The Marcott et al. "trick"

They put their own dates on the proxies they used in order to get the conclusion they wanted.

I have put up various comments on the Marcott paper before but I think the comments by Ross McKitrick below are the clearest so far -- and therefore worth adding here

On March 8, a paper appeared in the prestigious journal Science under the title A reconstruction of regional and global temperature for the past 11,300 years. Temperature reconstructions are nothing new, but papers claiming to be able to go back so far in time are rare, especially ones that promise global and regional coverage.

The new study, by Shaun Marcott, Jeremy Shakun, Peter Clark and Alan Mix, was based on an analysis of 73 long-term proxies, and offered a few interesting results: one familiar (and unremarkable), one odd but probably unimportant, and one new and stunning. The latter was an apparent discovery that 20th-century warming was a wild departure from anything seen in over 11,000 years. News of this finding flew around the world and the authors suddenly became the latest in a long line of celebrity climate scientists.

The trouble is, as they quietly admitted over the weekend, their new and stunning claim is groundless. The real story is only just emerging, and it isn’t pretty.

The unremarkable finding of the Marcott et al. paper was that the Earth’s climate history since the end of the last ice age looks roughly like an upside down-U shape, starting cold, warming up for a few thousand years, staying warm through the mid-Holocene (6,000 to 9,000 years ago), then cooling steadily over the past five millennia to the present. This pattern has previously been found in studies using ground boreholes, ice cores and other very long-term records, and was shown in the first IPCC report back in 1990. Some studies suggest it was, on average, half a degree warmer than the present, while others have put it at one or even two degrees warmer. A lot of assumptions have to be made to calibrate long-term proxy measures to degrees Celsius, so it is not surprising that the scale of the temperature axis is uncertain.

Another familiar feature of long-term reconstructions is that the downward-sloping portion has a few large deviations on it. Many show a long, intense warm interval during Roman times 2,000 years ago, and another warm interval during the medieval era, a thousand years ago. They also show a cold episode called the Little Ice Age ending in the early 1800s, followed by the modern warming. But the Marcott et al. graph didn’t have these wiggles, instead it showed only a modest mid-Holocene warming and a smooth decline to the late 1800s. This was odd, but probably unimportant, since they also acknowledged using so-called “low frequency” proxies that do not pick up fluctuations on time scales shorter than 300 years. The differences between the scale of their graph and that of others could probably be chalked up to different methods.

The new, and startling, feature of the Marcott graph was at the very end: Their data showed a remarkable uptick that implied that, during the 20th century, our climate swung from nearly the coldest conditions over the past 11,500 years to nearly the warmest. Specifically, their analysis showed that in under 100 years we’ve had more warming than previously took thousands of years to occur, in the process undoing 5,000 years’ worth of cooling.

This uptick became the focus of considerable excitement, as well as scrutiny. One of the first questions was how it was derived. Marcott had finished his PhD thesis at Oregon State University in 2011 and his dissertation is online. The Science paper is derived from the fourth chapter, which uses the same 73 proxy records and seemingly identical methods. But there is no uptick in that chart, nor does the abstract to his thesis mention such a ­finding.

Stephen McIntyre of climateaudit.org began examining the details of the Marcott et al. work, and by March 16 he had made a remarkable discovery. The 73 proxies were all collected by previous researchers, of which 31 are derived from alkenones, an organic compound produced by phytoplankton that settles in layers on ocean floors, and has chemical properties that correlate to temperature. When a core is drilled out, the layers need to be dated. If done accurately, the researcher could then interpret the alkenone layer at, say, 50 cm below the surface, to imply (for example) the ocean temperature averaged 0.1 degrees above normal over several centuries about 1,200 years ago. The tops of cores represent the data closest in time to the present, but this layer is often disturbed by the drilling process. So the original researchers take care to date the core-top to where the information begins to become useful.

According to the scientists who originally published the alkenone series, the core tops varied in age from nearly the present to over a thousand years ago. Fewer than 10 of the original proxies had values for the 20th century. Had Marcott et al. used the end dates as calculated by the specialists who compiled the original data, there would have been no 20th-century uptick in their graph, as indeed was the case in Marcott’s PhD thesis. But Marcott et al. redated a number of core tops, changing the mix of proxies that contribute to the closing value, and this created the uptick at the end of their graph. Far from being a feature of the proxy data, it was an artifact of arbitrarily redating the underlying cores.

Worse, the article did not disclose this step. In their online supplementary information the authors said they had assumed the core tops were dated to the present “unless otherwise noted in the original publication.” In other words, they claimed to be relying on the original dating, even while they had redated the cores in a way that strongly influenced their results.

Meanwhile, in a private email to McIntyre, Marcott made a surprising statement. In the paper, they had reported doing an alternate analysis of their proxy data that yielded a much smaller 20th-century uptick, but they said the difference was “probably not robust,” which implied that the uptick was insensitive to changes in methodology, and was therefore reliable. But in his email to McIntyre, Marcott said the reconstruction itself is not robust in the 20th century: a very different thing. When this became public, the Marcott team promised to clear matters up with an online FAQ.

It finally appeared over the weekend, and contains a remarkable admission: “[The] 20th-century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes, and therefore is not the basis of any of our conclusions.”

Now you tell us! The 20th-century uptick was the focus of worldwide media attention, during which the authors made very strong claims about the implications of their findings regarding 20th-century warming. Yet at no point did they mention the fact that the 20th century portion of their proxy reconstruction is garbage.

The authors now defend their original claims by saying that if you graft a 20th-century thermometer record onto the end of their proxy chart, it exhibits an upward trend much larger in scale than that observed in any 100-year interval in their graph, supporting their original claims. But you can’t just graft two completely different temperature series together and draw a conclusion from the fact that they look different.

The modern record is sampled continuously and as a result is able to register short-term trends and variability. The proxy model, by the authors’ own admission, is heavily smoothed and does not pick up fluctuations below a time scale of several centuries. So the relative smoothness in earlier portions of their graph is not proof that variability never occurred before. If it had, their method would likely not have spotted it.

What made their original conclusion about the exceptional nature of 20th-century warming plausible was precisely the fact that it appeared to be picked up both by modern thermometers and by their proxy data. But that was an illusion. It was introduced into their proxy reconstruction as an artifact of arbitrarily redating the end points of a few proxy records.

In recent years there have been a number of cases in which high-profile papers from climate scientists turned out, on close inspection, to rely on unseemly tricks, fudges and/or misleading analyses. After they get uncovered in the blogosphere, the academic community rushes to circle the wagons and denounce any criticism as “denialism.” There’s denialism going on all right — on the part of scientists who don’t see that their continuing defence of these kinds of practices exacts a toll on the public credibility of their field.

SOURCE  (See the original for links and graphics)




Is the Great Climate Alarm Winding Down?

Environmentalism is properly the ideology of controlling everything, which is called totalitarianism.’ Thankfully, it is difficult to squash human ingenuity, and industrialization will be a hard beast to slay, though it is neither impossible nor even complicated

While debate still swirls around climate change, recent reporting shows the debate’s hot and cold episodes cycle pretty in tune with changes in weather. Perhaps it will help to stand back and take a broad view.

Climate realists have long been aware that global average surface temperature had stopped sometime around 2000, and even a few years before. Lately alarmists had to admit it. The period with no warming is now as long as was period of warming on which fears were based—17 years according to a leaked draft of the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5)—despite continued rise of atmospheric carbon-dioxide concentration.

Observed global average temperatures (GAT) are, in fact, below IPCC’s 2007 Assessment Report’s lowest—and most confident—temperature predictions. The new view in the leaked AR5 shows a complete reversal of the AR4 view, which still touted catastrophic, anthropogenic global warming.

Prominent climate alarmists had to respond. Some, like Michael “Hockey-Stick” Mann, remain stalwart. Others, like James Hansen, first admitted the global temperature standstill was real, then, in what may have been a faux pas, said the lack of increased warming was due to an increase in global coal consumption.

IPCC Chairman Rajendra Pachauri acknowledged the “stalled” climate trend but employed the usual alarmist tactic and asked for more time to prove his predictions, thus kicking the can forty years down the road.

Even the U.K. Meteorological office produced updated reports on its temperature predictions, saying it expects no warming in the next five years. Previously, it had forecast an additional 0.1 degree Celsius in that time.

Indeed, the wheels seem to be falling off the climate alarmists’ wagon. Acclaimed physicist Freeman Dyson recently explained that the problem rests in the very heart of climate-change theory (if we can dignify it with that word): the substitution of (hopelessly unrealistic and guess-filled) modeling for experimental and real-world observation. With yet another hockey-stick depiction of past temperatures biting the dust, one wonders when not just the public but also political leaders will at last say, “Enough, children. Quit your fantasies and get back to the real world!”

The bottom line is that no one can say any longer that the world is warming dangerously.

This is in part due to the inherent faultiness of computer models used to predict future warming, which cannot even predict the past, let alone accurately predict the future. Yet, these climate models are the primary basis for increasing government involvement in (and spending on) climate change.

It wouldn’t be so terrible if the projected costs for some of the fixes didn’t cost trillions upon trillions of dollars. Britons are particularly subject to increased electricity and heating bills due to the exorbitant cost of wind power.

True science waits for answers, as opposed to playing guessing games and expecting homage. But that sort of post-normal science has crept into almost all the governments of the industrialized world. The fallacious thinking, post-normal science, and unwarranted alarmism have crept into Christian churches as well.

The fight isn’t over, and environmentalists are looking for influence wherever they can find it. And as it appears in the U.N. Earth Charter, among other places, it’s a dangerous influence.

Environment? Capitalism’s Is Best

Environmentalism affects every facet of life, not just economy and political freedom, though it certainly touches those. Dr. E. Calvin Beisner of the Cornwall Alliance likes to quip, “’Environment’ means my surroundings, and I can’t think of anything that isn’t my surroundings. So environmentalism is properly the ideology of controlling everything, which is called totalitarianism.”

Thankfully, it is difficult to squash human ingenuity, and industrialization will be a hard beast to slay, though it is neither impossible nor even complicated.

Standard of living has risen everywhere across the planet and continues to rise. Total wealth is also up. The cost of almost everything is down relative to income, including even the cost of catastrophe. There has never been less hunger or disease. Nothing is likely to stop this trend—unless it’s environmentalism, particularly because it plugs high-cost, low-reliability “renewable” energy over low-cost, high-reliability fossil fuels and nuclear.

Various means of trying to limit energy have been proposed, from a carbon tax to total cessation of fossil fuel use. All limit economic development, crucial to standard of living, and with it human health and well being. Any action that punishes the use of energy, including making it more expensive, undermines human life.

But for environmentalists, that’s okay. Sir David Attenborough, like many Greens and proponents of population control, expresses environmentalism’s implications for respect (or lack thereof) for human life:

We are a plague on the Earth. It’s coming home to roost over the next 50 years or so. It’s not just climate change; it’s sheer space, places to grow food for this enormous horde. Either we limit our population growth or the natural world will do it for us, and the natural world is doing it for us right now.

Such dangerous, anti-human thinking threatens everything the industrialized world has accomplished in the last two centuries with regard to health, prosperity, and political and legal reforms.

Although despite its grim outlook on the scientific front reports of climate alarmism’s death are greatly exaggerated, still it’s not doing well in the court of public opinion. That is likely due to the increasing absence of the predicted climate apocalypse, but the victory isn’t secure yet.

Activists in government and elsewhere continue rallying the troops. They can still inflict a huge amount of damage through new global or national legislation or court actions.

The Renewable Fuel Standard, for instance, which requires turning 40% of the U.S. fuel crop into ethanol as a “clean” fuel additive, is responsible for an extra 192,000 starvation deaths per year in developing countries and impoverishes everyone.
President Obama is trying to find new ways to apply old laws to break up the gridlock in the politically opposed houses of our bicameral legislature.

New political appointees to the EPA and other government organizations are trying to strictly limit or tax carbon emissions, sulfur emissions, and mercury emissions.

All of these measures cost money—money a growing world could better use in other ways, like reducing hunger and disease. If EPA wants to reverse the trend of increasing wealth and decreasing disease, poverty, and starvation, it is on the right track.

SOURCE




Climythology

by Peter Smith, commenting from Australia

Nobody with a life outside of “Greensville” cares very much anymore about climate change, earlier known as global warming. Do you even hear it now being discussed over cafe lattes in Balmain? No, you don’t. Only Tim Flannery and his alarmist ilk care. But political parties in Western democracies, as we have learnt to our great cost on the immigration front, have a life of their own, distant from the populace.

They have great moral purposes to pursue. Therefore governments of whatever complexion continue to pour billions of dollars of borrowed funds into schemes and businesses to support the production of inefficient energy. Nothing like this has happened before. We know that because industrial progress has largely been unremitting; built on cheap and progressively cheaper energy. Going backwards has not heretofore been favoured, if for no other reason than nasty nations, insistent on making progress, would have taken advantage, and invaded and subjugated their more primitive neighbours. And we know that because it regularly happened.

Is it possible that governments have collectively lost their senses? Yes, it is, when plagues of locusts or other pests in future years might effectively ground the ethanol-dependent US fleet and Air Force. Ditto here, if the Katter Party, aka, the Ethanol Party, has its way.

The risk to alarmists is that governments will catch up with the climate insouciance of their electorates and stop wasting money. Among other things, money will be saved by sacking people like Flannery and removing all of those research grants directed towards proving the undisprovable, which is that climate change does indeed exist and will eventually engulf our grandchildren in the most horrible of fates. Only research grants based on climate propositions which potentially can be shown to be false, in Popperian fashion, will be left standing; and few in number they will be.

What to do? The answer chosen by the alarmists is to become more alarmist in the hope of panicking the common man and woman or, at least, raising them from their torpor.

Hence we had Mr Flannery spruiking the latest report of the Climate Commission. He spoke of the angry summer; of 123 records broken; of it all taking us into new climate territory; and so on into what the PM might call hyper-bole. I don’t want to comment on this except to say that in Sydney I thought it was a very mild summer. Those who want a less personal, more scientific, debunking of Flannery’s flannelling might care to look at an excellent article in The Australian by Murray Salby, professor of climate at Macquarie University. He shows conclusively, so far as I can tell, as a non-scientist, that the summer just gone was unexceptional.

What does this all mean? In my view it means that alarmists seemingly have little affinity with the truth, the whole truth and nothing but the truth. This doesn’t mean that carbon dioxide is not warming the planet and thereby laying in store future grief. It means that snake-oil salesman are pushing the line and lessening our ability to find the truth. Let me give an instance from Flannery’s performance on the ABC’s 7.30 program.

Leigh Sales referred to figures showing that global temperatures had plateaued for the past 15 years or so. Flannery could have said, as did Dr Rajendra Pachauri when similarly challenged, that 15 years was too short a period to draw a conclusion or he could have tried to give some possible scientific reasons why the effect of CO2 emissions was being offset. Instead he chose to say that temperatures had not plateaued, but had continued to rise, when the temperature of “the oceans, the air and the land” are taken together. This is pure and simply sophistry at its most blatant and disgraceful. How can anything this man says be taken seriously after this?

If I were to suspend a solid body in a pan of water over a fire, the water would gradually heat as the hot air rose and transfer its heat to the surface of the solid body and, in turn, to the innards of the solid body. If I were to extinguish the fire I would expect the temperature of the whole mass of water and the solid body to continue to rise for a while. This is only my schoolboy physics or is it common sense?

In any event, the point at issue is not whether the temperature of the water and land are rising but whether CO2 emissions are materially heating the atmosphere. If the atmosphere cools or remains at a constant temperature for long enough in the face of rising CO2 emissions, it will be difficult to maintain the view that man-made global warming is a problem requiring the expenditure of billions of dollars and a resort to wholesale reliance on inefficient and unreliable green energy.

What is at stake is much too important to be the plaything of vested interests, fools or charlatans on either side of the argument.

According to Professor Salby, who I referred to above, the mean temperature in Australia in January this year was lower than in two previous Januaries during the time since 1979 when (accurate) satellite measurements have been available. And he notes that the summer from December to February “is even less remarkable”. If this is so, and it is surely verifiable, how can this summer be evidenced as being particularly untoward and “angry”?

We need people of objectivity and moderation in the climate arena, not snake-oil salesmen, if we are ever to get at the truth and put in place whatever practical and cost-effective action might possibly be called for; if in fact any such action is required.

SOURCE




Green energy on the back foot after carbon trading blow

Coal-fired electricity generation has seen a resurgence in Europe over the past two years

It's been a bad week for efforts to develop green energy around the world.  A new report from the International Energy Agency (IEA) says that progress towards carbon-free energy production has basically stalled.

"Despite much talk by world leaders," said IEA executive director, Maria van der Hoeven, "and despite a boom in renewable energy over the last decade, the average unit of energy produced today is basically as dirty as it was 20 years ago."

The IEA uses a complex calculation called the carbon intensity index to show how much CO2 is emitted to provide a given unit of energy.  The index stood at 2.39 tonnes of CO2 per tonne of oil in 1990. By 2010, it has shrunk fractionally to 2.37 tonnes.

The major reason for such a small reduction of that period, according to the IEA, was the resurgence of coal. And it continues to grow. Globally, coal-fired electricity generation rose by an estimated 6% from 2010 to 2012 , faster than non-fossil energy.

The major growth in coal came from developing economies, with China accounting for 46% of global coal demand in 2011.

But it's not just them.  Europe, the region that likes to think of itself as perhaps the greenest in the world, has also seen a return to coal in the last couple of years. While the US has turned to shale gas, Europeans have once again embraced the black stuff, as the cost of coal has plummeted.

However, it is not all bad news for the green sector. Renewables such as solar and wind have boomed in 2011 and 2012, perhaps driven by government spending.  They accounted for 19% of global electricity generation in 2011 which according to the report is "broadly on track to meet a 2C scenario by 2020" for a globally altered climate.

Electric vehicle sales have doubled (still a measly 110,000) while hybrid vehicles have finally broken the one million sales mark.

But turning this oil tanker (perhaps coal carrier is a better metaphor?) is not going to be easy.

And efforts will not have been helped by a vote in the European Parliament that rejected an attempt by the Commission to prop up the extremely ailing EU carbon market.

The EU Emissions Trading Scheme (ETS) has been seen as the world's best attempt to cut carbon by means of cap and trade. Essentially, 12,000 or so electricity generators and industrial heavy users of energy have had their emissions limited by EU law. The development of this market was seen as critical to both cutting emissions and driving investment in green energy.

But too many allowances were issued over the past few years - and the market price collapsed. The Commission attempted to rectify this by reducing the number of allowances due to issued in the next two years, a proposal known as backloading.

The Parliament though wouldn't wear it. Many MEPs held to the view that the collapsing carbon price was an accurate reflection of the real economy.

Some environmental campaigners have also welcomed the backloading breakdown. They argue that the market hasn't worked as it essentially has become a means of avoiding real carbon cuts by paying someone else to do them.

"We believe the failed backloading vote points to the fact that we need alternative tools - direct, ambitious, just regulatory policies," said Hannah Mowat from Fern, a NGO that has been working on carbon issues for a decade.

"We are now trying to galvanize support around more effective tools to achieve emissions reductions. " she added.

There is now going to be a serious amount of head-scratching among European academics and politicians on the best ways forward for green energy.

SOURCE




Europe Faces a Crisis in Energy Costs

The signs are everywhere. Britain has been unable to reach a deal for its first new nuclear power station since the 1990s. Spain, once a clean-energy enthusiast, has slashed its backing for wind and solar power.

Even the European Union’s flagship environmental achievement of recent years, its Emissions Trading System for carbon dioxide, is beset by existential doubts. On Tuesday, the European Parliament batted away an effort to bolster anemic carbon prices on the E.T.S.

Prices for permits to emit greenhouse gases, which have fallen as low as €3 per metric ton, are just a fraction of what they were a few years ago, meaning that they are no longer doing their intended job of inducing utilities and manufacturers to invest in new technology and switch to cleaner fuels.

Evidently, members of the European Parliament were more concerned about any further raising of energy costs that some European companies already say are putting them at a competitive disadvantage.

Europe is lurching through an energy crisis that in many respects parallels its seemingly unending economic crisis. Across Europe, consumer groups, governments and manufacturers are asking how their future energy needs can be met affordably and responsibly.

It is a question that is far more acute than in the United States, where the shale gas revolution has done wonders to ease energy angst. “Europeans are getting increasingly concerned about energy,” said Corin Taylor, an analyst at the Institute of Directors, a British business group. “Manufacturers are looking at U.S. energy prices with envy, and if they can, they are making investments in North America.”

European countries have yet to demonstrate that they can or in some cases even want to exploit their own potential shale gas troves. At the same time, most of Europe’s indigenous sources of oil and natural gas are in decline, making increased dependence on imports almost inevitable.

In some ways, Europe is a victim of its own success. It has made remarkable progress in switching to a future beyond oil and natural gas. For instance, last year, a hefty 23 percent of European power demand was met by electricity generated by renewable sources like wind and solar, compared with just 13 percent in 2002. This shift was “driven primarily by generous support policies for renewables,” said Susanne Hounsell, an analyst at the energy research firm IHS CERA in Paris.

But achievements like that have also brought problems. Most green electricity sources cannot compete with coal and natural gas on their own and require subsidies that are passed on to industry and consumers. The more power they generate, the higher those costs. Direct charges for renewables add about 18 percent to German household electric bills, with indirect costs putting on more.

In Britain, climate charges add 19 percent to the electricity prices that large manufacturers pay, according to Jeremy Nicholson, director of the Energy Intensive Users Group, which represents heavy industry. That helps make industrial processes that are heavy users of electricity, like aluminum smelting or steel making, endangered species in Britain.

Europe’s energy policies were conceived in a very different era, the early to mid-2000s and even before, when economic growth was robust and there seemed to be lots of leeway to add a few euros onto the cost of electricity, if that might help combat climate change.

In Europe today, to take only a couple of examples, steel production is down about 30 percent since before the financial crisis, and new car sales hit their lowest level last year since 1995. It is hard not to conclude that economic activity like manufacturing is decamping and moving to places like Asia and, increasingly, the United States.

European energy policy makers do not seem to have figured out that the world has changed. Britain, for instance, has just instituted a carbon tax on top of E.U.-wide carbon charges. The effort to raise the carbon price on the E.T.S. while Cyprus was melting down is another sign of tin-eared European policy making.

The vote against the changes to the E.T.S. could prove a wake-up call. Europe is probably going to achieve its objective of cutting greenhouse gas emissions 20 percent from 1990 levels by 2020 — mainly because the recession has cut industrial production and even driving. Now comes the harder part: cutting emissions 90 percent or so by 2050. Baby steps like a mini carbon tax are not going to get Europe there, analysts say.

A real debate on energy may be in the cards for the first time in years. “We are in the realpolitik of climate change now, where costs and competitiveness do matter,” said Fabien Roques, another analyst at IHS CERA.

“Our whole energy policy needs to be rethought. We don’t need to go for hell for leather in one go to meet targets,” said Ann Robinson, head of consumer affairs at uSwitch, a British company that provides consumer advice.

Ms. Robinson argues that instead of rushing huge investments into largely unproven and enormously expensive technologies like offshore wind, a phased approach would be preferable and would leave time for scientific advances that might produce cheaper and more effective solutions. Britain, where the average annual household energy bill has doubled to about £1,335, or $2,040, since 2006, is approaching a “tipping point” where large numbers of people decide to “switch off heat permanently,” she said.

SOURCE





Global Warming Slowdown: The View from Space

Since the slowdown in surface warming over the last 15 years has been a popular topic recently, I thought I would show results for the lower tropospheric temperature (LT) compared to climate models calculated over the same atmospheric layers the satellites sense.

Courtesy of John Christy, and based upon data from the KNMI Climate Explorer, below is a comparison of 44 climate models versus the UAH and RSS satellite observations for global lower tropospheric temperature variations, for the period 1979-2012 from the satellites, and for 1975 – 2025 for the models:



Clearly, there is increasing divergence over the years between the satellite observations (UAH, RSS) and the models. The reasons for the disagreement are not obvious, since there are at least a few possibilities:

1) the real climate system is not as sensitive to increasing CO2 as the models are programmed to be (my preferred explanation)

2) the extra surface heating from more CO2 has been diluted more than expected by increased mixing with cooler, deeper ocean waters (Trenberth’s explanation)

3) increased manmade aerosol pollution is causing a cooling influence, partly mitigating the manmade CO2 warming

If I am correct (explanation #1), then we will continue to see little warming into the future. Additional evidence for lower climate sensitivity in the above plot is the observed response to the 1991 Pinatubo eruption: the temporary temperature dip in 1992-93, and subsequent recovery, is weaker in the observations than in the models. This is exactly what would be predicted with lower climate sensitivity.

On the other hand, if Trenberth is correct (explanation #2), then there should be a period of rapid surface warming that resumes at some point, since the climate system must eventually try to achieve radiative energy equilibrium. Of course, exactly when that might be is unknown.

Explanation #3 (anthropogenic aerosol cooling), while theoretically possible, has always seemed like cheating to me since the magnitude of aerosol cooling is so uncertain it can be invoked in any amount desired to explain the observations. Besides, blaming a lack of warming on humans just seems a little bizarre.

The dark line in the above plot is the 44-model average, and it approximately represents what the IPCC uses for its official best estimate of projected warming. Obviously, there is a substantial disconnect between the models and observations for this statistic.

I find it disingenuous for those who claim that, because not ALL of individual the models disagree with the observations, the models are somehow vindicated. What those pundits fail to mention is that the few models which support weaker warming through 2012 are usually those with lower climate sensitivity.

So, if you are going to claim that the observations support some of the models, and least be honest and admit they support the models that are NOT consistent with the IPCC best estimates of warming.

SOURCE

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