The global warming deniers arguments exposed and refuted.
You'll find the arguments in italic, and the explanations beneath them. We've all heard them on this board before, and they all have been addressed by someone at some point or another. Well, here's a scientific, explanation for all those "arguments". It's a great place to start for those who do not have high level scientific training, and wish to know more on the subject.
Most deniers are too lazy to read (hence why they are still in denial), so if that's you, think of the reason why you don't believe, and scroll down the text and reading only the italics, until you come upon your "argument". Then read below. There's your answer. (I underlined this part just for you so you don't get overwhelemed with all these letters)
"The U.S. National Academy of Sciences and 10 other leading world bodies expressed the consensus view that "there is now strong evidence that significant global warming is occurring" and that "It is likely that most of the warming in recent decades can be attributed to human activities". And just last week, USA Today editorialized that "not only is the science in, it is also overwhelming".
It is puzzling then that the WSJ editors could claim that "the scientific case....looks weaker all the time".
While we resist commenting on policy matters (e.g. the relative merits of the Kyoto Protocol or the various bills before the US Senate), we will staunchly defend the science against distortions and misrepresentations, be they intentional or not. In this spirit, we respond here to the scientifically inaccurate or incorrect assertions made in the editorial.
Since that Byrd-Hagel vote eight years ago, the case for linking fossil fuels to global warming has, if anything, become even more doubtful.
This statement stands in stark opposition to the actual findings of the world scientific community (e.g. the various National Academies, the Intergovernmental Panel on Climate Change (IPCC)), and the vast majority of actual peer-reviewed scientific studies.
The Earth currently does seem to be in a warming period, though how warm and for how long no one knows.
If we interpret to "know" as "is judged to be the case based on the available evidence", the statement is patently false. As detailed in previous discussions at RealClimate (see here and here and here) it is the consensus of the scientific community, based on more than a dozen independent studies using both empirical data and theoretical models (including the most recent studies in Nature and Science), that average surface temperatures over the Northern Hemisphere during the past few decades appear to be unprecedented in a very long term context, probably over at least the past 2000 years.
In particular, no one knows whether this is unusual or merely something that happens periodically for natural reasons.
This is incorrect. The natural causes of past climate variations are increasingly well-understood, and they cannot explain the recent global warming. As discussed elsewhere on this site, modeling studies indicate that the modest cooling of hemispheric or global mean temperatures during the 15th-19th centuries (relative to the warmer temperatures of the 11th-14th centuries) appears to have been associated with a combination of lowered solar irradiance and a particularly intense period of explosive volcanic activity. When these same models are forced with only natural radiative forcing during the 20th century [see e.g. Crowley (2000)] they actually exhibit a modest cooling trend. In other words, the same natural forcings that appear responsible for the modest large-scale cooling of the "Little Ice Age" should have lead to a cooling trend during the 20th century (some warming during the early 20th century arises from a modest apparent increase in solar irradiance at that time, but the increase in volcanism during the late 20th century leads to a net negative 20th century trend in natural radiative forcing). In short, given natural forcing factors alone, we should have basically remained in the "Little Ice Age". The only way to explain the upturn in temperatures during the 20th century, as shown by Crowley (2000) and many others, is indeed through the additional impact of anthropogenic (i.e., human) factors, on top of the natural factors.
Most global warming alarms are based on computer simulations that are largely speculative and depend on a multitude of debatable assumptions.
This is not correct. Concern about global warming is not based primarily on models, but rather on an understanding of the basic physics of the greenhouse effect and on observed data. We know from data that we have caused the CO2 concentration in the atmosphere to rise sharply during the past century: it is now much higher than any time during the past 650,000 years (which is as far back as reliable ice core data exist). And we know that this rise in CO2-concentration changes the radiation balance of the planet and leads to a warming of global surface temperature. This is scientifically undisputed and well-established physics, which has been known since in the year 1896 the Swedish Nobel prize winner Svante Arrhenius calculated the climatic effect of a rise in CO2.
Since there is a continued increase in emissions of (in particular) CO2, continued greenhouse warming is highly likely to continue. The models serve merely to quantify these basic facts more accurately, calculate the regional climate response, and compute effects (such as the expected increase in ocean heat content or sea level) which can be tested against observed data from the real world.
The editorial then returns to the issue of paleoclimate reconstructions and the so-called "Hockey Stick", repeating literally each of RealClimate's documented "Hockey Stick" myths:
Then there's the famous "hockey stick" data from American geoscientist Michael Mann. Prior to publication of Mr. Mann's data in 1998, all climate scientists accepted that the Earth had undergone large temperature variations within recorded human history.
The actual prevailing view of the paleoclimate research community that emerged during the early 1990s, when long-term proxy data became more widely available and it was possible to synthesize them into estimates of large-scale temperature changes in past centuries, was that the average temperature over the Northern Hemisphere varied by significantly less than 1 degree C in previous centuries (i.e., the variations in past centuries were small compared to the observed 20th century warming). This conclusion was common to numerous studies from the early and mid 1990s that preceeded Mann et al (1998). The Mann et al (1998) estimates of Northern Hemisphere average temperature change were, in fact, quite similar to those from these previous studies (e.g. Bradley and Jones, 1993; Overpeck et al, 1997), but simply extended the estimates a bit further back (from AD 1500 to AD 1400). In reality, the primary contribution of Mann et al (1998) was that it reconstructed the actual spatial patterns of past temperature variations, allowing insights into the complex patterns of cooling and warming in past centuries. In fact, regional temperatures changes (e.g. in Europe) appear to have been significantly larger, and quite different, from those for the Northern Hemisphere on the whole. Neglecting the significance of the large regional differences in past temperature changes is another classic pitfall in the arguments put forward by many climate change contrarians (see Myth #2 here).
The WSJ editorial continues,
This included a Medieval warm period when the Vikings farmed Greenland and a "little ice age" more recently when the Thames River often froze solid.
The sentence, first of all, perpetuates two well-known fallacies regarding the so-called "Medieval Warm Period" and "Little Ice Age". See the RealClimate discussions of the Little Ice Age and Medieval Warm Period for explanations of why both the Viking colonization of Greenland and the freezing of the River Thames actually tells us relatively little about past climate change.
The actual large-scale climate changes during these intervals were complicated, and not easily summarized by simple labels and cherry-picked anecdotes. Climate changes in past centuries were significant in some parts of the world, but they were often opposite (e.g. warm vs. cold) in different regions at any given time, in sharp contrast with the global synchrony of 20th century warming.
The WSJ then continue with a statement that is problematic on several levels,
Seen in that perspective, the slight warming believed to have occurred in the past century could well be no more than a natural rebound, especially since most of that warming occurred before 1940.
Firstly, the overall warming of the globe of nearly 1 degree C since 1900 is hardly "slight". That warming is about 1/5 of the total warming of the globe from the depths of the last Major Ice Age (about 20,000 years ago) to present.
Secondly, the argument that the climate should have naturally "rebounded" with warming during the 20th century defies the actual peer-reviewed scientific studies which, as discussed earlier, suggest that the climate should have actually cooled during the 20th century, not warmed, if natural factors were primarily at play. Anthropogenic greenhouse gases are required to explain the observed warming. Also, it is incorrect that most of the warming occurred before 1940; in contrast, the warming since 1970 is larger than that up to 1940.
The WSJ proceeds with the claim that key scientific findings that are common to numerous independent studies (specifically that late 20th century hemispheric warmth is anomalous in the context of past centuries) can somehow be pinned on one particular research group or even individual (see Hockey Stick Myth #1 here):
Enter Mr. Mann, who suggested that both the history books and other historical temperature data were wrong. His temperature graph for the past millennium was essentially flat until the 20th century, when a sharp upward spike occurs -- i.e., it looks like a hockey stick. The graph was embraced by the global warming lobby as proof that we are in a crisis, and that radical solutions are called for.
This is patently incorrect.
The WSJ then echoes the final of the "Hockey Stick" myths discussed on RealClimate (see Myth #4 here), claiming that the "Hockey Stick" has now been discredited:
But then, in 2003, Canadian mathematician Stephen McIntyre and economist Ross McKitrick published a critique calling Mr. Mann's work riddled with "collation errors, unjustifiable truncations or extrapolation of source data, obsolete data, geographical location errors, incorrect calculations of principal components, and other quality control defects."
In fact, these claims have been demonstrated to be incorrect by an independent group of scientists at the National Center for Atmospheric Research (NCAR) . These authors have shown that the 'alternative' reconstruction promoted by McIntyre and McKitrick (which disagrees not only with the Mann et al reconstruction, but nearly a dozen independent reconstructions that agreee with the Mann et al reconstruction within statistical uncertainties) is the result of censoring of key data from the original Mann et al (1998) dataset. Unlike the original reconstruction of Mann et al (1998), the reconstruction that McIntyre and McKitrick produced using the censored data set fails standard statistical tests for validity, and, in the words of the NCAR group, is "shown to be without statistical and climatological merit".
Correct for those errors, they showed, and the Medieval warm period returns.
This is just bizarre. The claimed reconstruction of McIntyre and McKitrick, in fact, indicates anomalous warmth during the 15th century. This period doesn't fall even remotely within the interval commonly referred to as the "Medieval Warm Period" Instead, it actually falls within the heart of the "Little Ice Age" itself! The irony of contrarian supporters of the claims of McIntyre and McKitrick is that, if their reconstruction were valid (which it is not), it would actually argue for unusual warmth during the heart of the "Little Ice Age".
Mr. Mann has never offered a serious rebuttal to the McIntyre-McKitrick critique.
This is not true. In fact, Dr. Mann has demonstrated the falsehood of the various McIntyre and McKitrick claims in excruciating detail on RealClimate (see here and here). More significantly, however, McIntyre and McKitrick's claims have now been refuted by at least two independent teams of climate researchers (see here and here).
He has refused to fully explain his methodology.
Quite to the contrary, the methodology used was described in detail not just in the original 1998 publication, but in an expanded description provided last year on Nature's supplementary website. The original description was adequate for other researchers with appropriate training to closely reproduce both the algorithm and the published results. In fact, the NCAR researchers referred to above have made their code for implementing the Mann et al (1998) method publically available here. In the process (scroll down to bottom of this page) , they demonstrate the impacts of the numerous fundamental errors made by McIntyre and McKitrick. With this publically available code and data, anyone can reproduce and check the reconstruction of Mann et al (1998).
Meanwhile, a review of about 200 different temperature studies was published in 2003 by Willie Soon and Sallie Baliunas of the Harvard-Smithsonian Center for Astrophysics in the journal Climate Research. It likewise reaffirmed the longstanding consensus that there have been large temperature variations over the past millennium.
The irony here could not be more striking, for if the editors of the WSJ were familiar with the news reported by the WSJ, they surely should have been aware that the Soon and Baliunas study was discredited on the pages of the Wall Street Journal itself. Indeed, as described in that previous WSJ article, a team of leading climate researchers detailed the numerous fundamental flaws in the Soon and Baliunas paper in in the American Geophysical Union journal "Eos". This matter has been discussed elsewhere at great length, including previously on RealClimate both here and here (see "Myth #2").
computer models ...suggest the upper atmosphere should have warmed substantially in recent decades. But data from weather balloons and satellites don't match the projections.
There is indeed a discrepency between some analyses (but not others) of the satellite data in the lower troposphere and model predictions, yet the satellite data continue to undergo quality checking and re-processing and there are a few indications (such as Fu and Johansen, 2005) that problems still exist. The jury is still out on this issue (but they may be about to come back in to the room).
There's also the matter of the alleged melting of the Antarctic ice cover, threatening a catastrophic sea level rise. In fact, recent data suggest the ice is thickening and temperatures are dropping in most of the continent.
Models actually predict that the interior of the ice sheets should gain mass because of the increased snowfall that goes along with warmer temperatures, and recent observations actually agree with those predictions. Some areas, such as the Antarctic peninsula and the West Antarctic ice sheet are losing mass, consistent with temperature trends there.
Finally, an increasing number of scientists are concluding that variations in solar radiation associated with sun spots -- that's right, the heat of the sun -- play a major role in Earth's climate.
Solar forcing of climate is indeed an important component, and in the pre-industrial period appears to explain a significant share of the century-scale variability (though there is large uncertainty in the magnitude of the effect). There is likely an increase in the early 20th Century as referred to above, however, since 1950 there is no evidence for increases in solar activity (most indices are flat) and so it is highly unlikely to be able to explain the bulk of the current warming trend.
The WSJ editors then try to reverse nearly two decades of scientific research by promoting a qualitative graph (which is not actually based on any real data) that was offered simply as a schematic by the IPCC back in 1990:
So what would be a fair representation of how most scientists view the climate of the past 1,000 years? We'd suggest the graph nearby, which we reprint exactly as it appeared in the first report of the U.N.'s Intergovernmental Panel on Climate Change (hardly a group of oil-funded hacks) in 1990. It shows that our own warming period is neither unique nor all that hot.
The WSJ may prefer to use 15 year-old guesses on which to base their opinion, but the scientific community has an understandable preference towards up-to-date and quantitified research.
http://www.realclimate.org/index.php?p=167
