Sea Ice North: The new field of ice-free Arctic Ocean science
Sea Ice North: The new field of ice-free Arctic Ocean science
I recently read a paper in Physics Today entitled The Thinning of Arctic Sea Ice by R. Kwok and N. Untersteiner. (Nice essay by Untersteiner) This paper was written for a general scientist audience, and provides a good summary of the state of the science. The primary focus of the article is on understanding the small change to the surface energy balance required to explain the increased rate of sea ice melt in the summer. Some time ago I wrote a few blogs on Arctic sea ice; they can be found here and this one is most relevant: Sea Ice Arctic.
When the IPCC Assessment Report was published in 2007 the Arctic sea ice was in visible decline. In the summer of 2007 there was a record decline that caught the attention of both climate scientists and the broader public. As suggested in Kwok and Untersteiner immediately following the release of the 2007 IPCC report papers started to appear about how the IPCC synthesis had underestimated the melting of both sea ice and ice sheets. Much of this underestimate could be summed up as simplistic representation of the dynamics of ice melting. For example, brine-laden sea ice floating in salty sea water turns over. Snow gets on the top. It melts, then there are puddles and ponds that can flow down into ice. Simplistically, and I am a simpleton, it’s like a pile of ice cubes sitting in a glass versus stirring those ice cubes, or blowing air over the ice, heat gets carried around and ice melts faster.
The presence of large areas of open ocean in the Arctic is new to us. It motivates new research; it motivates claims to newly accessible oil, gas, and minerals; it motivates new shipping routes; it suggests changes in the relationships of nations; it motivates the development of a military presence. (All things Arctic from the Arctic Council) The natural progression of scientific investigation starts to explore, describe, and organize what is to us modern-day humans: a new environment, new ecosystems, and new physical systems. For example, the Mackenzie River now delivers a massive pool of fresh water into the ocean. Fresh and salt – big differences to flow in the ocean because the density is different; big difference to the formation of ice because the freezing temperature is different; and big differences in the plants and animals in the water.
Compared with trying to attribute the contribution of global warming to a particular weather event, it is easier to link the recent, rapid decrease of sea ice to a warming planet. The freezing, melting and accumulation of ice require persistent heating or cooling. It takes a lot of heat for a sustained period to melt continental-size masses of ice. Historically, the sea ice that was formed in the winter did not melt in the summer and there was a buildup of ice over many years – it accumulated; it stored cold. Around the edges of this multi-year ice are areas where the sea froze and melted each year. The melting of multi-year ice, therefore, represents the accumulation of enough heat to counter years of cold. The movement, poleward, of the area where ice freezes and thaws each year is the accumulation of spring coming earlier. The requirement for energy to persist and accumulate to affect changes in sea ice reduces the uncertainty that is inherent in the attribution of how much global warming has impacted a particular event.
Understanding the detailed mechanisms that provided the heat to melt the ice remains a challenge. (This is the real point of in Kwok and Untersteiner) We know it takes about 1 watt per square meter of energy to melt that much ice that fast. This could be delivered by the Sun, transported by the air, by the ocean, by warm water from the rivers of Canada and Siberia, by snow – yes, snow is energy. Once the ice is gone in the summer, then the ocean can absorb heat from the Sun. If there is growth of phytoplankton or zooplankton, then they might enhance the absorption of energy – yes, life is energy. Ocean acidification might change. The natural question that arises – do these processes that are active in this new environment work to accelerate sea ice melting or might they contribute to freezing of water. What are the local feedbacks? (This is above – see below.)
Another study that is of interest is the paper in Geophysical Research Letters, Recovery mechanisms of Arctic summer sea ice, by S. Tietsche and colleagues. This is a model study. With a model the scientist owns the world and can prescribe what it looks like. In these numerical experiments, the Arctic is prescribed with no ice. Then whether or not the ice recovers is explored. In these studies the ice does recover. The ocean does indeed take up extra heat in the summer, but it gives it up quickly in the fall. This is followed by the formation of first year ice in the winter. The ice-albedo feedback that might let the ice melt runaway is limited. Tietsche et al. conclude that it is not likely that Arctic sea ice will reach a tipping point this century.
This does not mean that summer ice loss will decrease. This does not mean that there will not be huge changes in the Arctic. This only says that it still gets cold in the winter.
Models: One of the things I like about the Kwok and Untersteiner paper is their brief discussion of models. They point out that none of the models available for the 2007 IPCC assessment were able to predict the rate of sea ice decrease. Looking forward, they state that the model projections for 2060 range from no sea ice in September to more sea ice than is observed today. The Tietsche et al. paper is a focused model experiment – not a climate projection. It is also a model result that, perhaps, helps to understand the differences in the 2060 projections. That is, how is the recovery of sea ice in the autumn represented in the projection models?
A couple of other points: First, the amount of energy needed to cause the observed melting in sea ice is 1 watt per square meter. If you calculate the amount of energy in the different factors at play in melting of sea ice, then the numbers are 10s of watts per square meter. As suggested above, there are many reservoirs of energy – the Sun, rivers, etc. So when we look at the different ways 1 watt per square meter can be delivered to the sea ice, then there are several paths. The existing models tell us that with the increased heat due to greenhouse gases, energy gets delivered to the Arctic and sea ice melts. The existing models say that there might be several different paths; it is likely, that several of them operate at different times. The second point: Of course the Tietsche et al. paper will enter as an isolated contribution to the political argument, Arctic “death spiral” – as will those of accelerated melt, New warning on ice melt.
r
Figure 1: Simplistic summary of Arctic sea ice
Useful links
Recent sea ice trends
Sea ice data
Rood’s Blogs on Ice
Reader Comments
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 — Blog Index
However, that does not take away from he fact that co2 concentrations do have an effect on temperature. So we are still responsible to some degree for our present warming trend.
And on the subject of feedback loops, you do understand that there are many positive feedback loops for warming right? That is one of the main reason scientists are so concerned with the arctic.
I also have a question for you, if co2 is not the main cause of our current warming, then what is?
They would both be acceptable. Do you have either one, by any chance?
Right. Either the feedbacks were enough to overthrow the warming effect of co2 or there was a natural cycle that was far more powerful than co2.
This is technically false. Assuming that there are NO climate feedbacks, the doubling of co2 has roughly the impact of a 1 Degree F temperature rise. However, in a climate filled with negative feedbacks, the effect of co2 might actually cool the climate. In a climate filled with positive feedbacks, the impact of co2 will be greatly magnified. We do not know much about the current climatic feedbacks in order to determine whether Man has participated in this current warming trend. The Climate Models all assume that co2 creates a positive feedback known as water vapour. They assume that the co2 heats the oceans, so that means that more water vapor must come from the oceans, right? Nope. Almost all of the water vapour is lost due to evaporation, and when the water droplets condense to form clouds, then this feedback has a net cooling impact. Feedbacks are what ultimately determine whether man has played a role in the climate. Natural cycles usually do not have feedbacks, so they are not as complicated to determine how much of an impact they have on the climate.
The Arctic is a very unique area. It is surrounded by continental landmasses. The PDO and the AMO surround the continental landmasses. When the oceans near the landmasses heat up, the landmasses heat up. Guess what happens to the Arctic since it is surrounded by warm continental landmasses? It warms up as well. The ocean currents from the PDO and AMO also help to warm the Arctic. In fact, most of the melting of the Arctic Sea Ice has occured from underneath. Which indicates that most likely, ocean currents, and the PDO/AMO are the reason for the melting of the Arctic Sea Ice since 1979.
I believe that since 1979, which is the most reliable data that we have, since satellites were launched then, that the PDO and AMO are solely causing that warming.
However, when one looks back a little bit further (and the error margins increase, since we are measuring the temperatures now with surface stations,) you will notice an identical warming trend when the PDO/AMO were warm. The Warming looks identical, and even according to the UN, co2 could not have played a role in the warming from 1900-1940. I suspect the same thing is going on right now.
Site has been down for a while. I imagine that UAH sustained some damage from the tornado outbreak. I would think it will be back up in a week or so.
That would make sense. Incredible damage in Alambama where UAH is.
http://www.youtube.com/watch?v=OU6hsYk_sWI
2. All that text about feedback loops are merrily your assumptions. Find me some peer reviewed evidence, and maybe I'll buy in to your assumptions.
About the PDO and AMO, you couldn't be more wrong. The PDO and AMO are climate indices. What is the PDO? A measure of SSTs in the Pacific. What is the AMO? A measure of SSTs in the Atlantic.
Why do they appear to magically follow the temperature plot of global warming? Because they make up that graph. The PDO and AMO are one little chunk of that graph.
Understood? I hate when people think PDO -> GW. PDO reflects GW.
GW
PDO
AMO
Notice, they're not perfect mirror images of each other. This is because one is taking global temperatures, and the other is taking temperatures for one little sector of the globe.
Additionally, the PDO & AMO are only known to have regional effects, limited to the N Hemisphere. Yet the S Hemisphere is warming too.
So neither the PDO, nor the AMO explain GW.
The PDO is detrended from the overall warming signal, so it shouldn't necessarily show any correlation at all. Overall a sufficiently long observation period, likely hundreds of years, it should average out to zero. The correlation of the PDO and global temperature change at least indicates that part of the warming we have seen could be simply cyclical redistribution of heat within the overall climate system. We simply are not able to measure everywhere with enough resolution to track all of these changes (e.g. measurements of the deep ocean are very sparse and large interpolations/assumptions are made).
Hmmm...Have to disagree here too. I do believe that the PDO is indicative of natural cyclical changes in the climate system that contribute to recent warming. However, it doesn't appear that they can be shown to be the only cause, as there is an underlying warming trend even when variations in the PDO are considered. Something has to be responsible for that, and CO₂ increases are certainly capable of causing some warming; thus it is reasonable to conclude that some of the warming is due to rising CO₂ levels.
There are also many ways in which we can cool the climate, such as the way aerosoles impacted the formation of clouds, which have a significant cooling impact on the climate.
Sure thing.
http://www.kirj.ee/public/Engineering/2007/issue_ 3/eng-2007-3-7.pdf
(Proceedings of the Estonian Academy of Sciences: Engineering, Volume 13, Number 3, pp. 260-268, September 2007)
- Olavi Kamer
http://www.leif.org/EOS/2009GL039628-pip.pdf
(Geophysical Research Letters, Volume 36, Issue 16, August 2009)
- Richard S. Lindzen, Yong-Sang Choi
http://www.kirj.ee/public/Engineering/2007/issue_ 3/eng-2007-3-7.pdfhttp://www.drroyspencer.com/Spen cer-and-Braswell-08.pdf
(Journal of Climate, Volume 21, Issue 21, November 2008)
- Roy W. Spencer, William D. Braswell
http://www.aai.ee/~olavi/cejpokfin.pdf
(Central European Journal of Physics, Volume 3, Number 2, June 2005)
- Olavi Kärner
http://www.aai.ee/~olavi/EE2007-ok.pdf
(Energy & Environment, Volume 18, Numbers 7-8, pp. 1059-1072, December 2007)
- Olavi Kärner
And when there are warm SSTs in the oceans, it is called a +PDO/AMO. The marine impact that the oceans can have is quite tremendous. Take New York City for Example. Severe Weather can usually never make it there at this time of year, since there is a more stable airmasses over NYC due to the marine onshore winds from the cool oceans that help cool NYC and make the atmosphere more stable there. The oceans have a huge impact on all continental landmasses.
I think that "little" is underexaggerated, but that's my opinion. Note that on the GISS map, the warming really occurs when the PDO/AMO are both warm, which is what has happened since the satellite data.
Right, because the PDO and AMO are a measurement of that particular location. They have a different impact on different places.
False.
Credit goes to BethesdaWX for making this image.
How about both?
There is still much uncertainly concerning climate sensitivity and feedbacks. Below are two more links concerning feedbacks from Dr.Spencer.
Strong Negative Feedback from the Latest CERES Radiation Budget Measurements Over the Global Oceans
Our JGR Paper on Feedbacks is Published
Concerning but not replying to № 162:
It is true that an overall negative feedback does not imply cooling, but they imply that warming will stabilize. The predictions of most climate models assume that destabilization of the system will occur and warming will far exceed that due to simple forcings alone.
Concerning the Texas A&M study:
The observation period is likely too short to make useful inferences about climate sensitivity; the same goes for Dr.Spencer's paper as well. We simply do not know which any certainty what the overall climate sensitivity is at this time.
With regards to the PDO, read this article
Link
If you don't want to read through the whole article, here's the main point:
Basically, as Sirmaelstrom said, the PDO index is created such that by the end of the period of time, there is no trend. What this guy does in this article, is he shows the data with the trend (first graph). With the trend, it shows warming.
What this all really means is that the PDO with the trend shows warming, just as global temperatures are.
So, raw PDO data trends(trend not removed), should roughly reflect global temperature trends (because they don't have the trend removed either). However, when the trend is removed, as in this case
it will not reflect global temperatures. Instead it will only reflect periods of warming and cooling. I believe this is what is misleading you to believe that the PDO is causing warming and/or cooling.
Please tell me how the PDO alters/changes/governs global temperatures.
That is the one piece of the puzzle your theory fails to explain. I've already showed how PDO with trend reflects global temps with trend, so if anything PDO reflects global temps, however if you still insist it's the other way around, please explain the mechanism for this process.
Surely you remember, correlation =/= causation
Sure thing. First, the PDO governs the temperatures by warming up the landmasses in both the Southern and Northern Hemisphere, where the landmasses brush the PDO. The Warmer than normal SSTs then warm the continental landmasses by warming the air that comes in the form of an onshore flow.
Next, as shown in my graph, the PDO and ENSO intertwine at the Equatorial Pacific. And what is very much known, is that the warming and cooling of the Equatorial Pacific greatly warms and cools the globe, due to Earth's Global Heat Budget. A cooler PDO would favor more strong La Ninas, which in turn would cool the globe.
.
Here is a news article from NASA supporting this.
QUOTE
"This multi-year Pacific Decadal Oscillation 'cool' trend can intensify La Niña or diminish El Niño impacts around the Pacific basin," said Bill Patzert, an oceanographer and climatologist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The persistence of this large-scale pattern tells us there is much more than an isolated La Niña occurring in the Pacific Ocean."
"The comings and goings of El Niño, La Niña and the Pacific Decadal Oscillation are part of a longer, ongoing change in global climate," said Josh Willis, a JPL oceanographer and climate scientist. Sea level rise and global warming due to increases in greenhouse gases can be strongly affected by large natural climate phenomenon such as the Pacific Decadal Oscillation and the El Nino-Southern Oscillation. "In fact," said Willis, "these natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it."
Correct. But remember that this could go both ways, such as co2 and temperature.
Yes, that is very interesting, although the error margins are probably even higher than the temperature proxy reconstructions to the year 1000.
Interesting nonetheless to see what this means for the future.
I have to admit, although I'm generally not concerned with what people say in response to my posts, it is refreshing to at least see someone make the effort to understand what I have to say despite the fact we probably disagree on a number of specifics.
I'm not entirely clear on what you meant in the last sentence, but I'm going to address with an assumption in mind. I can see where someone might conclude that the detrended PDO is simply a reflection of the global temperature trend. In a sense, we don't disagree on this. However, what is interesting to me is that the specific regional conditions that exist during a positive/negative PDO phase seem to correlate with periods of increases/decreases in global temperatures; the actual PDO index itself is just a number. I guess it is plausible that an increase in global temperatures could cause the changes we see during a positive PDO, but it seems more likely to me that the reverse happens. Maybe it's not even important which causes which, as it really just seems like an uneven warming trend.
The main point here, because of the way that we measure how much the earth has warmed, I believe a significant portion of the warming that we've seen could be due to cyclical redistribution of heat within the climate system, of which I don't think we have a complete enough understanding. I think the true warming signal would be better measured from time periods that attempt to neutralize this variation, say from 1945-1995 or something similar. Just working off the cuff here, and using GISS measurements as more desirable satellite measurements (in my opinion, of course) are not available that far back, I would say that would yield about 0.1°C warming per decade with PDO effects excluded; this warming would be due to other factors, of which CO₂ increases would certainly be a contributor.
An important consequence of this is that climate models assume far more warming than this, and consequently predict more warming than I think will verify. This is my opinion, of course.
Sure, but it seems pretty clear to me that looking at the two globes that the one on the right is going to have higher global SSTs than the one on the left. Am I only the only one that thinks this is obvious?
Seriously? The PDO was in a positive phase at least until the late 90s, and the long term phase is what seems to correlate to temperature trends. This is like saying that a La Niña begins right after the ENSO index peaks and begins decreasing.
Certainly possible, but I believe uncertain. I've never seen anything that convincingly places the cause of that cooler period on aerosols alone. Aerosols both cool and warm the atmosphere, depending on the type. There is still uncertainty on what the overall forcing due to aerosols is today, let alone forty years ago.
I'm not convinced that we can measure the "overall heat balance" with enough certainty. There are too many places where temperatures are too sparsely measured. Even outgoing longwave radiation is sparsely measured. We have an idea, but large uncertainties exist.
Sure! Could you present the evidence?
I'mI've got to go out for a while; I'll check back later this evening or tonight.Edited: LOL...What the heck?
Negative Feedbacks would reduce the warming, if they are not as great of a feedback. If the initial climatic response to co2 was 1 Degree F and the Feedback was -1.2 F, then co2 would cause -.2 Degree F of cooling, since the feedback is greater than the actual co2 increase itself.
Perhaps maybe the NH has more land than the SH?
Thus it is more variable than the SH, since the land temperatures are more variable than the ocean temperatures.
The Global Average though shows that when the PDO was cool, the temperatures cooled, and vise versa.
LOL I thought Global Warming meant more snow???
http://articles.cnn.com/2011-01-27/opinion/kaku.s nowstorms.global.warming_1_global-warming-monster- snowstorms-human-activity?_s=PM:OPINION
But we all love our conspiracy theories...
I have yet to see 1 personal attack from a "denier"
This is a made up myth that they always use when we really know where the attacks come from.
Just letting the 'readers' know.
Ok sure.
First the graphic.
I do too. Of course there is much more to it than that but at least you can see what the Heck I am talking about with it. I built a scale model of one and made youtube videos of it working in a stream I found here in Alabama.I works perfectly even in a very slow current which is 20 times less than the speed of the Gulfstream.
One thing for certain is that oceans store much more heat than the atmosphere because water has a much higher specific heat temp than air. So ocean cycles like the PDO and AMO do have an affect on the climate of earth. But this affect is not nearly the same as co2's affect. Ocean cycles affect the distribution of heat on earth. Co2 ghgs and other aerosols actually affect the total heat of earth's system. Unfortunately since temp graphs only show surface temps and not total heat of the earth, the AMO and PDO and other cycles alike (think ENSO) can give us a false sense of warming or cooling..
So in a global sense, the PDO and AMO have no affect on the total heat of earth. They only affect where the heat will be. However since we don't measure the total heat of earth, our graphs are altered by these cycles.
So to say the PDO or AMO are causing gw is wrong, because if we measured the total heat content of earth's system, these cycles would have zero effect. This is not the case with things like ghgs (co2), aerosols, or solar output, which actually affect the total heat entering or escaping earth's system.
There's personal attacks on both sides
That may be true, Tom--but only one side has science behind it. Sitting back and playing nice and hoping the deniers will eventually "get it" if we just politely explain the facts and let them think about it simply hasn't worked. We're going on decades now, and the planet continues to get warmer and warmer, while denialists, emboldened and bolstered by pro-pollution dollars, have weaseled their way into the halls of Congress.
One side's right; the other side isn't. Please don't fall prey to the siren song of false equivalence.
So are you saying that cooling the Gulfstream by 15 to 20 degrees during the summer months will have no effect on global climate?
right and wrong with regard to what?
The fact that globe is warming? Ok
but the future effects and how much warming humans are responsible for is still debated.
Of course they are debated; that's how science works, or is supposed to. But in the real world, this hasn't happened with AGW.
See, a science-minded person looks at the overwhelming data and says, "While the theory isn't fully fleshed out, and some details have yet to be filled in, it fits and appears to be getting more correct with each passing day." And the most profitable corporations in the most profitable industry the world has ever known look upon this as a threat.
Meanwhile, the person who is unfamiliar with the scientific method looks at that same data and says, "Gee, the theory isn't fully fleshed out, and some details have yet to be filled in, so therefore it doesn't fit and must be rejected altogether." And the most profitable corporations in the most profitable industry the world has ever known look upon this as an opportunity.
Which side do you imagine gets the money? The financial backing? And all that money buys attention from the mainstream media. It buys political candidates. It buys huge and well-orchestrated disinformation campaigns. And so gullible Americans--especially on the same end of the political spectrum that believed until Wednesday that the President was born outside the country--have listened to those campaigns, and the comforting words they produce. "There's no warming. CO2 is healthy for you. Our product can dump hundreds of billions of tons of pollutants into the atmosphere every year with absolutely no ill effect."
No more, Tom. The confident quiet displayed by scientists has been misinterpreted as weakness or lack of conviction by those who care only about profit, and that has to stop. Holding hands and singing "Kumbayah" with the denialists has only made things worse; it would be insanity to keep doing what we've been doing.
Thomas Jefferson famously said, "Ridicule is the only weapon which can be used against unintelligible propositions." So ridicule I will.
I discussed that already on Post 171. I'll repost it here, however.
POST 171
From NASA
"This multi-year Pacific Decadal Oscillation 'cool' trend can intensify La Ni%uFFFDr diminish El Ni%uFFFDmpacts around the Pacific basin," said Bill Patzert, an oceanographer and climatologist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The persistence of this large-scale pattern tells us there is much more than an isolated La Ni%uFFFDccurring in the Pacific Ocean."
The El Nino exerts extra energy into the atmosphere. With a PDO, that creates more El Ninos, which in turn released more energy into the air.
Your link is off topic, which is why I question your reading comprehension. We aren't talking about the THC. We're talking about the PDO/AMO.
That sentence is technically incorrect. The PDO can not be "cooling off" since it is not a measurement of temperature. The PDO is measured the same way a velcoity time graph in physics would be measured.
Note that while the velocity time graph in this image shows a decrease near the end, the position time graph continues to increase. The position time would be the temperature and the velocity time would be the PDO.
Sad and low personal attack.
Interesting image there Cyclone. How do you plan to implement these tunnels?
Viewing: 151 - 201
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 — Blog Index