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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. 201
    sam says:

    RE #182 / 185 Lynn Vincentnathan

    I wasn’t laughing at any predicted humanitarian tragedy! The reason why I thought the pictures were funny is that the contrast, lighting, color, and potentially the time of year were totally different in the two pictures. That and I couldn’t tell what I was even supposed to be looking for!

    So I’m gonna go ahead and believe this guy:,indian-ecology-minister-ramesh-says-i-was-right-on-glaciers-melting.html and not you.

    [Response: How convenient for you. – gavin]

  2. 202
    Tom S says:

    Figure 4 is missing the 2009 data point, which is a bit confusing when reconciling 2009 as being the 2nd hottest year. The last data point (2008) is the lowest temp in 8 years which confuses the discussion.

  3. 203
    Septic Matthew says:

    Advancing and retreating glaciers here:

    It’s a review that refers ahead to a report later in the issue. There are links to other studies. I’ll see what I can find that is more specific to advances within the 20th century.

  4. 204
    Septic Matthew says:

    Here is an advancing glacier in Canada, 1954-1960

  5. 205

    172 Doug Bostrom,

    You said: On a related note, I’m going to head off to the Web-0-Sphere and see what I can discover about what we can expect in the way of the ocean burping out heat from time to time, as opposed to absorbing it obediently and smoothly. I have to wonder how much of a contribution to variability this is.

    I say: Where did you get the idea that the ocean “burped out heat from time to time?” You only have to go to the Dec.28, 2009 post to see how heat goes into the ocean. The NOAA chart showing heat content of the top 700 meters should give you a good record to go on. No burping to my eye.

    Just click on:

    And then maybe you will report back that there was indeed an increase in ocean heat content of about 10×10^23 Joules over the 20 years under discussion, so our overfed friend will believe me. And maybe then we can talk about how that much heat got into the oceans, and why it happened so powerfully from 1985 to 2005, (and not meaning it stopped there).

    I wonder why said fed friend thinks I have control over how the ocean integrates its heat input. If I need to teach the ocean how to do that I should next get on with teaching water to run downhill.

  6. 206
    Doug Bostrom says:

    Al Fresco says: 18 January 2010 at 6:40 PM

    “I am not talking about the article referring to the work of Latif. I am talking about the article written by Smith and D’Aleo that accuses NASA climate scientists of manipulating data…”

    And Gavin replies:

    “But there is no there, there. It’s based on nothing but ignorance as explained previously. ”

    Gavin refers to an update to the “Unforced Variations 2” thread:

    I’m loath to second-guess here but I don’t think that’s a sufficiently forceful response.

    Again, looking to recent examples, you can expect your work to be attacked on its very strengths. The brick and mortar of the case for AGW is data, observations. Insufficiently contested attacks on the foundations of your research is potentially disastrous.

    There was no “there, there” w/regard to Kerry’s treatment, the Swiftboat argument was wholly based on exploitation of ignorance. Nonetheless an impression was successfully conveyed that turned off a sufficient proportion of the electorate to change the outcome of that election.

    Post mortem analysis of Kerry’s Swiftboat debacle yields a consensus that Kerry was late in rebuttal, allowing an attack that its face initially seemed ridiculous to take root and ruin his chances for election. He trusted in rationality, to his great loss.

    It’s sad commentary that time should need to be devoted to swatting down rank untruths before they turn into lethal infections. All the same, effective message coordination and delivery is sorely needed for people carrying the banner of mainstream science when stakes are so high. Is this distasteful, wrong somehow? No. It may be irritating but it’s urgently necessary.

    This seems to be the go-to place for climate change information. There are other helpful sites but the primary locus of contention seems to be here.

  7. 207
    sam says:

    Sure, I concede that it looks like some or maybe even a majority of the glaciers are shrinking. But if I had to place money on it, I bet it will continue to snow in the himalayas for a long long long time and this snow will have to go somewhere. Whether it melts off in 6 months or is buffered in a glacier for 1 thousand years the water still has to go somewhere!

    What I don’t understand is that people on the pro AGW side of this issue will assume that any side effect of predicted global warming are negative. Isn’t it at the simplest (and perhaps most accurate) level just as likely that the side effects might be positive? It’s just a temperature increase, it has no evil, diabolical spirit or intelligence! [edit – OT]

    [Response: You are fighting straw men. Melting glaciers do have impacts for irrigation, summer river flow and the potential formation of unstable proglacial lakes. They are also very clear signs that the planet is indeed warming. But no-one as far as I can tell has ever said this is the worst possible impact of global warming – I would put sea level rise and shifts in the sub-tropical arid zones much higher up in the list. You do touch on a real issue – which is that absent our reliance on the status quo, climate change is neither good nor bad. However, we have built our cities, our agriculture, our infrastructure in the expectation that climate won’t change too much – whether that is a reliance on the statistics of 100-year floods, or the hardiness of plants, or the height of the sea wall, or depth of the sewers, or the availability of irrigation. We, sometimes unconsciously, rely on services that are provided by the climate – by rainfall, by ecosystems, by currents, by winds. All of these things could be changed given enough time, goodwill and money – but don’t underestimate how hard it would be to resettle a big fraction of Bangladesh, or to build a barrage in New York Harbor, or build extra reservoirs to provide the water storage no longer provided by the snow pack. Some adaptations will be easy – the English can grow better grapes, heating costs for the Swedes might decrease – but lots won’t be. And the faster things change, the more costly it will be. NB. Might I suggest if you want to argue here, you confine yourself to criticising things that are said here, and not on the wilder shores of the internet. People looking for stupidity will also find it, but don’t confuse that with reasoned discussion. However, if reasoned discussion is not your goal, you will be happier somewhere else. – gavin]

    Gavin, I’ve thought about most the things that you bring up here but it is on the magnitude and impact that we totally differ. I’m sorry if I tend to try to ridicule but I, like many people, do not give much credit to the underlying theory that you advance. If it’s worth anything you seem to be far and away the most credible and tireless spokesman your side has. But let’s be honest, the last 2 months have left you with much work to say the least. Either way in about 30 years (or less) you will either be hailed as a genius or well… the opposite. Take care.

  8. 208
    Lynn Vincentnathan says:

    RE #182, here is the weblink to the Kehrwald, et al. article re Himalayan glacier mass loss and its implications for freshwater resources —

    And the other article about threats to freshwater (including a discussion of melting glaciers and snowpacks) –

    #194, Sam, you can read these articles, and even the IPCC section the critics are citing – Ch. 10 Asia of the WG2 ( pp. 493-494) –

    The critics were right to suspect the 2035 claim (with the WWF cited), just as I did & decided not to quote it (and I’m not even a climate scientist or glaciologist), but the rest of the section is a pretty good explanation of the problem, even tho (except for the 2035 claim) the IPCC is a pretty conservative document.

    Science and individual scientific studies are conservative, requiring 95% confidence before making a claim (would anyone with a suspicious lump wait years and year before the doc was 95% confident it was cancerous?); and the IPCC is conservative times 1000, because so many scientists have to agree on what to say. We cannot wait 30 years to start deciding to mitigate CC, we have to start yesterday, and even then it might be too little too late.

  9. 209
    Mal Adapted says:


    “Overplurification” – LOL! Your own invention? Masterful! More like that, please 8^)!

  10. 210
    Hank Roberts says:

    Doug, there are other bloggers competently handling the dumptruck loads of ‘contention’ hauled in every day — individuals perfectly able to take apart the garbage pile and report on it. RC’s Contributors are doing the research and teaching about it.

    This is the meme of the weekend, apparently: Google finds about 580 for:
    Smith and D’Aleo that accuses NASA climate scientists of manipulating data

    Page through it to see where it’s popular. I got through five pages of results and didn’t find a reliable climate blogger even talking about it.
    Nor a newspaper, nor a reliable PR or political blog.

    So — eventually someone will dissect the claim and address it.
    But — why not you? I mean, demanding that someone else, like Gavin, take time out to deal with each of these stories just means more of them will get hauled in and dumped. It’s not the best use of his time, until and unless he decides to address it.

  11. 211
    Hank Roberts says:

    Well, Doug, after reading about nine pages of Google results, I found an actual reputable source taking on the story you’re asking about.

    Try here: the Columbia Journalism Review

    Cover Story — January / February 2010
    Hot Air
    Why don’t TV weathermen believe in climate change?

    That piece ends with these words:

    The biggest difference I noticed between the meteorologists who rejected climate science and those who didn’t was not how much they knew about the subject, but how much they knew about how much they knew—-how clearly they recognized the limits of their own training. Among those in the former category was Bob Breck, the AMS-certified chief meteorologist at Fox affiliate WVUE in New Orleans and a thirty-two-year veteran of the business. Breck rejected the notion of human-driven climate change wholesale-—“I just find that [idea] to be quite arrogant,” he told me. Instead, when Breck talked to local schools and Rotaries and Kiwanis clubs about climate change, he presented his own ideas: warming trends were far more dependent on the water vapor in the atmosphere than carbon dioxide, he told them, and the appearance of an uptick in global temperatures was the result of the declining number of weather stations in cold rural areas.

    These theories were not only contradictory of each other, but had also been considered and rejected by climate researchers years ago. But Breck didn’t read much climate research; “the technical journals are controlled by the professors who run the various societies,” he told me, and those professors were hopelessly dependent on the “gravy train of grants from the NSF” that required them to propagate “alarmist theories.” When I mentioned the AMS, Breck bristled. “I don’t need the AMS seal-—which I have,” he said. “I don’t need their endorsements. The only endorsements I need are my viewers, and they like what I do.”

    As Breck went on, I began to get a sense of the enormity of the challenge at hand. Convincing someone he is an expert is one thing. Actually making him one—well, that is another thing entirely. 

  12. 212
    Paul C says:

    Great..thanks for the links and I’ll give it a try.

    No harm – no foul, and no offense taken.

  13. 213
    Hank Roberts says:

    PS, if you dig far enough into a Google search, you’ll find, after the echo chambers, a PR Newswire press release that sums up j’accuse:

    Suggested exercise: take long, juicy phrases from the press release and count how many times they show up verbatim, copied and pasted.

    The accusation they make (apparently expanded to an hour of TV time; I wonder who’s sponsoring this show?):

    “… The report reveals that there were no actual temperatures left in the computer database when NASA/NCDC proclaimed 2005 as “THE WARMEST YEAR ON RECORD.” The NCDC deleted actual temperatures at thousands of locations throughout the world as it changed to a system of global grid points, each of which is determined by averaging the temperatures of two or more adjacent weather observation stations. So the NCDC grid map contains only averaged, not real temperatures …”

    Gasp! It’s like they used — arithmetic!

  14. 214
    Hank Roberts says:

    However, you can continue to rely on your local TV weatherman, because he doesn’t do arithmetic. He just points to the pictures and talks to you, in a calm, reassuring voice. He knows what’s true and what’s not true:

  15. 215
    Ray Ladbury says:

    Sam says, “But let’s be honest, the last 2 months have left you with much work to say the least.”

    And this is different from the past 20 years…exactly…how? It is never easy to tell people what they do not want to hear. Unfortunately, we have to keep trying because what you don’t want to hear happens to be the truth.

    Sam, there are mountains of evidence that tell us unequivocally that it is warming. There are mountains of evidence that tell us that WE are the ones doing it. We have about a dozen different lines of evidence that all agree on how much warming we are likely to see, and we know of lots of adverse effects that will occur if it does warm significantly.


    The early portion of this period corresponds to the onset of agriculture, and with it human civilization. Prior to this time, humans had been hunter gatherers. Why did they pick this particular time to switch to agriculture? We don’t know, but every element of the infrastructure of human civilization was developed during this period of exceptional climatic stability. It is now warmer than it has been during any sustained period during the HCO.

    Now read this:

    This period coincides with one of the greatest mass extinctions in global history.

    Are we bringing about another such period? We do not know–but the fact that we do not know OUGHT TO SCARE YOU. Uncertainty is not your friend, Sam.

    The evidence doesn’t change because of a few hacked and carefully selected emails. It is still there, and it still points undeniably at a potentially serious crisis for human civilization even as human population soars to 9-10 billion. Science is our best guide to figuring out what to expect and to developing possible solutions. You can either go with what the science and evidence tell you, or you can go 180 degrees against it. Science or anti-science. Pick.

  16. 216
    gary thompson says:

    why the delay in updating the graph for the US? still doesn’t have a data point for 2009 but the other graphs have been updated.

  17. 217
    Regg says:

    To Mark (item 49) about lack of warming in the 50s, 60s..

    Maybe tons of dust by about 1000 nuclear bomb testing by both the US and Russia at the same period of time. It takes not much to lower the global temps – just one volcano. Imagine 1000 nuclear test (aerial : from the ground up).

    It’s getting warmer since they stop the aerial testint and went underground (mid 60s). But don’t tell that to the GOP, it might give them ideas ;-)

    For the rest .. Jim and all your group – wow, your patience and determination.

  18. 218
    Tim Jones says:

    Re: 203 Septic Matthew says:
    18 January 2010 at 8:08 PM
    Here is an advancing glacier in Canada, 1954-1960

    Few and far between aren’t they? Not to mention this one occurred during the period of well noted aerosol cooling
    before the US Clean Air Act was codified.

  19. 219
    Tim Jones says:

    CLIMATE: Senate’s top EPA critic raked in utilities’ campaign cash
    “One of the Senate’s most vocal critics of U.S. EPA’s climate rules is also Congress’ top recipient of campaign funds from the electric utility industry. Alaska Republican Lisa Murkowski, who was elected to Senate GOP leadership last year and holds a key post on the Energy and Natural Resources Committee, received more campaign contributions from the utility industry than any other lawmaker during the 2009-2010 election cycle, according to data compiled by the nonpartisan Center for Responsive Politics. Last year, Murkowski received $157,000 from electric utilities, and since 2005, she has received more than $244,000, according to the center’s data.”

    Who woulda thought…

  20. 220

    My own opps #65 ….. I’ve never really used AO language, living in the Arctic I should since it is perrhaps easier than saying that there is usually a high North of Alaska mimicking the the Arctic Ocean gyre current. However positive associated with a Low pressure and negative with a High pressure is as confusing as negative lapse rates with inverrsions and positive ones with adiabatic lapse rates, someone didn’t think AOI nomenclature through. Who has the authority colder air is more negative than warmer air? Haha ! Perhaps some academic living in Florida…. Now I correct and add , look at the sat pic, quite telling :

    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 negative 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 negative 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…

  21. 221
    Tim Jones says:

    CLIMATE: IPCC to review Himalayan glacier claim

    The chief of the U.N.’s Intergovernmental Panel on Climate Change (IPCC) said today that it would investigate claims that the group’s 2007 report made an erroneous claim that the Himalayan glaciers were receding faster than in any other part of the world and could “disappear altogether by 2035 if not sooner.”

    This past weekend, Britain’s Sunday Times reported that the 2035 claim was taken from an interview with an Indian glaciologist in New Scientist a decade ago. Separately, last month the BBC quoted J. Graham Cogley of Trent University as saying that the IPCC authors “misread 2350 as 2035,” calling the 2035 forecast an “egregious” error.

    “We will take a view of this,” the IPCC chairman, Rajendra Pachauri, said in comments broadcast on the CNN-IBN network.

    India’s environment minister, Jairam Ramesh, has repeatedly challenged the IPCC’s glacier claims, saying there is no “conclusive scientific evidence” linking global warming to the melting of glaciers (AFP/Yahoo News, Jan. 18). — PV

    Debate heats up over IPCC melting glaciers claim
    “In 1999 New Scientist reported a comment by the leading Indian glaciologist Syed Hasnain, who said in an email interview with this author that all the glaciers in the central and eastern Himalayas could disappear by 2035.”

    The original article is here:

  22. 222
    Thomas says:

    Gavin your response to 189 “But there is no there there” is technically correct, but Al’s point is that this is a PR battle, which has little to do with truth, and everything to do with fallible human perceptions. The PR types have some knowledge of their field and know something about damage control.

    I have another question. Actually I want to conjecture a little theory about modification of the shortterm effects of negative AO on hemispheric or global temperatures. I would think that if the arctic air outbreaks come over the ocean, that this air will rapidly heat up because of the warmer water, but if they come over land, the airmass will stay cold longer. And of course by conservation of mass, we must have southerly winds at some latitudes as well. But in any case, if the cold comes down over land, it can contribute to short term global cooling, but if it comes down over water -not so much as it rapidly moderates. In weather speak, what I am conjecturing is that the longitude of where the different phases of the Rossby waves probably has a significant short term effect on global temperature.

  23. 223
    Doug Bostrom says:

    Hank Roberts says: 18 January 2010 at 8:46 PM

    “I don’t need their endorsements. The only endorsements I need are my viewers, and they like what I do.”

    Like seamen and their food: They know what they like, and they like what they know.

    Saves glucose.

    “So — eventually someone will dissect the claim and address it.
    But — why not you? I mean, demanding that someone else, like Gavin, take time out to deal with each of these stories just means more of them will get hauled in and dumped. It’s not the best use of his time, until and unless he decides to address it.”

    “Eventually”? When, after literally hundreds of millions of television viewers and newspaper readers have been confused by inaccurate and mendacious crap? A sizable fraction of the human population? How many of those will ever be set right? Why wait until the damage is done?

    Hank, I’m not demanding anything. I can only offer advice informed by a modicum of observation.

    What I’ve observed is that while there are other great sites for information on AGW— ClimateSkeptic, ClimateProgress, et al– this site is the most trafficked, most likely because it’s run by actual practicing scientists in the field and is the horse’s mouth.

    I have in fact recently dipped my oar into some other sites with comments but the problem is, what you or I contribute some dozens or hundreds of lines into a comments thread is reaching an audience that was small to begin with and is even smaller yet, for instance here on the –5th page– deep of a trace that’s mostly noise. Who’s going to read it? Practically nobody; those that do drill down to this level are rare and frankly a bit odd, present company included.

    Slashing the level of allowed commentary here (including 95% of what I write, maybe 5% of your contributions) would improve the SNR in comments, but again these are trivial suppressed sidebands compared to the main modulation.

    We can gnash our teeth and cry in our beer about our lamentable general level of science education and critical thinking skills but at the end of the day, first impressions count and stick. Leaving first impressions in the hands of propagandists working on behalf of fossil fuel interest is a bad idea.

    Gavin and his colleagues have the bully pulpit. Somebody needs to use every iota of air time available from the lectern to address timely topics here and those do undeniably include a lot of calculated synthetic bullshit.

    We know from documentation that the opposition is to a certain extent running a coordinated effort. I don’t see coordination here.

    Formally enrolling the help of a pro such as James Hoggan would be helpful. That person would probably suggest that partnering w/SkepticalScience would be a good move.

    Obviously it is not Gavin’s or the other RC proprietors’ responsibility to do this, but ignoring the requirement is going to lead to a result that is far from optimal and will leave us deeply unhappy.

    Again, look to history. Look at the enrollment of professionals in the opposition. A good result is not just going to happen on its own.

  24. 224
    Lynn Vincentnathan says:

    RE #201, Sam, I also agree with you that the WWF claim of near total meltdown by 2035 seemed suspicious, and I did NOT include that in my recent paper, but the article you cite does say there is retreat, and that is the main issue:

    India’s Minister for Environment and Forests Jairam Ramesh Monday said “I was right on the glaciers” while maintaining that the Himalayan glaciers are “indeed” receding, which is a cause for great concern, but the view that these rivers of ice would melt down completely by 2035 due to global warning is “alarmist” and without any scientific basis.

    “It is a clear vindication of our position. (But) It is a serious issue. (Himlayan) glaciers are serious issues for India. Most of the Himalayan glaciers are in a poor state, but the report that suggested that the glaciers will vanish completely by 2035 is alarmist and misplaced,” Ramesh told reporters in New Delhi.

    So it is serious (their agriculture is gravely threated by this, if not today, then in the near future, within 100 to 200 years), and this retreat is most likely due to anthropogenic GW, esp in the context of most other glaciers around the world in the mid and lower latitutes retreating (heat does melt ice). So we have a responsiblity to reduce our GHGs, AND (good news) we in the rich nations can do so while saving money.

    It would be pure calousness and lack of human compassion not to do what we can to help by reducing our GHGs, especially when it’s no skin off our noses and even a boon to us.

  25. 225
    RalphieGM says:

    Mr. Hansen – I read your article with an open mind. Then, wham, at the end you CONCLUDE with the following:

    “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.”

    Yet your article brought out NO evidence that supported this conclusion – ya kinda threw that thought in there at the end. And that’s what makes me skeptical – its called jumping to conclusions.

  26. 226

    Lynn Vincentnathan says:
    18 January 2010 at 8:20 PM

    “The critics were right to suspect the 2035 claim (with the WWF cited), just as I did & decided not to quote it (and I’m not even a climate scientist or glaciologist), but the rest of the section is a pretty good explanation of the problem, even tho (except for the 2035 claim) the IPCC is a pretty conservative document.”

    You misunderstand the issue. The issue is that IPCC reports are supposed to rely upon the “best” peer-reviewed research published in reputable scientific journals. The WWF report and the New Scientist news article do not qualify as best science practice published in reputable scientific journals.

    The section in the IPCC chapter is not a pretty good explanation as you say because it is not based on good science and therefore the reference and interpretation should be expunged from the IPCC chapter.

  27. 227
    Hank Roberts says:

    Regg, I’d guess that’s not likely. Hemphill/Daly blogged that theory.

    I’ve never seen convincing (or any) numbers attached to it.

    By contrast, the ‘nuclear winter’ models, for both the original ‘USA-USSR massive exchange’ and the more recent ‘India-Pakistan limited war’, assume cooling due to quite a bit of black smoke from burning cities.

    Of the surface nuclear tests, many were airbursts intended to minimize fallout by keeping the fireball off the ground. That includes China’s surface tests, which also did not produce any weather events I know of.

    I found one paper that might help:

    Journal Of Geophysical Research, Vol. 106, No. D11, pages 12.067-12.097, June 16, 2001

    An emerging ground-based aerosol climatology: Aerosol Optical Depth from AERONET

    “… a few multi-year spatial studies have contributed to our knowledge and experience (Table 1). The following section reviews those investigations past and present that significantly addressed long-term measurements over widely distributed locations…. Records dating to 1956 clearly showed the influence of volcanic eruptions on stratospheric loading however no long term discernable trends are observable suggesting no anthropogenic induced trends….”

  28. 228
    Hank Roberts says:

    For Gary Thompson: there’s quite a lag involved in turning all the individual station records into that one final dot on the annual chart!

    Compare last year’s dates:

    Jan. 13, 2009: 2008 calendar year temperature summary was posted.

  29. 229
    Doug Bostrom says:

    What I wrote: “What I’ve observed is that while there are other great sites for information on AGW— ClimateSkeptic, ClimateProgress…”

    Oops. Scratch ClimateSkeptic, replace w/SkepticalScience. Wow.

  30. 230

    Lynn Vincentnathan says:
    18 January 2010 at 8:20 PM

    “Science and individual scientific studies are conservative, requiring 95% confidence before making a claim (would anyone with a suspicious lump wait years and year before the doc was 95% confident it was cancerous?); and the IPCC is conservative times 1000, because so many scientists have to agree on what to say. We cannot wait 30 years to start deciding to mitigate CC, we have to start yesterday, and even then it might be too little too late.”

    This statement is wrong on many counts.

    1. You are confusing statistical probability (95% confidence) with scientific interpretation.
    2. The IPCC is not conservative times 1000 because many scientists who disagree with an interpretation are ignored.
    3. We can and should wait until the science is in (and it isn’t) before making any decisions on climate change.
    4. The situation is not as urgent as you make it out to be.
    5. Why do we have science at all when we have people like yourself saying let’s go with our gut rather than wait for the truth? You are basically saying that gut feelings are more important than the science.

  31. 231
    David Horton says:

    #178 “Of course the cold waether doesn’t demonstrate the climate is cooling. However, the warmist would have a little more credibility on these issues if they would speak up when warm weather is used to demonstrate that the climate is warming. When that happens Climate warmist are either silent or they are all too happy to join in.
    [Response: Not true. Find one comment by a scientist on this site that demonstrates inconsistency on these kinds of issues. – gavin]”

    Gavin that’s fine but incomplete. Two things that could be added. First, the claim by us “warmists” is not that a hot day doth global warming make but that RECORD hot days, or RECORD hot sequences, both indicate global warming because there are far more record high temps being set (especially in Australia it seems) than low ones. And second, if you want to illustrate what is coming our way in 10, 20, 30 years time, then heatwaves and many extremely hot individual days (together with the droughts and bushfires that result) are a pretty good illustration of what people can expect. Should we pretend instead that global warming has no consequences?

  32. 232
    Didactylos says:

    “sam” said: “Either way in about 30 years (or less) you will either be hailed as a genius or well… the opposite.”

    Yeah, right! In 30 years, the same thoughtless people criticising Gavin (and thousands of other scientists) will be complaining (with absolutely no sense of irony) that these same scientists failed to warn them, and that now it is too late for action.

    Sometimes, humanity really makes me sick. You need to listen now, while action isn’t going to be prohibitively expensive. If you delay 30 years, then dealing with climate change will be many times more difficult – and we will have to deal with the irreversible changes whether we like it or not.

    Ask yourself this: how has history remembered other people who have taken needed (or unneeded) precautions against future events? Good grief – the wisdom of acting with foresight is so obvious that it has been spelled out by just about every major religion I can think of. Remember Noah’s ark? The parable of the wise and foolish virgins?

    It’s not rocket science. You take prudent precautions based on the knowledge available to you at the time.

  33. 233
    Ibrahim says:

    Maybe you should take a look at the PDO.

  34. 234
    pointer says:

    So I was over at Joe Romm’s place, and he linked to a real blast from the past:

    LUBOS MOTL!!! whose seems to think it odd that January 2010 is set to be the warmest January on record even though it was soooooo cold. His explanation? The latent heat of snow. I’m clearly not a Motl-level genius so I didn’t understand his post at all. What a moron I am! Clearly the answer can’t be that the cold was confined to exactly those places on the planet with a high density of media outlets.

  35. 235
    Edward Greisch says:

    Dr. Hansen: The notation “high low” with one of the words stricken through needs to be explained to most people. “Standard deviation” is Greek to most people. The math IQ assumed by the author is possessed by 1% of the people. The same goes for the math training. Most people are allergic to math and will stop reading at the first sign of a mathematical concept or symbol.

    [Response: It’s not notation, it’s an editorial fix of a statement that was wrong. – gavin]

  36. 236
    Johannes Rexx says:

    Gavin, your response to comment 36 demonstrates that you choose to ignore the obvious. Foobear’s comment is right on the mark and you dismissed it out of hand. Showing a par-broiled earth is scaremongering despite your unwillingness to recognize it.

  37. 237
    Edward Greisch says:

    184 Richard Ordway: Where can you be safe from global warming? I suggest Mars, as long as very few people can get there. Transportation is such that no place on Earth is safe. Mars is safe because it is beyond reach. Global warming is likely to be an extinction event, or nearly so. That means planet-wide.

    why it would worsen exactly?: 1. Famine. Because the rain moves. 2. Methane fuel-air explosions from melting tundra peat bogs 3. H2S made by sulfur bacteria that take over anoxic hot oceans.

    Why doesn’t RealClimate have a special page on this stuff? I have posted the details too many times already.

  38. 238
  39. 239
    Completely Fed Up says:

    sam: “I bet it will continue to snow in the himalayas for a long long long time and this snow will have to go somewhere.”

    But that’s not a bet on the table, sam. Nobody in the IPCC and AGW science says that snow won’t fall.

    Your bet is like betting with astrophysicists talking about how the end of the sun will occur that tomorrow the sun will still be there.

  40. 240
    Completely Fed Up says:

    “And then maybe you will report back that there was indeed an increase in ocean heat content of about 10×10^23 Joules over the 20 years under discussion”

    Jim, why the 20 years?

    It’s an odd figure.

    Why not 150 (the length of time since anthropogenic CO2 started)?

    Or each second, averaged over 1 year (to be scientific)?

  41. 241
    Completely Fed Up says:

    Septic: “Dr Latif, I believe, invites misquotation:”

    Nope, he doesn’t.

    His phraseology allows those with malignant purpose to selectively quote mine. Even to make words up to make a quote-a-like.

    As they have done.


    Latif: a downturn of a few years, even a decade or so
    RW Radio: a cooling period for the next 20 years.
    RW Radio buddy: yeah, 30 years


  42. 242

    jeannick: 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

    BPL: The Earth’s surface cools, on global annual average, by about 80 watts per square meter by evaporation and evapotranspiration. By contrast, it cools by 17 watts per square meter in pure convection and conduction, and 389 watts per square meter in longwave radiation. The first atmosphere model I’m aware of to account explicitly for the role of latent and sensible heat in cooling the surface at the expense of the atmosphere was written by Manabe and Strickler in 1964.

  43. 243


    Don’t think in terms of moving to a better climate. The danger is that human civilization will collapse due to an agricultural crash and a widespread lack of fresh water.

    Buy a house in an isolated rural area, preferably at the top of a hill so it’s defensible, and with land around it you can raise crops on. Raise them “biodynamically,” in short flexible-plastic greenhouses, with individual attention. Dig privies and set up rain barrels for when the municipal water system fails, and set up a windmill and solar cells to generate power for when the electrical utility fails. Surround the whole thing with a good, solid stone fence, preferably about two feet thick. To avoid trouble with the authorities, just make it decorative, but when civilization falls, string concertina wire along the top, or an electrified fence.

    Stock up on long-term-storable food and water. Also firearms, ammunition, and medical supplies. If you can get people to stay with you, that would be great–concentrate on farmers and gardeners, one or more doctors or nurses, maybe a marksman or martial arts expert to help defend the place.

  44. 244

    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.

    JB: JB: Nope. It did not get radiated. The 10×10^23 Joules accumulated in the oceans over the period 1985 to 2005.

    BPL: Duh! The subject was what would happen if it had gone into the atmosphere instead.

    JB: That is what the NOAA chart says. And they only measure down to 700 meters. And if it had been radiated, the air temperature would have gone up roughly another 7.5 degrees.

    BPL: Only if it happened all at once. Otherwise most of it would have radiated away by now.

    Listen: The temperature of the Earth is not primarily due to STORED heat. It’s from the radiation balance at the top of atmosphere.

  45. 245

    BPL: You need 30 years to tell a climate trend. 10 years tells you nothing at all.
    Temperature has risen strongly over the past 30 years.

    Don Shor: Right. 1/3 of the period is irrelevant. Got it.

    BPL: Can’t you read? Temperature has risen strongly COUNTING the last ten years (20 + 10 = 30). The TREND is strongly up. The last ten years don’t tell you the TREND any more than the first ten years or ten years picked at random. It’s not a big enough sample size.

    The trend is still STRONGLY up. Deal with it.

    And crack a book on introductory statistics. Brown and Brown is a good one.

  46. 246
    Syl says:

    But the main question from skeptics has not been answered.

    Why the decline in the number of temperature points? 1000 data points seems awfully small to get a mean temperature of the earth. There`s over 30000 McDonalds restaurants in the world – but we use only 1000 thermometers?

    I’m from Canada, and there’s no way 39 thermometers can give an accurate reading of the average temperature in Canada.

    [Response: Actually you are over-estimating enormously. First, the fact is that temperature anomalies have very high spatial correlation at the monthly and annual scale – that is to say that if Montreal is having a cold winter, than so is Toronto and Quebec City. For the monthly scale, the number of spatial degrees of freedom is around 60-100 in each hemisphere. Thus if they were well placed you could get away with ~200 stations for the globe in order to get a good estimate of the mean anomaly (within 0.05 deg C say). But there are many more than that so that they can provide good checks on each other. You can check this by simply dropping half the stations and seeing whether you get basically the same number. – gavin]

  47. 247
  48. 248

    Richard Steckis (230),

    Your number 3 is especially off the mark. We are used to making decisions in the face of uncertainty every day. Ideally, a decision should be based on the available information, with its inherent uncertainties. It is a question of risk management, and Lynn’s analogy to a health issue is very apt: A health diagnosis is never 100% certain, yet if the potential risks of business as usual (e.g. continuing to smoke) are grave, you’d do wise to change your course of action (e.g. quit smoking). Given the information about the relative risks (i.e. probabilities and effects), what is the best course of action? That is the question. “Waiting until the science is in” (when is that?) is not the answer.

  49. 249
    Jim Bouldin says:

    Ray Ladbury says:
    The evidence doesn’t change because of a few hacked and carefully selected emails.

    Au contraire!

  50. 250
    Ray Ladbury says:


    1. You are confusing statistical probability (95% confidence) with scientific interpretation.

    Whiskey-Tango-Foxtrot does this even mean? Most of the scientific interpretation is based on probabality–for instance, there is a better than 95% probability that CO2 sensitivity is greater than 2 degrees per doubling.

    2. The IPCC is not conservative times 1000 because many scientists who disagree with an interpretation are ignored.

    Bullshit. Unless by “many” you mean to include scientists with zero expertise in climate science. 97% of actively publishing climate scientists agree with the consensus. What is more, the dissenters offer nothing in the way of coherent interpretation of the science. And clear evidence of the conservatism of the IPCC is found in the toned down language of the summaries relative to the technical documents.

    3. We can and should wait until the science is in (and it isn’t) before making any decisions on climate change.

    What science, specifically, do you contend is missing? (Careful here, Steckis, it’s only fair to warn you that I’m baiting a trap with this open-ended question.)
    4. The situation is not as urgent as you make it out to be.

    And you base this on what other than your usual wishful thinking? Dude, we’ve got methane bubbling out of swamps in Siberia. We’ve got the second warmest year on record occurring at the end of a prolonged solar minimum! We’ve got the ocean acidifying. And we’ve got a problem that requires us to completely revamp our energy infrastructure to solve it. How is that not urgent?

    5. Why do we have science at all when we have people like yourself saying let’s go with our gut rather than wait for the truth? You are basically saying that gut feelings are more important than the science.

    Uh, no. She’s saying that when your gut and the science are on the same side, you should probably listen.