ttowntom

Of course it does, because the data since then so clearly demonstrates that CO2 forcing was dramatically overstated. That's bad news for the sky-is-falling crowd. You can call 1998 "freakishly hot" all you want, but the fact remains that it was *cooler* than what many GW fanatics were predicting it to be back in the mid-1980s. And since 1998, temperatures have been flat. There's no evidence of any trend at all:

I said no such thing. Hansen didn't assume any specific emissions level. He gave three hypothetical scenarios, and projected a temperature increase for all three. The methodology is appropriate, and I have no quibble with it. The problem is that ALL THREE SCENARIOS drastically overpredicted warming. That's the end of the proof, right now. Now, if we want to move beyond that to determine just how much in error he was, it's appropriate to look at which of the three scenarios best fits reality. It is, of course, scenario A, as this graph of global emissions clearly demonstrates: Let's summarize. Hansen tried to tell us that, even if the entire world drastically reduced emissions, we would, by 2008, already be seeing severe warming. And if we did nothing -- which effectively we did -- we'd see even worse effects, rising to nearly 1.2C by now. But in reality, we've really just warmed up 0.3C, despite the massive increase in emissions. A clear demonstration that CO2-based forcing has been drastically overstated. I said the same thing in 1988. And I'll be saying the same thing when the IPCC finally winds up agreeing with me, around the time it releases its Fifth Assessment Report.

Not a problem. That IS what the paper states. Read it again. I'm not sure why you're struggling so with the language here, but it's really very clear. Not even close to correct. World emission rates have *risen*, not declined. Scenario B assumed a decline, to level off forcing. But actual global emission rates have risen.

It's an urban myth, with a (very small) kernel of truth. There are two areas of the Pacific which tend to trap trash, due to the circulating currents (known as 'gyres', in particular). One is much larger than the size of Texas, in fact. However, thinking its a solid heap of trash and plastic waste is nonsense...it is in fact, to the normal eye, an average patch of ocean, with only a moderately higher chance of finding a piece of trash in it than anywhere else in the sea. That's why you'll never find pictures of any gigantic mound -- it doesn't exist.

Can people not read plain English? Scenario B assumed a freeze in emissions growth, to level off forcing. Good god, this is ludicrous. Once again, the English is very plain. From the paper, Sec 4.1: "Scenario C drastically reduces trace gas growth between 1990 and 2000 such that the greenhouse climate forcing ceases to increase after 2000". The paper makes it MORE explicit on page 9362. I quote, "In Scenario C...after 2000, CO2 ceases to increase...after 2000, CH4 ceases to increase....no increases occur for the other CFCs, O3, stratospheric H2o, or any other greenhouse gas" Any questions still? And finally, you ignore the most important point. All three scenarios drastically overpredicted warming.. The point is proven; abundantly so.

Come, sir, you're on a board with "science" in the title. Surely you can use your head better than that. First of all, your NOAA graph is VERY far out of date (it stops at 2006). Second of all, its computing running means for entire years, not displaying the actual month-by-month data. Thirdly, the trendline is calculated from all the way back in 1900. Do you not realize the start point of a linear regression influences the entire line? I gave you a link to the actual raw data, current as of Feb 2008. Graph it yourself and see. Stop from 1998 (or 1997 or 1999 if you prefer), and see what the actual trend for the past 10 years is. Here's what you get: Source data: Already done in Post #38. AR3 predictions, and link to AR4 predictions. Compare for yourself. Draw your own conclusions for the "reasons for the change". They're obvious, however. AR1 projected too high. AR2 too high. AR3 too high. Are you really so surprised that AR4 again scaled back predictions?

This was already addressed by myself as well as another poster. The curve represented as Scenario A in the graphs predicts warming of some 1.2C by today, as calculated from the "nominal" value of the 1951-1980 mean anomaly (standard practice in climatology). What is the current temperature now though? Just 0.32C above nominal, for the 12-month running average ending Feb 2008, according to the Hadley Center for Climate Prediction: http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/monthly The observed value is even lower, if you look at the satellite troposphere data (RSS, UAH, etc). But let's not pick the data which makes the best argument for us...it's not neccesary, as every single data outlet, up to and including GISS itself, proves conclusively that warming was drastically overpredicted. Still worse for the alarmists, the rise since 1998 has been zero (for those that dispute this, plot the data above and drop a linear regression trendline.) This is the point that, for model predictions made in the 1980s, that we should be seeing warming increase still further. Yet the rate didn't increase, it has nearly shut itself off. For those who want to pick one of the lesser predictions (which still overpredict warming, just by a smaller degree), let's clarify just what those scenarios are: Scenario A - The world continues to grow emissions at 1988 levels. Scenario B - The world freezes GHG emissions growth rates so that the forcing remains linear.. Scenario C - The world halts GHG emissions by the year 2000. Scenario A is the closest to reality, and yet it drastically overpredicted actual warming. Fast-forward to 2001, and we see IPCC AR3 scaling back their predictions somewhat. In the years since this report was released, we already see a reality diverging sharply from the predictions, which ranged from a decadal increase of 0.15C up to nearly 0.6C. Yet That brings us to 2007, where IPCC AR4 has once again reduced predictions. They now place climate sensitivity at 3C. It's too soon to say definitively this value is too high...but recent research and observational data indicates it still is.

One model? I demonstrated that every model referenced by the IPCC overpredicted warming. Every one. The earlier the model, the more they overpredicted. The projections made by AR4 (2007) are almost still certainly overzealous, but they're far closer than the utter nonsense predicted by one and all during the 80s and 90s.

Attack mode? My position has already been amply proven. Warming has not been "underpredicted", it's been consistently overpredicted, nearly always by a huge margin. I entered here with the specific purpose of setting the record straight, which I have.

Translation: any scientist who disagrees with the third-rate hacks who founded RC is obviously wrong -- no need to even consider their data, evidence, or arguments! Must make life a lot easier than actually using that gray matter, eh? And I'm even further removed from the Chicken Little sky-is-falling stories, given I've been hearing them in one form or another since the 1960s. Not nearly as ironic as taking GCMs as gospel, despite their utter lack of predictive ability, and automatically discounting any research which disagrees with their conclusions, simply because "the model says it ain't so". There is no observational evidence for a climate sensitivity anywhere near what the models predict. In fact, their "predicted" sensitivity has been being lowered for decades. Eventually, they'll get it right, and stop dramatically overpredicting future warming. But for now, they're useless as predictive tools.

A couple off the top of my head: Douglass, et al (2007) International Journal of Climatology of the Royal Meteorological Society: A comparison of tropical temperature trends with model predictions http://www3.interscience.wiley.com/cgi-bin/abstract/117857349/ABSTRACT?CRETRY=1&SRETRY=0 Schwartz, 2007, Journal of Geophysical Research: Heat Capacity, Time Constant, and Sensitivity of Earth's Climate System: http://www.ecd.bnl.gov/steve/pubs/HeatCapacity.pdf Zhen-Shan, Sun-Xian: Multi-scale analysis of global temperature changes and trend of a drop in temperature in the next 20 years: http://www.springerlink.com/content/g28u12g2617j5021/ Dr. Soon from Harvard-Smithsonian had a recent paper on the same topic as well, though I can't find a non-subscription link to it atm. And of course, the Belgium Royal Meteorological Society came out last year with an official statement saying CO2's effects have been "grossly overstated". And, most telling of all, is the fact that there's been no warming trend since 1998, and no statistically significant warming trend since about 1995. Finally, there are plenty of peripheral papers, which don't directly address the CO2 sensitivity issue, but cast doubt on it in other manners, such as demonstrating the current warming trend began ~250 years ago (i.e. before the industrial age), or ones correlating solar activity to temperature changes, such as those by Svensmark of the Danish Space Institute, or Shaviv in Israel, and Usoskin's (the world's foremost solar physicist) recent conversion to a belief in solar-induced recent climate change.

Your mistake lies in assuming "all the previous research" said the same thing. The myth of "conensus" resurfaces again. But as anyone who regularly reads the literature knows, no such beast exists. As for the idea that this is "just a single paper", there are a dozen just in the last year alone which demonstrate the role of CO2 in climate change has been drastically overestimated. In fact, the mounting pile of evidence in papers prior to March 2006 (the cutoff period for inclusion in AR4) is the entire reason for those scaled-back predictions. The "piercing" has already been done. It's just not something done all at once, by a single paper. It's a continual process, which has slowly refuted those original doomsday scenarios. Is the IPCC still overpredicting warming? Almost certainly, in light of recent research...but even their existing predictions aren't all that frightening. Those still believing in doomsday have their heads in the sand.

Anyone following the debate already realizes the IPCC has repeatedly scaled back predictions in each of their reports. Here's the graph from IPCC AR3 (2001), which shows a range of predictions for warming by 2100 to be between 1.4C - 5.7C: Now contrast that with the projections graph on page 762 of AR4 (2007), which shows a range from 0.5C - 4.1C: http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch10.pdf Go back to the heady days of the 1990s, and you'll see many predictions with values ranging all the way up to an astonishing 10C or more! Clearly nonsense, from the paleo record if nothing else...but it didn't stop those soothsayers from getting published in peer-reviewed journals, and having thousands of credulous reporters unquestioningly repeat their nonsense.

I said no such thing, and don't try to change the subject. The fact that the IPCC has had to repeatedly lower their assessments proves the point. Predictions of global warming have perpetually and dramatically overstated the degree of actual warming experienced. Simple, unequivocal truth. The blind fervor with which you defend your faith might be admirable in, say a Catholic bishop or an Islamic mullah. But it has no place in scientific debate.

Only to those unable to read a simple line graph. This is really getting ludicrous. I show you 10-year old predictions and you say that's not long enough to judge. I point out 20-year old predictions and you imply they're too old? The point stands. No GCM prediction has ever been close to being accurate. The latest IPCC estimates in 2007 scaled back warming estimates dramatically (down to about a 3C sensitivity), and they're still overstating warming by 30-50%. And btw, this is more than just "one paper". It's the official prediction of NASA's GISS, published in multiple papers, several books, thousands of media reports, and at least two testimonies before Congress. Ah, you are right. My apologies to misattributing iNow.

I'm glad you asked! James Hansen's (NASA GISS) predictions from 1987 (published in an 1988 paper) are quite illuminating. They were, in fact, used for the basis of the IPCC's first assessment report, and this paper (along with Hansen's later works are still heavily cited today): He calculated three scenarios. Scenario A assumed continued growth of CO2 emissions at current levels -- this is in fact very close to what has happened in the 21 years since he made those predictions. And what was the calculated temperature rise by 2008? A full 1.0C above the 1951-1980 mean. What did temperatures actually rise? As of last month, they're 0.2C. Warming was overpredicted by 500%. The *coolest* of the 3 was based on the assumptions that the world would stabilize CO2 emissions by the year 2000. Even for that scenario, Hansen predicts a warming of 0.62C by 2008. But -- even though emissions have continued nearly unrestrained, warming has only been a tiny fraction of that. The facts are clear. Models predictions from the 1980s and 1990s were hugely overstated. People who claim the "models predicted less warming than we've seen" are wrong, plain and simple. Source to Hansens's 1988 paper is here: http://pubs.giss.nasa.gov/docs/1988/1988_Hansen_etal.pdf

And yet you have no problem claiming those same models "underpredicted" warming? Odd, since you claim to believe it's too early to tell. The fact remains that those observations *have* come to pass. The models predicted a decadal warming trend that ranged from of 0.15C to nearly 0.6C. This is far above what we've actually seen for the past 10 years. The models overpredicted warming, and seriously so.

Err, that's a line graph. It's for the *entire* period from 2000 to 2100. And yes, we're only 8 years in, but you can't compare predictions to a reality which has not yet occurred. Nevertheless, we can compare predicted decadal rises from the 1990s with the true situation 10 years later. And Voila! We see huge discrepancies already. If the models aren't accurate even 10 years in, what does that say about their performance over 100 years? Model predictions have continually overstated temperature increases. The IPCC scaled *back* predictions in the 2007 AR4 report, to bring them better in line with reality.

The "classic" explanation of the EFS paradox is a hypothesis without observational data to support it, and one that involves two wholly separate processes (the sum warming & greenhouse gases declining) which just happen to coincidentally work in lockstep to keep temperatures relatively even. I think Dr. Shaviv's hypothesis explains this much better -- a young sun rotates much faster, creating a much stronger solar wind. The increased corpuscular radiation compensates for much of the lower irradiance. As for explaining past climatic variations, from the Cryogenian to the Paleocene-Eocene boundary, the standard explanation involves Milankovich-cycle induced triggers, followed by feedback effects, some of which include GHG-based forcings. Nothing in the paper contradicts that. It merely resets the relative balance of the various factors somewhat. If you believe Miskowlczi is discounting the greenhouse effect, you've misread the paper. The maximum bound from CO2-based forcing is likely in the range of 2-3C, a figure which -- again, according to Miskowlczi, agrees extremely well with TIGR data. Venus certainly seems to have a greenhouse effect, but claiming its a proven runaway process is off base. Venus merely demonstrates the upper bound for an atmosphere with 250,000X as much CO2 as essentially zero H2O is much higher-- again, not surprising. The fact remains, that with zero data on surface fluxes, one can't fit *any* model of surface temperatures to Venus. It's all simply supposition, and the author rightly avoids it. And as an aside, I must point out that attributing all the Venusian excess heat on GHGs is no more than supposition itself. The Magellan mission found evidence of extraordinarily high levels of volcanism on Venus, with a surface dominated by lava plains. For all we know, much of that excess heat is due to geologic processes. Eh? The only links I see in that article are to a peer-reviewed Hungarian journal, and a peer-reviewed paper from Brookhaven Labs. Other than that, it has a few quotes from the actual scientists involved, and that's it. So where are you getting this "prisonplanet" strawman?

Stuff and nonsense. IPCC AR3 (2001) gave an ensemble of model predictions, which ranged from 1.5C up to nearly 6.0C in total warming: Yet the observed decadal warming trend now stands at only 0.14C: http://vortex.nsstc.uah.edu/public/msu/t2lt/tltglhmam_5.2 The continual overprediction of warming in fact explains why AR4 downgraded their forecasts for maximum warming substantially.