Still good news: global temperatures remain stable, at least for now.

Summary:  Today we look at good news (rarely seen here), the stabilization of global temperatures. The long rise during the past two centuries, which produced many forecasts of imminent doom, has leveled off since the late 1990s — as shown by all the major temperature datasets.  It’s not something the mainstream wants us to know, as it spoils the narrative set by alarmists.  This pause might not last, but it is unexpected — and should spark some reflection on our handling of this — and other shockwave threats.

The data is clear: temperatures have stabilized. The significance of the data is not, but each year increases the odds that the trend has changed — rather than the pause being just a statistical blip.  This post is a brief update to the more detailed post of 3 February 2012, which includes additional (and longer-term) data plus statements by major climate scientists about the data. Also see The IPCC sees the pause in global warming!

Contents

1. The Globe & Mail breaks the story!
2. The new UK Met Office dataset
3. A prominent climate scientists comments
4. The Met Office replies
5. Global Sea Surface temperatures
6. The satellite temperature record
7. Early articles about the warming pause
8. Is this cherry-picking the historical data?
9. For more information: other studies
10. My view of the climate science debate
11. Other chapters in this series
12. Other posts about climate science

This article has been extensively updated as new information has become available.  Changes have been marked.

(1)  The Globe & Mail breaks the story!

“Global warming stopped 16 years ago, reveals Met Office report quietly released, and here is the chart to prove it“, Globe & Mail (“Canada’s newspaper”), 13 October 2012 — Opening and closing:

The figures reveal that from the beginning of 1997 until August 2012 there was no discernible rise in aggregate global temperatures. This means that the ‘pause’ in global warming has now lasted for about the same time as the previous period when temperatures rose, 1980 to 1996.

… So let’s be clear. Yes: global warming is real, and some of it at least has been caused by the CO2 emitted by fossil fuels. But the evidence is beginning to suggest that it may be happening much slower than the catastrophists have claimed – a conclusion with enormous policy implications.

Please click to read the full story. It quotes two climate scientists.  First Professor Judith Curry, Chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology:

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{deleted; see her remarks in section #3}

And Professor Phil Jones, director of the Climate Research Unit at the University of East Anglia:

{He} would not normally be expected to agree with her. Yet on two important points, he did. The data does suggest a plateau, he admitted, and without a major El Nino event – the sudden, dramatic warming of the southern Pacific which takes place unpredictably and always has a huge effect on global weather – ‘it could go on for a while’.

Like Prof Curry, Prof Jones also admitted that the climate models were imperfect: ‘We don’t fully understand how to input things like changes in the oceans, and because we don’t fully understand it you could say that natural variability is now working to suppress the warming. We don’t know what natural variability is doing.’

He insisted that 15 or 16 years is not a significant period: pauses of such length had always been expected, he said. Yet in 2009, when the plateau was already becoming apparent and being discussed by scientists, he told a colleague in one of the Climategate emails: ‘Bottom  line: the “no upward trend” has to  continue for a total of 15 years before we get worried.’

But although that point has now been passed, he said that he hadn’t changed his mind about the  models’ gloomy predictions:  ‘I still think that the current decade which began in 2010 will be warmer by about 0.17 degrees than the previous one, which was warmer than the Nineties.’

Only if that did not happen would he seriously begin to  wonder whether something more profound might be happening. In other words, though five years ago he seemed to be saying that 15 years without warming would make him ‘worried’, that period has now become 20 years.

Jones said something similar to the BBC on 13 February 2010.

(2)  The new UK Met Office dataset

The UK Met Office released the HadCRUT.4.1.1.0 aprox 3 September 2012.  This is probably the basis for the Daily News story.

Here is a graph using this, the latest long-term data, from “Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: the HadCRUT4 data set“.  Looking back further into history, data shows temperatures substantially rising in the 19th century, but the case for attributing that to the small anthropogenic release in CO2 is quite weak.  Most studies date substantial anthropogenic effects after WWII: 1950 for the BEST project, 1960 for the IPCC.

For more information see this page about Global-average temperature records by Dr Peter Stott at the Met Office.

(3)  A prominent climate scientists comments on the article

A reply to the article posted at her website, Climate Etc, by Professor Judith Curry (Chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology). She didn’t agree with the aspects of the quote attributed to her in the article.

… I agree that 16 years is too short,  given the timescales of the PDO and AMO, to separate out natural versus anthropogenic variability (but this cuts both ways:  the warming period between 1980 and 1998 was arguably amped by the PDO and AMO).   … Here is the text I emailed Rose, in response to his questions:

The data confirms the existence of a ‘pause’ in the warming. The impact of this pause within the climate dynamic community has been to focus increased attention on the impact of natural variability, particularly the impact of internal multi-decadal oscillations in the ocean.  The new climate model calculations for the AR5 have focused on trying to assess what it would take to accurately simulate these multi-decadal ocean oscillations and how predictable they might be.  These new observations and climate modeling results will hopefully impact the the IPCC AR5 deliberations so that we do not see the same overly confident consensus statements that we saw in the AR4.

You might be interested in my recent blog post: RS Workshop on Handling Uncertainty in Weather & Climate Prediction. Part I.

The flawed assumption behind the orthodoxy was that natural variability is merely ‘noise’ superimposed on the long term trend.  The natural variability has been shown over the past two decades to have a magnitude that dominates the greenhouse warming signal.  It is becoming increasingly apparent that our attribution of warming since 1980 and future projections of climate change needs to consider natural internal variability as a factor of fundamental importance.  I sincerely hope that the AR5 provides an assessment of what we know and what we don’t know and areas of disagreement, rather than trying to manufacture a consensus.

Climate models are very complex, but they are imperfect and incomplete.  In that context the problem is how people interpret the simulations from climate models in view of the uncertainties and imperfections.

For context on this issue, see these other Climate Etc. posts:

• Pause(?), 4 November 2011
• Trends, change points, and hypotheses, 7 February 2012
• ‘Pause’ discussion thread, 14 October 2012 — Analysis of the Mail article
• ‘Pause’ discussion thread: Part II, 16 October 2012 — Analysis of the Guardian rebuttal of the Mail article
• ‘Pause’ : Waving the Italian Flag, 17 October 2012 — The three-valued logic approach of the “Italian flag analysis”

(4)  The Met Office replies

On October 14 the UK Met Office issued a reply on their blog to the Mail.  Here is the money paragraph:

The linear trend from August 1997 (in the middle of an exceptionally strong El Nino) to August 2012 (coming at the tail end of a double-dip La Nina) is about 0.03°C/decade, amounting to a temperature increase of 0.05°C over that period, but equally we could calculate the linear trend from 1999, during the subsequent La Nina, and show a more substantial warming.

As we’ve stressed before, choosing a starting or end point on short-term scales can be very misleading. Climate change can only be detected from multi-decadal timescales due to the inherent variability in the climate system. If you use a longer period from HadCRUT4 the trend looks very different. For example, 1979 to 2011 shows 0.16°C/decade (or 0.15°C/decade in the NCDC dataset, 0.16°C/decade in GISS). Looking at successive decades over this period, each decade was warmer than the previous – so the 1990s were warmer than the 1980s, and the 2000s were warmer than both. Eight of the top ten warmest years have occurred in the last decade.

Over the last 140 years global surface temperatures have risen by about 0.8ºC. However, within this record there have been several periods lasting a decade or more during which temperatures have risen very slowly or cooled. The current period of reduced warming is not unprecedented and 15 year long periods are not unusual.

Repeat: “during the past 140 years the global surface temperatures have risen by about 0.8ºC” (1.4ºF).  Not yet the disaster commonly described in the news media; as yet not an unusual temperature variation in terms of the past few thousand years of history.  Also, it’s difficult to assess the seriousness of this without know the precision of the estimates. Measuring global temperature (especially sea surfaces) for 140 must have quite large error bars.

Also, the Met Office response is technically correct, but raises a severe operational problem: scientific theories must be falsifiable. We should know in advance what data will disprove a model’s forecast.  This pause is significant because the major models failed to predict it, and because it’s duration has reached the durations some prominent climate scientists previously said would be significant.  With no boundary conditions, or ones that are extended as they’re reached, forecasts of catastrophic anthropogenic global warming become a matter of faith — not science.

From the comments to this article on the Met Office Blog:

We agree with Mr Rose that there has been only a very small amount of warming in the 21st Century. As stated in our response, this is 0.05 degrees Celsius since 1997 equivalent to 0.03 degrees Celsius per decade.

(5)  Global Sea Surface temperatures (SST)

The temperature datasets that get the most attention measure land surface temperatures. Not only are the seas 70% of the Earth’s surface, but the oceans are the primary reservoir of heat for the coupled sea-air system in which we live. Unfortunately we don’t have good historical data (for this purpose) before roughly 1982.  There are several datasets of accurate global SST data after the early 1980s; for details see Bob Tisdale’s “An Overview Of Sea Surface Temperature Datasets Used In Global Temperature Products“.

Here is a graph of NOAA Sea Surface Temperature data from Bob Tisdale’s website, which combines both direct measurements (ie, ships and buoys) and satellite data)  Again, no warming since the late 1990s.  SST’s show the effect of the large decadal-scale cycles (eg, La Nina – El Nino in the tropical Pacific), which effect global temperatures.

The Argo project, a network of high-tech buoys fully deployed in 2007, now provides high quality data of global ocean temperatures at various depths.  This will answer many questions about climate dynamics, and allow development of better models.  For more information see:

• Argo.net Home page
• Argo at the Scripps Institution of Oceanography

(6)  The satellite temperature record

Satellite data is often described by non-experts as the definitive source of global temperatures. It’s not that simple, as explained in this article by the National Institute of Standards and Technology (NIST), 6 February 2012:

Satellites do not measure temperature directly; instead they measure the amount of radiation incident on their sensors at various key wavelengths and sometimes polarizations associated with different meteorological phenomena and different sections of the atmosphere or surface. Those data are then processed by different groups using various methods to yield temperature equivalents.

Also, adjustments must be made for sensor decay, change of satellite orbits, and replacement of satellites.

There are three major datasets:  the National Oceanic and Atmospheric Administration (NOAA), Remote Sensing Systems (RSS, data from NASA satellites), and the University of Alabama at Huntsville (UAH).  This graph from the NIST article shows that the recent temperature plateau appears in all three datasets.

Here is the UAH data through August 2012 (source: Roy Spencer, co-developer of the data series):

(7)  Early articles noting the stabilization of global temperatures

• “What happened to global warming?“, BBC, 9 October 2009
• “World will ‘cool for the next decade’“, New Scientist, 9 September 2009 — Summary of forecasts about decadal cooling (e.g., “Advancing decadal-scale climate prediction in the North Atlantic sector“, Mojib Latif et al, Nature, 1 May 2008
• “Climatologists Baffled by Global Warming Time-Out“, Der Spiegel, 19 November 2009
• “World may not be warming, say scientists“, The Times, 14 February 2010

(8)   Is this cherry-picking the historical data?

No, it’s not.  See “Trends, change points & hypotheses“, Judith Curry posted at Climate Etc, 7 February 2012 — Excerpt:

Back to the issue of cherry picking data, and interpreting the temperature time series for the past two decades.

Is the first decade+ of the 21st century the warmest in the past 100 years (as per Peter Gleick’s argument)? Yes, but the very small positive trend is not consistent with the expectation of 0.2C/decade provided by the IPCC AR4. In terms of anticipating temperature change in the coming decades, the AGW dominated prediction of 0.2C/decade does not seem like a good bet, particularly with the prospect of reduced solar radiation.

Has there been any warming since 1997 (Jonathan Leake’s question)? There has been slight warming during the past 15 years. Is it “cherry picking” to start a trend analysis at 1998? No, not if you are looking for a long period of time where there is little or no warming, in efforts to refute Hypothesis I.

… And none of this data analysis is very satisfying or definitive owing to deficiencies in the data sets, particularly over the ocean.

(9)  For more information: other studies (this will be updated as more appear)

Note the surge of articles about the pause in 2010 and especially 2011.  They come in two kinds.  Once assesses the statistical significance of the pause.  The second attempt to explain the pause in terms of known climate models.  While significant, these are exercises in fitting — matching the models to new data — and do not validate the models as would successful predictions.

(a)  “Do global temperature trends over the last decade falsify climate predictions?”, J Knight et al. Part of  “State of the Climate in 2008“, Editors T C Peterson and M O Baringer, Bulletin of the American Meteorological Society, August 2009:

ENSO-adjusted warming in the three surface temperature datasets over the last 2–25 yr continually lies within the 90% range of all similar-length ENSO-adjusted temperature changes in these simulations. Near-zero and even negative trends are common for intervals of a decade or less in the simulations, due to the model’s internal climate variability. The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.

(b)  “Does the Global Warming Pause in the Last Decade: 1999-2008?“, Shaowu Wang et al, Advances in Climate Change Research, issue #1 2010 — Abstract:

Issues related to the pause of global warming in the last decade are reviewed. It is indicated that:

1. The decade of 1999-2008 is still the warmest of the last 30 years, though the global temperature increment is near zero;
2. Natural factors such as volcanism, solar radiation, ENSO, and thermohaline circulation can have impact on the inter-annual and inter-decadal variability of global mean temperatures. However, it will not mask the global warming trend for a long time;
3. Temperatures of China continue to increase in 1999-2008 with an increment of 0.4-0.5°C per 10 years.

(c)  “Climate science: Decadal predictions in demand“, Mark A. Cane, Nature Geoscience, 21 March 2010 — Free copy here.  Red emphasis added.

Over the past decade, the mean global temperature did not rise much, if at all. This pause in global warming cannot be attributed to cutbacks in greenhouse-gas emissions by the planet’s human population, so it must be nature taking a turn towards colder temperatures. The extent to which such natural climate variability can be predicted on decadal timescales is not known.

Creating useful climate predictions is not straightforward. … The Miami workshop turned the attention of both climate scientists and stakeholders to decadal predictions of climate, a field that is still in its infancy (if not prenatal). Decadal climate predictions aim to cover the gap between seasonal to interannual prediction with lead times of two years or less and projections of climate change a century ahead.

… Therefore, the hope for useful skill in predicting natural variability is far from assured. The climate system is chaotic and it is not known how predictable decadal variations are, even if we had perfect models and sufficient observations to determine the initial state with high precision.

Perhaps there is something special about a decadal timescale that affords predictability, but perhaps not: decadal variability may just be the part of a featureless spectrum of frequencies that we happen to pick out of our instrumental records because they are only about 150 years long. Several valuable efforts to extend the record with palaeoproxy data were reported (L. Stott, Univ. Southern California, USA; B. Horton, Univ. Pennsylvania, USA; P. Swart and H. Wanless, Univ. Miami, USA), but these data are still too sparse and uncertain to allow a firm assessment.

As one example, according to the current leading idea, the Atlantic Multidecadal Oscillation is generated by atmospheric noise (E. Schneider, Center for Ocean, Land, Atmosphere/George Mason Univ., USA). If indeed random processes are at the heart of decadal variability, as strongly supported by the talk of C. Deser (National Center for Atmospheric Research, USA), this might seem to doom hopes for decadal predictability. However, the possibility remains that, once underway, the evolution of important patterns of variability could be projected forward.

… Demand for accurate decadal prediction is running ahead of supply. This imbalance challenges us to determine how much of the natural climate variability that will contribute substantially to global climate in the next few decades is predictable. Even if it turns out that climate is essentially not predictable at a decadal scale, projections of future climate will be misleading unless we gain a fuller understanding of the range of natural variability in store for us in a warmer world.

(d)  “Reconciling anthropogenic climate change with observed temperature 1998–2008“, Robert K. Kaufmann et at, Proceedings of the National Academy of Science, 19 July 2011 — Abstract:

Given the widely noted increase in the warming effects of rising greenhouse gas concentrations, it has been unclear why global surface temperatures did not rise between 1998 and 2008. We find that this hiatus in warming coincides with a period of little increase in the sum of anthropogenic and natural forcings. Declining solar insolation as part of a normal eleven-year cycle, and a cyclical change from an El Nino to a La Nina dominate our measure of anthropogenic effects because rapid growth in short-lived sulfur emissions partially offsets rising greenhouse gas concentrations.

As such, we find that recent global temperature records are consistent with the existing understanding of the relationship among global surface temperature, internal variability, and radiative forcing, which includes anthropogenic factors with well known warming and cooling effects.

(e) “Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods“, Gerald A. Meehl et al, Nature Climate Change, 18 September 2011 –Examines 10-year long pauses. Abstract:

There have been decades, such as 2000–2009, when the observed globally averaged surface-temperature time series shows little positive or even slightly negative trend (a hiatus period). However, the observed energy imbalance at the top-of-atmosphere for this recent decade indicates that a net energy flux into the climate system of about 1W m-2 should be producing warming somewhere in the system. Here we analyse twenty-first-century climate-model simulations that maintain a consistent radiative imbalance at the top-of-atmosphere of about 1W m-2 as observed for the past decade. Eight decadeswith a slightly negative global mean surface-temperature trend show that the ocean above 300m takes up significantly less heatwhereas the ocean below 300m takes up significantlymore compared with non-hiatus decades. The model provides a plausible depiction of processes in the climate system causing the hiatus periods, and indicates that a hiatus period is a relatively common climate phenomenon and may be linked to La Niña-like conditions.

(f)  “Global warming, human-induced carbon emissions, and their uncertainties“, JingYun Fang et al, Science China – Earth Science, October 2011 — Free copy here. Abstract:

In recent decades, there have been a number of debates on climate warming and its driving forces. Based on an extensive literature review, we suggest that

1. climate warming occurs with great uncertainty in the magnitude of the temperature increase;
2. both human activities and natural forces contribute to climate change, but their relative contributions are difficult to quantify; and
3. the dominant role of the increase in the atmospheric concentration of greenhouse gases (including CO₂) in the global warming claimed by the Intergovernmental Panel on Climate Change (IPCC) is questioned by the scientific communities because of large uncertainties in the mechanisms of natural factors and anthropogenic activities and in the sources of the increased atmospheric CO₂ concentration.

More efforts should be made in order to clarify these uncertainties.

(f)  “Separating signal and noise in atmospheric temperature changes: The importance of timescale“, Ben Santer et al, Journal of Geophysical Research (Atmospheres), 18 November 2011:

Because of the pronounced effect of interannual noise on decadal trends, a multi‐model ensemble of anthropogenically‐forced simulations displays many 10‐year periods with little warming. A single decade of observational TLT {temperature of the lower troposphere} data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal. Our results show that temperature records of at least 17 years in length are required for identifying human effects on global‐mean tropospheric temperature.

(g)  New paper: “Deducing Multi-decadal Anthropogenic Global Warming Trends Using Multiple Regression Analysis“, Jiansong Zhou and Ka-Kit Tung, Journal of the Atmospheric Sciences, in press — Free abstract; article is gated.

Potentially important conclusion:

When the AMO is included, in addition to the other explanatory variables such as ENSO, volcano and solar influences commonly included in the multiple linear regression analysis, the recent 50-year and 32-year anthropogenic warming trends are reduced by a factor of at least two. There is no statistical evidence of a recent slow-down of global warming, nor is there evidence of accelerated warming since the mid-20th century.

Abstract:

In order to unmask the anthropogenic global warming trend imbedded in the climate data, multiple linear regression analysis is often employed to filter out short-term fluctuations caused by El Nino-Southern Oscillation (ENSO), volcano aerosols and solar forcing. These fluctuations are unimportant as far as their impact on the deduced multidecadal anthropogenic trends is concerned: ENSO and volcano aerosols have very little multi-decadal trend. Solar variations do have a secular trend, but it is very small and uncertain. What is important, but is left out of all multiple regression analysis of global warming so far, is a long-perioded oscillation called the Atlantic Multi-decadal Oscillation (AMO). When the AMO Index is included as a regressor (i.e. explanatory variable), the deduced multi-decadal anthropogenic global warming trend is so impacted that previously deduced anthropogenic warming rates need to be substantially revised. The deduced net anthropogenic global warming trend has been remarkably steady and statistically significant for the past 100 years.

Hat tip to Watts Up with That.

(10) My view of the climate science debate

The world has been warming during the past two centuries — which fact by itself shows a natural component (CO2 increases rising slowly until after WWII).

There is a debate about the attribution (causes) of past warming — which probably varied over time — between natural drivers (eg, rebound from the Little Ice Age, solar influences) and anthropogenic drivers (eg, co2, aerosols, land use changes).

The IPCC reports make few claims about attribution of current climate activity to warming to date, as that remains actively debated in the literature.

There is an even larger debate about climate forecasts, both the extent of future CO2 emissions (the IPCC consensus does not reflect well the debate among geologists about the extent of fossil fuels reserves), and the net effects of the various anthropogenic effects.

For the past five years my recommendations have been the same:

• More funding for climate sciences. Many key aspects (eg, global temperature data collection and analysis) are grossly underfunded.
• Wider involvement of relevant experts in this debate. For example, geologists, statisticians and software engineers have been largely excluded — although their fields of knowledge are deeply involved.

(10)  Other chapters in this series

1. What we know about our past climate, and its causes
2. Good news!  Global temperatures have stabilized, at least for now.
3. Is it possible to debate climate change with true believers? See the replies to Thursday’s post.  Comments welcomed!
4. What can climate scientists tell about the drivers of future warming?
5. What can climate scientists tell us about the drivers of future warming?  – part two of two
6. The slow solar cycle is getting a lot of attention. What are its effect on us?
7. Still good news: global temperatures remain stable, at least for now
8. Kevin Drum talks about global warming, illustrating the collapse of the Left’s credibility
9. When did anthropogenic CO2 become the major driver of modern warming?

(11)  Other posts about climate science

(a)  For more information see the other FM Reference Pages:

• Science and Nature – my articles.
• Science & nature – studies & reports
• Science & Nature – general media articles
• Articles from the 1970′s about global cooling/warming

Posts about melting polar ice and rising sea levels:

1. An example of important climate change research hidden, lest it spoil the media’s narrative, 22 May 2009
2. About that melting arctic ice cap, 17 April 2010
3. Fear or Fail: about the melting Greenland ice sheet, 24 May 2010
4. Today’s good news, about rising sea levels, 3 June 2010 — Esp note the links to articles and studies!
5. It’s time to worry (again) about disappearing arctic ice, 8 June 2010
6. Climate Armageddon postponed (again): the melting polar ice, 9 October 2010
7. Looking into the past for guidance about warnings of future climate apocalypses, 17 October 2010

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