Sea Ice South (2): Another Brick in the Wall
Sea Ice South (2): Another Brick in the Wall
My previous entry was setting the foundation for understanding the differences between sea ice in the northern and southern hemispheres. It focused on the physical geography of the Earth. Specifically, the distribution of land and ocean are different at the two poles; hence, there is no reason to expect one pole to behave like the other pole - beyond perhaps, they both get very cold in the winter.
This entry will focus on the basics of the physical climate needed to understand sea ice. As summarized in Spencer Weart’s excellent history, we have known for a long time that water vapor and carbon dioxide are ingredients of the atmosphere that are important to our ability to live on the planet. Specifically, based only on the amount of energy coming from the Sun, the temperature of the surface of the Earth should be about zero degrees Fahrenheit. It is the presence of greenhouse gases in the atmosphere that holds heat close to the surface for a while, leading to an average temperature closer to, say 60 degrees Fahrenheit.
When thinking about the climate, it is important to remember that the Earth is always cooling to get rid of the energy that comes from the Sun. A good way to experience this cooling and the effects of greenhouse gases is to spend a summer night in Death Valley, CA, and another summer night in the Everglades, FL. Because of the lack of water after sunset it cools down much faster in Death Valley. I like to think of this tendency to cool as a thermal spring always pulling the Earth towards zero degrees.
We have to remember another fact of the Earth, which is the tilt of the axis of rotation that is responsible for the seasons. As a result of this tilt, the solar energy that is directly received at the poles goes through huge cycles every year. In winter it is dark, and there is no direct solar heating of the pole. In the summer there is continuous light, but the heating is weak because the Sun is low in the sky. As a result of this tilt, far more energy comes into the Earth in the tropics than at the poles.
Interestingly, when we look at the energy leaving the Earth, on an annual average basis, there is not a huge difference between the poles and the tropics. What that means is that the “excess” of energy entering the Earth in the tropics is moved towards the poles, where there is a net loss of energy to space. This energy is carried from the tropics to the poles by the oceans and the atmosphere. Without transport of energy to the poles, in winter, when the Sun is not present at the poles, the temperature would drop to 100s of degrees below zero. That does not happen, but it still gets cold – cold enough to make ice.
That’s what the oceans and the atmosphere do. They are fluids that move to even out the distribution of energy – or effectively, heat. Therefore, the role of the atmosphere and ocean is pretty straightforward; they are not random and chaotic and unconstrained. They respond to heating and cooling through well understood physical mechanisms – like gravity and pressure. Another important force is due to the rotation of the Earth (see link at bottom).
One of the interesting things about transport is that it occurs in, let’s say, events or features. A useful metaphor on people’s minds this week is the Mississippi-Atchafalaya River Basin. The Mississippi and Atchafalaya Rivers carry a LOT of water in a channel to the Gulf of Mexico, where it immediately spreads out of the channel. You might say that it fans out, but it really doesn’t just diffuse into the Gulf. It moves as distinct features, as seen in this 2001 figure of sediment from NASA’s Earth Observatory.
Figure 1: Sediments in the Gulf of Mexico from Mississippi and Atchafalaya Rivers.
The water is channeled by the river basins; it is not like a shallow film of water spread out between Brownsville, TX and Homestead, FL. The water is channeled, and big events, like the spring runoff are responsible for a large portion of the transport. The atmosphere and oceans behave in the same way - heat is transported, preferentially, in certain places, for example in ocean currents such as the Gulf Stream and atmospheric storm tracks.
Let’s focus on the ocean. If a current like the Gulf Stream brings a lot of warm water to Greenland, then what keeps all of that water from piling up in the Arctic? There has to be a return flow, and that return flow takes cold water back towards the tropics. The Earth’s weather is just part of mixing warm and cold.
Okay, it’s time to pull together this information. The temperature at the poles, especially in the winter, is largely determined by oceanic and atmospheric transport of heat. Alternatively, the heating and cooling at the winter pole is not day-to-day determined by the radiative energy from the Sun and greenhouse gas concentrations. The heat transport occurs in preferential locations, and return flow takes cold air and water back towards the tropics in preferential locations. Fluctuations in the preferential locations mean that warm and cold regions move around. Given the information from the previous blog, the North and South Poles are different. Hence sea ice behavior is different.
Sea ice – I am setting the foundation for sea ice. From two blogs ago, one on the Northern Hemisphere, there was a number associated with the melting of the Arctic sea ice. That number is 1 watt per square meter. The melting of the Arctic sea ice that has been observed over a certain amount of time, say a decade or two, is consistent with a sustained, change in the energy balance of 1 watt for every square meter – that’s about a square yard – 3 feet by 3 feet. How much energy does this represent? Let’s go to an iconic figure of the radiative balance the Earth updated by Trenberth et al. in 2009.
Figure 2: The global annual mean Earth’s energy budget for the Mar 2000 to May 2004 period (W m–2). The broad arrows indicate the schematic flow of energy in proportion to their importance. (from Trenberth et al. , 2009)
I am mainly interested in sizes. The amount of energy at the top of the atmosphere from the Sun is about 341 watts per square meter. Ultimately, that is also just about the amount of energy that goes back to space. In the various ways that energy is absorbed and reflected and transported there are numbers in the figures that are 10s watts per square meter. Down at the very bottom of the figure is the amount absorbed by the Earth – in this figure 0.9 watt per square meter. (Very close to 1, I note.)
If we look at the energy that is transported to and away from the poles as well as that associated with energy from the Sun and emitted back to space, then there are several paths that deliver or take away 10s of watts per square meter. A change of 1 watt per square meter can be realized in several ways. And if we get right down to sea ice it gets more complicated. What happens if there is more fresh water in the ocean because of more rain, more snow, more melting of ice sheets? Fresh water freezes at a higher temperature than salt water. So could it in fact get warmer and freeze more ice in the ocean because the water is less salty? Plausible, I assert – it would become a matter of measurements, and numbers, and untangling the many different paths that energy is provided to and taken away from the surface of the sea.
Next time I will get a little more specific about the southern ocean and its sea ice.
r
(If you want to see cool movies that show how rotation organizes flow go to MIT and look at these movies.)
Useful links
Recent sea ice trends
Sea ice data
Rood’s Blogs on Ice
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Hate to say but I already assigned that to you blokes
back at post 71.
Read it and weep.
You sir are a skeptic and therefore do not deserve an
answer, simple empirical evidence gets in the way of
AGW guilt. Same old story, same old song and dance.
Original Sin
the condition of sin that marks all humans as a result of Adam's first act of disobedience.
And anything else that can be blamed on us.
Or Perpetual Guilt
some religions teach perpetual guilt/shame as a corrective device, and some people accept those teach- ings as their soul's guide.
ECOguilt as a religion. seems fitting.
Kudos to Bill McKibben for a very well-written piece of political propaganda; what you can't prove with actual evidence, strongly imply as eloquently as possible. To be sure, it's an effective editorial--Mr. McKibben would've made a great lawyer--however, in the end, it is just an editorial and nothing more.
What problems do you have with the UAH data set? Certainly it has it's limitations, as do all of the data sets. How has the UAH data "[not] been shown to be exactly objective"?
* * *
№ 294
You're going to go crazy following that thing day-to-day. The recent drop doesn't look all that different than the normal amount of variation we've seen all year. If it were to stay level at the present value for the rest of the month, it looks like the seasonally-adjusted UAH monthly value would be similar to April's (just eye-balling here though). Of course, I think it's more likely that it will rise some, and the May value will be somewhat higher than the April one.
Two Greenland Glaciers Lose Enough Ice to Fill Lake Erie
ScienceDaily (May 24, 2011) — A new study aimed at refining the way scientists measure ice loss in Greenland is providing a "high-definition picture" of climate-caused changes on the island.And the picture isn't pretty.
In the last decade, two of the largest three glaciers draining that frozen landscape have lost enough ice that, if melted, could have filled Lake Erie.
The three glaciers -- Helheim, Kangerdlugssuaq and Jakobshavn Isbrae -- are responsible for as much as one-fifth of the ice flowing out from Greenland into the ocean.
"Jakobshavn alone drains somewhere between 15 and 20 percent of all the ice flowing outward from inland to the sea," explained Ian Howat, an assistant professor of earth sciences at Ohio State University. His study appears in the current issue of the journal Geophysical Research Letters.
As the second largest holder of ice on the planet, and the site of hundreds of glaciers, Greenland is a natural laboratory for studying how climate change has affected these ice fields.
Researchers focus on the "mass balance" of glaciers, the rate of new ice being formed as snow falls versus the flow of ice out into the sea.
The new study suggests that, in the last decade, Jakobshavn Isbrae has lost enough ice to equal 11 years' worth of normal snow accumulation, approximately 300 gigatons (300 billion tons) of ice.
"Kangerdlugssuaq would have to stop flowing and accumulate snowfall for seven years to regain the ice it has lost," said Howat, also a member of the Byrd Polar Research Center at Ohio State.
Surprisingly, the researchers found that the third glacier, Helheim, had actually gained a small amount of mass over the same period. It gained approximately one-fifteenth of what Jakobshavn had lost, Howat said.
The real value of the research, however, is the confirmation that the new techniques Howat and his colleagues developed will provide scientists a more accurate idea of exactly how much ice is being lost.
"These glaciers change pretty quickly. They speed up and then slow down. There's a pulsing in the flow of ice," Howat said. "There's variability, a seasonal cycle and lots of different changes in the rate that ice is flowing through these glaciers."
Past estimates, he said, have been merely snapshots of what was going on at these glaciers in terms of mass loss. "We really need to sample them very frequently or else we won't really know how much change has occurred.
"This new research pumps up the resolution and gives us a kind of high-definition picture of ice loss," he said.
To get this longer-timeframe image, Howat and colleagues drew on data sets provided by at least seven orbiting satellites and airplanes, as well as other sources.
"To get a good picture of what's going on, we need different tools and each one of these satellites plays an important role and adds more information," Howat said.
The next step is to look at the next-largest glaciers in Greenland and work their way down through smaller and smaller ice flows.
"Currently, the missing piece is ice thickness data for all of the glaciers, but a NASA aircraft is up there getting it. When that's available, we'll be able to apply this technique to the entire Greenland ice sheet and get a monthly total mass balance for the last 10 years or so," he said.
Along with Howat, Yushin Ahn, a postdoctoral fellow at Ohio State's Byrd Polar Research Center; Ian Jouglin of the University of Washington; Michael van den Broeke and Jan Lenaerts, both of Utrecht University in the Netherlands, worked on the project.
The work is supported in part by the National Aeronautics and Space Administration and by the Climate, Water and Carbon Program at Ohio State.
Link
On the lighter side.
http://www.youtube.com/watch?v=H7wdKg8rYL0&featur e=iv&annotation_id=annotation_633970
times in the past but if your plan works it would be
a monumental attempt at a global thermostat. Decrease
the heat flow north and in theory refreeze the north.
If this works as planned, the EU is going to want have a say at the controls, it would seem to me and some in British Isles. How will much it cost?
A snippet below:
Is summer 2011 set to be a scorcher?
Paul Hudson
Last but by no means least comes Joe Bastardi formerly at Accuweather.com and now at US company Weatherbell, based in New York.
His analysis is often second to none, and he has an army of followers and private clients in America. I contacted him at the weekend, and he has produced a very interesting analysis which you can read on his website by clicking here.
Joe expects a summer warmer and drier than average, a 'decent English summer' as he put it to me. But he also thinks that a long hot summer (he uses the example of 2003 which across Europe was one of the hottest on record) is 'highly doubtful'.
His main reasoning is that temperatures higher up in the atmosphere have cooled dramatically, and are much cooler than during the last hot European summer in 2003.
In fact upper level temperatures at 25,000 ft are cooler than at just about any time in the 13 year data set he showed me.
This he says will act as a lid on the level of temperatures that can be achieved - in short, if temperatures at the surface that you and I experience get too high, the colder than normal temperatures aloft would cause a destabalisation of the atmosphere, leading to higher rainfall.
Finally, a close look at the climate records indicates that blocking weather patterns through Spring which have led to the very dry weather across parts of the country mostly give way to a less settled scenario through the following summer, although there are exceptions to this, like in 1976, 1995 and 2003.
As ever, long range forecasting is fraught with dangers and even the most skilled operators can get it wrong. But a summer along the lines of 1976, although it can't be ruled out, would be a big surprise. But as ever it will be very interesting to see who is right.
And by the way, Mr Bastardi also told me he is more than happy for me to add that he thinks we are in for a prolonged cold winter again this year. Now that would raise a few eyebrows!
Link
The "diurnal cycle effects" referred to in the link you gave seems to be a reference to the orbital drift of some of the satellites. The NOAA-15 satellite--from which some of the channels of the Discover AMSU data comes--is one of these satellites. However, the Ch.5 data and the SST data do not come from this satellite; this data comes from the Aqua satellite which maintains it's orbit's equatorial crossings at 1:30am and 1:30pm, and does not have the bias that the NOAA-15 satellite has. The UAH lower tropospheric temperature estimates also do not use NOAA-15 data.
See the link below for more detail:
Daily Global Temperature Updates on the Discover Website: An Updated Tutorial
I'm flattered you remain so obsessed with me, but, seriously, for the benefit of the blog, perhaps it'd be best if you moved on to something else?
For what it's worth, though, I am writing yet another novel. Perhaps I'll send you an autographed copy... ;-)
On the graph from the Univ. of Col. below, the global mean sea level has spent some time below the linear trendline over the last couple years. I'd say it's still too short to say there's a change in the overall trend. It probably has more to do with the fact that we've seen two significant La Niña events over the last few years. Time will tell.
From here.
I was thinking 30 billion to save 30 trillion in damages by 2050. The great thing about regulating Gulfstream Kinetic Energy is that it can regulate our climate. They are not an on off switch for our climate they are in fact a thermostat.
The depth and breadth of denialism in this country is astounding at times. For years--decades, even--climatologists have been saying that one of the likely side effects of warming will be an increase in the frequency and severity of extreme weather events. And now that that seems to be happening, denialists are falling all over themselves trying to claim there is absolutely no link whatsoever between the current warming and the weather events. What's going on nowadays is just par for the course, they say. Normal. Typical. Average.
Right. Keep telling yourselves that...
So does this mean that sea level was falling prior to 1998 since the change in sea level was negative? The axis is delta mm, or change in mm elevation. Negative numbers would mean it was falling. Where was it falling? In Colorado?
No. Nowhere in my post did I say that. I stated that "the global mean sea level has spent some time below the linear trendline over the last couple years". This was in response to RMueller's post where he was alluding to the idea that sea-level rise has slowed over the last few years, which indeed it has. However, as a stated in my post, I don't think the recent slowdown can yet be seen as a change in the long term trend.
№ 317
Some climatologists may be saying that severe events will increase due to warming, and computer models may indeed show this as well--after all, they are designed with this assumption in mind. However, observational evidence does not yet show a connection which is why we cannot attribute recent severe events to global warming, nor can we rule it out. Just following the science here.
It would take a truly slanted point-of-view to claim that the recent uptick in the severity and frequency of extreme weather events absolutely has nothing to do with climate change, especially when that's been predicted for years. As Dr. Masters frequently states when talking about the correlation between the two, we don't know. Now, that doesn't mean there is a correlation. But neither does it mean there is not. Stating either with certainty is, at this time, foolish. If you disagree with that assertion, please feel free to try to prove me wrong.
And I truly don't "pounce" an anyone who thinks differently than I do. But science deals in absolutes. If someone comes here and claims that the sun is closer than the moon, I will "pounce" on him. Not because he disagrees with me, but because I know him to be wrong. Period. I suppose that person could respond by calling me an arrogant know-it-all. That's certainly his prerogative--but it doesn't make him anywhere near right.
OOPS! They had to raise the annual tornado count bar from 1200 to 1400. Thanks fossil fuels. Sadly,they may still have to do it again!
Gulfstream Kinetic Energy lowers the annual count bar!Ya'll with me yet?
"Many" scientists don't disagree. A handful do. The overwhelming majority are in very close agreement about what's happening.
It would suggest that--if only it were true. But your statement is utterly false, as those "record cold temps" aren't really records; they're merely below the average of the last decade.
See the previous answer.
Yes, we're taking a 150-year record. And a 300-year record. And a 500-year record. And a 1,000-year, and a 5,000 year, and a 10,000 year, and a 100,000-year record.
There's nothing "only" about rapid warming.
Yes, there is. I define a consensus in this case as "the large majority of people qualified to speak in their field agree that the planet is warming rapidly, and it's because of fossil fuels".
See the fourth paragraph above.
Yes. But it's never grown so warm so fast without mass die-offs. Never.
Wrong. Plain wrong. And for the record, just once I'd like to hear a denialist explain how not allowing a single industry to ruin the planet for everyone else equates to forcing us back to the stone age. Seriously, what does that even mean?
Now, don't ask me to link once again to the vast amounts if science supporting the above positions; I and others have done so numerous times, so at this point you know where to find the info you need.
What you see in most ice cores is essentially a 100 year average temperature, plus or minus 30 years. What really happened during those 100 years, on a scale of individual years or decades cannot be determined.
I didn't mean to be so obtuse,
the graphic in your post says that prior to 1998 (say 1996) the change in Global Mean Sea Level is -10 mm, based on the University of Colorado graph, corrected for seasonal trends and glacial rebound, etc.
The Y axis in the graph you posted, is not elevation, it is change in elevation (that is usually what Delta means). That means, to me, that global mean sea level fell a centimeter in 1996.
If the delta refers to some vertical datum or something else, please elucidate. I'm trying to figure out what your graph is saying.
I followed the link. It says that Glacial rebound is making the oceans deeper somehow, that is partially compensating for thermal expansion. I thought rebound made the oceans shallower as the continental shelves sprung back.
All that said, I still don't get your/their graph. Is it pressure or water surface elevation they are measuring the change of?
Thanks,
Ahh...I think I see what you were referring to. I'm not sure why the delta was given on the vertical scale of the graph. I was and still do assume that the y-axis is simply in units of mm Mean Sea Level as an anomaly to some arbitrary zero point. The rate given in the graph of the overall rate (given as 3.1 ± 0.4 mm/yr) seems to be consistent with the idea that the vertical axis is simply mm of mean sea level.
In short, I think the y-axis is indeed elevation in this graph. I'll admit, the use of the delta does confuse the issue a bit, but I think it's simply included to indicate amount of change from the arbitrary zero level. If the graph was intended to show
accelerationrate of change of MSL instead, I think it would have been labelled as dMSL/dt.I was perhaps a bit abrupt in my response as well, I guess. No hard feelings here.
Edited/Added: I guess 'acceleration of MSL' is not actually what you were assuming the y-axis was. You were indicating that it was 'rate of change of MSL'. Made changes to the post. I still think this in not what is being indicated. If it were 'rate of change of MSL' it would have been labelled 'mm/yr' for the y-axis. In that case, the overall trendline would be 'acceleration of MSL' and the value with correct units would be 3.1 ± 0.4 mm/yr²
Proxy data quite clearly show that global temperature fluctuations during the interglacial cycles of the past several hundred thousand years were much slower--by an order of magnitude--than is the current warming. The fact is, global temps appear to have never risen this fast outside of major catastrophic events such as the PETM (which saw many extinctions after the global temp rose 11.F over a period of 20,000 years).
That just doesn't seem like something we should be inducing out of negligence and/or a desire to enrich a relatively small handful of people.
Scientists. Not Fox News hosts or ExxonMobil "climate specialists".
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