Good article about scientific consensus

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O.K. Where is the True Climate Theory? Has any such theory been produced yet? I suspect not because the complexities are mathematically intractable and a whole class of possible climate drivers (solar output, orbital variation, wobble, cosmic ray effects on cloud formation) have not been given their proper weight. Can the True Climate Scientists explain why Greenland was green in the medieval warm period which was 300 years prior to the industrial revolution and there were less than a half billion humans on the planet? I would really like to hear an explanation of that. Imagine! Globally warming without any excess CO2 production by humans. Incontheivable!

ruveyn

I'm admittedly far removed from scientific research these days, but if my memory is correct, the significant part of the data is in the rate of change. Never before has the earth seen warming at its current rate (not by a whole lot) which aligns itself nearly perfectly with the rise CO2. And solar output (really?! - as if this would ever be omitted), orbital variation, and wobble were always factored into the models that I used to use. I'm pretty sure that cosmic ray effects on cloud formation were included as well, but I can't remember specifically.

The argument that solar output is causing recent global warming is false. Lockwood 2008 ( http://rspa.royalsocietypublishing.org/ ... 7.abstract ) shows that "the contribution of solar variability to the temperature trend since 1987 is small and downward; the best estimate is −1.3% and the 2σ confidence level sets the uncertainty range of −0.7 to −1.9%." So if anything changes of solar output are cooling the planet as solar activity decreases. That can be seen clearly in this graph that shows that although temperature was correlated to solar activity before 1970 the rise in temperature after 1970 can´t be explained by solar activity (blue line) as it diminishes as temperature (red line) continues to rise.




Figure: Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS ( http://data.giss.nasa.gov/gistemp/table ... s+dSST.txt ). Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Solanki ( http://www.mps.mpg.de/projects/sun-clim ... i_1611.txt ). TSI from 1979 to 2009 from PMOD.



The conclusion confirmed by many studies is that while the sun contributed to warming in the early 20th Century, it has had little contribution (most likely negative) in the last few decades.

Regarding cosmic rays, it has been proposed that they modulate the cloud cover and thus influence tropospheric temperatures. In order to scientists calculate the maximum possible role of cosmic rays in recent warming, global temperatures were compared to cosmic radiation levels measured by neutron monitors at the Earth's surface (Krivova 2003) ( http://www.mps.mpg.de/dokumente/publika ... ki/r47.pdf ). That author concludes that while there was good correlation between cosmic radiation and temperature prior to 1970, the correlation breaks down sharply after 1970. The analysis concludes that "between 1970 and 1985 the cosmic ray flux, although still behaving similarly to the temperature, in fact lags it and cannot be the cause of its rise. Thus changes in the cosmic ray flux cannot be responsible for more than 15% of the temperature increase"



Figure: Reconstructed cosmic radiation (solid line before 1952) and directly observed cosmic radiation (solid line after 1952) compared to global temperature (dotted line). All curves have been smoothed by an 11 year running mean (Krivova 2003).



There are other problems proving the causality link between cosmic rays and cloud formation. One of the key proofs of Svensmark's cosmic ray theory is the high correlation between low cloud cover and cosmic rays. However, the correlation between cosmic rays and cloud anormalities broke down in 1991 (Laut 2003) ( http://stephenschneider.stanford.edu/Pu ... ut2003.pdf ). The correlation completely breaks down in 1994.




Figure: Low cloud cover (blue line) versus cosmic ray intensity (red line) (Laut 2003).



The theory that cosmic rays effect cloud formation also has other problems. As cosmic radiation shows greater variation in high latitudes, one would expect larger changes in cloud cover in polar regions. This is not observed (Sloan 2007) ( http://arxiv.org/PS_cache/arxiv/pdf/070 ... 4294v1.pdf ). That author also studies the nuclear reactor accident at Chernobyl. Ionization from the radioactivity would be expected to produce an increase in cloud cover. However there was no evident increase in cloud cover following the accident in the various regions in the vicinity of Chernobyl.

The models are correct. They couldn´t find any other factor besides CO2 to simulate what had already happened unless the extra CO2 was added to the model. Nothing else could account for the rise in temperatures over the last century.

That is correct. The temperature had to rise just 4 to 7 degrees Celsius to get Earth out of the ice age. But that change happened during a 5,000 years period!! !! In the past century alone, the temperature has climbed 0.7 degrees Celsius, roughly ten times faster than the average rate of ice-age-recovery warming. Models predict that Earth will warm between 2 and 6 degrees Celsius in the next century. When global warming has happened at various times in the past two million years, it has taken the planet about 5,000 years to warm 5 degrees. The predicted rate of warming for the next century is at least 20 times faster. This rate of change is extremely unusual.

References: Nasa´s Earth Observatory http://earthobservatory.nasa.gov/Featur ... /page3.php

During the eruptions of the Siberian Traps and the Dekkan Traps the temperature rose a great deal more than in the recent era. Enough to wipe out 99 percent of the life on the planet.

ruveyn

Which show the potential danger of global warmimg.

You miss the point. Millions of years of volcanic eruptions produced a lot more temperature than has ever been produced in modern times. The eco-phreaks have grossly exaggerated the amount of temperature change. The world was warmer prior to the Little ice Age (1300-1800) than it is now.

ruveyn

Michael E. Mann et al. on “On Past Temperatures and Anomalous late-20th Century Warmth” ( http://coast.gkss.de/staff/storch/pdf/S ... m20032.pdf ) while replying to the articles of Soon and Soon and Baliunas make the claim that the preponderance of scientific evidence points that recent hemispheric-scale warmth is unprecedented in the context of the past millennium.

As instrumental data for use in computing global mean surface temperatures are only available for about the past 150 years estimates of surface temperature changes further back in time must make use of historical documents and natural archives. These are "proxy" indicators, such as tree rings, corals, ice cores and lake sediments, that are used to reconstruct the patterns of past climate change.

A large number of reconstruction for the Northern Hemisphere climate change now support the conclusion that the hemispheric-mean warmth of the late 20th century is likely unprecedented in the last 1000 years. These evidences are:


Bradley, R.S., and P.D. Jones, "Little Ice Age" summer temperature variations: their nature and relevance to recent global warming trends, The Holocene, 3, 367-376, 1993.

Overpeck, J., K. Hughen, D. Hardy, R. Bradley, R. Case, M. Douglas, B. Finney, K. Gajewski, G. Jacoby, A. Jennings, S. Lamoureux, A. Lasca, G.M.J. Moore, M. Retelle, S. Smith, A. Wolfe, and G. Zielinski, Arctic Environmental Change of the Last Four Centuries, Science, 278, 1251-1256, 199 ( http://helios.hampshire.edu/~srNS/Svalb ... turies.pdf )

Mann, M.E., R.S. Bradley, and M.K. Hughes, Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties, and Limitations, Geophysical Research Letters, 26, 759-762, 1999. ( http://www.ltrr.arizona.edu/webhome/apr ... BH1999.pdf )

Crowley, T.J., and T. Lowery, How Warm Was the Medieval Warm Period?, Ambio, 29, 51-54, 2000.

Jones, P.D., T.J. Osborn, and K.R. Briffa, The Evolution of Climate Over the Last Millennium, Science, 292, 662-667, 2001. ( http://courses.eas.ualberta.ca/eas453/r ... l_2001.pdf )

Folland, C.K., T.R. Karl, J.R. Christy, R.A. Clarke, G.V. Gruza, J. Jouzel, M.E. Mann, J. Oerlemans, M.J. Salinger, S.-W. Wang, Observed Climate Variability and Change, in Climate Change 2001: The Scientific Basis, edited by J.T. Houghton et al., pp. 99–181, Cambridge Univ. Press, New York, 2001.



These reconstructions are made for the northern hemisphere where it is believed that the “medieval warm period” was more intense.

Also preliminary evidence from Briffa and Osborn (2001) from tree ring density data, in “Low-frequency Temperature Variations from a Northern Tree-ring Density Network" on the Journal of Geophysical Research Atmospheres suggests that 20th century may be the warmest period since the past two millennia. ( http://www.agu.org/pubs/crossref/2001/2 ... 0617.shtml )

Also according to Mann climate model simulations employing estimates of natural and anthropogenic radiative forcing changes [Crowley, 2000; Gerber et al, 2003; Bertrand et al, 2002; Bauer et al, 2003] agree well, for the most part, with the proxy-based reconstructions (based on tree rings, corals, ice cores and lake sediments etc…). The simulations, furthermore, show that it is not possible to explain the anomalous late 20th century warmth without the contribution from anthropogenic forcing factors [e.g., Crowley, 2000].


References for the models:

Crowley, T.J., Causes of Climate Change over the Past 1000 Years, Science, 289, 270-277, 2000. ( http://www.geos.ed.ac.uk/homes/tcrowley ... ce2000.pdf )

Gerber, S., F. Joos, P. Brügger, T. F. Stocker, M. E. Mann, S. Sitch, and M. Scholze, Constraining temperature variations over the last millennium by comparing simulated and observed atmospheric CO2, Climate Dynamics, 20, 281-299, 2003. ( http://www.meteo.psu.edu/~mann/shared/a ... mDyn03.pdf )

Bertrand C., M.F. Loutre, M. Crucifix, A. Berger, Climate of the Last millennium: a sensititvity study. Tellus, 54(A), 221-244, 2002. ( http://onlinelibrary.wiley.com/doi/10.1 ... 0287.x/pdf )

Bauer, E., M. Claussen, and V. Brovkin, Assessing climate forcings of the earth system for the past millennium, Geophysical Research Letters, 30 (6), doi: 10.1029/2002GL016639, 2003. ( http://www.mpimet.mpg.de/fileadmin/staf ... grl_03.pdf )



Figure from Michael E. Mann et al. “On Past Temperatures and Anomalous late-20th Century Warmth” All series are shown with respect to the 1961-90 base period.

[img][800:899]http://i367.photobucket.com/albums/oo119/MaxPower555/mann.jpg[/img]



Also there is another important article by Michael Mann. His widely cited article called “Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly” in Science Magazine in 2009, Michael E. Mann et al. ( http://www.sciencemag.org/cgi/content/a ... /5957/1256 ) try to study the spatial patterns of global temperatures over the past 1500 years. They use a global climate proxy network to reconstruct the surface temperature patterns over this interval. Their conclusion is that the medieval period is found to display warmth that matches or exceeds that of the past decade in some regions, but which falls well below recent levels globally.

Wedge, how much of a percentage change is the average temperature of the Earth undergoing in terms of the Kelvin scale?

'Keet, the Kelvin scale is in the same increments as the centigrade scale: 2-5 degrees C = 2-5 degrees K. The difference is that K starts at -273.15C, and C starts at 273.15K. If you want to look at a percentage change, you'll have to start with a normal range and the normal range is going to have the same spread regardless of whether it's in C or K.

Yes, the Kelvin scale has the exact same increments as the Celsius scale, however when considering amount of change in comparison to a numerical value considering the smaller default value ensues a larger percentage alteration and vice versa. Consider that the average temperature of the Earth is 288 Kelvin or 15° Celsius. If there were a 5 degree plus or minus change, then on the Kelvin scale the numerical range is 283 to 293 but on the Celsius scale the numerical range would be 10° to 20°.

...ten degrees vs. ten degrees. The mathematical difference is identical; trying to make a distinction here is meaningless.

In regard to the physical universe, such is identical. However, when presenting data to an audience, it makes a lot of difference in rhetorical terms. What are the methods of data presentation utilized by proponents of what is now labeled "climate change" (and was previously "global warming" and prior to that "global cooling")? Do you consider their methods of presentation to be honest?

Actually, no. There is a mathematical difference by far. A range of 10 degrees on the Celsius scale whereby the average temperature of the Earth is 15°, i.e. 10° to 20° is much larger in terms of numerical percentage of difference with respect to the numerical value of the mean temperature in Celsius as compared to the mean temperature in Kelvin (288 K). Increasing from 15 to 20 is a percentage difference of (20-15)/15 = 0.33... = 33%, whereas increasing from 288 to 293 is a percentage difference of (293-288)/288 = 0.017 = 1.7%

If you look a few posts back, someone was talking about establishing a normal range before doing percentage calculations. Because of the different zero points in C and K, you would have to do something like this, otherwise percentages would be meaningless.

Whatever flaws there may be in climate science and whatever mistakes they might have made, you can be sure they weren't that dumb.

By no means am I claiming that they are dumb, rather that they can be crafty. Such as in the development of graphs. Notice the increments on graphs for change in average temperature have to be very fine. If you were to plot it out full-scale with absolute zero being the y-axis orgin, then you'd need a magnifier in order to not see a nearly flat line.