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.”
(Revelle and Suess 1957)
"One Big Greenhouse"
(Source: TIME Magazine, May 28, 1956)
The temperature of the earth's surface depends largely on two minor constituents of the atmosphere: water vapor an carbon dioxide. They are transparent to the short-wave energy (light and near infra-red) that comes from the sun, but opaque to most of the long-wave heat radiation that tries to return to space. This "greenhouse effect" traps heat and makes the earth's surface considerably warmer than it would be if the atmosphere had no water vapor or carbon dioxide in it. An increase in either constituent would make it warmer still. Warm eras in the geological past may have been caused by CO2 from volcanoes.
At present the atmosphere contains 2.35 trillion tons of carbon dioxide, existing in equilibrium with living plants and sea water (which tends to dissolve it). Up to 1860, man's fires added only about 500 million tons per year, and the atmosphere had no trouble in getting rid of this small amount. But each year more furnaces and engines poured CO2 into the atmosphere. By 1950, it was 9 billion tons. By 2010, if present trends continue, 47 billion tons of carbon dioxide will enter the air each year.
This will be only 2% of the total carbon dioxide, but if it is more than can be dissolved by the oceans or absorbed by plants or minerals, the concentration of CO2 in the atmosphere will tend to increase. The greenhouse effect will be intensified. Some scientists believe that this is the cause of recent warming of the earth's climate.... ( Source: scitech.quickfound.net ).
"Invisible Blanket"
(Source: TIME Magazine, May 25, 1953)
In the hungry fires of industry, modern man burns nearly 2 billion tons of coal and oil each year. Along with the smoke and soot of commerce, his furnaces belch some 6 billion tons of unseen carbon dioxide into the already tainted air. By conservative estimate, the earth's atmosphere, in the next 127 years, will contain nearly 50% more CO2.
This spreading envelope of gas around the earth, says Johns Hopkins physicist Gilbert N. Plass, serves as a great greenhouse. Transparent to the radiant heat from the sun, it blocks the longer wavelengths of heat that bounce back from the earth. At its present rate of increase, says Plass, the CO2 in the atmosphere will raise the earth's average temperature 1.5 degrees Farenheit every 100 years.
As the blanket of CO2 gets thicker, it also prevents the tops of clouds from losing heat as rapidly as before. The smaller temperature difference between the cloud base and top cuts down the air currents which must circulate through the cloud before rain or snow can form. Lowered rainfall will make a drier climate. Less cloud cover will be formed, more sunlight will reach the earth, and the average temperature will rise still higher.... ( Source: scitech.quickfound.net ).
"Getting Warmer?"
(Source: TIME Magazine, May 15, 1950)
Is the U.S. climate getting warmer? U.S. meteorologists observing and charting the weather with growing exactitude over the past 20 years are no closer to agreement on the question than their predecessors of a century ago. Last week a Washington convention of the American Meteorological Society heard strong evidence to favor the warmup theory.
Dr. Richmond T. Zoch of the Weather Bureau reported that Washington temperature records, begun in 1862, show that Washington's climate had warmed by about 3.5 degrees Farenheit since then. Harvard's Dr. John H. Conover backed Dr. Zoch. He said that a 100-year record kept at the Blue Hill Meteorological Observatory and at nearby Milton Centre, Mass. showed a 3 degree increase. Dr. Conover had gone to the trouble of finding the early Victorian thermometer used in 1849 and checking it against modern instruments, made allowances for the differences. In further support of his position, he pointed out that the Blue Hill records were made in a large state park well outside of Boston. So they were immune to the heating effect attributed to great modern cities. ( Source: scitech.quickfound.net ).
From Grand Dad - "Winters were colder" then - to Guy Stewart Callendar
In the 1930s, the press began to call attention to numerous anecdotes of above-normal temperatures. The head of the U.S. Weather Bureau's Division of Climate and Crop Weather responded in 1934. "With 'Grand-Dad' insisting that the winters were colder and the snows deeper when he was a lad," he said, "...it was decided to make a rather exhaustive study of the question."
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It may have been the press reports of warming that stimulated an English engineer, Guy Stewart Callendar, to take up climate study as an amateur enthusiast.
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After countless hours of sorting out data and penciling sums, Callendar announced that the temperature had definitely risen between 1890 and 1935, all around the world, by close to half a degree Celsius (0.5°C, equal to 0.9°F).
Callendar's statistics gave him confidence to push ahead with another and more audacious claim. Reviving an old theory that human emissions of carbon dioxide gas (CO2) from burning fuel could cause a "greenhouse effect," Callendar said this was the cause of the warming.
Callendar's graphs showing a rise of temperature around the world from the 1880s to the mid 1930s:
From Quarterly J. Royal Meteorological Society 64, 223 (1938).
Source: Spencer Weart: The Discovery of Global Warming
"For the benefit of rapidly propagating mankind..."
(Svante Arrhenius, 1908)
“By the influence of the increasing percentage of carbonic acid in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind.”
(Svante Arrhenius, 1908)
On the Influence of Carbonic Acid (CO2) in the Air upon the Temperature of the Ground
(Svante Arrhenius, 1895)
A great deal has been written on the influence of the absorption of the atmosphere upon the climate. Tyndall [1865] in particular has pointed out the enormous importance of this question. To him it was chiefly the diurnal and annual variation of the temperature that were lessened by this circumstance. Another side of the question, that has long attracted the attention of physicists, is this: Is the mean temperature of the ground in any way influenced by the presence of heat-absorbing gases in the atmosphere?
Extract from a paper presented to the Royal Swedish Academy of Sciences, 11th December, 1895/ published in Philosophical Magazine 41, 237-276 (1896)
In Table VII of the abstract(--Variation of Temperature caused by a given Variation of Carbonic Acid--) Arrhenius presents calculations for different concentrations of 'carbonic acid' (CO2).
Please note that the section Carbonic Acid=1.5 is presenting quite accurate figures for the 21th century, if compared to the IPCC AR4, or the climateprediction.net results:
bbc.co.uk: Climate Future Results Show Sweltering Britain
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