Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Term:

Settings

Beginner Intermediate Advanced No Definitions Definition Life:

All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Recent Comments

Comments 130251 to 130300:

Quietman at 13:00 PM on 7 July 2008

There is no consensus
paledriver I have been following along but I did not realize that it was the same one because of the number and date. So this petition is still circulating?

paledriver at 01:43 AM on 7 July 2008

There is no consensus
Qietman, if you go to the link provided by #62 you'll find it's the same old Petition Project by OISM. If you go to my posts 4,8,12,14 and 28 (to begin with) you'll get a start on that petition and the "inhofe 400".

Quietman at 10:06 AM on 6 July 2008

There is no consensus
Will Nitschke There have been several updates to the link that you posted. Below is the latest one only. U.S. Senate Report: Over 400 Prominent Scientists Disputed Man-Made Global Warming Claims in 2007 Senate Report Debunks "Consensus" UPDATE: More and more scientists continue to declare their dissent of the ‘consensus.’ (LINK) Climate Skeptics Reveal ‘Horror Stories’ of Scientific Suppression (NYC Climate Conference Report - Part One of Reports) March 6, 2008 "Many prominent scientists participating and attending were very impressed by the New York City climate conference. Hurricane researcher and Meteorologist Stanley B. Goldenberg of NOAA (National Oceanic and Atmospheric Administration) in Miami praised the Heartland Instituted sponsored conference. “The fact is that this conference is evidence that there are numerous respected, established and in many cases world-renowned scientists who have done careful research in various areas of ‘climate change’ that sharply differ with the [UN] IPCC results,” Goldenberg told the New York Times."

Quietman at 09:53 AM on 6 July 2008

There is no consensus
paledriver I was under the impression that this was a newer petition. Are you saying that this is the same one as the 20k scientists earlier in this thread?

tlewellen at 07:55 AM on 6 July 2008

Global warming stopped in ~~1998~~, ~~1995~~, ~~2002~~, ~~2007~~, ~~2010~~, ????
Quietman If I were to chose a collarobator to make a discovery, I might choose you. Open minds tend to prevail in science. What I see that is difficult about understanding the climate is that there appear to be 10 variables, all dependant on the others. In basic Physics, theories are easy to test because there were only a few variables, all easily measured and constrained. No such situation exists with climate and weather. The complexities are more like String theory or Chaos theory. And, Quiteman, you are correct about the sites. Most sites are more Political Science, that science. Tom

tlewellen at 07:41 AM on 6 July 2008

It's the sun
Quietman, BriMan,TruthSeeker, et al As just a curious layman, it is good to see that the banter and debate on this site is broad and deep. This kind of debate in the press and Congress would do our nation some good. GW, I assume, will be like much of science through history. It is seldom complete, even when we think it is. Whether it was the Catholic Church's belief that the earth was the center of the Universe, or a long held believe that there were only four elements, or even that for some time most believed that there were 24 chromosomes. Good scientists hold to the facts in front of them. Great scientists keep looking when the science does not match the facts. Reading your inciteful remarks, I can conclude we are still very short of good data and great science. There is still so much to debate.

paledriver at 23:59 PM on 5 July 2008

There is no consensus
in response to number 62. this was when they claimes 17,000.....".. took a sample of 30 of the 1,400 signatories claiming to hold a Ph.D. in a climate-related science. Of the 26 we were able to identify in various databases, 11 said they still agreed with the petition -- one was an active climate researcher, two others had relevant expertise, and eight signed based on an informal evaluation. Six said they would not sign the petition today, three did not remember any such petition, one had died, and five did not answer repeated messages. Crudely extrapolating, the petition supporters include a core of about 200 climate researchers -- a respectable number, though rather a small fraction of the climatological community.". this from when it was first released......"The Marshall Institute co-sponsored with the OISM a deceptive campaign -- known as the Petition Project -- to undermine and discredit the scientific authority of the IPCC and to oppose the Kyoto Protocol. Early in the spring of 1998, thousands of scientists around the country received a mass mailing urging them to sign a petition calling on the government to reject the Kyoto Protocol. The petition was accompanied by other pieces including an article formatted to mimic the journal of the National Academy of Sciences. Subsequent research revealed that the article had not been peer-reviewed, nor published, nor even accepted for publication in that journal and the Academy released a strong statement disclaiming any connection to this effort and reaffirming the reality of climate change. The Petition resurfaced in 2001.". and more...."Of 100 names googled, only about 2 percent turn out to be scientists with any training relevant to climatology, usually physics. A small number -- about 15 percent -- were other kinds of scientists or physicians, but with no relevant training. Several in this overall pool of scientists were quite elderly. The remainder were either people with no scientific credentials whatsoever (40 percent), or names that did not appear in the search -- highly improbable nowadays if indeed such people existed." so the petition is clearly a fabrication.

Quietman at 10:16 AM on 4 July 2008

It's the sun
Bri-Man To bring you up to speed (at least on this site) the 70's are referenced because in the mid to late 70's the solar forcing stopped following the temperature line. Their argument, which is that of the IPCC, is that CO2 induced AGW explains the increases from 1975 on. Those of us skeptical of this argument have several positions, mine is vulcanism and plate tectonics which have been more active since the full alignment in 1976. The most recently active thread is "Arctic sea ice melt - natural or man-made?" and the discussion is somewhat heated.

Bri-Man at 03:34 AM on 4 July 2008

It's the sun
Stop listening to the media and paid celebrities. They have no sort of degree in science and are just reading from a script. This has all stemed from "Yellow Science." It used to be that we listened to the scientists from both sides of the argument. Now we don't even listen to them at all, we listen to the media, politicians and paid celebrities, none which have any clue of what they are talking about. It's a shame that the scientists on the other side of the fence don't get the same main stream media attention that Al Gore does. But the reason for this is very simple and clear....MONEY. Over 50 Billion dollars has been spent world wide for Global Warming research. These scientists don't even have to come up with anything significant to get paid, they just have to sign there name with a little PhD right next to it. Big corporations have also made a killing selling "Green" products. Governments world wide will never let these scientists get world wide attention either because they can't admit they have been DUPPED into believeing that the sky was falling and that they just spent billions of your tax dollars on it. Keep an open mind, look at """"ALL"""" of the science and then draw your conclusions.

Bri-Man at 03:20 AM on 4 July 2008

It's the sun
Why does this site keep referencing the 70's? The planet if over 4 billion years old and has been chaning ever since. You are sitting here talking about the last few hundred years like they have been of any kind of significance in the last 4 billion. It's just a spec, not even that really. More drastic changes have happened (climate wise) in Earths history then the industrial revolution. Does anybody else think that this is a form of "Vanity?" Short of nuclear fallout, I don't think that we could put a dent in this planets way of working. I do think however that pollution is bad for us humans, and we should look at that more then global destruction.

Bri-Man at 03:15 AM on 4 July 2008

It's the sun
Remeber what Einstein said, "No amount of experimentation can ever prove me right; a single experiment can prove me wrong."

TruthSeeker at 03:40 AM on 3 July 2008

Arctic sea ice melt - natural or man-made?
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

TruthSeeker at 01:02 AM on 3 July 2008

TruthSeeker at 00:47 AM on 3 July 2008

TruthSeeker at 00:46 AM on 3 July 2008

barry schwarz at 14:52 PM on 1 July 2008

It hasn't warmed since 1998
Hadley's own analysis for the trend 1998 - 2007 concludes; "A simple mathematical calculation of the temperature change over the latest decade (1998-2007) alone shows a continued warming of 0.1 °C per decade." http://www.metoffice.gov.uk/corporate/pressoffice/myths/2.html

Quietman at 02:07 AM on 1 July 2008

We're heading into an ice age
Actually we can't head into an ice age at this point in time because we are already in one. Technically this is an interglacial period within the current ice age, ie. this is not "Earth Normal" climate, which is much hotter. Interglacial means "between glacations" and is about as unstable a climate as possible on this planet. That is assuming that it is an interglacial rather than the ice age ending (far worse for us). It also assumes that another glacation will occur. Looking at graphs of prior interglacials and glacations there is a particular constant: it warms slowly for thousands of years then cools rapidly (it looks very similar to a sawtooth inventory graph). Another fact is that CO2 has been very high when it suddenly became very cold (it did nothing to stop the glacations). So be afraid, be very afraid.

shawnhet at 01:27 AM on 1 July 2008

Arctic sea ice melt - natural or man-made?
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, :)

barry schwarz at 18:50 PM on 30 June 2008

barry schwarz at 14:13 PM on 30 June 2008

Quietman at 13:14 PM on 30 June 2008

Climate's changed before
A change or two in climate history has recently been revealed indicating change happens faster than thought: Fossils Found In Tibet Revise History Of Elevation, Climate ScienceDaily (June 12, 2008) — About 15,000 feet up on Tibet's desolate Himalayan-Tibetan Plateau, an international research team led by Florida State University geologist Yang Wang was surprised to find thick layers of ancient lake sediment filled with plant, fish and animal fossils typical of far lower elevations and warmer, wetter climates. Greenland Ice Core Analysis Shows Drastic Climate Change Near End Of Last Ice Age ScienceDaily (June 19, 2008) — Information gleaned from a Greenland ice core by an international science team shows that two huge Northern Hemisphere temperature spikes prior to the close of the last ice age some 11,500 years ago were tied to fundamental shifts in atmospheric circulation.

Response: This would indicate that climate is more sensitive than realised which means the climate response to CO2 forcing will be greater than current estimations.

Quietman at 04:53 AM on 30 June 2008

Arctic sea ice melt - natural or man-made?
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).

Quietman at 04:22 AM on 30 June 2008

Volcanoes emit more CO2 than humans
The current work on vulcanism in the south Pacific: Olsen et al. Rapidly changing flows in the Earth’s core. Nature Geoscience 1, 390 - 394 (2008) Published online: 18 May 2008 | doi:10.1038/ngeo203 Subject Category: Geomagnetism, palaeomagnetism and core processes Rapidly changing flows in the Earth's core Nils Olsen & Mioara Mandea A large part of the Earth's magnetic field is generated by fluid motion in the molten outer core. As a result of continuous satellite measurements since 1999, the core magnetic field and its recent variations can now be described with a high resolution in space and time. These data have recently been used to investigate small-scale core flow, but no advantage has yet been taken of the improved temporal resolution, partly because the filtering effect of the electrically conducting mantle was assumed to mask short-period magnetic variations.. Here we show that changes in the magnetic field occurring over only a few months, indicative of fluid flow at the top of the core, can in fact be resolved. Using nine years of magnetic field data obtained by satellites as well as Earth-based observatories, we determine the temporal changes in the core magnetic field and flow in the core. We find that the core flow is spatially localized and involves rapid variations over a few months, with surprisingly large local accelerations. Our results suggest that short-term fluctuations of the core magnetic field are robust features of rapid core dynamics and should be considered in the development of future numerical models of the geodynamo. Danish National Space Center/DTU and Niels Bohr Institute at Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen, Denmark GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany Correspondence to: Nils Olsen1 e-mail: nio@space.dtu.dk

Quietman at 04:02 AM on 30 June 2008

Arctic sea ice melt - natural or man-made?
"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.

Quietman at 03:05 AM on 30 June 2008

Arctic sea ice melt - natural or man-made?
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.

Quietman at 02:50 AM on 30 June 2008

Arctic sea ice melt - natural or man-made?
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?

Philippe Chantreau at 09:00 AM on 29 June 2008

Arctic sea ice melt - natural or man-made?
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.

Quietman at 04:29 AM on 29 June 2008

Arctic sea ice melt - natural or man-made?
p.s. Nothing about this planet is well understood, despite claims to the contrary. Our young scientists have much to learn.

Quietman at 04:26 AM on 29 June 2008

Arctic sea ice melt - natural or man-made?
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.

chris at 23:43 PM on 28 June 2008

Arctic sea ice melt - natural or man-made?
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.

Philippe Chantreau at 12:14 PM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Shawnet, the Tale of the Tape at Cryosphere Today seems to disagree with you: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg The magnifying function helps to see that the current level is significantly lower than any in 01-02. What data are you using?

Philippe Chantreau at 11:51 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Quietman, thank you for the condescending tone. It is a good reminder of what we all should try to avoid, I will be more watchful to not reproduce anything like it. Shawnet, the comparison I was concerned about on that graph was between this year and last year. The current extent does not bode well for what Sep minimum will be, but time will tell.

shawnhet at 08:20 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Chris, "Question (a) has an explanation that is well-supported by the scientific evidence: massive enhancement of the Earth's greenhouse effect. The warming in the arctic is pretty much as expected from supplementing the Earth's greenhouse gases with extra CO2, methane, nitrous oxides, tropospheric ozone and CFC's. There may well be a significant contribution from BC although we've had pretty much all the forcing from that source already according to Hansen and Nazarenko, and it's not clear that the warming effect of BC has been greater than the cooling effect of other manmade aerosols. Certainly according to Hansen, and Ramanathan and Carmichael, the total worldwide aerosol effect (BC et al) is a cooling one. It may be net warming in the arctic 'though. One would have to look at the numbers carefully, if the appropriate one's are available." Chris, the point about the SH and NH is that the GE can't explain the loss of ice in the SH, *because there isn't one*. There's a gain(and one reasonably close to the loss in the NH). Since there is the same amount of CO2 in the SH as the NH, CO2 cant explain the state of the cryosphere in toto. Phillippe:"Shawnet, the ice area is actually very close to what it was last year, due to a period of fast melting in the spring: http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png" I don't think that what I said and what you said really disagree. It is just a question of what you are comparing it to. I was comparing it to the early part of this century, while your link compares it to the 1979-2000 mean. Cheers, :)

chris at 07:03 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Quietman, If you consider that "undersea vulcanism" is contributing to global (or regional) warming, then you need to give us some evidence. Remember that: (i) the mid-ocean plates have been slowly ripping themselves apart for countless (almost!) millenia. Has this process suddenly intensified since the middle of the 20th century? Evidence please. (ii) one of the more active mid ocean plate-separations lies towards and then in Iceland, as the plates carrying America and Europe rip apart at the mid-Atlantic ridge. This is a region with massive "vulcanism" (undersea and above sea). However, this region is one of the rare locations on earth that has actually cooled since the middle of the 20th century. How can "vulcanism" provide an explanation for warming (global or regional) if one of, if not the most active, region "vulcanism"-wise has actually cooled a tad since the mid 20th century? Explanation please. (iii) Science progresses on the basis of evidence. If you'd like to pursue "vulcanism" as a contributory factor in local or global warming, you'll need to find some evidence. You can't keep ducking these straightforward requests and expect to be taken seriously. Evidence please. Otherwise we're likely to be skeptical of your unsupported claims! Note btw: (a) that greenhouse-gas induced warming (resulting largely from massive enhancement of the atmospheric carbon dioxide concentration) is hardly a "myth". One of the very papers that you cited in support of something or other, concludes with a determination of the earth's climate sensitivity to doubling atmospheric [CO2]: 2.3 °K< ΔT2xCO2 <4.1 °K . (“2xCO2” is subscripted)[***] Which say's: “2.3 degrees Kelvin is less than the change in temperature from doubling [CO2], which is less than 4.1 degrees Kelvin” (Tung and Camp consider that the climate sensitivty is around 3 oC (+/- a bit). [***]Tung and Camp: http://www.amath.washington.edu/research/articles/Tung/journals/solar-jgr.pdf Clearly Tung and Camp don't consider man-made enhancement of the earth's greenhouse effect via massive enhancement of the atmospheric CO2 concentration "a myth". (b)that science doesn't progress on the basis of "blogs" and "columns"! (c) that unsubstantiated denigration of scientists (your unsubstantiated comments re Hansen) doesn't constitute skepticism! I hope you're not one of those " ...closed minds that will not even look at a paper if they don't like the author". (d) It's not only science that is all about the evidence. Skepticism too is all about the evidence!

Quietman at 05:57 AM on 28 June 2008

Volcanoes emit more CO2 than humans
John A little more detail here. "A major part of Earth's volcanism happens at the so-called mid-ocean ridges and, therefore, completely undetected on the seafloor." Bathymetric chart of the Gakkel Ridge (Nice photo and charts)

Quietman at 05:40 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Philippe Yes I could but there are too many. I did my homework, now you can google it just as easily. I have better things to do at this time of year. The weather is quite pleasant, low 70's with a cool canadian breeze and I have several acres to take care of. I have to restrict my on-line time to coffee breaks so I really do not have the time to look up the links for my paper collection which is a few hundred megabytes at this time. You and chris can continue believing in the CO2 induced AGW myth if you want to, otherwise investigate like I did.

Quietman at 05:32 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Undersea vulcanism - more than just eruptions and those eruptions do not cause cooling, they cause warming. This is not atmospheric ejecta. You have done your CO2 homework, not study up on vulcanism and plate tectonics, geomagnetism and ocean forcings.

Quietman at 05:28 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
chris "This notion seems to be creeping in, in an unsubstantiated manner!" It is unsubstantiated only to a few deniers. At all the other columns and blogs I have read, it is acknowledged. The world around you sees the increased vulcanism, why don't you? Or are you confusing vulcanism with eruptions? And don't bother to quote Hansen, he has too much to lose by admitting that he started this whole thing in error, rendering his work useless.

chris at 05:09 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Re "vulcanism" This notion seems to be creeping in, in an unsubstantiated manner! So it's worth pointing out that volcanic eruptions generally result in short periods of cooling due to the release into the high atmosphere of volcanic aerosols that are relatively quickly washed out of the skies. This is an obvious and well-documented effect of volcanos. Thus the eruption of Pinatubo and the subsequent trosposphere and ocean surface cooling "pulse" was useful in analysing the response of the Earth to reduced forcing and the rate of recovery after superficial cooling, and so on: e.g.: Soden BJ et al (2002) Global cooling after the eruption of Mount Pinatubo: A test of climate feedback by water vapor, Science 296, 727-730. And very large volcanic eruptions are well known for their rather unpleasant cooling effects (e.g. Tambora and the subsequent "year without a summer"). We've had quite a few volcanic eruptions since the middle of the last century, and so the global temperature rise has been periodically "knocked back" by these cooling "pulses": e.g. see Figure 1 of: http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf So if someone has a notion that "vulcanism" is contributing to global (or regional) warming, then a little bit of substantiation with some scientific evidence would be nice!

Philippe Chantreau at 04:01 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Shawnet, the ice area is actually very close to what it was last year, due to a period of fast melting in the spring: http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png Quietman, you say " have seen evidence cropping up everywhere for increased worldwide vulcanism since 1976." Can you point to papers where that evidence is compiled and (better) analyzed?

Quietman at 03:27 AM on 28 June 2008

Volcanoes emit more CO2 than humans
Some evidence: "Healy Researchers Make A Series Of Striking Discoveries About Arctic Ocean" — Contrary to their expectations, scientists on a research cruise to the Arctic Ocean have found evidence that the Gakkel Ridge, the world's slowest spreading mid-ocean ridge, may be very volcanically active. They also believe that conditions in a field of undersea vents, known as "black smokers," could support previously unknown species of marine life ScienceDaily (Nov. 29, 2001) "Fire Under Arctic Ice: Volcanoes Have Been Blowing Their Tops In The Deep Ocean" — A research team led by the Woods Hole Oceanographic Institution (WHOI) has uncovered evidence of explosive volcanic eruptions deep beneath the ice-covered surface of the Arctic Ocean. Such violent eruptions of splintered, fragmented rock--known as pyroclastic deposits -- were not thought possible at great ocean depths because of the intense weight and pressure of water and because of the composition of seafloor magma and rock. ScienceDaily (June 26, 2008) I would think that this is an indication of increased vulcanism.

Quietman at 02:54 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Philippe No more than AGW did, neither is about 2007. Both are about recent warming. I have seen evidence cropping up everywhere for increased worldwide vulcanism since 1976 but it has been steadily ignored. Am I the only one making the solar connection? Gravitational stress stronh enough to effect the sun has to also be more than strong enough to effect the earth's inner circulation.

chris at 02:43 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Shawnet, There are two questions aren't there! (a) What's caused the remorseless attenuation of arctic sea ice since the 1960's? (b) What's caused the massive excess summer melt in 2007? and you also asked again: (c) why the difference betwen the Nrthn. and Srthn. hemisphere? Question (b) has been more or less answered (see the excellent summary of the science by John Cook at the top of the page). It seems that the remorseless attenuation of arctic sea ice since the 1960's has made the ice sheet very vulnerable to short term summer "weather" conditions. Note that while the winter arctic sea ice extent has recovered a tad, it's the summer sea-ice extent that is the critical factor, and so we'll have to wait to see to what extent 2007 was a recoverable blip. Question (c) has been answered pretty much (see posts #66/#69) The differences in the effects of global warming on Antarctic and Arctic are reasonably well defined. It's largely a question of sea and ocean currents and the way that excess heat is distributed from the lower latitudes to the higher. There may be some BC contribution. After all there is little BC found in the Antarctic (on the other hand the cooling aerosols also predominate in the Arctic cf the Antarctic). Vulcanism is a red herring I suspect [for (a), (b) and (c)]. It doesn't make a lot of sense at all. One needs to make a clear cut explanation of how this "vulcanism" works. At the very least one needs to address the facts that: (i) the most volcanically-active region in the the Arctic or Antarctic is the area in and around Iceland (an eruption every 5 years on average; 1/3'd of all lava expelled in the last 500 years is in Iceland which not only sits astride the opening of the plates running along the opening Atlantic basin, but also above a "mantle plume")... ...however the region around Iceland and S. Greenland is the one area of the Arctic that has actually cooled a tad since the 1960's. How can "vulcanism" be an explanation for marked warming when the most volcanically-active region has cooled??? (ii) The vulcanism in the Arctic (and Antarctic) is of long-long-standing (millions of years). Without some evidence that this vulcanism has (a) all of a sudden increased markedly in the relevant regions and periods, (b) that any thermal energy is of a magnitude and appropriately distributed to contribute to the observed melt, and so on....one should remain rather skeptical of such a notion. Question (a) has an explanation that is well-supported by the scientific evidence: massive enhancement of the Earth's greenhouse effect. The warming in the arctic is pretty much as expected from supplementing the Earth's greenhouse gases with extra CO2, methane, nitrous oxides, tropospheric ozone and CFC's. There may well be a significant contribution from BC although we've had pretty much all the forcing from that source already according to Hansen and Nazarenko, and it's not clear that the warming effect of BC has been greater than the cooling effect of other manmade aerosols. Certainly according to Hansen, and Ramanathan and Carmichael, the total worldwide aerosol effect (BC et al) is a cooling one. It may be net warming in the arctic 'though. One would have to look at the numbers carefully, if the appropriate one's are available.

shawnhet at 01:12 AM on 28 June 2008

Arctic sea ice melt - natural or man-made?
Chris, "Hansen and Nazarenko point out that the BC emissions that affect the arctic (mostly from Eurasia) dropped sharply in the 1990's due to the breakup of the former Soviet Union. So, again, that tends to argue against the contribution from BC as a major contributor to the acceleration of artic sea ice recession since around 2000, let alone the very dramatic anomalous drop of summer sea ice last year. Presumably the reduction in total aerosol load from Eurasia will have both "cooling" effects (reduction of BC component) and "warming" effects (reduction of aerosol screening of surface solar irradiation), so things are unlikely to be straightforward!" I agree that BC is unlikely to be a major contributor in the last year. This is likely the result of a natural confluence of factors, especially considering that the sea ice extent has already rebounded to around the 2001-2002 levels.(http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.jpg). Much more interesting IMO is why the Antarctic and Arctic changes are in opposite directions for the last while. BC may go part of the way to explaining this though it probably can't explain the whole thing. I wouldn't be surprised if the trend is the result of many things, possibly including ocean currents, BC and vulcanism. Cheers, :)

Philippe Chantreau at 16:36 PM on 27 June 2008

Arctic sea ice melt - natural or man-made?
Are you suggesting that the 1999-2001 events melted the ice in 2007?

Quietman at 15:20 PM on 27 June 2008

Arctic sea ice melt - natural or man-made?
John I think we are finding a little more evidence of my vulcanism hypothesis: "International expedition discovers gigantic volcanic eruption in the Arctic Ocean" Please read Fire under the ice Public release date: 25-Jun-2008, (natural causes).

Renfield at 13:25 PM on 27 June 2008

There is no consensus
If the Caribbean Academy of Sciences and the Royal Irish Academy endorse man made global warming can any person with a conscience still doubt? Mr Hansen from NASA's Goddard Institute thinks the doubters should be punished. Shouldn't they be given the opportunity to recant? Water boarding causes no lasting damage and requires no carbon use whatsoever, unlike burning at the stake, etc. Mr. Hansen let slip a prediction for the future. "All the Arctic sea ice will be gone in five to ten years." Going out on a limb, isn't he. He might be alive to reap the ricicule. I've marked my calendar: "Look for hell fire and inundation". For now, I'll keep the beach property.

Quietman at 12:02 PM on 27 June 2008

Can animals and plants adapt to global warming?
Looks like we did it again" "'Unintended Consequence' The decision to place polar bears under the protection of the Endangered Species Act came in response to the continued "loss of sea ice," the bear's natural habitat, that would put them "at risk of becoming endangered in the foreseeable future," according to a statement by the Department of the Interior on May 14. There is no mention that the danger to polar bears stems from hunting. In the same statement, Secretary of the Interior Dirk Kempthorne specifically noted that "limiting the unintended harm to the society and economy of the United States" was a concern. What did not seem to be a priority, however, was the harm to the economy in Arctic Canada, home to about two-thirds of the world's polar bear population, which is estimated at 20,000 to 25,000." [ABC (US) News]

chris at 08:29 AM on 26 June 2008

Arctic sea ice melt - natural or man-made?
Yes, fair enough...notice however that Hansen and Nazarenko: (i) conclude their abstract with ["However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future"] and: (ii) have, in their more recent work downgraded the role of black carbon/snow/ice albedo effects. The paper you cited is here: J. Hansen and L. Nazarenko (2004) Soot climate forcing via snow and ice albedos; Proc. Natl. Acad. Sci 101 423-428 (abstract below [*]) The paper can be downloaded from NASA/GISS: http://pubs.giss.nasa.gov/docs/2004/2004_Hansen_Nazarenko.pdf Note that Hansen and Nazarenko assign a total black ice/albedo forcing of 0.15 W/m2 and a total contribution to global warming since 1880 of 0.17 oC. However they later reassess this and downgrade the contribution of black ice/albedo forcing to 0.05 W/m2 (and total contribution to global warming of 0.065 oC) in their more recent study: Hansen, J. et al (2007) Climate simulations for 1880-2003 with GISS modelE. Clim. Dynam., 29, 661-696. (see Appendix A5) This can also be downloaded from NASA/GISS: http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_3_small.pdf A recent study by Flanner et al (2007), concludes that the BC effect in the arctic has been quite significant too [**]. Hansen and Nazarenko point out that the BC emissions that affect the arctic (mostly from Eurasia) dropped sharply in the 1990's due to the breakup of the former Soviet Union. So, again, that tends to argue against the contribution from BC as a major contributor to the acceleration of artic sea ice recession since around 2000, let alone the very dramatic anomalous drop of summer sea ice last year. Presumably the reduction in total aerosol load from Eurasia will have both "cooling" effects (reduction of BC component) and "warming" effects (reduction of aerosol screening of surface solar irradiation), so things are unlikely to be straightforward! e.g. Hansen and Nazarenko (2004) say: ["Snow samples in the 1980s (6), including sites in Alaska, Canada, Greenland, Sweden, and Spitzbergen, and on sea ice in the central Arctic, yielded typical BC amounts of 10–50 ppbw (excluding Greenland). "Arctic haze" studies (19) showed that most of the aerosols originated in Europe and the Former Soviet Union (FSU) in winter/spring driven by circulation around the Icelandic Low and Siberian High. BC emissions from Eurasia probably declined sharply in the 1990s as, e.g., FSU BC emissions fell by a factor of four with the collapse of the FSU economy (20). Reduced BC emissions are not necessarily permanent in the face of possible economic recovery, increased shipping in the opening Northwest and Northeast Passages, regional hydrocarbon resource development, and increased use of diesel-powered vehicles."] Hansen and Nazarenko (2004) abstract [*] "Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m2 in the Northern Hemisphere. The "efficacy" of this forcing is 2, i.e., for a given forcing it is twice as effective as CO2 in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future." [**]M. G. Flanner et al (2007) Present-day climate forcing and response from black carbon in snow, J. Geophys. Res. 112, D11202

shawnhet at 06:00 AM on 26 June 2008

Arctic sea ice melt - natural or man-made?
Here's an alternative POV, "Fig. 6 shows the change in surface albedo in our transient climate simulation for 1880–2002 for March to April and May to June. The specified spectral-mean snow albedo changes were 0.83 × 1.5% ~ 1.25% for snow/ice in the Arctic Ocean and 0.83 × 3% ~ 2.5% for snow over Northern Hemisphere land. The surface albedo changes are diminished over land by vegetation masking of the snow (14), which is very effective in forested areas but ineffective in tundra regions with little vegetation. The warming of the surface and air due to the soot albedo effect enhances the surface albedo changes over both land and ocean because of enhanced snow aging (increased grain size) and especially because of the earlier onset of spring melt. Thus, the soot-lowered albedo and increased temperatures initiate positive feedbacks via earlier snowmelt and rainfall. Fig. 5 shows the change in the net short-wave heating of the surface for the same periods as in Fig. 6. Note that the regional flux changes at the surface are as much as 10 W/m2 and more. This compares with a typical annual-mean forcing of <1 W/m2 (Fig. 1). Clarke and Noone (2) calculated a maximum May-to-June surface flux perturbation of ≈6 W/m2 for an assumed snow albedo perturbation of 2%. Given that our soot-imposed albedo change for the period 1880-2002 was only ≈1.25% (over sea ice), this means that we find a surface heating about twice as large as that calculated by Clarke and Noone (2). The cause of this difference is the positive feedbacks in our climate model that reduce the albedo further, especially the acceleration of the summer melt season. Our results are not in disagreement with those of Clarke and Noone (2), because they mentioned in their concluding remarks the likelihood that such positive feedbacks would enhance the soot albedo effect. These positive feedbacks, especially the acceleration of the melt season, have practical implications. The perturbations of surface fluxes are largest in the regions of sea ice, permafrost, glaciers, and the low altitude portion of the Greenland ice sheet that is subject to summer melt. This suggests that soot may contribute to thinning of sea ice (16), melting permafrost, glacier retreat, and accelerating movement of Greenland ice (17)." http://www.pnas.org/cgi/content/full/2237157100/DC1/2 Soot climate forcing via snow and ice albedos James Hansen * , and Larissa Nazarenko * Cheers, :)

Climate Science Glossary

Term Lookup

Settings

Term Lookup

Settings

Latest Posts

Recent Comments