Guest post by Dr. Don J. Easterbrook
1934 has long been considered the warmest year of the past century. A decade ago, the closest challenger appeared to be 1998, a super-el nino year, but it trailed 1934 by 0.54°C (0.97°F). Since then, NASA GISS has “adjusted” the U.S. data for 1934 downward and 1998 upward (see December 25, 2010 post by Ira Glickstein) in an attempt to make 1998 warmer than 1934 and seemingly erased the original rather large lead of 1934 over 1998. The last phases of the strong 2009-2010 el nino in early 2010 made this year another possible contender for the warmest year of the century. However, December 2010 has been one of the coldest Decembers in a century in many parts of the world, so 2010 probably won’t be warmer than 1998. But does it really matter? Regardless of which year wins the temperature adjustment battle, how significant will that be? To answer that question, we need to look at a much longer time frame‒centuries and millennia.
One of the best ways to look at long-term temperatures is with isotope data from the GISP2 Greenland ice core, from which temperatures for thousands of years can be determined. The ice core isotope data were obtained by Minze Stuiver and Peter Grootes from nuclear accelerator measurements of thousands of oxygen isotope ratios (16O/18O), which are a measure of paleo-temperatures at the time snow fell that was later converted to glacial ice. The age of such temperatures can be accurately measured from annual layers of accumulation of rock debris marking each summer’s melting of ice and concentration of rock debris on the glacier.
The past century
Two episodes of global warming and two episodes of global cooling occurred during the past century:
1880 to 1915 cool period. Atmospheric temperature measurements, glacier fluctuations, and oxygen isotope data from Greenland ice cores all record a cool period from about 1880 to about 1915. Many cold temperature records in North America were set during this period. Glaciers advanced, some nearly to terminal positions reached during the Little Ice Age about 400 years ago. During this period, global temperatures were about 0.9 ° C (1.6 ° F) cooler than at present. From 1880 to 1890, temperatures dropped 0.35 ° C (0.6° F) in only 10 years. The 1880 –1915 cool period shows up well in the oxygen isotope curve of the Greenland Ice Sheet.
1915 to 1945 warm period. Global temperatures rose steadily in the 1920s, 1930s, and early 1940s. By the mid-1940s, global temperatures were about 0.5 °C (0.9° F) warmer than they had been at the turn of the century. More high temperature records for the century were recorded in the 1930s than in any other decade of the 20th century. Glaciers during this warm period retreated, temperatures in the 1930s in Greenland were warmer than at present, and rates of warming were higher (warming 4°C (7° F) in two decades). All of this occurred before CO2 emissions began to soar after 1945, so at least half of the warming of the past century cannot have been caused by manmade CO2.
1945 to 1977 cool period. Global temperatures began to cool in the mid–1940’s at the point when CO2 emissions began to soar. Global temperatures in the Northern Hemisphere dropped about 0.5° C (0.9° F) from the mid-1940s until 1977 and temperatures globally cooled about 0.2° C (0.4° F). Many of the world’s glaciers advanced during this time and recovered a good deal of the ice lost during the 1915–1945 warm period. Many examples of glacial recession cited in the news media show contrasting terminal positions beginning with the maximum extent at the end of the 1880-1915 year cool period and ending with the minimum extent of the recent 20 year warm period (1977-1998). A much better gauge of the effect of climate on glaciers would be to compare glacier terminal positions between the ends of successive cool periods or the ends of successive warm periods.
1977 to 1998 global warming The global cooling that prevailed from ~1945 to 1977 ended abruptly in 1977 when the Pacific Ocean shifted from its cool mode to its warm mode in a single year and global temperatures began to rise, initiating two decades of global warming. This sudden reversal of climate in 1977 has been called the “Great Pacific Climate Shift” because it happened so abruptly. During this warm period, alpine glaciers retreated, Arctic sea ice diminished, melting of the Greenland Ice Sheet occur.
The abruptness of the shift in Pacific sea surface temperatures and corresponding change from global cooling to global warming in 1977 is highly significant and strongly suggests a cause-and-effect relationship. The rise of atmospheric CO2, which accelerated after 1945 shows no sudden change that could account for the “Great Pacific Climate Shift”.
1999 to 2010 global cooling. No global warming has occurred above the 1998 level and temperatures have declined slightly.
The past 500 years
Temperature oscillations recorded in Greenland ice cores over the past 500 years (Fig. 2) are truly remarkable. At least 40 periods of warming and cooling have occurred since 1480 AD, all well before CO2 emissions could have been a factor.
The past 5,000 years
Figure 3 shows oxygen isotope ratios from the GISP2 Greenland ice core for the past 5,000 years. Note that temperatures were significantly warmer than present from 1500 to 5000 years ago.
The past 10,000 years
Most of the past 10,000 have been warmer than the present. Figure 4 shows temperatures from the GISP2 Greenland ice core. With the exception of a brief cool period about 8,200 years ago, the entire period from 1,500 to 10,500 years ago was significantly warmer than present.
Another graph of temperatures from the Greenland ice core for the past 10,000 years is shown in Figure 5. It shows essentially the same temperatures as Cuffy and Clow (1997) but with somewhat greater detail. What both of these temperature curves show is that virtually all of the past 10,000 years has been warmer than the present.
So where do the 1934/1998/2010 warm years rank in the long-term list of warm years? Of the past 10,500 years, 9,100 were warmer than 1934/1998/2010. Thus, regardless of which year ( 1934, 1998, or 2010) turns out to be the warmest of the past century, that year will rank number 9,099 in the long-term list.
The climate has been warming slowly since the Little Ice Age (Fig. 5), but it has quite a ways to go yet before reaching the temperature levels that persisted for nearly all of the past 10,500 years.
It’s really much to do about nothing.
http://www.ncdc.noaa.gov/paleo/pubs/alley2000/alley2000.gif
hmm.
I’m a bit flummoxed. With a La Nina now, and also very weak period of solar activity for a few years, I expected global temperatures to be much cooler. But even if you just use uncontaminated satellite data (UAH MSU) and ignore Hansen, we’ve had a pretty warm year. I know that air temperature is a bad metric, and ocean heat content would be much better measure of global temperature, but still…
What gives?
Don´t Miss Climate´s Big Picture!!!
1. “Earth on the Brink of an Ice Age,” by Gregory F. Fegel, January 14, 2010, at http://www.lewrockwell.com/orig11/fegel1.1.1.html .
2. “Burt Rutan´s comprehensive new report on Global Warming science fraud: Version 4.0 dated 3 July 2010,” at http://rps3.com/Pages/Burt_Rutan_on_Climate_Change.htm .
3. “Science bulletin: ´Sun heats Earth!´, Russian research forecasts global cooling,” by Jerome R. Corsi, October 27, 2009, at http://www.wnd.com/index.php?fa=PAGE.view&pageId=114261 .
4. “´Hottest Year On Record´Myth Based On Fabricated Temperature Data,” by Christopher Booker, London Telegraph, Sunday, December 19, 2010, at http://www.prisonplanet.com/hottest-year-on-record-myth-based-on-fabricated-temperature-data.html .
5. The Anthropogenic Global Warming (AGW) theory has produced zero reproducible scientific data since its inscription, and should therefore be rejected. (The AGW theory is not science, it is an anti-science ideology, driven foremost of anti-human population control, manipulation, and socialism.)
Say no to Climategate, Junk Science, and Cap and Trade.
WORSE THAN AWEFUL
Forgot to point out how nightmarishly BS your narrative for Fig. 5 is too.
You wrote: “Another graph of temperatures from the Greenland ice core for the past 10,000 years is shown in Figure 5. It shows essentially the same temperatures as Cuffy and Clow (1997) but with somewhat greater detail. What both of these temperature curves show is that virtually all of the past 10,000 years has been warmer than the present. [ Figure 5. Temperatures over the past 10,000 years recorded in the GISP2 Greenland ice core] So where do the 1934/1998/2010 warm years rank in the long-term list of warm years? Of the past 10,500 years, 9,100 were warmer than 1934/1998/2010. Thus, regardless of which year ( 1934, 1998, or 2010) turns out to be the warmest of the past century, that year will rank number 9,099 in the long-term list.”
Actually, the Fig 5 Graph is in ‘years before present (2000 AD)’, but it doesn’t end at zero years before present (THAT would be 2000), but at “95” (years before present), in other words the graph ends in 1905 AD. Nice work, Don! [sarc on] 1934, 1998, or 2010 are not even on the graph in Figure 5! The graph ends before we’d see the temperature surge of the modern warm period.
effed up.
Nice premise, it needs an explanation on why isotope ratios are reliable temperature indicators (why should we belive them and not a single tree in Siberia or a half metric ton of coral or incidence of mcDonalds wrappers at each geological layer for that matter).
Also that first graph looks seriously shifty, measuring an 1890 temperature on an axis marked “global Temp deviation 1960-91” makes my hackles rise, so does a text about how hot 1934 was when attached to a graph that dosn’t show it.
Hi moderator, combining my two comments (AWEFUL and WORSE THAN AWEFUL) into just one below this line, better organized by shredding every figure’s narrative in following order:
———————————————————-
SIMPLY AWEFUL
Figure 1. is biased. Atmospheric CO2 ppm (on year average) has been rising since at least 1900 AD, with no periods of “without change / without increase” since. While CO2 soared during the pre-1980 global cooling period, it ‘soared’ also and even more so during the warming period that followed, but the text just says “CO2 increase”, which makes it sound like it increased less than the previous period, which isn’t the case. In short: Fig. 1. is both biased and factually incorrect (a.k.a. [/SNIP]).
Figure. 2 indeed illustrates beautifully that “At least 40 periods of warming and cooling have occurred since 1480 AD, all well before CO2 emissions could have been a factor.”, but that’s another matter than 2010’s place on the temperature record. If temperatures were off the charts during any year since 1960 (like perhaps 1998, 2004 or 2010?), in comparison to the temperatures shown on this 480 year graph (what you call “500 years”), it doesn’t show. It ends in 1960.
Fig 3. “Figure 3 shows oxygen isotope ratios from the GISP2 Greenland ice core for the past 5,000 years. Note that temperatures were significantly warmer than present from 1500 to 5000 years ago.”
Um… “Warmer than present?? It is presently 2010, the year you’re talking about. Yet the timeline ends in 2000, and… -wuwt- the data actually end in… doesn’t say, but it looks like around 1850, not showing ANYTHING about the last century, let alone “the present”. Note THAT.
Fig 4. It would be nice to know what “the present” is in Fig. 4. Is it 1905 AD? 2000 AD? 1992? 1997? 2010? “Modified from Cuffy and Clow, 1997″ And IF years of data were added after 1992 (when GRISP2 Ice Core drilling was completed.), where did the other data (of who knows how many years) come from? Please state exact sources for any graph, and if possible where ALL the data for a graph came from (especially when datasets are combined with different smoothing, etc. – we know how easily one can manipulate perceptions doing this).
Figure 5. at least shows that “the present” is 2000 AD, though it also doesn’t say where the post-1992 temperature data came from, and at which point they’re grafted onto the ice core data. Oh wait… it’s much worse! The graph doesn’t end in 2000!!! For Figure 5., you wrote: “Another graph of temperatures from the Greenland ice core for the past 10,000 years is shown in Figure 5. It shows essentially the same temperatures as Cuffy and Clow (1997) but with somewhat greater detail. What both of these temperature curves show is that virtually all of the past 10,000 years has been warmer than the present. … So where do the 1934/1998/2010 warm years rank in the long-term list of warm years? Of the past 10,500 years, 9,100 were warmer than 1934/1998/2010. Thus, regardless of which year ( 1934, 1998, or 2010) turns out to be the warmest of the past century, that year will rank number 9,099 in the long-term list.”
–> The Figure 5 Graph, Dr., is in ‘years before present (2000 AD)’, but it doesn’t end at zero years before present (THAT would be 2000), but at “95″ (years before present), in other words the graph ends in 1905 AD. Nice work, Don! [sarc on] 1934, 1998, or 2010 are not even on this graph! The graph ends before we’d see the temperature surge of the modern warm period.
[/SNIP]. One of the worst science (?) postings I’ve seen here at WUWT.
[Vulgarities removed… bl57~mod]
Another prediction comes in…you fell for my bait.
You are not learning Leif, temperature cannot be compared directly with solar output without allowing for the ocean cycles….this is one of Dr. Easterbrooks main platforms. Think PDO.
The overall trend of both graphs matches nicely but don’t expect an exact match.
The article confuses US temperatures (1934 vs 1998) vs global temps. More, the GISP ice core record ends in 1905. But the double-peaking modern warm period (with warm peaks in 1940 and 2005) is lower than the medieval or Roman warm period.
Concerning global temperatures, HadCRUT has several issues. First, the HadSST dataset has been artificially increased in 1998 by 0.1 °C, thus gaining 0.07 °C since (see Bob Tisdale blog). Second, the CRUTEM station record trend is estimated to be doubled because of UHI in 1993-2008 (McKittrick, Pielke, Spencer etc.). So the real difference between warm 40ties and 2000s is less than 0.4 °C what HadCRUT says today, maybe 0.2 °C.
The purpose of DR. Easterbrook’s essay is to look beyond recent temperature measurements and thus view climate as it should be seen – at the millennial and larger scale. Where the real patterns can be viewed and perhaps compared to solar and other phenomena that also occur on those scales.
He uses oxygen isotopes, as a proxy as have many others for analysis of anything to do with water. The isotope chemistry of water is reasonably well understood as are the variations in isotopic composition due to temperature and other factors.
The of oxygen isotopes as a temperature proxy is not without errors, but the errors and their sources are also reasonably well understood – unlike the errors associated with treemometers, particularly those treemometers from certain abnormal forms of coniferous trees found in harsh climates (i.e. split-bark bristlecombs in CA or stunted larch in Siberia).
What the Greenland ice core isotopes provide is a tool for identifying a pattern of climate change in Northern Hemisphere covering the last 10,000+ years. It shows, as Dr. Easterbrook has patiently been saying for many years, that climate change is normal, natural, and not particularly tied to anthropogenic CO2 emissions.
While the isotope data don’t pinpoint exact temperatures (no proxy that I know, not even alcohol in glass or electronic temperature proxies can do that), they do provide very good evidence that temperatures have fluctuated a great deal since the last ice age, with the Greenland ice core ones showing the greatest range (much like the arctic temperature amplification we have seen over the last 30 years and during the 1930’s and 40’s). And they also show that the current warming is not unique or special, and can be better described as really quite insignificant in comparison with other far more spectacular periods of warming.
We as individuals have the freedom of either believing Dr. Easterbrook’s essay as a reasonable interpretation of the data, or we can dismissing it as the senile ramblings of a retired scientist, as some in the climate alarmist business have done.
My own training as a geologist, with experience in glacial processes and isotope geochemistry, biases my own views and predisposes me to weigh in favor of Dr. Easterbrook.
I look forward to seeing him on the news after January, when Congress might ask his opinion on a few things of great importance.
MVB says: WORSE THAN AWEFUL [sic] Actually, the Fig 5 Graph is in ‘years before present (2000 AD)’, but it doesn’t end at zero years before present (THAT would be 2000), but at “95″ (years before present), in other words the graph ends in 1905 AD. Nice work, Don! [sarc on [sic] ] 1934, 1998, or 2010 are not even on the graph in Figure 5! The graph ends before we’d see the temperature surge of the modern warm period.
Not even up to nitpicking quality, MVB. See Figures 1 and 2 for the modern curves. The 1934, 98, 2010 data are extensively covered elsewhere. You probably don’t know that, because you’ve been spending all your time at porn sites.
[/SNIP]
Indeed, you are.
[No reason to repeat his conveyed vulgarity…bl57~mod]
Steven Mosher says: “…The operative question is not “has it been this warm before” the operative questions are.
1. What’s our best estimate of the temp over the next 100 years.
There isn’t any.
2. Can we do anything about it
No.
3. should we, if we can.
No.
Use of irrelevant graphs for the topic make this article total [/snip]:
– Figure 1. is erroneous and deceptive in its wording. Atmospheric CO2 ppm (on year average) has been rising since at least 1900 AD, with no periods of “without change / without increase” since. And temperature graphs that smoothened wouldn’t show record years anyhow.
– Figure. 2 has no bearing on 2010′s place on the temperature record since it ends in 1960. And it’s a 480 year graph , not 500 years.
– Fig 3. ‘s data end somewhere before 1900 AD (doesn’t even say), but in any case giving no information about the present, so comparison statements about any year since are worthless in.
– Fig 4. doesn’t state when its “present” is, either, but the arrow pointing at the “present temperature” appears to point at the coldest of the Little Ice Age.
– Fig. 5’ s data end in 1905 AD (95 years before present with the present at 2000 AD), making all you say about Fig 5’s implications absolute [/snip].
Seriously, no one else here having an issue with erasing almost the entire Modern Warm Period from a graph and adding “The climate … has quite a ways to go … before reaching the temperature levels that persisted for nearly all of the past 10,500 years.”???
I recently wrote to my Conservative (supposedly RW) MP to ask about their policy on climate change. I’d mentioned the failure of Copenhagen and this was part of the response.
“Although no legally binding deal was secured at Copenhagen I do not agree that other states are doing nothing. As we continue to seek global agreements, there is rapid action in China and Japan. In the USA where prospects of early cap and trade legislation are slim, the US Government plans to push businesses hard through the EPA.”
It doesn’t matter what skeptics find in articles like this, the outcome is already settled.
Steven Mosher what does the hmmm mean in reference to the Alley holocene graph?
don,t worry about the graph being up to date, just put your head out the window ,you will soon know the temp at that time and date you put your head out the window, if you are a greeny you will not know what date it is or time you put your head out of the window ????
Re: [Vulgarities removed… bl57~mod]
BS is BS and, as I recall, it’s okay to call it that. If you need an example:
http://wattsupwiththat.com/2008/07/27/penn-and-teller-on-carbon-credits/
And F is not a vulgar letter, either. How about:
PATHETIC posting!
[I need not approve a comment; I can simply move it to the spam cache or trash it. So if you want to argue… it will be with yourself. … bl57~mod]
What baffles me is that after all these DECADES they suddenly feel the need to ‘adjust’ 1934 downward while ‘adjusting’ 1998 upward. Can’t the agency that sent man to the moon read a thermometer? We here on WUWT know the crap these people are up to but the vast public don’t have a clue they are being tricked.
jorgekafkazar says:
December 29, 2010 at 12:18 am
Not even up to nitpicking quality, MVB. See Figures 1 and 2 for the modern curves.
You’re wrong, jorgekafkazar. Fig 1. isn’t calibrated to the other graphs, so comparing it to the rest of the Holocene doesn’t fly. And Dr. Don J. Easterbrook’s narrative, such as for Fig 5., implies a ‘present’ that is not on the graph he’s talking about.
And 1934 was an American record, not a global one; ’98 and el nino year, 2004 not mentioned here, and the data for 2010 isn’t actually in yet. [SNIP what I’d like to call you.] I’m familiar with the information. I just find it ‘a shame’ [if that’s still an okay word to use] when an article drops to similarly low standards as those that are constantly critiqued here.
[And “vulgarities removing moderator” [sic] bl57~mod, I think you missed the baseless ad hominem attack “You probably don’t know that, because you’ve been spending all your time at porn sites.”]
It is clear from the graphs presented that the climate of Greenland is not representative of other parts of the world, notably Europe. This is seen totally clearly by the fact that the ‘Little Ice Age’ temperatures in Greenland were higher than in the late 19th century.
It is extremely stupid to try and correlate one place’s data with ‘global trends’. The only thing this data represents is the history of Greenland which, as we know, shows an inverse correlation in general with Western Europe.
I don’t think this argument has any more merit than those of the warmers and I suggest that both sides stop their grandstanding and return to doing science properly.
It is always good to have a rant from someone like MVB, as it serves to remind us all exactly what alarmist ‘logic’ is all about.
The fact that GISS has grossly manipulated historic temperature data is completely irrelevant, so is the fact that most of this inter-glacial period has been warmer than now. AGW cult members have been taught that because “grants are good”, then anything from Mannian maths to distorted science is also good.
It is possible a very inconvenient truth is now occurring for those trumpeting that “2010 is the warmest year ever”. The global temperature anomaly -as measured by satellites -has been decreasing over the past few months. In the last couple of days it has started to plunge:
http://www.google.co.uk/url?sa=t&source=web&cd=1&sqi=2&ved=0CBoQFjAA&url=http%3A%2F%2Fdiscover.itsc.uah.edu%2Famsutemps%2F&rct=j&q=daily%20temperatures%20AMSU&ei=UAAbTZTOEMSIhQf-saS3Dg&usg=AFQjCNHwDnwlQaZ_ZNRZ6HA-8L7ugy5xIw&cad=rja
Ed Murphy,
You say that a smoke filled greenhouse is warmer than one with clear air.
Has anyone done the experiment to find out if a greenhouse with 2,000ppm CO2 is warmer than one with 400ppm, everything else being equal?
Or is that not relevant?
Chris says: I’m a bit flummoxed. With a La Nina now, and also very weak period of solar activity for a few years, I expected global temperatures to be much cooler. But even if you just use uncontaminated satellite data (UAH MSU) and ignore Hansen, we’ve had a pretty warm year. I know that air temperature is a bad metric, and ocean heat content would be much better measure of global temperature, but still…
What gives?
The problem is that we can’t really measure the “Average temperature” of the planet very well for several rather well understood but consistently ignored fundamental reasons.
The first, and most basic, involves some math that most folks don’t know. The math of fractals. Fractals are all around us and involved in a huge number of common things, but most folks just think they are pretty pictures like Mandelbrots. But mountains are fractile as are coastlines.
How long is the coastline of Britain?
http://en.wikipedia.org/wiki/Coastline_paradox
The only correct answer is “It depends on the length ruler you use when measuring”.
Mountains are fractal as well. As are many (most all?) natural surfaces. So it ought to come as no surprise that temperatures of those surfaces have fractal properties as well. I’ve measured a 30 F or so difference between my back porch and fence on a rainy day. Where you measure determins the answer you get.
Then GISS and UEA and others spend loads of hours turning all this into homogenized data cheese food product. That does NOT improve it.
OK, the land data are sucky. So go with the sats…
Except the surface is still fractal, the IR emissions are widely variable, and now you are measuring different stuff. IMHO, the reason they are still reading high while land has gone low is heat flow
Heat is leaving the planet. Fast.
The uv level has dropped, the air thickness has shrunk, we’ve not had sats watching during this kind of thing, and it’s flummoxed THEM. They are seeing the cloud TOPS and those are warm as that’s where the heat is being DUMPED as it leaves the planet. This will take about a decade to get the oceans cold and during that time the oceans will continue to drop while the tops of the clouds keep announcing “more heat to leave the planet today, nice and warm”. The basic problem here is that HEAT is not TEMPERATURE but everyone measures temperature and pretends it’s heat. Just wrong.
So, what’s a person to do?
In my opinion there are two things you can reasonably do. Find long lived thermometers that have not changed and are still being recorded. Look at them. Now you are not changing the size of your ruler as you measure the fractal. When they are looked at, they show cooling. Slight, but present. The other thing you can do is watch the snows and rains. Clouds convect heat to their tops, then dump it to space when the water condenses (or hail and snow freeze) and it falls back to earth. As the rains fall and snow accumulates, you can count every drop has “HEAT left the planet”. If that count goes up, we’re cooling. Over the last 30 years we heard a lot about AGW induced droughts. I think that properly causality runs the other way. Something (probably high solar UV output or few clouds ala Svensmark) caused lower precipitation, that then meant less heat left, that results (eventually) in higher temperatures. Now we’ve got less solar output (less UV and thinner atmosphere, and / or more clouds) and we’re getting more precipitation. That’s heat leaving (makeing warm cloud TOPS in the process). Eventually the land will show lower temps everywhere, but for now it’s mostly just under the precipitation areas (i.e. the N.H. snows and Australian rains) and some years after that, the sats will catch up as heat transport reduces and clouds cool off.
This GEOS sat picture has a nice color indication of a warm cloud top. The green splotch over N. America:
http://chiefio.files.wordpress.com/2010/12/ir-28dec2010-na_goes20152010362jp2qbd.jpg
I’m under the rain from that cloud and it’s cold down here underneath. Rain and cloud radar from below here:
http://chiefio.wordpress.com/2010/12/29/storm-coming-you-say/
so you can see what it’s like from below where I can personally tell you it has been cold and wet all day. That article also includes a very cold sea surface chart / graph as seen from space. It is cold UNDER that “warm cloud top” (thats how that color is described in the legend to that picture in this article):
http://chiefio.wordpress.com/2010/12/28/ignore-the-day-at-your-peril/
which also covers a bit about the daily nature of heat flow off the planet and into warm cloud tops on the way to space.
Yes, this description is somewhat ‘speculative’ in that I can’t cite a reference for each bit of it. I’ve not “done the foot notes”. But all the parts are there for you to see. The GEOS sat seeing a “warm cloud top”. The cold rain below. The patterns of heat flow off planet via convection and condensation releasing heat. The basic physics of the whole thing.
So yes, it’s a bit speculative to say that the temperature reporting would do things the same way GEOS does and be fooled by cloud tops. Then again, they do measure higher in the air than “land surface” …
Hope that helps.
Max Hugoson
If I remember correctly there are three primary isotopes of Oxygen being O16, O17 and O18. Of these O16 is the most common. The three isotopes behave almost identically in terms of their chemistry, almost being the important rider here. Water that incorporates O18 or O17 is heavier than water that incorporates O16. When water evaporates from any surface (land, plants, lakes, rivers etc) the molecules containing the lighter isotope tend (slightly) to preferentially end up in the resulting vapour. When water condenses from vapour it is the molecules containing the heavier isotope that tend (slightly) to preferentially end up in droplet form (rain, hail, snow).
The result is that oceans become enriched in O18 relative to precipitation.
Rain falling on coastal areas is enriched in O18 relative to rain in continental interiors.
Precipitation on an ice sheet at low elevation is enriched O18 relative nearby areas at higher elevation.
As total ice volume increases worldwide during an ice age the ocean becomes more enriched in O18 because the growing land-based ice tends to be relatively rich in O16.
As an ice sheet expands in basal area, water has to travel further to get to the central region, so with time the O18 content of precipitation (mainly snow) here is expected to decrease. As the elevation of the ice increases the O18 content of new precipitation also decreases. O18 tends to drop out in the “first squeeze” leaving the O16 to precipitate out later.
But on top of elevation, distance and time factors the O18 content of precipitation is also a function of the temperature of precipitation. The O18 tends to drop out of water vapour at a warmer temperature than the O16 or O17.
So the basic answer to your question, when stripped back to bare essentials, is that O18 is easier to precipitate than O17 or O16.
Please note that unlike most of climate science, the essential behaviour of the isotopes of oxygen is well established science. It has been thus for decades. The known behaviour of isotopes of oxyen has been a tool for physicists, chemists, geochemists, archaeologists, oceanographers, palaenotologists and others for decades. There is a substantial literature available on the geochemistry of the isotopes of oxygen. There is a vast literature available on the isotopic ratios of a varaiety of marine microfossils. These fossilised ratios, measured from ocean floor cores painstakingly centimetre by centimetre reveal the changes in the volume of both the oceans and the ice sheets in great detail. Similarly the isotopic ratios measured directly from ice-core samples reveal the temperature of precipitation, so long as the distance from the nearby oceanic evaporative source is known and so long as the altitude of precipitation is known. Naturally some estimation is required as the ice may move from its original altitude, and there may have been a wide evaporative source area, with varying surface conditions. So numerous ice cores and pits, both deep and shallow, have been undertaken to get a good handle on the important variables. Within realistic error bands the raw results are reasonably convincing. Similarly the isotopic signature of rivers, lakes, streams and groundwater has recieved considerable attention. The modern and ancient isotopic signature of oceanic water has also been investigated in detail, both surface water, intermediate water and bottom water (based on fossilized planktonic organisms and sea-floor dwelling organisms). Cyclical changes in the ratio of oxygen isotopes in seawater has been tied conclusively to cycles in the obliquity and precession of the earths spin axis and somewhat more arguably to the eccentricity of the earths orbit around the sun. This is the major line of evidence connecting long-term climate fluctuation to orbital-scale mechanics.
Peter Miller I just wish I could get that software to draw the graph at Roy Spencer’s site. It never seems to work for me.
“I don’t know why you can’t access the image,”
If anyone ever gets the 404 error, just copy and paste the address into the address bar.
And no, I don’t know either why this works and the direct method does not