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2009 temperatures by Jim Hansen

Filed under: — group @ 17 January 2010 - (Français)

This is Hansen et al’s end of year summary for 2009 (with a couple of minor edits). Update: A final version of this text is available here.

If It’s That Warm, How Come It’s So Damned Cold? 

by James Hansen, Reto Ruedy, Makiko Sato, and Ken Lo
The past year, 2009, tied as the second warmest year in the 130 years of global instrumental temperature records, in the surface temperature analysis of the NASA Goddard Institute for Space Studies (GISS). The Southern Hemisphere set a record as the warmest year for that half of the world. Global mean temperature, as shown in Figure 1a, was 0.57°C (1.0°F) warmer than climatology (the 1951-1980 base period). Southern Hemisphere mean temperature, as shown in Figure 1b, was 0.49°C (0.88°F) warmer than in the period of climatology.

Figure 1. (a) GISS analysis of global surface temperature change. Green vertical bar is estimated 95 percent confidence range (two standard deviations) for annual temperature change. (b) Hemispheric temperature change in GISS analysis. (Base period is 1951-1980. This base period is fixed consistently in GISS temperature analysis papers – see References. Base period 1961-1990 is used for comparison with published HadCRUT analyses in Figures 3 and 4.)

The global record warm year, in the period of near-global instrumental measurements (since the late 1800s), was 2005. Sometimes it is asserted that 1998 was the warmest year. The origin of this confusion is discussed below. There is a high degree of interannual (year‐to‐year) and decadal variability in both global and hemispheric temperatures. Underlying this variability, however, is a long‐term warming trend that has become strong and persistent over the past three decades. The long‐term trends are more apparent when temperature is averaged over several years. The 60‐month (5‐year) and 132 month (11‐year) running mean temperatures are shown in Figure 2 for the globe and the hemispheres. The 5‐year mean is sufficient to reduce the effect of the El Niño – La Niña cycles of tropical climate. The 11‐year mean minimizes the effect of solar variability – the brightness of the sun varies by a measurable amount over the sunspot cycle, which is typically of 10‐12 year duration.

Figure 2. 60‐month (5‐year) and 132 month (11‐year) running mean temperatures in the GISS analysis of (a) global and (b) hemispheric surface temperature change. (Base period is 1951‐1980.)

There is a contradiction between the observed continued warming trend and popular perceptions about climate trends. Frequent statements include: “There has been global cooling over the past decade.” “Global warming stopped in 1998.” “1998 is the warmest year in the record.” Such statements have been repeated so often that most of the public seems to accept them as being true. However, based on our data, such statements are not correct. The origin of this contradiction probably lies in part in differences between the GISS and HadCRUT temperature analyses (HadCRUT is the joint Hadley Centre/University of East Anglia Climatic Research Unit temperature analysis). Indeed, HadCRUT finds 1998 to be the warmest year in their record. In addition, popular belief that the world is cooling is reinforced by cold weather anomalies in the United States in the summer of 2009 and cold anomalies in much of the Northern Hemisphere in December 2009. Here we first show the main reason for the difference between the GISS and HadCRUT analyses. Then we examine the 2009 regional temperature anomalies in the context of global temperatures.

Figure 3. Temperature anomalies in 1998 (left column) and 2005 (right column). Top row is GISS analysis, middle row is HadCRUT analysis, and bottom row is the GISS analysis masked to the same area and resolution as the HadCRUT analysis. [Base period is 1961‐1990.]

Figure 3 shows maps of GISS and HadCRUT 1998 and 2005 temperature anomalies relative to base period 1961‐1990 (the base period used by HadCRUT). The temperature anomalies are at a 5 degree‐by‐5 degree resolution for the GISS data to match that in the HadCRUT analysis. In the lower two maps we display the GISS data masked to the same area and resolution as the HadCRUT analysis. The “masked” GISS data let us quantify the extent to which the difference between the GISS and HadCRUT analyses is due to the data interpolation and extrapolation that occurs in the GISS analysis. The GISS analysis assigns a temperature anomaly to many gridboxes that do not contain measurement data, specifically all gridboxes located within 1200 km of one or more stations that do have defined temperature anomalies.

The rationale for this aspect of the GISS analysis is based on the fact that temperature anomaly patterns tend to be large scale. For example, if it is an unusually cold winter in New York, it is probably unusually cold in Philadelphia too. This fact suggests that it may be better to assign a temperature anomaly based on the nearest stations for a gridbox that contains no observing stations, rather than excluding that gridbox from the global analysis. Tests of this assumption are described in our papers referenced below.

Figure 4. Global surface temperature anomalies relative to 1961‐1990 base period for three cases: HadCRUT, GISS, and GISS anomalies limited to the HadCRUT area. [To obtain consistent time series for the HadCRUT and GISS global means, monthly results were averaged over regions with defined temperature anomalies within four latitude zones (90N‐25N, 25N‐Equator, Equator‐25S, 25S‐90S); the global average then weights these zones by the true area of the full zones, and the annual means are based on those monthly global means.]

Figure 4 shows time series of global temperature for the GISS and HadCRUT analyses, as well as for the GISS analysis masked to the HadCRUT data region. This figure reveals that the differences that have developed between the GISS and HadCRUT global temperatures during the past few decades are due primarily to the extension of the GISS analysis into regions that are excluded from the HadCRUT analysis. The GISS and HadCRUT results are similar during this period, when the analyses are limited to exactly the same area. The GISS analysis also finds 1998 as the warmest year, if analysis is limited to the masked area. The question then becomes: how valid are the extrapolations and interpolation in the GISS analysis? If the temperature anomaly scale is adjusted such that the global mean anomaly is zero, the patterns of warm and cool regions have realistic‐looking meteorological patterns, providing qualitative support for the data extensions. However, we would like a quantitative measure of the uncertainty in our estimate of the global temperature anomaly caused by the fact that the spatial distribution of measurements is incomplete. One way to estimate that uncertainty, or possible error, can be obtained via use of the complete time series of global surface temperature data generated by a global climate model that has been demonstrated to have realistic spatial and temporal variability of surface temperature. We can sample this data set at only the locations where measurement stations exist, use this sub‐sample of data to estimate global temperature change with the GISS analysis method, and compare the result with the “perfect” knowledge of global temperature provided by the data at all gridpoints.

1880‐1900 1900‐1950 1960‐2008
Meteorological Stations 0.2 0.15 0.08
Land‐Ocean Index 0.08 0.05 0.05

Table 1. Two‐sigma error estimate versus period for meteorological stations and land‐ocean index.

Table 1 shows the derived error due to incomplete coverage of stations. As expected, the error was larger at early dates when station coverage was poorer. Also the error is much larger when data are available only from meteorological stations, without ship or satellite measurements for ocean areas. In recent decades the 2‐sigma uncertainty (95 percent confidence of being within that range, ~2‐3 percent chance of being outside that range in a specific direction) has been about 0.05°C. The incomplete coverage of stations is the primary cause of uncertainty in comparing nearby years, for which the effect of more systematic errors such as urban warming is small.

Additional sources of error become important when comparing temperature anomalies separated by longer periods. The most well‐known source of long‐term error is “urban warming”, human‐made local warming caused by energy use and alterations of the natural environment. Various other errors affecting the estimates of long‐term temperature change are described comprehensively in a large number of papers by Tom Karl and his associates at the NOAA National Climate Data Center. The GISS temperature analysis corrects for urban effects by adjusting the long‐term trends of urban stations to be consistent with the trends at nearby rural stations, with urban locations identified either by population or satellite‐observed night lights. In a paper in preparation we demonstrate that the population and night light approaches yield similar results on global average. The additional error caused by factors other than incomplete spatial coverage is estimated to be of the order of 0.1°C on time scales of several decades to a century, this estimate necessarily being partly subjective. The estimated total uncertainty in global mean temperature anomaly with land and ocean data included thus is similar to the error estimate in the first line of Table 1, i.e., the error due to limited spatial coverage when only meteorological stations are included.

Now let’s consider whether we can specify a rank among the recent global annual temperatures, i.e., which year is warmest, second warmest, etc. Figure 1a shows 2009 as the second warmest year, but it is so close to 1998, 2002, 2003, 2006, and 2007 that we must declare these years as being in a virtual tie as the second warmest year. The maximum difference among these in the GISS analysis is ~0.03°C (2009 being the warmest among those years and 2006 the coolest). This range is approximately equal to our 1‐sigma uncertainty of ~0.025°C, which is the reason for stating that these five years are tied for second warmest.

The year 2005 is 0.061°C warmer than 1998 in our analysis. So how certain are we that 2005 was warmer than 1998? Given the standard deviation of ~0.025°C for the estimated error, we can estimate the probability that 1998 was warmer than 2005 as follows. The chance that 1998 is 0.025°C warmer than our estimated value is about (1 – 0.68)/2 = 0.16. The chance that 2005 is 0.025°C cooler than our estimate is also 0.16. The probability of both of these is ~0.03 (3 percent). Integrating over the tail of the distribution and accounting for the 2005‐1998 temperature difference being 0.61°C alters the estimate in opposite directions. For the moment let us just say that the chance that 1998 is warmer than 2005, given our temperature analysis, is at most no more than about 10 percent. Therefore, we can say with a reasonable degree of confidence that 2005 is the warmest year in the period of instrumental data.

Figure 5. (a) global map of December 2009 anomaly, (b) global map of Jun‐Jul‐Aug 2009 anomaly. #4 and #2 indicate that December 2009 and JJA are the 4th and 2nd warmest globally for those periods.

What about the claim that the Earth’s surface has been cooling over the past decade? That issue can be addressed with a far higher degree of confidence, because the error due to incomplete spatial coverage of measurements becomes much smaller when averaged over several years. The 2‐sigma error in the 5‐year running‐mean temperature anomaly shown in Figure 2, is about a factor of two smaller than the annual mean uncertainty, thus 0.02‐0.03°C. Given that the change of 5‐year‐mean global temperature anomaly is about 0.2°C over the past decade, we can conclude that the world has become warmer over the past decade, not cooler.

Why are some people so readily convinced of a false conclusion, that the world is really experiencing a cooling trend? That gullibility probably has a lot to do with regional short‐term temperature fluctuations, which are an order of magnitude larger than global average annual anomalies. Yet many lay people do understand the distinction between regional short‐term anomalies and global trends. For example, here is comment posted by “frogbandit” at 8:38p.m. 1/6/2010 on City Bright blog:

“I wonder about the people who use cold weather to say that the globe is cooling. It forgets that global warming has a global component and that its a trend, not an everyday thing. I hear people down in the lower 48 say its really cold this winter. That ain’t true so far up here in Alaska. Bethel, Alaska, had a brown Christmas. Here in Anchorage, the temperature today is 31[ºF]. I can’t say based on the fact Anchorage and Bethel are warm so far this winter that we have global warming. That would be a really dumb argument to think my weather pattern is being experienced even in the rest of the United States, much less globally.”

What frogbandit is saying is illustrated by the global map of temperature anomalies in December 2009 (Figure 5a). There were strong negative temperature anomalies at middle latitudes in the Northern Hemisphere, as great as ‐8°C in Siberia, averaged over the month. But the temperature anomaly in the Arctic was as great as +7°C. The cold December perhaps reaffirmed an impression gained by Americans from the unusually cool 2009 summer. There was a large region in the United States and Canada in June‐July‐August with a negative temperature anomaly greater than 1°C, the largest negative anomaly on the planet.

Figure 6. Arctic Oscillation (AO) Index. Positive values of the AO index indicate high low pressure in the polar region and thus a tendency for strong zonal winds that minimize cold air outbreaks to middle latitudes. Blue dots are monthly means and the red curve is the 60‐month (5‐year) running mean.

How do these large regional temperature anomalies stack up against an expectation of, and the reality of, global warming? How unusual are these regional negative fluctuations? Do they have any relationship to global warming? Do they contradict global warming?

It is obvious that in December 2009 there was an unusual exchange of polar and mid‐latitude air in the Northern Hemisphere. Arctic air rushed into both North America and Eurasia, and, of course, it was replaced in the polar region by air from middle latitudes. The degree to which Arctic air penetrates into middle latitudes is related to the Arctic Oscillation (AO) index, which is defined by surface atmospheric pressure patterns and is plotted in Figure 6. When the AO index is positive surface pressure is high low in the polar region. This helps the middle latitude jet stream to blow strongly and consistently from west to east, thus keeping cold Arctic air locked in the polar region. When the AO index is negative there tends to be low high pressure in the polar region, weaker zonal winds, and greater movement of frigid polar air into middle latitudes.

Figure 6 shows that December 2009 was the most extreme negative Arctic Oscillation since the 1970s. Although there were ten cases between the early 1960s and mid 1980s with an AO index more extreme than ‐2.5, there were no such extreme cases since then until last month. It is no wonder that the public has become accustomed to the absence of extreme blasts of cold air.

Figure 7. Temperature anomaly from GISS analysis and AO index from NOAA National Weather Service Climate Prediction Center. United States mean refers to the 48 contiguous states.

Figure 7 shows the AO index with greater temporal resolution for two 5‐year periods. It is obvious that there is a high degree of correlation of the AO index with temperature in the United States, with any possible lag between index and temperature anomaly less than the monthly temporal resolution. Large negative anomalies, when they occur, are usually in a winter month. Note that the January 1977 temperature anomaly, mainly located in the Eastern United States, was considerably stronger than the December 2009 anomaly. [There is nothing magic about a 31 day window that coincides with a calendar month, and it could be misleading. It may be more informative to look at a 30‐day running mean and at the Dec‐Jan‐Feb means for the AO index and temperature anomalies.]

The AO index is not so much an explanation for climate anomaly patterns as it is a simple statement of the situation. However, John (Mike) Wallace and colleagues have been able to use the AO description to aid consideration of how the patterns may change as greenhouse gases increase. A number of papers, by Wallace, David Thompson, and others, as well as by Drew Shindell and others at GISS, have pointed out that increasing carbon dioxide causes the stratosphere to cool, in turn causing on average a stronger jet stream and thus a tendency for a more positive Arctic Oscillation. Overall, Figure 6 shows a tendency in the expected sense. The AO is not the only factor that might alter the frequency of Arctic cold air outbreaks. For example, what is the effect of reduced Arctic sea ice on weather patterns? There is not enough empirical evidence since the rapid ice melt of 2007. We conclude only that December 2009 was a highly anomalous month and that its unusual AO can be described as the “cause” of the extreme December weather.

We do not find a basis for expecting frequent repeat occurrences. On the contrary. Figure 6 does show that month‐to‐month fluctuations of the AO are much larger than its long term trend. But temperature change can be caused by greenhouse gases and global warming independent of Arctic Oscillation dynamical effects.

Figure 8. Global maps 4 season temperature anomalies for ~2009. (Note that Dec is December 2008. Base period is 1951‐1980.)

Figure 9. Global maps 4 season temperature anomaly trends for period 1950‐2009.

So let’s look at recent regional temperature anomalies and temperature trends. Figure 8 shows seasonal temperature anomalies for the past year and Figure 9 shows seasonal temperature change since 1950 based on local linear trends. The temperature scales are identical in Figures 8 and 9. The outstanding characteristic in comparing these two figures is that the magnitude of the 60 year change is similar to the magnitude of seasonal anomalies. What this is telling us is that the climate dice are already strongly loaded. The perceptive person who has been around since the 1950s should be able to notice that seasonal mean temperatures are usually greater than they were in the 1950s, although there are still occasional cold seasons.

The magnitude of monthly temperature anomalies is typically 1.5 to 2 times greater than the magnitude of seasonal anomalies. So it is not yet quite so easy to see global warming if one’s figure of merit is monthly mean temperature. And, of course, daily weather fluctuations are much larger than the impact of the global warming trend. The bottom line is this: there is no global cooling trend. For the time being, until humanity brings its greenhouse gas emissions under control, we can expect each decade to be warmer than the preceding one. Weather fluctuations certainly exceed local temperature changes over the past half century. But the perceptive person should be able to see that climate is warming on decadal time scales.

This information needs to be combined with the conclusion that global warming of 1‐2°C has enormous implications for humanity. But that discussion is beyond the scope of this note.

Hansen, J.E., and S. Lebedeff, 1987: Global trends of measured surface air temperature. J. Geophys. Res., 92, 13345‐13372.
Hansen, J., R. Ruedy, J. Glascoe, and Mki. Sato, 1999: GISS analysis of surface temperature change. J. Geophys. Res., 104, 30997‐31022.
Hansen, J.E., R. Ruedy, Mki. Sato, M. Imhoff, W. Lawrence, D. Easterling, T. Peterson, and T. Karl, 2001: A closer look at United States and global surface temperature change. J. Geophys. Res., 106, 23947‐23963.
Hansen, J., Mki. Sato, R. Ruedy, K. Lo, D.W. Lea, and M. Medina‐Elizade, 2006: Global temperature change. Proc. Natl. Acad. Sci., 103, 14288‐14293.

932 Responses to “2009 temperatures by Jim Hansen”

  1. 51
    Matthew L. says:

    #37 CFU
    Wouldn’t want to steal Gavin’s job! ;-)

    This is always the problem with this branch of climate science. If the only way we can tell a trend measured in fractions of a degree is over 30 year timescales, and we have only been measuring temperature (reliably) for a hundred years, then there are simply too few data points to work with – so you have to get into the job of prediction. Not a practice that has a good track record in any field.

    I do think the graphics need sorting out a bit. After all it is the main way climate science communicates with the media.

    I definitely think the temperature charts need a less narrow vertical range and, despite Gavin’s derision, #36 Foobear has a point. Deep blue to deep brown is used to describe whatever temperature variance is being shown on the map. In one it is -4 to +9.6 and in another it is -3.6 to +3.7. This makes it difficult to compare the maps at all. Why not use a more sophisticated ‘absolute’ scale rather than a relative one? Human eyesight is remarkably well attuned to shades of different colours (it is the way JPG images work), so you could use a much finer gradation of tones than you might imagine.

    Another point is that white is generally seen as a ‘hot’ colour, whereas in these graphics white is used as the neutral colour for ‘no change’. As this dominates the picture it makes it look like it is dominated by heat – parboiled even.

    In UK weather reports traditionally green is used as the colour for temperate, er, temperatures. Ever deeper shades of blue are used for sub zero temperatures, mid-green fading to pale yellow for 0 – 20c then yellow merging to orange for temperatures 21 – 30. You could use something similar for the temperature variance in these maps.

    By the way, not a good day for clmate sooth-sayers in the UK press today…
    – World misled over Himalayan glacier meltdown

    – Al Gore tries to cool ‘climate spin’ by correcting claims of North pole thaw

    – BBC forecast for Met Office: changeable

  2. 52
    Daniel C. Goodwin says:

    Message 11 and its response deal with popular befuddlement at statements like “Green vertical bar is estimated 95 percent confidence range (two standard deviations) for annual temperature change.”

    This brings to mind the general tone of Hansen’s recent tome (“Storms of my Grandchildren”). I greatly appreciate Hansen’s enthusiasm for sharing the gritty grimy technical details – in case there are some people who really want to understand why and how we know what we know about the climate. I found the whole book intellectually invigorating. But at the same time, it’s hard for me to imagine that most people will have any patience for this sort of thing. And that right there may be where the real hard problem is.

  3. 53
    Vinny Burgoo says:

    Can anyone explain why the NSDC/NOAA thinks that UK Decembers were several degrees Celsius colder in 1971-2000 versus 1961-1990 when the UK Met Office reckons they were slightly warmer?

    Latest December anomalies available here:

    Straight to the graphics:

  4. 54
    moonshine says:

    to #3 – Hansen does support replacement technology such as nuclear power, read his writings.

    Even [edit] Greenpeace (as opposed to scientists) dropped their opposition to nuclear energy.

    Perhaps later this year Greenpeace is going to tell us that they actually always supported nuclear energy, everyone just misunderstood … :D

  5. 55
    Hank Roberts says:

    > 1950s and 1960s

    You can look this stuff up; reading for yourself will probably be much more helpful to you, once you think it through, than getting some guy on a blog to type some fragmentary answer from memory. Suggestions:

    start here
    finds, among much else:“clean+air+act”+”global+warming”+aerosol+sulfate+temperature
    finds, among much else:

  6. 56
    Hank Roberts says:

    Oops. Double quotes don’t work inside WordPress example Google links, they break; copy and paste those into the Google search box

  7. 57
    Ian Turney says:

    Its worth noting that in the southern hemisphere Australia has just had the warmest decade on record and for the last few months has been experiencing record and mid 40C temps two months before their normal peak in that range. Whilst here in New Zealand we have had one of our coldest January (Summer)months largely driven by El Nino, allowing cold Antarctic air to push up into the Southern Ocean. So the extremes keep getting more extreme. But the mirror Pole affects both in the northern and southern hemispheres is interesting that instability is occuring with the result that some regions within both hemispheres are experiencing unexpected and extreme cold and warmth.

  8. 58
    François Marchand says:

    A bit off topic, but… The urban heat effect does exist, and we have proof of it right here in Paris : nowadays, on a regular basis, on the pavement of our capital city, one can see olive trees bloom , and one can even pluck ripe olives from them. Fifty miles away from Paris, and even a couple hundred miles down South, it still is impossible to witness such events.
    True, but think about that for a sec. : fifty years ago, that would have been utterly unthinkable. No olive tree in its right mind would have survived North of the 45th parallel. Actually, drawing a bit adventurous plans on the future, some Brits have even started planting olive trees in Southern England.
    For about a week, we had to bear with what is now called a “cold wave” : temperatures barely went down below five degrees C, at night only…

  9. 59
    David B. Benson says:

    Mark (49) — Nobody is quite sure. Sulfates and other aerosols from industrialization without pollution controls?

  10. 60
    Al Fresco says:

    Thank you for the informative article.

    I have recently gotten myself into a debate with a denier in the letters section of my local newspaper. I am not a climate scientist and rely heavily on mainstream science websites such as RealClimate to help me substantiate the scientific consensus on global warming.

    Recently my opponent brought up the report by Smith and D’Aleo which is proliferating in the denial-o-sphere under inflammatory titles such as “NASA Caught in Climate Data Manipulation; New Revelations…”

    This report is now enjoying an inordinate amount of underserved media attention. I trust that the community of climate scientist appreciates the necessity (and urgency) of preparing a rebuttal directed at clarifying specific issues raised in this polemic. I know I am anxiously awaiting its completion so that I can set the record straight.

  11. 61
    Joel Shore says:

    #49 (Mark): I believe that the lack of warming in the mid-twentieth century is understood to be mainly due to the rapid increase in anthropogenic aerosol pollutants at a time when greenhouse gas levels were rising but not yet that high. This view is supported by the different temperature behavior seen in the Northern and Southern Hemispheres (since most of the pollutants were released and remained in the Northern Hemisphere). There may also have been some natural contributions to cooling from a few large volcanic eruptions and from a reduction…or at least secession of increase…in solar luminosity.

    Note that the responses to aerosol pollutants and to greenhouse gases (CO2 in particular) are somewhat different because the concentration of aerosols is roughly proportional to their rate of emission (because their lifetime in the atmosphere is short) while the concentration of CO2 is roughly proportional to the cumulative (integrated) emissions over time. In such a scenario, it is possible for the cooling effects of the aerosols to dominate at early times but the warming effects of greenhouse gases to surpass them at later times. (Of course, the details of the rate of emissions, and in particular, the fact that emissions of aerosol pollutants decreased in most developed countries later in the century due to pollution controls, also plays a role.)

  12. 62
    tharanga says:

    I mangled my comment in 50 a bit. Meant to say that annual data are less noisy than monthly, and so on.

    In any case, I’d appreciate if anybody can clarify what the authors are saying there. I also don’t grasp what we’re to draw from the comparison between Fig 8 and Fig 9. Perhaps I’m a little slow today.

  13. 63

    tharanga: I think the answer to your question is ‘yes’: there is a confusion here between the ‘range’ and ‘average’ of a set of anomalies.

    cjs London: 0030 hrs.

  14. 64
    Chris Dudley says:

    It seems to me that the explanation of the Arctic Oscillation Index may differ from that of other groups. NSIDC calls the negative phase the time when the Arctic Sea Level Air Pressure is high Similarly here:

    The present post would seem to come into agreement with those descriptions if high pressure is switched with low and low with high. Then, a negative excursion in the Index still leads to low temperatures (here at mid-northern latitudes) in all descriptions and makes more physical sense in terms of how wind patterns respond I think.

    [Response: ?? They are consistent. The AO was very negative in December which is a high pressure at the pole, combined with low pressure in the mid-latitudes. – gavin]

    [Further response: Sorry! There was an error in the Fig 6 caption. Fixed now. – gavin]

  15. 65

    Great article by the GISS group, much appreciated.

    I observe -AO driven largely by clouds heat combination, where as a strong High pressure usually over the Arctic Ocean Gyre (North of Alaska) current has clear air creating cooling in winter long night so strong there is a “punch” at its center actually creating a break in the ice as if High pressure center air has a heavy footprint. The opposite, a dominant Low Pressure is a sign of clouds heat exchange between the Arctic Ocean and lower cloud decks. Clouds predominated until recently, now taking a look, the ice appears extremely “loose” “cracked” , rather fluid. Surface (and Upperr Air) temperatures were unusually above normal, and so wind storms more frequent , exacerbating ice fluidity. a lack of sea ice consolidation is in the making by the once usual and now missing extreme long night cooling means next time a High pressure, or a stong positive AO appears, there will be great flushing NE of Greenland . I believe -AO and moderate to strong EL-Nino are a tandem, as or if El-Nino fades towards being La-Nina like in 1998, AO will turn positive making Arctic Ocean ice more vulnerable to the rising towards solstice sun, by lack of clouds and exacerbated flushing, possibily recreating a 2007 extreme melt event, however starting from a much thinner, more fluid pack ice base. a bad year for Arctic Ocean pack ice cover is highly likely…

  16. 66
    Jim Bouldin says:

    Matthew L (51), seriously, what are you talking about? Suppose we measure temperature in deg C x 10, or x 100. Will those larger values somehow convince you of the “significance” of a documented temperature change? Or if measured in C/10, make you even less convinced. The units, and the way those units are expressed in graphs, are beside the point. The point is the degree to which physical and biological processes are affected by a given change in thermal energy, regardless of its units. Forest fuels, spring snowpacks, and glacier mass balances don’t care too much about the units etched on mercury thermometers.

  17. 67
    Don Shor says:

    28 Jim Bouldin says:
    17 January 2010 at 3:11 PM
    Don Shor says:
    Figure 4 undercuts the use of the term “strong” for the last decade of that three-decade period. Unfortunately, this is the sort of imprecise language that causes problems.

    The “problem”, I would say, is in how you fail to recognize that the statement in the article is referring to a 30 year period, not to any individual 10 year period. Seems pretty clear to me.
    If you show a chart illustrating that in the last decade of the 30-year period the rate of global temperature increase has slowed, it is not precise to say that the 30 year period shows a strong increase.

    31 Doug Bostrom says:
    17 January 2010 at 3:28 PM

    Perhaps it would be better if the phrase was “summarizing all of the available data, we see a long‐term warming trend that has become strong and persistent over the past three decades” or something to that effect.

    No, over two of the past three decades. The rate of global temperature increase over the last decade has been at the low end of the “expected” range (I hesitate to use the term “projected” range). And overall the warming trend has been persistent over many decades. There is variability.

    35 Completely Fed Up says:
    17 January 2010 at 3:45 PM
    And when they’re on the line, the communicator isn’t the problem: zombie ears don’t hear too good.
    I really don’t understand why juvenile name-calling of this sort continues to be allowed on thjs blog. For the record, I’m not a denialist, nor even a skeptic. I just have an aversion to imprecise statements by scientists, and to exaggerations by the media.
    My father was a geophysicist (at Scripps), who taught me to be cautious about scientists who had found or sought the limelight, for two reasons:
    1. when quoted by the media, their statements tend to be misquoted or distorted.
    2. those who seek the limelight often lose their professional objectivity.
    Scientists need to be objective and accurate. Dr. Hansen is arguably the most prominent scientist in the whole field of climate change. He needs to speak very carefully, to avoid and discourage exaggerations, and needs to write his conclusions very accurately.

    49 Mark says:
    17 January 2010 at 5:26 PM
    What is the scientifically accepted reason for the lack of warming during the 50s and 60s?

  18. 68
    Doug Bostrom says:

    Al Fresco says: 17 January 2010 at 6:31 PM

    “Recently my opponent brought up the report by Smith and D’Aleo which is proliferating in the denial-o-sphere…”

    “This report is now enjoying an inordinate amount of underserved media attention. I trust that the community of climate scientist appreciates the necessity (and urgency) of preparing a rebuttal directed at clarifying specific issues raised in this polemic.”

    Huh. I took a quick look around and cannot find much media coverage of this, but lots of reverberation in the doubter community. A quick survey found the story in the UK’s Telegraph, which is sort of an official extension to WUWT and CA, not elsewhere.


    “What it shows is that, just like in Britain at the Climatic Research Unit (CRU) temperature data records have been grotesquely distorted by activist scientists in order to exaggerate the appearance of late 20th century global warming. They achieved this – with an insouciant disregard for scientific integrity which quite beggars belief – through the simple expedient of ignoring most of those weather station sited in higher, colder places and using mainly ones in warmer spots. Then, they averaged out the temperature readings given by the warmer stations to give a global average. Et voila: exactly the scary “climate change” they needed to persuade bodies like the IPCC that AGW was a clear and present danger requiring urgent pan-governmental action.

    The man who spotted all this is a computer programmer called EM Smith – aka the Chiefio. You can read the full report at his excellent blog. ”

    If you go and visit the “Chiefio” blog, you’ll find a level of discussion that’s even worse than WUWT. It’s like dropping into the locker room of a football team losing badly: all hollow bluster and boo-ya, bereft of winning points, more than a bit smelly.

    Poor Telegraph, the company they have to keep.

    Not to say that a match dropped into poor fuel by an arsonist cannot erupt into a destructive fire. The message conveyed by Chiefio and his band of apes is familiar: “Government scientists are corrupt, you cannot trust data.” The Big Lie, repeated by little teeny tiny pipsqueaks, laughable on its face. Yet if your ankles are gnawed by enough yapping Pomeranians, you may yet bleed to death.

    Somebody with authority ought to do a response that’s not buried in comments thread.

  19. 69

    re # 3 Dennis Baker said: “Mr Hansen you have demonstrated at Fossil Fuel powered electrical generating facilities, and testified for greenpeace activists whom have demonstrated at Fossil Fuel powered electrical generating facilities!

    yet to the best of my knowledge neither you or greenpeace support replacement technolgies, why is that?”

    Jim Hansen publishes articles in major peer reviewed journals that stand up over time (unlike Lindzen, Pielke, Singer, Soon and most other contrarians). Jim Hansen’s scientific work (in the journals and conferences)is considered outstanding.

  20. 70

    44 Doug Bostrom,

    Right you are about my point, except I am trying to point out that the energy going into the oceans, deep ocean that is, is huge compared to the little bits that seem to actually stick to the air.

    And I am trying to find out how this is accounted for in the climate modeling. In pursuit of this, I keep finding descriptions that suggest that it is not accounted for at all, or in some cases, not adequately.

    Are all the arguments about atmospheric temperature missing the bigger issue of ocean temperature?

  21. 71
    Hank Roberts says:

    > Al Fresco
    > D’Aleo
    Easy to rebut. My opinion (just another reader here, mind you): Tell people not to expect you to do their research for them; you shouldn’t feel the need to try to encompass in letter columns of a local newspaper a real research effort worthy of a high school senior. Give them a few pointers, point out that the guy’s a PR expert not a scientist, and makes things up. That’s easy to confirm.'aleo

    Trying to rebut every bunk point raised in every newspaper letters column is, well, not very focused.

    This should suffice:'aleo

    Need more? Do the obvious searches, for example'aleo'aleo

  22. 72
    Hank Roberts says:

    Urk. WordPress doesn’t handle apostrophes in links to searches; you’ll need to copy those out and paste them into your browser navigation box for them to open properly for you.

  23. 73
    Tim Jones says:

    Re: 49 Mark says:

    “What is the scientifically accepted reason for the lack of warming during the 50s and 60s?”

    Frequently Asked Question 9.2
    “In the early part of the 20th century, global average temperature rose, during which time greenhouse gas concentrations started to rise, solar output was probably increasing and there was little volcanic activity.
    During the 1950s and 1960s, average global temperatures levelled off, as increases in aerosols from fossil fuels and other sources cooled the planet. The eruption of Mt. Agung in 1963 also put large quantities of reflective dust into the upper atmosphere. The rapid warming observed since the 1970s has occurred in a period when the increase in greenhouse
    gases has dominated over all other factors.”

    Use Google

  24. 74

    “The urban heat effect does exist, and we have proof of it right here in Paris : nowadays, on a regular basis, on the pavement of our capital city, one can see olive trees bloom , and one can even pluck ripe olives from them. Fifty miles away from Paris, and even a couple hundred miles down South, it still is impossible to witness such events.”

    I don’t know what you are implying? Do you not think that mainstream science has not deeply looked into this (especially the big oil-paid contrarians?) and taken it into account in the open peer reviewed process under intense scrutiny many years ago? We have been studying climate factors since at least 1824 (Fourier)[energy imbalance]. Scientifically, the heat island effect is extremely old news. Even the contrarians (whose work does not stand up over time in the journals) have stopped raising this issue.

    What do you think happens if the Earth’s urban heat island effect temperatures are totally eliminated from the Earth’s average temp record…the average still goes up!

    There are no cities where most of the warming is currently happening (the poles) as well and where the warming was first projected to happen most mathematically since 1896 (Arrehenius).

    Here’s a few of the peer-reviewed journal studies on the urban heat island effect alone:

    Howard 1833
    Oke 1987
    Lo C. P et al., 1997
    Camilloni et al.,2004
    Q. Li1 et al., 2004
    Crutzen, 2004
    Price, 1979
    Voogt, 2003
    Baik et al., 2001
    H Taha, 1997
    SM Khan, 2001
    Y Delage, 1970
    KP Gallo et al., 1993
    DB Olfe et al., 1971
    BW Atkinson et al., 2003
    SH Schneider, 1989
    H Taha, 1988
    AC Comrie, 2000
    JS Golden et al., 2006
    TR Karl et al., 1988
    TR Oke et al., 1991
    L Jiahong et al., 1998
    M Santamouris et al., 2004
    JL McElroy et al., 1993
    Y Shimoda et al,. 2003
    H KUSAKA, 2004
    GT Johnson, 1991
    SM Khan, 2001
    MA McGeehin et al., 2001
    A Haines et al., 2004
    L Xuechun et al., 2005
    JM Giovannoni et al., 1987
    HE Landsberg et al., 1970
    E JAUREGUI et al., 2009
    JA Winkler et al., 1981
    H Taha et al., 1999
    DR Streutker et al., 2002
    PP Childs et al., 2005
    M Santamouris et al., 2007
    DJ Sailor et al., 2004
    AJ Brazel et al., 2002
    M Colacino et al., 1982
    A Iino et al., 1996
    IPCC 1997, 2001, 2007

    …There are probably quadruple this number or more of mainstream peer reviewed journal studies on the heat island effect… This is an extremely well studied subject. Now think of how many there are for global warming dating to 1824 which refer to studies from the 1700s/1600s on panes of glass and boxes with them retaining heat with them.

    …and this is not a comprehensive list or of those including all the studies of the urban heat island effect done of individual cities such as Anchorage, New York City, Athens, etc….

  25. 75
    Ray Ladbury says:

    Al Fresco, As usual, Smith and D’Aleo is much ado about nothing. First, it affects only a couple of stations. Second, the data concerned are anomalies, not absolute temperatures, which tend to correlate better over different topography. Gavin has discussed this on the Unforced Variations2 post

  26. 76
    Tim Jones says:

    Re:51 Matthew L. says:

    “By the way, not a good day for clmate sooth-sayers in the UK press today…”
    – World misled over Himalayan glacier meltdown

    I’m not so sure Times Online is an unbiased resource.
    Perhaps better discussion on the subject in a parallel report is here:

    “Satellite images show Himalayan glacier receded 1.5 km in 30 years”
    “Rajendra Pachauri, chairman of the IPCC, blasted the research, calling it “unsubstantiated” and said “ We do need more extensive measurement of the Himalayan range but it is clear from satellite pictures what is happening.” He likened the explanations to “climate change deniers and school boy science”.
    “Raina admits in his paper that there is a lack of available data. For the moment long-term data exists for only 20 to 30 Himalayan glaciers and that there was only one automated weather station recording climatic data in the Himalayas, he said.”
    “According to Raina, all glaciers under observation in the Himalayan region during the past three decades have shown cumulative negative mass balance (determined by annual snow precipitation). Degradation of the glacier mass has been the highest in Jammu and Kashmir state, relatively lower in Himachal Pradesh region, even less in Uttarakhand, and the lowest in Sikkim — showing a declining trend from the north-west to the north-east.”

    I don’t think we can relax just yet. Though the IPCC was embarrassed, climate scientists caught themselves on this one.
    (excerpt from TimesOnline)
    “Last week the IPCC refused to comment so it has yet to explain how someone who admits to little expertise on glaciers was overseeing such a report. Perhaps its one consolation is that the blunder was spotted by climate scientists who quickly made it public.”

  27. 77
    Lynn Vincentnathan says:

    #9, Leanan, I tend to look for other evidence, rather than trying to decide who’s right on particular issues. The fact that glaciers around the world are melting and shrinking, ice disappearing in the Arctic, and ice sheets disintegrating and breaking off in the Antarctic tells me it’s warming.

  28. 78
    nigel jones says:

    Good article. But the satellite data for the upper atmosphere show 1998 as the warmest year to date and a general trend closer to the Hadcrut graph.

    Isnt this the most accurate data? Doesnt this indicate at least a significant slowing in global warming since 1998? Why is the giss and upper atmosphere satellite data different?

    Im not a sceptic and have studied a little climatology a million years ago. I may be missing something obvious but an explanation would help.

  29. 79
    evagrius says:

    Could someone give a response, ( in the media), to this?

    It would be nice to see a refutation intelligible to laypeople, ( such as myself).

  30. 80
    Septic Matthew says:

    Figure 1a shows 2009 as the second warmest year, but it is so close to 1998, 2002, 2003, 2006, and 2007 that we must declare these years as being in a virtual tie as the second warmest year. The maximum difference among these in the GISS analysis is ~0.03°C (2009 being the warmest among those years and 2006 the coolest). This range is approximately equal to our 1‐sigma uncertainty of ~0.025°C, which is the reason for stating that these five years are tied for second warmest.

    Well Said.

  31. 81
    Septic Matthew says:

    It looks like the warming over the 20th century is about 0.9C. Is that a generally accepted figure, or fair interpretation of the graph (or both)?

  32. 82

    Tim Jones #76: I must say I was a bit surprised when I looked up the IPCC report and there it was, a reference to WWF, 2005 (my response was another acronym, WTF?).

    I’m sure errors have slipped into the IPCC’s reports. The only puzzle is why this one took so long to surface. Contrast this with the extremely careful handling of sea level rise, where contributions from melting ice caps were removed if modelling wasn’t considered reliable.

    On the other hand, from “sceptics” I still get reports that satellite data shows no warming, a claim that was discredited in 2005. There is a double standard here: the slightest error on the side of the mainstream is blown up out of all proportion, whereas egregious errors on the denial side are simply ignored.

    Finally, thanks RC team for this article. A nice piece of work.

  33. 83
    Joel Shore says:

    Re #79 (evagrius): One thing that to look at is simply how horrendously shoddy and biased the reporting in that article is. One of the major climate scientists quoted (Latif) says that article misinterpreted his research: Folks from Britain may be able to give you a better perspective, but my impression is that the Daily Mail is not exactly thought of as a serious newspaper, to put it mildly.

  34. 84
    Doug Bostrom says:

    Jim Bullis, Miastrada Co. says: 17 January 2010 at 8:19 PM

    “Right you are about my point, except I am trying to point out that the energy going into the oceans, deep ocean that is, is huge compared to the little bits that seem to actually stick to the air.

    And I am trying to find out how this is accounted for in the climate modeling. In pursuit of this, I keep finding descriptions that suggest that it is not accounted for at all, or in some cases, not adequately.”

    Perhaps it’s one of those questions that’s been asked so many times, nobody can stand to answer it again? Not your fault if you’re last in the queue. For that matter perhaps you were not insulting enough when answering the question, heh.

    If the ocean heat sink were not accounted for at all, the models would be wildly off.

    If I remember correctly you were originally wondering less about the absence of oceans in the model, more about what level of detail is involved?

    Given the enormous capacity of even the first kilometer of ocean, presumably it can be treated as a lump with enormous inertia for the time being. This paper seems to suggest so, though it’s kind of a fossil:

    My caveman knowledge of thermodynamics tells me, the more heat is pushed into the ocean the harder it’s going to push back. As the ocean becomes more saturated, it stands to reason that more detail in the models will be helpful.

    It’s really big. It’s really cold. Can’t you just tell what a super expert genius I am on this!?

  35. 85
    Mark says:

    Re: 1950s and 1960s – Thank you Hank, David, Joel and Don. Quite helpful!

  36. 86
    Al Fresco says:

    Thanks to all. Your comments have been most helpful.

    I still think, however, that it would be beneficial to the cause to have a more comprehensive response to the Smith/D’Aleo article.

  37. 87
    Jefferson says:

    @ 67

    >> those who seek the limelight often lose their professional objectivity <<<

    Scientists are often criticized for not getting their research out to the public. Now if we try, we're also damned.

    You're concerns are valid but self-correcting.

  38. 88
    dhogaza says:


    Al Fresco, As usual, Smith and D’Aleo is much ado about nothing. First, it affects only a couple of stations. Second, the data concerned are anomalies, not absolute temperatures, which tend to correlate better over different topography.

    Yeah, well, one might imagine people long ago talking about “maritime environments”.

    Surely, though, they were proto-commie-pinko-hippy-freak-genocidal-maniacs.

    What other kind of person would notice fronts blowing off the ocean and dominating the weather?

  39. 89
    Hank Roberts says:

    >Daily Mail … mini ice age
    “… In the hotly contested competition to see who are the biggest tossers in the british newspaper industry there has been an early entry this year by the Daily Mail: The mini ice age starts….”

  40. 90

    re 79 Evagrius wrote: “”Could someone give a response, (in the media), to this?”” (they already have-RO).

    “”The bitter winter afflicting much of the Northern Hemisphere is only the start of a global trend towards cooler weather that is likely to last for 20 or 30 years, say some of the world’s most eminent climate scientists.


    “”It would be nice to see a refutation intelligible to laypeople””

    Urrrr… *what global cooling trend????*

    Lots of the globe is currently experiencing *record warming*. Doesn’t anyone read? Global warming means GLOBAL (averages). This regional cooling has been covered in the last two threads.

    Certain people are on purposely ignoring this highly visible and understandable information although it is publicly available. It is unbelievable that people are falling for this. This stuff is easy for anyone to understand.

    The parts of the Earth currently cooling (as opposed to parts of the Earth which are currently warming) are most likely linked to a regional effect of an interlinked high and low pressure system (NAO)which is known to be at an extreme level right now (and still only affects parts of the globe in spite of this).

    Okay…. all this back and forth stuff you seem to hear in the media is granted, I guess, a bit confusing. But don’t believe the media with its hype of immediate death by the ice ages, Y2K, bird flu, etc. They have to sell copy and they (and talk show hosts) are as much scientists as my German Shepherd. You need to read the peer review journals where there is no talk of global cooling that stands up over time and never has been (and don’t count National Geographic, Time or Newsweek as journals either…not to insult them but “they ain’t publishing scientists.”
    WMO global 2009 temperature analysis:

  41. 91
    Didactylos says:

    Matthew L.: You have it backwards. When choosing ranges and scales for a graph, the goal is to clearly show the information that is of interest. When discussing global warming, the primary thing of interest is the trend, on century and decadal scales.

    What is not of interest is the month to month and year to year weather noise. If you just chart what the thermometer outside your window shows every day, then you could waste a decade and you would never, ever get anything that hints of global warming. To trot out an old trope, you wouldn’t see the wood for the trees.

    Your only motive in wanting to concentrate on the noise and ignore the trend must be so that you can justify inaction. Well, the trend is there, and only the most egregious of liars have managed to hide it by messing with the scales as you suggest.

    Manipulating a graph so that a statistically significant trend becomes invisible is simple deception. And yes, some deniers do stoop that low.

  42. 92
    Didactylos says:

    evagrius, it’s just tabloid nonsense. I don’t think any of the cited scientists agree with a word of it.

    Frankly, anyone getting their “science” from a tabloid like the Daily Mail deserves to be misled.

  43. 93
    jyyh says:

    First, I’m not really an expert on oceanic cycles.
    My interpretation of Latif et. al is that they seem to think the melt of the arctic has reached a level that induces colder winters in Atlantic coasts. Once theres enough water coming from arctic it induces the type of weather pattern seen this past month. My guess is they expect this weather pattern to continue whole year around in the future. On contrast, this IMHO would mean rapid warming in north Pacific – Siberia – Arctic Canada, as they do not deny the increasing greenhouse effect that is a result of anthropogenic interruption of natural carbon cycles (Rising CO2 -> sightly risen temperatures (oceanic and land) -> Slightly risen methane and clathrate outbreaks -> a bit more risen temperatures -> increased ice melt in Greenland -> Gulf stream stays diverted -> locally cooler in the areas near by.) I’d say ‘Local North Atlantic Micro-Nano Cool Period may start here’ to tone it down. If true, agriculture will be less affected here than elsewhere, if you want the positive aspect. I think the global climate is the result of balances between tropics (namely, ITCZ) and both poles (partly secluded by the polar jetstream), if that is of any help in thinking this.

    On another matter, the SH was 2nd warmest when the NH was much lower in the placement in 2009 according to GISS averages. Has there been some unusual weather phenomenon during winter 2008-2009 that has leaked some of the NH temperature rise to the SH?

  44. 94
    jeannick says:


    There seems to be little debate on the most visible , most important effect of Climate , weather or seasons , the water cycle
    The power involved are enormous , at the human scale , clouds and precipitations , either rain or snow , are the most appreciable manifestation of weather for the layman or professionals in many fields
    on any discussion on the weather

    The hydrological cycle is a pump removing heat from the liquid water interface and flinging millions of tonnes up in the atmosphere ,
    that amount of work must be accounted for
    evaporation can cool whole landmasses in the matter of hours ,
    those process are understood in their principle since centuries but it’s hardly discussed as a forcing ,even less quantified

    the only thing I could find was

    is there some further research available on the subject of the hydrological cycle feedback on the climate ?


  45. 95
    Anonymous says:

    Maybe you can address these claims.
    The detailed report by D’Aleo is available at

    [Response: Here. – gavin]

  46. 96
  47. 97
    moonshine says:

    Re evagrius 79: It was on ClimateProgress recently:

  48. 98
    Urs Neu says:

    An update of the ENSO-corrected global temperature (i.e. global temperature corrected for the ENSO induced interannual variations) presented in would be interesting and an alternative to the 5y running mean.

    A simple statistical correction for the ENSO influence (GT minus 0.1*half-year-timelagged-MEI-Index; derived from the correlations of the last 40 years) shows that 2009 was the warmest year in the record if the ENSO influence is taken into account. This seems to be the case for all available global data sets (GISS, HadCRUT, NOAA), although the HadCRUT data set is not yet available to the end of the year.

    If taking into account the current solar minimum, too, 2009 is a clear leader.

  49. 99
    Completely Fed Up says:

    “Good article. But the satellite data for the upper atmosphere show 1998 as the warmest year to date and a general trend closer to the Hadcrut graph.

    Isnt this the most accurate data?”

    So the CRU data is now the most accurate…

  50. 100

    JB: The 10×10^23 Joules that went into the ocean from 1985 to 2005 would raise the air temp by 7.46 degrees C if that energy had gone into the atmosphere instead.

    BPL: If it happened all at once, yes. If it happened at the same RATE it had gone into the ocean, most of it would have radiated away into space by now.