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Arctic sea ice melt - natural or man-made?

Posted on 9 June 2008 by John Cook

Arctic sea ice has declined steadily since the 1970s. However, the 2007 summer saw a dramatic drop in sea ice extent, smashing the previous record minimum set in 2005 by 20%. This has been widely cited as proof of global warming. However, a popular mantra by climatologists is not to read too much into short term fluctuations - climate change is more concerned with long term trends. So how much of Arctic melt is due to natural variability and how much was a result of global warming?

The long term trend in Arctic sea ice

Global warming affects Arctic sea ice in various ways. Warming air temperatures have been observed over the past 3 decades by drifting buoys and radiometer satellites (Rigor 2000, Comiso 2003). Downward longwave radiation has increased, as expected when air temperature, water vapor and cloudiness increases (Francis 2006). More ocean heat is being transported into Arctic waters (Shimada 2006).

As sea ice melts, positive feedbacks enhance the rate of sea ice loss. Positive ice-albedo feedback has become a dominant factor since the mid-to-late 1990s (Perovich 2007). Older perennial ice is thicker and more likely to survive the summer melt season. It reflects more sunlight and transmits less solar radiation to the ocean. Satellite measurements have found over the past 3 decades, the amount of perennial sea ice has been steadily declining (Nghiem 2007). Consequently, the mean thickness of ice over the Arctic Ocean has thinned from 2.6 meters in March 1987 to 2.0 meters in 2007 (Stroeve 2008).

 

Global warming has a clearly observed, long term effect on Arctic sea ice. In fact, although climate models predict that Arctic sea ice will decline in response to greenhouse gas increases, the current pace of retreat at the end of the melt season is exceeding the models’ forecasts by around a factor of 3 (Stroeve 2007).

 


Figure 1: September Arctic Sea Ice Extent (thin, light blue) with long term trend (thick, dark blue). Sea ice extent is defined as the surface area enclosed by the sea ice edge (where sea ice concentration falls below 15%).

What caused the dramatic ice loss in 2007?

The sudden drop in sea ice extent in 2007 exceeded most expectations. The summer sea ice extent was 40% below 1980's levels and 20% below the previous record minimum set in 2005. The major factor in the 2007 melt was anomalous weather conditions.

An anticyclonic pattern formed in early June 2007 over the central Arctic Ocean, persisting for 3 months (Gascard 2008). This was coupled with low pressures over central and western Siberia. Persistent southerly winds between the high and low pressure centers gave rise to warmer air temperatures north of Siberia that promoted melt. The wind also transported ice away from the Siberian coast.

In addition, skies under the anticyclone were predominantly clear. The reduced cloudiness meant more than usual sunlight reached the sea ice, fostering strong sea ice melt (Kay 2008).

Both the wind patterns and reduced cloudliness were anomalies but not unprecedented. Similar patterns occurred in 1987 and 1977. However, past occurances didn't have the same dramatic effect as in 2007. The reason for the severe ice loss in 2007 was because the ice pack had suffered two decades of thinning and area reduction, making the sea ice more vulnerable to current weather conditions (Nghiem 2007).

Conclusion

Recent discussion about ocean cycles have focused on how internal variability can slow down global warming. The 2007 Arctic melt is a sobering example of the impact when internal variability enhances the long term global warming trend.

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Comments 101 to 150 out of 529:

  1. Shawnet, re: "Since there is the same amount of CO2 in the SH as the NH, CO2 cant explain the state of the cryosphere in toto." O.K., but nobody says that CO2 can explain the state of the cryosphere in toto! Two points: (A) As well as CO2, there are the other man-made greenhouse gases (methane, nitrous oxides, CFC's, tropospheric ozone), there are man-made aerosols, there are variations in solar outputs, volcanic eruptions.... (B) One then has to consider how various wind and ocean currents distribute thermal energy around the world. The net thermal imbalance (that gives us global-scale warming or cooling) is a summation of all of (A): -CO2 dominates -other greenhouse gases make a significant contribution -aerosols are nett cooling -solar variation has made no significant contribution since the late 50's (perhaps a slight cooling one overall) -volcanic eruptions make sporadic cooling "pulses" etc. (the numbers for many of these contributions are in the Ramanathan and Carmichael paper leebert cited - see posts #39/#48) So global warming IS largely about greenhouse gases, the full effects of which are attenuated by our aerosol emissions. (B) relates to the manner in which this excess thermal energy is distributed around the world. It doesn't depend on the location of CO2, and the fact that the CO2 concentrations are the same in the Nrthn. and Srthn. hemisphere, is a red-herring with respect to the distribution of thermal energy (excess heat) measured at the Earth's surface. After all, land warms faster than the oceans since the oceans provide a massive sink which buffers surface warming. So obviously the Nrthn. hemisphere warms faster than the Srthn. Major ocean currents carry heat from the low latitudes to the high Nrthn latitudes (Arctic!), whereas ocean currents in the deep Srthn. hemisphere "insulate" the Antarctic from heat absorbed in the low latitudes….. That's all pretty well understood (see post #66). Since the time of detailed satellite observation the Antarctic sea ice hasn't changed very much at all: a small trend of around +12,000 km2 per year for the summer sea ice extent: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.south.jpg ...whereas during the same period, the Arctic summer sea ice trend is around -85,000 km2 per year (more like -131,000 km2 per year since 2000-ish). http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.jpg Note that the data presented at the site you linked to in post #59 is a little bit misleading, since, first, it's considering only a single year, secondly it gives the sea ice extent at one particular snapshot in time (Jan 31st 2008!), and thirdly it doesn't really compare like with like. For example the concern is for SUMMER ice extent since this is the period in which solar irradiation directly affects surface warming through albedo effects from sea ice melting (and black carbon too!). Thus it's more appropriate to compare sea ice extent in late summer in the Arctic (Aug-Sept) with sea ice extent in late summer in the Antarctic (Feb-March). Note btw, that the Antarctic sea ice extent was apparently larger in the period 1900-1960 than now[*], so it too has undergone some attenuation, but in the last 20-ish years it's been pretty steady. But that's not unexpected given our understanding of the manner in which thermal energy from low latitudes distributes to higher latitudes. [*] N. A. Rayner et al. (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century; Journal Of Geophysical Research, 108, NO. D14, 4407.
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  2. Philippe Thank you, I am quite pleased that you recognized my complaint. Just because I am retired does not mean that I have time on my hands, albeit more than I had as an engineer. In an agrarian community winters are slow but this is planting and pest control season. If you are interested I have posts with links under the volcano thread. While vulcanism is still discounted by many scientists, more is discovered every day, and if Dr. Fairbridge was correct in his solar hypothesis, more evidence will be found soon, thanks to modern satellites. The most recent two are in the south Pacific.
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  3. p.s. Nothing about this planet is well understood, despite claims to the contrary. Our young scientists have much to learn.
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  4. Your condescending tone was ill-used against me, I did not direct anything of the sort a you. You bring us back to a previously discussed point: why is it that Fairbridge "hypothesis" has not been thoroughly investigated by planetary and solar scentists? As for your post #103, it's your opinion. Everybody has one. Many of these scientists are as old or older than you. It now sounds like you're being condescending toward an entire scientific and academic community.
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  5. Philippe Sorry, I was under the impression that you understood the sarcasm. My issue is back to a previously discussed point: why is it that Fairbridge "hypothesis" has not been thoroughly investigated by planetary and solar scentists?
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  6. And yes Philippe, I have very little respect for the post JFK education standards in the U.S. with the "no one left behind" concept used to reduce the passing average to the lowest common denominator. On the other hand I have the greatest respect for those who have overcome this handicap.
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  7. "Resonant interactions between solar activity and climate" Tobias, S.M.; Weiss, N.O. Journal of Climate. Vol. 13, no. 21, pp. 3745-3759. Nov. 2000 Solar magnetic activity exhibits chaotically modulated cycles with a mean period of 11 yr, which are responsible for slight variations in solar luminosity and modulation of the solar wind, while the earth’s atmosphere and oceans support oscillations with many different frequencies. Although there are several mechanisms that might couple solar variability with climate, there is, as yet, no compelling evidence that a direct forcing is sufficiently effective to drive climatic change. In many nonlinear systems resonant coupling allows weak forcing to have a dramatic effect. An idealized model is considered, in which the solar dynamo and the climate are represented by low-order systems, each of which in isolation supports chaotic oscillations. The climate is represented by the Lorenz equations: solutions oscillate about either of two fixed points, representing warm and cold states, flipping sporadically between them. The effect of a weak nonlinear input from the dynamo to the climate that tends to push it toward the warm state is computed. This input has a significant effect when the ‘typical frequencies’ of each system are in resonance. The solution is now asymmetric, with the warm state preferred. The degree of asymmetry is less than might be anticipated, because resonant forcing extends the duration of oscillations about either state, and so increases the timescale for flipping. The presence of grand minima in the solar output leads to complicated intermittent behaviour in the climate. Consequently, the results of frequency analysis are sensitive to the duration of time series that is used. It is clear that the resonance provides a powerful mechanism for amplifying climate forcing by solar activity. Surface warming by the solar cycle as revealed by the composite mean difference projection Charles D. Camp and Ka Kit Tung Received 29 March 2007; revised 15 May 2007; accepted 14 June 2007; published 18 July 2007. Geophys. Res. Lett., 34, L14703, doi:10.1029/2007GL030207. ABSTRACT [1] By projecting surface temperature data (1959?2004) onto the spatial structure obtained objectively from the composite mean difference between solar max and solar min years, we obtain a global warming signal of almost 0.2_K attributable to the 11-year solar cycle. The statistical significance of such a globally coherent solar response at the surface is established for the first time. Citation: Camp, C. D., and K. K. Tung (2007), Surface warming by the solar cycle as revealed by the composite mean difference projection, Geophys. Res. Lett., 34, L14703, doi:10.1029/2007GL030207. Conclusion [11] We propose that spatial information be used to filter the surface-temperature data to obtain a cleaner solar-cycle response. At the global scales, an objectively determined spatial filter can be constructed using the composite difference between the solar-max years and the solar-min years. This filter effectively removes the shorter interannual variations, such as from ENSO. We obtained a globally averaged warming of almost 0.2_K during solar max as compared to solar min, somewhat larger than previously reported. More importantly, we have established that the global-temperature response to the solar cycle is statistically significant at over 95% confidence level. The spatial pattern of the warming is also of interest, and shows the polar amplification expected also for the greenhouse-warming problem. The method used here, the CMD Projection, is one of two methods we have tried that take advantage of the spatial information, the other method being the LDA method. Although not as optimal as the LDA method, the CMD Projection possesses most of the advantages of the former while being much simpler to understand and implement. As it turns out, the spatial patterns deduced by the two different methods are very close to each other. However, the LDA method yields a more accurate estimate of the solar-cycle response in the sense that its error bar is only half as large. [12] We will argue in a separate paper that the observed warming is caused mostly by the radiative heating (TSI minus the 15% absorbed by ozone in the stratosphere), when taking into account the positive climate feedbacks (a factor of 2?3) also expected for the greenhouse warming problem. Solar-Cycle Warming at the Earth?s Surface and an Observational Determination of Climate Sensitivity. By Ka-Kit Tung and Charles D. Camp Department of Applied Mathematics, University of Washington, Seattle Washington, USA Journal of Geophysical Research, submitted. ABSTRACT The total solar irradiance (TSI) has been measured by orbiting satellites since 1978 to vary on an 11-year cycle by about 0.07%. From solar min to solar max, the TSI reaching the earth?s surface increases at a rate comparable to the radiative heating due to a 1% per year increase in greenhouse gases, and will probably add, during the next five to six years in the advancing phase of Solar Cycle 24, almost 0.2 ?K to the globally-averaged temperature, thus doubling the amount of transient global warming expected from greenhouse warming alone. Deducing the resulting pattern of warming at the earth?s surface promises insights into how our climate reacts to known radiative forcing, and yields an independent measure of climate sensitivity based on instrumental records. This model-independent, observationally-obtained climate sensitivity is equivalent to a global double-CO2 warming of 2.3 -4.1 ?K at equilibrium, at 95% confidence level. The problem of solar-cycle response is interesting in its own right, for it is one of the rare natural global phenomena that have not yet been successfully explained. 7. Conclusion Using NCEP reanalysis data that span four and a half solar cycles, we have obtained the spatial pattern over the globe which best separates the solar-max years from the solar-min years, and established that this coherent global pattern is statistically significant using a Monte-Carlo test. The pattern shows a global warming of the Earth?s surface of about 0.2 ?K, with larger warming over the polar regions than over the tropics, and larger over continents than over the oceans. It is also established that the global warming of the surface is related to the 11-year solar cycle, in particular to its TSI, at over 95% confidence level. Since the solar-forcing variability has been measured by satellites, we therefore now know both the forcing and the response (assuming cause and effect). This information is then used to deduce the climate sensitivity. Since the equilibrium response should be larger than the periodic response measured, the periodic solar-cycle response measurements yields a lower bound on the equilibrium climate sensitivity that is equivalent to a global warming of 2.3 ?K at doubled CO2. A 95% confidence interval is estimated to be 2.3-4.1 ?K. This range is established independent of models. 11-Year solar cycle in the stratosphere extracted by the empirical mode decomposition method K.T. Coughlin, K.K. Tung University of Washington, Box 352420, Seattle, WA 98195, USA Received 19 October 2002; received in revised form 26 February 2003; accepted 26 February 2003 Advances in Space Research 34 (2004) 323?329 Abstract We apply a novel method to extract the solar cycle signal from stratospheric data. An alternative to traditional analysis is a nonlinear empirical mode decomposition (EMD) method. This method is adaptive and therefore highly efficient at identifying embedded structures, even those with small amplitudes. Using this analysis, the geopotential height in the Northern Hemisphere can be completely decomposed into five non-stationary temporal modes including an annual cycle, a QBO signal, an ENSO-like mode, a solar cycle signal and a trend. High correlations with the sunspot cycle unambiguously establish that the fourth mode is an 11-year solar cycle signal. 5. Conclusion A clear solar cycle signal is observed in the 30 mb geopotential height using the nonlinear, non-stationary EMD method. The total geopotential height at 30 mb is spatially averaged over all longitudes and from 20N to 90N. No specific grouping of the data is used in this analysis. The entire timeseries is completely decomposed into five modes and a trend. Using a Monte-Carlo simulation, the power in each mode is compared to the power in 500 decompositions of random noise. The fourth mode is found to have an average power far above the noise level and therefore is a significant signal. The correlation between this signal and the solar cycle proxy is 0.70 which is also significant given our estimation of the degrees of freedom in the mode. Using a regression with AR errors, the significance of the correlation is verified. The result is both a statistically and visually convincing solar cycle signal in the total 30 mb geopotential height. Further analysis at lower levels and with latitudinal variations will be presented in our forthcoming paper.
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  8. As for evidence of increased vulcanism that are causing hot spots and more active El Ninos, etc. Surprisingly Rapid Changes In Earth’s Core Discovered - ScienceDaily (June 20, 2008) — The movements in the liquid part of the Earth’s core are changing surprisingly quickly, and this affects the Earth’s magnetic field, according to new research from DTU Space. Olsen et al. Rapidly changing flows in the Earth's core (I have posted the abstract in the volcano thread).
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  9. Phillippe, my apologies, I think I was looking at 2000 not 2001 or 2002, your graph makes it pretty clear that the sea ice seems to be heading for another low year(though I am not sure that the spring melt is all that atypical). chris, "O.K., but nobody says that CO2 can explain the state of the cryosphere in toto! Two points: (A) As well as CO2, there are the other man-made greenhouse gases (methane, nitrous oxides, CFC's, tropospheric ozone), there are man-made aerosols, there are variations in solar outputs, volcanic eruptions.... (B) One then has to consider how various wind and ocean currents distribute thermal energy around the world. The net thermal imbalance (that gives us global-scale warming or cooling) is a summation of all of (A): " But that is essentially my point, if regional climates can be influenced by something besides the net thermal imbalance, then answering (a), as you did above is premature at best unless all you are saying is that the slight temperature increase of the last couple decades has had an impact of the sea ice(something that probably no one disagrees with). You seemed to suggest that one can explain the recent trend solely in terms of CO2. I'll accept your numbers for the SH ice extent from the beginning of satellite measurement (I don't have the inclination to try to read the graphs that closely), but just eyeballing the numbers since 2000 does give an overall increase in the SH summer ice extent as around +1 million, which puts the most recent trend in the same ballpark magnitude (though of opposite sign) as trend in summer sea ice in the NH(even higher if you start it earlier). Given a cyclically changing climate(like the one we have) one can prove pretty much any point one wants to by selectively choosing one's starting point. My point is that the recent(ie the last 10 yrs) changes in *global* sea ice can't be explained by CO2. Cheers, :)
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  10. What about this statement from BRET STEPHENS piece in WSJ published on July 1st? "The Arctic ice cap may be thinning, but the extent of Antarctic sea ice has been expanding for years." Is this true, if so how does that support global warming? http://online.wsj.com/article/SB121486841811817591.html?mod=fpa_mostpop
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  11. What about this statement from BRET STEPHENS piece in WSJ published on July 1st? "The Arctic ice cap may be thinning, but the extent of Antarctic sea ice has been expanding for years." Is this true, if so how does that support global warming? http://online.wsj.com/article/SB121486841811817591.html?mod=fpa_mostpop
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  12. What about this statement from BRET STEPHENS piece in WSJ published on July 1st? "The Arctic ice cap may be thinning, but the extent of Antarctic sea ice has been expanding for years." Is this true, if so how does that support global warming? http://online.wsj.com/article/SB121486841811817591.html?mod=fpa_mostpop
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  13. What about this statement from BRET STEPHENS piece in WSJ published on July 1st? "The Arctic ice cap may be thinning, but the extent of Antarctic sea ice has been expanding for years." Is this true, if so how does that support global warming? http://online.wsj.com/article/SB121486841811817591.html?mod=fpa_mostpop
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  14. Granted, I have not read all of the comments at this posting, but I have read many of them, and I keep seeing ones that say the world is experiencing unusual warming. Professor Syun-Ichi Akasfu, who studies sea ice and weather, makes a compelling case using peer-reviewed articles that any warming we have seen in recent times is in line with warming that we would expect to see as we recover from the Little Ice Age. Would someone who is prophesier of catastrophic global warming please comment on the case he makes. A paper that he wrote on the subject is "Is the Earth still recovering from the 'Little Ice Age'? : A possible cause of global warming." As for me I don't believe in the catastrophic claims at all. I believe it's all fear-mongering, led by people and groups with political and financial ends in mind or by those who jump on bandwagons without sufficient evidence or who simply scare easily. The fact that the recent temperature measurements of the oceans show them to be cooling slightly in recent years, not heating up, is just one of many reasons that I don't believe this is true, along with the fact that the warmest decade of the last century was the 1930s and the fact that before temperatures stopped rising in about 2003, the world had just hit its 3,000-year average temperature. I also find it a bit amusing that at an earlier posting at this site, the authors go to lots of trouble to show that increased ice creation in the Antarctic is a regional anomaly, while at this posting they want us to believe that ice melting in the Arctic is not a regional anomaly. Again, someone please read the professor paper and comment on the whole argument and all of his proof; don't just try to key on some little nuance so that you can ignore the big picture. Thank you and have a great and hopefully warm day! Here in Wisconsin, we are finally experiencing some summer-like temperatures.
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    Response: The various points you make are covered at the following pages: Obviously increasing Antarctic sea ice is a regional anomaly because the Southern Ocean is warming faster than the rest of the oceans of the world. As for Arctic sea ice, the article on this page makes the point that the recent dramatic drop in sea ice was also a regional anomaly - superimposed on the long term trend of falling sea ice. There's your big picture.
  15. Somewhat belated: Antarctic sea ice: http://psc.apl.washington.edu/zhang/Pubs/Zhang_Antarctic_20-11-2515.pdf From the Abstract: "The model shows that an increase in surface air temperature and downward longwave radiation results in an increase in the upper-ocean temperature and a decrease in sea ice growth, leading to a decrease in salt rejection from ice, in the upper-ocean salinity, and in the upper-ocean density. The reduced salt rejection and upper-ocean density and the enhanced thermohaline stratification tend to suppress convective overturning, leading to a decrease in the upward ocean heat transport and the ocean heat flux available to melt sea ice. The ice melting from ocean heat flux decreases faster than the ice growth does in the weakly stratified Southern Ocean, leading to an increase in the net ice production and hence an increase in ice mass. This mechanism is the main reason why the Antarctic sea ice has increased in spite of warming conditions both above and below during the period 1979–2004 and the extended period 1948–2004." In other words, a less dense surface layer reduces heat convection from below, which outweighs the increased warming from above. I little known fact: satellite observations began in 1972/1973 for the Arctic/Antarctic. But they aren't as sophisticated as subsequent measurements, and there is a gap in from 1976 to 1978 which is filled with more conventional observational data. However, the recent increase in SH sea ice doesn't match what it was in the early '70s, and there is proxy data showing a large loss starting mid century, but that is disputed. SH Sea Ice: http://cce.890m.com/changes/images/sh-extent.jpg The global trend is clearly down: http://cce.890m.com/changes/images/global-extent.jpg Also, kurt, the '30s were not warmer than current temperatures. In the US, they were similar to today, but global temperatures in the '30s were nowhere close to what they are presently.
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  16. TruthSeeker: You can read some more about Antarctic and GW here: http://www.realclimate.org/index.php/archives/2008/02/antarctica-is-cold
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  17. cce Without the current system in place in the 1930s, and the poor measurement of most of the globes temperatures, exactly how do you know 1934 was actually not globally hot. Where were the reading points? Did they measure ambient temp from every point using the same or comparable instruments? This is one of the most imprecise sciences there is and eveyone acts as if its absolute fact. Unbelieveable!
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  18. Quietman, The coverage and precision is more than adequate to establish with statistical certainty that the '30s was colder than recent temperatures. GISTEMP, for example, calculates that the last decade was 0.4 to 0.5 degrees warmer which is significant given that the uncertainty is between 0.1 and 0.2 degree. "We just don't know anything" is a discredit to the work of a lot of people. Even if you don't accept that, there is certainly more evidence that it is warmer today, yet we have people going around talking about "the fact that the warmest decade of the last century was the '30s" which isn't even true for the US.
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  19. cce I agree that in areas where temperatures were actually measured in the U.S. and it's advanced allies that what you say is true. I disagree that this is true for most points outside of the U.S. and it's allies. And since this climate change is considered "climate shift" by many scientists rather than global warming, I feel that it is a point of critical contention. In the part of the world I live in GW does not exist and in fact the reverse has been the rule for many years. It only seems to exist in the nearby large cities and at the north polar cap. So when you say that the entire world is warming it certainly can not be confirmed by most people living in totally unaffected areas that nobady seems to take into account. Measurements taken from orbit appear to be much more accurate than those taken from the ground or at sea level. This data does not exist from the 1930s and therefore the incidence of error is higher than claimed.
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  20. 93~ On 'Vulcanism' (or the heat component derived from earth core processes) Science 30 March 2007: Vol. 315. no. 5820, pp. 1813 - 1817 DOI: 10.1126/science.1137867 Research Articles Seismostratigraphy and Thermal Structure of Earth's Core-Mantle Boundary Region R. D. van der Hilst,1* M. V. de Hoop,2 P. Wang,1 S.-H. Shim,1 P. Ma,3 L. Tenorio4 Abstract: "Accounting for a factor-of-two uncertainty in thermal conductivity, core heat flux is 80 to 160 milliwatts per square meter (mW m–2) into the coldest D'' region and 35 to 70 mW m–2 away from it. Combined with estimates from the central Pacific, this suggests a global average of 50 to 100 mW m–2 and a total heat loss of 7.5 to 15 terawatts." The estimated total energy consumption of mankind this year is 14 terawatts...the estimated energy released from the earth core is 7.5 -15 terawatts. This energy is expressed in several ways, only one of which is volcanic eruptions, ALL of which affect climate. Not an insubstantial factor in the process.
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  21. Quietman, The rate of warming by the two major satellite analyses differ by about 20% since 1979. In fact, they bracket HadCRUT and GISTEMP -- RSS shows more, UAH shows less. It is simply not true that they are more accurate than the surface records. Maybe one is, but not both. And it's not UAH. Regardless of which you use, warming is more or less consistent: http://cce.890m.com/giss-vs-all.jpg It is hard to believe that the surface record became reliable at the instant the satellies came online. Obviously, the further back in time you go, the worse the coverage, but you have to show large systematic bias in one direction for the instrumental record to be so far off as to make us question whether the '30s/'40s were warmer than the present. The recent "mid century cooling" problem was discovered by comparing SST to meteorological records, which are indepedent of one another. There was no inconsistency found in the 30's, and the problems in the '40s was with the SST, not the land based measurements. You aren't going to find >0.4 degrees of hidden warmth in the '30s and '40s to somehow make those temperatures equivalent to modern temps.
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  22. cce No argument here, you just proved my point. We don't know how much it has actually warmed. We do know that it has been warming erratically for the last 5 million years, each max high just a bit more than the previous max high but the max low quite a bit warmer than the previous max low. It's the long return from an ice age (not the last glacation but the entire 4th ice age). Just look at a 5 million year climate graph.
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  23. Mizimi Interesting paper, thanks.
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  24. The premise that it was warmer globally in the 30s is not sound. For one thing if the sceptics argue that measuring devices are not considered accurate today then they must have been much less accurate in the 30s in the USA. Instead of worrying about temperature measurements let's look at the evidence instead, such as the dramatic widespread melting of arctic ice and the speeding up of glaciers. This rapid melting did not happen in the 30s because the heating was restricted to minor parts of the planet, like the USA. Recent data confirms the rapid increase in melting.
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  25. Quietman, No, I did not prove your point. Your point is that we "don't know" that it is warmer now than in the '30s. We do know. The amount of warming is bounded by uncertainty, and even with that uncertainty we know that it is warmer. Ocean temps, thermometers, sea level, etc. They all indicate that it is warmer now. And it is not the "long return" from an ice age. Those influences require thousands of years, and are not relevent to temps in the '30s compared to now.
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  26. cce Re: "And it is not the "long return" from an ice age. Those influences require thousands of years, and are not relevent to temps in the '30s compared to now." Apples and Oranges. Not thousands but millions (yes the earth is older than 6000 years) regardless of your bible. We do not have accurate measurements for the 30s. That you can argue until you are blue in the face but its a fact. I worked with state of the art measuring equipment in the 1980s and it was inaccurate compared to the equipment we used in the 1990s but you want me to believe 1930s equipment was better? Got a bridge to sell to?
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  27. to s/b too
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  28. cce Regardless of how accurate the measurements were the warming did occur. That is not and never has been my argument. My argument is that it is not CO2 induced AGW. The exact amount is irrelevant.
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  29. sandy winder Re: "Recent data confirms the rapid increase in melting." Yes it does indeed but the temps have lowered, proving that the melting is internal and nothing to do with GHG.
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  30. So let me get this straight,if the data shows that temps in the 30s were hotter than now, the data is accurate, but if on further review the data shows that the 30s weren't hotter than now,the data isn't accurate? Heads I win, tails you lose.
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  31. Lee Grable The entire issue is somewhat irrelevant. U.S. records show that 1934 eas the hottest year and that the 30s were all warmer than normal. At that time many parts of the world did not even measure temps so the argument for global temp is moot. The level of accuracy compared to today was terrible and it's still not all that great. But we can't ignore that fact that the polar ice has melted to an unusual degree and glaciers are generally in recession so we need to face the fact that parts of the earth are warming. What is needed now is to determine the actual cause and if it is curable. I don't think CO2 is the cause but humans may still be partly at fault through other pollutants such as fertilizers. But we can not say that we know for sure what the cause is and should not stop looking. I still feel that there is much more forcing from the earth itself than some are willing to credit.
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  32. If the issue is irrelevant, why bring it up?
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  33. Accelerated polar melt is a precursor to Gulf Stream slowdown as the planets puts into place a simple cause and effect failsafe cooling with time as a constraint mechanism. As it strives too maintain its global ambient temperature An organism that dwells in hostile space environments needs survival contingences, it’s responding to a perceived threat, man made or not. It’s ironic that at a time we begin to understand the limits of the known universe, we fail to appreciate the limits of the very planet we depend on for the continued survival of all dependent species We must not discount the planets ability at radical simpatico adaptation; however we should not second guess a far more superior system which has survived for eons in hostile space environments. The part we play may be minuscule in comparison, but misguided in the extreme. We’ve rushed at the wheel for control, only to find there is no driver; there never was, the planet sets the course and it always will. A global sustainable future for our species is like asking a chain smoker to self prescribe a remedy that doesn't involve kicking the habit. This is why we procrastinate on global climate change This why we renege on global warming mitigation We are hooked on fossil fuel Usage That chronological innovative fossil fuel use has driven us to where we are The majority of Large-scale oil dependent economies have a foot placed firmly on a pedal that over time has become frozen into an accelerated position. And this is why I fear for our future and that of the planet. Because the first step towards recovery, is to seek professional help We have none to help us, but ourselves. It will take a groundswell of global affirmative action and Unparalleled agreement by dynamically opposed governments in the Short-term, for the long-term mitigation of radical global climate change.
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  34. Lee Grable Actually I did not bring it up, comment 115 did. This thread is about last summer's polar melt.
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  35. Quietman,Kurt in post 114 brought it up. But my point still stands. This is part of the pattern that I've seen from the skeptic side over the last few years,that the small amount of data you use to support your arguements is accurate,and to be relied on, but when more data is added that debunks your arguement, all of a sudden the data isn't accurate. It happens over and over again. And when push comes to shove, you skeptics,( and I'm not talking about you personally) resort to flat out lying and falsifying information to advance your arguement. An example of what I'm talking about is what led me to this website in the first place. I Was over at the petition project website, reading their "peer reviewed" report debunking the MMGW consensus,in the report, they showed a graph comparing solar activity with global temps over the last century. Of course, the graph showed a direct corelation between the two. And I thought, if this is true it would raise serious doubts about whether greenhouse gasses were the cause of the warming we've seen. So I google searched, and found this website. In the "it's the sun" thread, there was an identical graph showing that solar activity has basically flattened out since the 70's, while global temps rose to the levels were seeing now. The other differance between the two graphs is that the PP graph offered no references to the data represented on the graph, while the graph here clearly showed where the data came from. That's another pattern I've noticed.Now if I have to choose who to believe, I'm going to lean toward those who use referenced data over those who don't.
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  36. Lee Grable Actually I am not willing to concede the point of accuracy, it's just not very important to this discussion. We have already beaten this one to death on another thread. If you look at Johns "view all arguments" you will see this is a large site and John has asked everyone to keep the subject matter relevant to the thread. I am trying to comply to his wishes. As far as the solar graphs, see "Its the sun", we have not quite beaten that one to death yet. The last thread on temp measurements was "A new twist on mid-century cooling" and I think it's still active as well.
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  37. Lee PS As far as this thread goes I am in agreement with John that Kay's paper does explain the melt as natural but the thinning of the ice from prior years made it worse. I only disagree that it was CO2 that was the cause. My reasons are explained in part in the above comments and in other threads, such as "It's Volcanos".
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  38. CCE, Your reply made sence, thanks. This topic of discussion focuses mostly on Sea Ice. If global warming is occuring, can sea ice really identify if the cause is natural or man made?
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  39. Good question TruthSeeker. However, the "if" GW is occurring, I find rather funny. The melt is in itself indication that is is occurring and fast. To get somewhat back on topic, it's worth looking at the latest NSIDC graph, showing extent getting every day closer to last year's staggering low. The overall slope for August is interesting compared to last year. So is the fact that no inflexion has started yet. http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png
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  40. Philippe, In #38 you said "Black carbon is nonetheless anthropogenic." Not completely... there are significant natural sources.
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  41. Almost play on words. Thanks for the reminder but stay healthy. Pointers?
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  42. A year or so ago I watched an interview with a climatologist. (can't recall the name) He stated that the long term effect of Artic ice melt will actually result in a reversal or a balancing. His reasoning was that the melt would increase moisture in the Arctic and result in large cloudy regions with increased snowfall. This would build snow/ice fields, these in turn would act as reflectors resulting in a counter-balance and mitigate the ice melt.. This appears to make some logical sense to me because the Artic at present is considered a desert region due to the very low precipitation levels. Increased precipitation levels would therefore alter that standard and possibly have positive results that might not be foreseen at present.----Your thoughts please!
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  43. Andy Bryski Because of the predominant air currents the increased snow falls in asia (last winter was a good example). This was mentioned in a paper by Mackey last summer.
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  44. Quietman, It is not the "long return from an ice age" over any time period. It's not apples and oranges. You are talking apples and aliens from outer space. The "erratic" temperature changes over the last 5 million years have nothing to do with the temperatures of the 1930s versus today. The data we have from the '30s is accurate enough to establish that it is warmer now. Land based measurements tell us it is warmer now. Ocean base measurements tell us it is warmer now. Tide guages tell us it is warmer now. Simultaneous glacial melting in every region tells us this. It is a fact, established from independent lines of evidence that it is warmer now than in the '30s. No one is saying that measurements in the '30s are better than they are now. I'm interested in how anyone could come up with such a characterization based on anything written in this thread. And 1934 is not the warmest year on record in the US. It is statistically tied with 1998 for that record.
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  45. cce>> Tide guages tell us it is warmer now. Not according to Dr. Nils-Axel Mörner. http://www.publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/12we18.htm
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  46. cce Sorry to disagree but it has everything to do with it. The cause of these oscillations is the same thing that we are now experiencing. If CO2 were a strong GHG you would not be alive to ponder the question because the Earth would be another Venus right now. Your argument has as much logic as the creationist or the I.D. proponents. That is why skeptics consider AGW alarmism to be a religion, there is a hypothesis but blind faith in a hypothesis simply is not logical.
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  47. Quietman, who are you to "concede the point of accuracy"? Lies are Lies. Period!! Your side LIES.Period!! It's importent to every disscusion on global warming. Period!!! I find your 'arguement' to be more of the same denialist claptrap junk that I've seen everywhere that this subject is discussed. Period!!
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  48. One side KNOWINGLY LIES,(the skeptic side), one side doesn't,(the science side).Who do you believe? Quietman?
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  49. As far as the solar graphs, look at the solar graphs ON THIS WEBSITE!! It's been layed to rest. You continually prove my point. You concider the very few facts that don't support the MMGW are valid, and yet you concider that the vast majority of facts that prove that MMGW are valid are'nt. The very despription of blind faith. And if John feels that I'm violating some sacred comment board rule, then let him speak up. You don't have any say.
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  50. Lee Grable I do not have a "side", th4e sides are alarmists and deniers and I am neither. And what do solar graphs say? Without the sun GHGs are meaningless, they are a feedback of solar radiation. It's cooler now because the sun is not providing as much radiation for GHGs to act on (not rocket science). You fundamentalist types ever do any reading?
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