Bob Tisdale
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- Name: Bob Tisdale
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Confusion?
Joseph Romm: Your comments about "Advancing decadal-scale climate prediction in the North Atlantic sector" mention that CO2 levels have "wildly outpaced" the CO2 growth of the referenced model scenarios. You failed to mention the Keenlyside statement on page 4 ("Nature" page 87) that notes that if greenhouse gases grew or were frozen at 2000 levels, it had little impact on their forecasts: "To investigate the sensitivity of the predictions to greenhouse gas forcing only, the two forecasts were repeated assuming that greenhouse gases were stabilized at year 2000 values. The predictions for the MOC and surface temperature remain basically unchanged. Thus, in the near future, natural decadal variability in the Atlantic and Pacific may not only override the regional effects of global warming, but temporarily weaken it." To reinforce the above, the following are the "Nature" links to Figures 3 and 4 of Keenlyside et al. Most of the projected trends are flat or declining from 2005 through 2010, their "decadal scale" forecast, including the models that included greenhouse gases.
Figure 3:
http://www.nature.com/nature/journal/v453/n7191/fig_tab/n ...Figure 4:
http://www.nature.com/nature/journal/v453/n7191/fig_tab/n ...Your comments here also seem to miss the overall intent of the paper. In terms that most non-technical readers would feel comfortable with, temperature, the Keenlyside et al letter to "Nature" clearly deals with the model-predicted stabilization and reduction, over a future ten year period:
1.In the temperature difference in the Atlantic Ocean Sea Surface Temperature (SST) between Northern and Southern Hemispheres (what Keenlyside et al refer to as "Atlantic SST dipole");
2.In European surface air temperature (SAT);
3.In North American SAT;
4.In Eastern Tropical Pacific SST; and
5.In global temperature;
all resulting from the anticipated return of the natural oscillation in Atlantic Ocean temperature and flow, called Atlantic Meridional Overturning Circulation (MOC), to its 1950 to 2005 mean. Recall the title of Keenlyside et al: "Advancing decadal-scale climate prediction in the North Atlantic sector". These are predictions or forecasts for the next decade.I downloaded Figures 3(cells b through d) & 4 from the paper, and highlighted the projected decreases in temperature where the Keenlyside et al froze greenhouse gas levels. Refer to:
Figure 3: http://i26.tinypic.com/e9j4tv.jpg
Figure 4: http://i31.tinypic.com/263k2sz.jpgEyeballing them, over 10 years, with greenhouse gas levels frozen, Keenlyside et al are predicting the following changes in temperature due to the natural reduction in Atlantic MOC:
Atlantic SST Dipole = -0.25 deg C
European SAT = -0.32 deg C
North American SAT = -0.3 deg C
Eastern Tropical Pacific SST = -0.03 deg C
Global Temperature = -0.04 deg CThe European and North American surface air temperature drops are significant.
Why are the forecasts with frozen greenhouse gas levels important? They identify the contribution of a natural component of climate change and could be used to imply the significant percentage that one single component, the Atlantic MOC, had on climate in the past--the last 10 years, 30 years.
That is, did the Keenlyside et al models indentify one-third of the contributions of the Atlantic Multidecadal Oscillation (AMO) as it rose from its trough 30 years ago? A global temperature variation of 0.12 deg C (0.04*3) is in line with the values identified in a Knight et al paper (Reference 14 in Keenlyside et al), and in line with the implied contribution identified by RealClimate in their glossary on the Atlantic Multidecadal Oscillation, "This pattern is believed to describe some of the observed early 20th century (1920s-1930s) high-latitude Northern Hemisphere warming and some, but not all, of the high-latitude warming observed in the late 20th century."
Knight et al paper:
http://holocene.meteo.psu.edu/shared/articles/KnightetalG ...Real climate glossary page on AMO:
http://www.realclimate.org/index.php?p=38There might be other natural year-to-year and decadal variations that could override those reductions, from El Nino/La Nina episodes, from changes in solar irradiance, from stratospheric volcanic aerosols, from natural variations in Pacific SST known as the Pacific Decadal Oscillation (North Pacific) and the Pacific Interdecadal Oscillation (basin-wide), but those are the impacts the authors forecast from the natural variable of Atlantic MOC.
On Next decade may see rapid warming, not cooling posted 1 year, 6 months ago 8 ResponsesClick here to view comment in original post
The Dressler Examples and Graph
Andrew Dressler writes, "The reason is clear. A warming rate of 3 degrees C per century corresponds to an annual average rate of warming of 0.03 degrees C per year."
Actually, the reason is pretty unclear with warming rates like that. I took the pleasure of marking up your graph in the following:
http://i30.tinypic.com/2e31u2d.jpg
Please identify the warming rate of 3 degrees C per Century in your graph. The total temperature scale is approximately 1.0 degree C, and the period covers a span of 158 years. I believe your rates should have been somewhere in the neighborhood of 0.5 to 0.8 degrees C per Century and 0.005 to 0.008 per year. And people wonder why skeptics are skeptical.
If, for example, you subtract out a 75 to 95% natural component of that, let's say 90% for simplicity sake, you're left with 0.05 to 0.08 degrees per Century and 0.0005 to 0.0008 per year, due to anthropogenic sources. Of course, natural noise (ENSO, AMO, PDO, TSI) hides AGW signals.
Now subtract the other anthropogenic heat sources from the remaining AGW 0.05 to 0.08 degree rise over the 20th Century: land-use changes, black soot on snow, brown clouds (each of which is reported to have as much as a 50% contribution), methane, chlorofluorocarbons, etc. The remainder leaves little room for a CO2 contribution.
Another bad example: Andrew Dressler writes, "At the same time, interannual variability, such as El Niño events, are of the order of 1 degree C per year. Thus, over short time scales, the slow upward trend can be completely swamped by the large year-to-year variability." An El Nino perturbation of 1 degree per year? That would overwhelm your graph. Your source of El Nino data is in error.
From Trenberth et al "Evolution of El Nino-Southern Oscillation and global atmospheric surface temperatures"(2002): "It shows that for the 1997-1998 El Nino, where N3.4 peaked at approximately 2.5 C, the global mean temperature was elevated as much as 0.24 C." This equates to a 0.096 degree C change in global temperature for a 1 degree C change in the NINO 3.4 region. Therefore, for your 1 deg C perturbation in global temperature to be the result of an El Nino, that El Nino would have had to have been more than 4 times larger than the 97/98 "El Nino of the Century". An El Nino with a NINO3.4 reading of 10+ degrees C hasn't been recorded.
RegardsOn Climate change must be examined over decades, not years posted 1 year, 6 months ago 68 Responses
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The IPCC Poster Years
Max: You fail to mention that during the IPCC poster years of 1976-1999 the PDO was positive, there was a predominance of El Ninos (vs La Ninas), which goes along with the PDO being positive, the AMO rose from its trough to near max, and solar irradiance (TSI) rose to the highest levels in 8,000 years. Recall that low-amplitude Solar Cycle 20 ended about 1976 and was then followed by three successive high amplitude cycles. On Climate change must be examined over decades, not years posted 1 year, 6 months ago 68 Responses
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Ice Sheet Collapse
I find it curious that AGW can be blamed when there has been no Antarctic warming for the last 29+ years. The trends are negative. They need to find another reason for the calving of an ice island. It's not AGW.
SoPol Negative Trend:
http://tinypic.com/fullsize.php?pic=ehrp3&s=3&cap ...
SoPol Land Negative Trend:
http://tinypic.com/fullsize.php?pic=35bxmy1&s=3&c ...
SoPol Ocean Negative Trend:
http://tinypic.com/fullsize.php?pic=2nle1yp&s=3&c ...
Graphs are of MSU data
There an oceanic connection between El Nino oscillations and the Southern Ocean. Maybe that can be used to help explain any regionalized warming, if there is any. Or maybe it's just the natural calving of what has been called an Ice Island for many years.
http://www.jpl.nasa.gov/releases/2002/release_2002_54.htm ...
Full paper here.
http://neptune.gsfc.nasa.gov/publications/pdf/pubs2002/2_ ...
Regards
On Not looking good for ice shelf in the Antarctic posted 1 year, 7 months ago 1 ResponseClick here to view comment in original post
Great Post, But
I enjoy reading your blog. I especially like the term delayer.
But here are a few observations:
Your link to Wattsupwiththat is over a month old. Global temperatures have continued to drop. Here's a more recent link to their analysis.
http://wattsupwiththat.wordpress.com/2008/02/19/another-g ...
Regarding your comparison of 1998 and 2007: That analysis fails to mention that the peak anomaly of 2007 (January) was a result of the 2006/2007 El Nino, which continued to warm the planet well through mid year. Recall that there is a 3-month lag between ENSO anomalies and global temperature fluctuations. The La Nina didn't really start to impact global temperature until November/December of 2007.
Your comment on solar "this explanation doesn't even note that total solar irradiance in 1999 was 0.3 W/m2 higher than in 2007" fails to consider the 2- to 5-year lag between solar and global temperature.
"2005 was also an unusually warm year, the second highest in the global record, but was not boosted by the El Niño conditions that augmented the warmth of 1998." 2005 was actually boosted by positive El Nino temperatures in the NINO3.4 region until September, where the 1998 El Nino turned into a very strong La Nina starting mid-year. In fact, the average ONI temperature for 1998 (the year of the Historic El Nino) was 0.21 deg C lower than 2005. Refer to the NOAA El Nino data here.
http://www.cpc.noaa.gov/products/analysis_monitoring/enso ...
The Hadley Centre graph is extremely outdated. Updated is here:
http://www.cru.uea.ac.uk/cru/data/temperature/nhshgl.gif
On the current graph, the smoothed data (the black line) appears to be in a downward trend for the last 4 years, which makes it possible for the Watts and Pielke analysis with which you begin this post.
The observational data (the black line) in the graph you included in your "Climate Forecast: Hot, and then Very Hot" link ended in 2004. I've updated the graph with a big black "X" where the global temperature is now. http://tinypic.com/view.php?pic=2e0r0qb&s=3 It's outside (below) the confidence levels of the authors, indicating they missed the mark so far. They better hope for a stong El Nino, because it's going to take the earth a couple of years to respond to an upturn in solar when that eventually happens.
You failed to mention the Atlantic Multidecadal Oscillation, which, if it hasn't started to drop, it should start its 30 year decline soon. That'll chop some more off global temperature.
Other than that, I liked the article. I don't agree with it, but I liked it.
On Hadley Center says we're warming, not cooling posted 1 year, 7 months ago 8 Responses
