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Nature: Global Temperatures Are a Falling Trend
New submitter sosume writes "An article in Nature shows that temperatures in Roman times were actually higher than current temperatures. A team lead by Dr. Esper of the University of Mainz has researched tree rings and concluded that over the past 2,000 years, the forcing is up to four times as large as the 1.6W/m^2 net anthropogenic forcing since 1750 using evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (0.31C per 1,000 years, ±0.03C) than previously reported, and demonstrated that this signature is missing in published tree-ring proxy records."
All the article says is that forcings related to orbital mechanics may have been larger on a millenium time scale than estimated before. Even that is speculation - the core of the paper is presenting a improved method for evaluating tree ring proxies. The paper, however, does not call into doubt that the industrial age has added a significant greenhouse gas forcing, which gets bigger as we continue to add CO2 and methane.
Ubi solitudinem faciunt, pacem appellant.
These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times.
In other words: estimates of temperature in medieval/Roman times based on tree ring data may well be too low.
If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
Indeed, RealClimate notes that if you remove dendrochronology records from Mann et al (2008), you actually get a lesser pre-industrial cooling trend. Of the dozens of independent lines of evidence, tree rings have long been one of the *least* suggestive of disproportionately high GHG forcing versus other forcings, so it's always funny to see them called out as though the case for global warming rests on them. ;) (The reason that they're often called out is because they're *really tricky* to use well; so many things affect tree growth that have to be accounted for, and the factors vary greatly from location to location)
sed "s/SJW.*$/... never mind. I was about to say something stupid, and also, I'm a troglodyte./Ig"
No, the burden of proof is always on the person making the affirmative statement. It's usually very difficult to prove a negative. However, in many cases we're willing to accept a theory that makes sense and fits all the observed data.
This retarded press release was written by someone that can't even GRASP the science, or purpose, of the published paper. Please, for the love of god, stop posting science topics on /. based on what some ingrate with a word processor posts up to some off-beat web periodical with a political agenda. The "graph" given by the press release article doesn't even appear in the paper and is missing a lot of annotations and descriptions necessary to properly evaluate the data. Important things. Like a Y-axis. And the method used to develop the data- surprise, most of it's modeled/reconstructed. Which is FINE if you grasp what they were trying to do with this publication.
And before I jump into the paper can we clearly define what journal an article is published in? Saying "Nature" is misleading. It's "Nature: Climate Change". Not similar, at all.
The paper is a methods paper. It's outlining a very interesting way to get at fine-resolution temperature fluctuations on a not-so-far-back time scale. Additionally, the moving average rise in temperature isn't suggesting it was HOTTER back then than now (as this submission and the press release indicate) but that instead our ESTIMATES of how hot it was are off.. SLIGHTLY. How far off? Here, let me copy primary literature for you. I hear that's good journalistic practice.
"...These findings together with the trends revealed in long-term CGCM runs suggest that large-scale summer temperatures were some tenths of a degree Celsius warmer during Roman times than previously thought. It has been demonstrated4 that prominent, but shorter term climatic episodes, including the Medieval Warm Period and subsequent Little Ice Age, were influenced by solar output and (grouped) volcanic activity changes, and that the extent of warmth during medieval times varies considerably in space. Regression-based calculations over only the past millennium (including the twentieth century) are thus problematic as they effectively provide estimates of these forcings that typically act on shorter timescales. Accurate estimation of orbitally forced temperature signals in high-resolution proxy records therefore requires time series that extend beyond the Medieval Warm Period and preferably reach the past 2,000 years or longer6. Further uncertainty on estimating the effect of missing orbital signatures on hemispheric reconstructions is related to the spatial patterns of JJA orbital forcing and associated CGCM temperature trends. First, the simulated temperature trends, indicating substantial weakening of insolation signals towards the tropics, can at present be assessed in only two CGCMs (refs 7, 8). More long-term runs with GCMs to validate these hemispheric patterns are required. Whereas the large-scale patterns of temperature trends seem rather similar among the CGCMs, the magnitude of orbitally forced trends varies considerably among the simulations. Additional uncertainty stems from the weight of tree-ring data and varying seasonality of reconstructed temperatures in the large-scale compilations. Although some of the reconstructions are solely composed of tree-ring data, others include a multitude of proxies (including precipitation-sensitive time series) and may even include non-summer temperature signals. Some of these issues are difficult to tackle, as the weighting of individual proxies in several large-scale reconstructions is poorly quantified. The results presented here, however, indicate that a thorough assessment of the impact of potentially omitted orbital signatures is required as most large-scale temperature reconstructions include long-term tree-ring data from high-latitude environments. Further well-replicated MXD-based reconstructions are needed to better constrain the orbital forcing of millennial scale temperature trends and estimate the consequences to the ongoing evaluation of recent warming in a long-term context."
I wish I could just copy past the whole article into peoples brains and make them understand the difference between science and sensationalism.
So let's see, there are a few holes in your argument. I don't think your environmentalist point of view is necessarily wrong, but some of the evidence you provide is flawed.
It's important you realize that the majority of photosynthesis doesn't include trees, see for example algaes: http://en.wikipedia.org/wiki/Carbon_sink
Additionally, our cars are not even a blip on the global scale for carbon output: http://www.dailymail.co.uk/sciencetech/article-1229857/How-16-ships-create-pollution-cars-world.html
Furthermore, while it isn't on a global scale, we've basically stopped having a negative impact on forest sizes here in the US for a while: http://www.wendmag.com/greenery/2011/02/the-u-s-has-more-trees-now-than-100-years-ago/
Next, many of the sources of greenhouse gases are unrelated to burning things, and just normal biological processes which are involved in food PRODUCTION: http://science.howstuffworks.com/environmental/life/zoology/mammals/methane-cow.htm
Food for thought (pun intended), but I'm not challenging your goals, just want you to be more informed in your arguments or you make yourself and any others that hold your views look bad.
"Oolons
Did Lewis read the same paper?
Thanks to the link below I got to read the actual paper - the standard of reporting on this issue is atrocious. The paper looked at tree data from a small area of Scandinavia. Also pointing out that they have experienced a lot less warming in recent years than other northern areas.... Hmm do you think that may be true 1000's of years ago - it could have been warmer or cooler than the global average we don't know. So for CLIMATE in Lewis's article read WEATHER, i.e. Local effects for which it is extremely inaccurate to extrapolate to the world. Glad my knee jerk feeling that this was a daft extrapolation has been verified by the paper."
and
Anonymous Coward
Paper says:
"These findings, together with the missing orbital signature in published dendrochronological records, *suggest* that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data *may* underestimate pre-instrumental temperatures including warmth during Medieval and Roman times."
Lewis says:
"CLIMATE WAS HOTTER IN ROMAN, MEDIEVAL TIMES THAN NOW: STUDY"
flame on...
The English word fart is one of the oldest words in the English vocabulary.