|When (if at all) did human co2 emissions begin to affect the climate?19-12-2010 23:25|
|co2 emissions (humans ones) have seen significant increases since the 1850s, but the bulk since 1950s, when should we have expected major effects on the climate to have occured, surely a build up at the beginning (in the mid 18th C onwrds) would have been required before any effect on the climate would have occured (especially as human production of c02 was so small at first relative to the last 70 years).|
What Iam saying is, when should we expect to see influence by humans emissions of c02 on the climate when we look at past records from 1850 to present).
|Hi tantalus, and welcome to the forum! |
If you look at the latest IPCC report (AR4 from 2007), you'll find this figure, where natural and anthropogenic model forcings (according to IPCC) are compared:
So according to this figure, humans actually first began to affect the temperature seriously from the 1970's.
I have seen similar graphs with more details and better resolution... maybe I will dig them up later. Hopefully this one shows the main point.
assuming this is widely agreed upon (since 1970s) across the literature, we are only looking for changes in temp. in the last 40 years , I was under the illusion that human influences was often considered further back, over a longer period and that increases in global temp. were often considered since the 1870s onwards, however according to your source above we are looking for an increase in the last 40 years and the previous increases are considered natural (as in from 1850s-1970). I have often seen comparisons (at least I thought I had) of current temp. to 1850, 1850 to my understanding was a particurly cold decade coming out of the remnants of the little ie age, am I correct in stating that a comparison betwee 1850s and last 40 years is often mentioned in illustrating that humans have caused a rise in global temp. means, obviously this would appear faulty if that was a comparison against an especially cold decade coming at the end of a very cold climate period a hundred years before any proposed human effects on the global temp.
am I mistaken, or are all searches for human effects on global temp. post 1970? and are there comparisons often made of the current temp. to the temp. from 1850 ?
Edited on 20-12-2010 17:54
|My take on this whole issue is rather different from those I've read here to date.|
I think I can sum it all up now.
A few scientists convinced themselves that we're heading for trouble, a lot more thought it'd probably be a good idea to have a look at this, afterall, there's not a lot else to do at the moment with all these new PhD students. Some politicians decided that this looked like a good band wagon to hitch a ride on; some of the scientists involved have been coughing discretely, and pointing out that we really don't know enough yet, but possibly with a bit more time, money & research we'll have a better idea. Some more scientists have also decided that now they've rubbed the lamp and a Genie's popped out, they'd better start thinking hard about which three questions they should be asking it, because knowing what Genies are like, there's going to be tears before bedtime if they don't get it right!
In the mean time, plenty of hangers on have realised that there's a few easy bucks to be made and careers to be advanced here and if anyone rocks the boat, there's going to be trouble! They have been caught over egging the pudding recently and no amount of manufactured hysteria on this issue will save the slop they have been living off for the last two decades from going sour .
As I see it thats the current state of play here.
Edited on 23-12-2010 20:54
|CO2 being a greenhouse gas was demonstrated by C.J. Fox in 1909, A. Angstron in 1918, and Chamberlain and Fowle in 1916, 1917, and 1918.|
"As a dam built across the river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial rays produces a local heightening of the temperature of the Earth's surface." -- J. Tyndall, "Further Researches on the Absorption and Radiation of Heat by Gaseous Matter," in "Contributions to Molecular Physics in the Domain of Radiant Heat," New York: Appleton, 1873, p. 117
Testimony of Commander Roger Revelle, U.S. Congress, House 84 H1526-5, Committee on Appropriations, Hearings on Second Supplemental Appropriation Bill (1956), pp. 474, 473. Arctic may become navigatable due to increased atmospheric CO2.
Several scientists independantly successfully predicted the current global temperature anomaly as far back as the year 1931, based primarily on estimates of rising atmospheric CO2.
Arrhenius successfully predicted the increased temperature today (1c +-.2) and his predictions for year 2100 match the current predictions.
In 1931 E.O. Hulburt calculated that a doubling of atmospheric CO2 will increase global average temperature by 4c. He published his paper in the journal "Physical Review." He also noted that trippling CO2 would raise Earth's temperature 7c.
S.G. Callendar in the late 1930s also correctly predicted the current global temperature anomaly; he also predicted many of the adverse effects we would see 70 years before we, now, see them.
Callendar even showed, in 1938, that the available global data at the time already showed a temperature increase. He published the paper in the Quarterly Journal of the Royal Meteorological Society, 64:223 (1938). http://www.rmets.org/pdf/qjcallender38.pdf
By the 1950s scientists such as Suess and Revelle were issuing warnings about the warming effects of CO2 in the atmosphere; Bell Labs started making audio/video films warning about the problem at the time.
By 1957 there was consensus among scientists that by the year 2000 we would see the Arctic sea ice start to melt and not reform, and possibly even the Antarctic. In a 1957 _Time_ interview, Suess and Revelle pointed out that the greatest warming will occur at the Earth's poles. They also said thermal expansion would raise the world's oceans, though they did not know by how much.
By the end of the 1950s the science was settled. It was, and still is, "a done deal."
In 1965 Lyndon Johnson stated in a special message to Congress that humans had already altered the composition of the atmosphere AND THAT GLOBAL CLIMATE CHANGE WAS ALREADY HAPPENING.
Wally Broecker, on 8 August 1975, stated "... by early in the next century [carbon dioxide] will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years." He correctly predicted an overall 20th Century global warming of 0.8ºC due to CO2. http://blogs.ei.columbia.edu/climate/files/2009/10/broeckerglobalwarming75.pdf
The predictions were so successful that by year 1980 there were no more skeptics on the issue. Even before 1980 the USA executive office was convinced, and discussed with scientists possible solutions. For example, Richard Feynman worked with the elite science advisory team (a half-dozen volunteers) charged with advising the United States Executive Office on solutions to curb CO2.
By 1992, George Bush1 issued statements warning about the problems the world faced by global warming, and signed an international agreement regarding "making concrete actions to protect the planet."
E.O. Hulburt "The Temperature of the Lower Atmosphere of the Earth," Physical Review, vol. 38, Issue 10, pp. 1876-1890: "Calculation shows that doubling or tripling the amount of Co2 into the atmoshphere increases the average surface temperature by about 4° and 7°K respectivly..."
S.G. Callendar, Quarterly Journal of the Royal Meteorological Society, 64:223 (1938), "The artificial production of carbon dioxide and its influence on temperature."
Suess and Revelle, _Time_ Magazine "One Big Greenhouse." (May 28, 1956): http://www.time.com/time/magazine/article/0,9171,937403,00.html
"As the air gets warmer, sea water will get warmer too, and CO2 dissolved in it will return to the atmosphere. More water will evaporate from the warm ocean, and this will increase the greenhouse effect of the CO2. Each effect will reinforce the other, possibly raising the temperature enough to melt the icecaps of Antarctica and Greenland, which would flood the earth's coastal lands."
President Lyndon Johnson: "Air pollution is no longer confined to isolated places. This generation has altered the composition of the atmosphere on a global scale through radioactive materials and a steady increase in carbon dioxide from the burning of fossil fuels." (February 8, 1965) "Special Message to the Congress on Conservation and Restoration of Natural Beauty."
|Yeah, and in 1975, various publications printed articles predicting the coming ice age.|
The more outrageous and preposterous the idea, the more press it gets.
This one pays billions in *research* dividends, and as Climategate has shown, these phonies will lie through their teeth to keep the government billions flowing.
|Into the Night★★★★★
No gas or vapor can warm the Earth. Only the Sun warms the Earth. For the Earth to become warmer, it needs more energy from the Sun for only the Sun can provide it.
The Parrot Killer
Into the Night wrote:
Yes and no. Largely yes. The moon is essentially the same distance from the sun as our earth is, but it is cold. Why? No atmospheric blanket to retain the heat.
But after 100% of the radiated energy has been absorbed by the atmosphere, that's it. You can't continue to capture radiant energy when all of it has already been converted to kinetic energy in the form of faster molecules, chiefly water vapor (15,000 ppmv, compared to only 400 ppmv, or parts per million volume.)
Now let's see Desert Old Man explain how ppmv is different from ppm, and how the infrared spectra of water vapor and carbon dioxide compare.
Let's talk science, shall we?
|Into the Night★★★★★
RenaissanceMan wrote:Into the Night wrote:
The Moon isn't cold. Neither is the outer skin of the ISS.
Daytime temperatures on both can easily reach 250 deg F. The Moon isn't just nighttime temperatures.
RenaissanceMan wrote:Heat can't be trapped or retained.
An atmosphere is mass. It takes time to heat and cool it, just as any other mass.
The Moon has no appreciable atmosphere. On Earth, we have an atmosphere containing water, carbon dioxide, methane, and other so-called 'greenhouse' gases.
Yet the daytime temperature of the Earth never reaches 250 deg F anywhere on Earth. The daytime temperature at the surface is much COLDER than the daytime surface temperature of the Moon.
At least until the atmosphere loses energy again to space.
Sure. You seem to understand it better than most people here. Your posts have been refreshing to read. My thanks for joining climate-debate.com.
The Parrot Killer
Edited on 14-05-2018 20:18
Into the Night wrote:Heat can't be trapped or retained.
Really? You don't wear a coat in the snow? No gloves because your body heat "can't be trapped or retained"?
The mass of earth's atmosphere is trivial compared with the mass of earth and oceans. Super trivial.
The specific heat of water is one of its important attributes, contributing to the stability of our body temperature among many other things.
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