Arctic sea ice: more bad news for 2014

NASA has just released data gathered from JAXA, the Japanese equivalent of NASA, on how much Arctic ice melted this year. The results are not good….in fact, they’re really bad. This is the sixth biggest year for ice melt, all the others of which have occurred since the year 2000. If you’re living in Miami, move: Miami Beach will be lost to rising seas within the next 20 years. If you don’t believe me, see what local government in Florida are already doing. The combination of loss of wetlands and rising sea levels will take out most barrier island like Miami….if the intensified hurricanes don’t leve it first.

Before I went to Churchill I posted a piece on why you need to be concerned about Arctic ice melt. I will probably sound like I”m stuck on a feedback loop (I don’t know that the metaphor of a “broker record” with a scratch in it that forces the needle to keep going back over the same section of the record has any continuing meaning in this digital age), but this concept is important for EVERY citizen EVERYWHERE to understand.

Ice reflects more than 90% of the sunlight it receives. Most of what comes in, goes out. Open sea water, by comparison, is dark, and absorbs about 90% of the solar radiation that hits is.

Think about that. As the ice melts, more solar radiation gets absorbed in the Arctic sea water. This is a lot of energy, more than the equator receives during July because the day up north is so much longer. If the ice is gone, that energy is going into the water, and is staying there. True, the ice will reform, but the water is warmer each year. This is a classic example of a positive feedback loop. Assuming relatively constant conditions, the Arctic will continue to heat. Water has one of the highest capacities for heat storage of all materials, often 10 times that of metals, and 3-5 times that of land.

If this continues, the permafrost in Russia, Alaska, Canada and Scandinavia will start to melt. As we discussed before, there’s a lot of undigested carbon in the tundra. If the permafrost melts completely, it will release exponentially more carbon than we’ve managed to put into the atmosphere since 1750. The drought in California and the American West will seem minor compared to the heat rise if that happens, and the worldwide flooding caused by sea rise will be devastating. Remember, the highest point in Florida is 119 feet above sea level. Florida, Louisiana, and lots of places in the American South will be the first to be inundated with the rising seas.

I am quite pessimistic about our taking any significant action that would make things better. Our children, grandchildren, and great-grandchildren will not look back kindly upon us if we don’t, and I’m sad to say that I think that a flooded, heat-stricken world will be our legacy to them.

Autumnal equinox

One of the surprising things about teaching science is that you realize that most people don’t have a clue about what causes the seasons. They think that it’s winter when we’re farthest away from the sun…which makes sense until you realize that our CLOSEST approach to the sun is on January 5, in the very dead of winter in the Northern Hemisphere.

Today is semi-officially the autumnal equinox, the day that fall begins. I spent the morning looking through videos on YouTube to try to find one that accurately shows why the autumnal equinox is important, namely, why the day and the night are the same length all over the word (hence the name “equinox.” I finally gave up, and have posted instead the above diagram.

For whatever reason, many textbooks display the earth as rotating straight up and down, with its axis of rotation perpendicular to the plane of the orbit of the earth around the sun. In fact, the axis of rotation is tilted about 23.5° off of the vertical. Any good globe will reflect this inclination.

The axis of rotation does not vary much as the earth orbits the sun. (There are some long-term wobbles that over long periods of times for humans–about 26,000 years–have the axis pointing to a different “North Star,” and long-term but small changes in the angle of inclination are the probable reason for Ice Age, but for out purposes we can assume that the axis is fixed, leastwise during our own lifetimes.) This, in turn, means that the earth will be inclined toward the sun in the Northern Hemisphere between March and September, and the Southern Hemisphere will get its turn for summer between September and March.

The 3-D geometry of a sphere rotating at a 23.5° angle from the vertical is difficult to visualize even when you see it, and almost impossible to describe when you can’t. However, if you take a properly inclined globe and walk around a center light (like a lamp without the lampshade) and keep the axis of rotation pointed in the same direction, you’ll find two points where the axis is perpendicular to the line drawn from the lamp to the globe. If you look at the illumination of the globe at that point, you’ll see that lights up exactly half of the earth. The earth is still inclined (most animations make it go upright, which is wrong, wrong, wrong), but the figure above gets it right on both the autumnal and vernal (spring) equinoxes.

Another feature of the equinoxes is that the sun rises directly in the east and sets directly in the west. That’s why many ancient monuments like Stonehenge or the Maya temples are aligned on an east-west axis. It takes 100-200 years of living in a location to figure such things out. The Griffith Observatory in Los Angeles has lines embedded in the concrete so you can line up and see the sun rise directly in the east and set directly in the west. I actually saw something similar in 2007, my first year of teaching. I happened to be riding a bus along a stretch of the 10 freeway just to the west of downtown Los Angeles that I knew was laid out exactly east-to-west, and watched the sun come up in the middle of the road. For the next six months, it rose off to the right (i.e., to the south) and then returned in mid-March, where it rose to the north for the next six. Even modern people can occasionally duplicated the efforts of our ancestors!

In the Northern Hemisphere, our days will shorten and be shorter than the nights until thereabouts of December 22, which will be the shortest day of the year. At that point the sun will be as far to the south as it will get, and between December 22 and the spring equinox, will travel back until it again crosses the east-west line. After that, the days will again be longer than the nights for another six months. One way of looking at the equinoxes is that the next six months will either bring nights longer than the days (autumnal equinox) or days longer than the nights (spring equinox).

Nothing new (except spectacular photographs) in the Holuhran eruption

The fissure eruption at Holuhraun in Iceland has remained more or less constant for the last week, and the announcements of the civil authorities are monotonously the same:  the eruption continues at the same rate as before, and it could stop or or it could spread to Bárðarbunga or have further smaller eruptions under the ice around the Dyngjujökull glacier. Or not.  There may be a big jökulhlaup, or a small one, or none at all.

The biggest news this week is that the sulfur dioxide emissions seem to be reaching all over the island, including the capital of Reykjavík. Rain has arrived, though, which washes dissolves the sulfur dioxide and, yes, washes it to the ground as acid. You can begin to see just how it was that a fifth of the Icelandic population died after 1782-83 and the sulfur dioxide emissions at the Loki fissure to the south.

We are still getting some spectacular pictures of the eruption. The picture above is from NASA of Holuhraun taken on September 6, 2014. The eruption shows even through the clouds. Also, Ólafur Haraldsson has put together an amazing short film of the eruptions. I particularly like what he’s done because you can see the heat waves rippling up around the caldera. Some of the bursts shot up to about 120 meters (almost 400 feet). Here’s the link to his film on Vimeo. Ólafur has a nice discussion of the geography and history of the area. As you would expect from someone who made the film, he’s also an accomplished photographer, and you should check out his website at www.olihar.com

From the air, Greg Duncan has also a number of astonishing shots which can give you a better idea of what the eruption looks like as a whole. He does a nice job of capturing the water-like flow of basaltic pahoehoe lava before it outgasses and slows to a’a. Find his photos here. (To navigate through the 17 photos he offers, click on the thumbnail of the picture in the upper right-hand corner of the page.) Be sure to look at photo 17, which will give you an idea of how water erodes lava.

On the more dangerous side, you can look at a close-up (like, 50 feet) phot0graphy spread from the Daily Mail and see if it qualifies for a Darwin award.

Sulfur dioxide and lava dams in Iceland

The Holuhraun fissure eruption in Iceland north of the Bárðarbunga volcano has not yet produced a spectacular ashfall grounding flights between Europe and North America (though it may yet), and is a reminder that volcanic eruptions can be long-term, relatively unspectacular events. By now, however, there are at least a couple of things that are clear: (1) the emissions of sulfur dioxide is enormous, and (2) we may seem some very interesting geomorphology develop in the coming weeks if the lava from Holuhraun dams part of the watershed from the Vatnajökull ice cap that flows into the Jökulsá á Fjöllum glacial river.

While the second will be more spectacular, the first concern will ahve a much larger impact. The freezing winters of the mid-1780’s in Europe were caused by sulfurous emissions fromt he Loki fissure to the east of the Vatnajökull ice cap, no far at all from the current eruptions. In fact, the fissures at Loki, which run down from the Grímsvötn volcano, which itself is not far from Bárðarbunga. The sulfur emissions are the greatest that Iceland has measured since it started testing for sulfur dioxide emissions in 1970. 44 years is not much of a record, though, and I have been looking for–and not finding–any scientifically-based commentary on whether this is likely to have an impact on the weather worldwide.

The sulfur dioxide is certainly having local effects. Pretty much everybody has to stay away from the eruption site, and all people east of the eruptions have been advised to stay indoors. Local sheep farmers are moving their sheep to the west of the Jökulsá á Fjöllum, in part to avoid harm to their livestock from noxious gasses (the 1783 sulfur dioxide killed enough sheep that one-fifth of the Icelandic population starved to death in the following two years) and, I suspect, in part to make sure the sheep are on the market side of the river if we end up if a subglacial eruption that causes a jökulhlaup flood that wipes out the bridges.

Of less world-wide importance, but possibly more geological and geographic interest, is the possibility that the part of the Jökulsá á Fjöllum will be cut off and will form a lagoon or lake, or possibly even new waterfalls. Thus far the lava has cut off some of the western tributaries while forcing the eastern tributaries farther east across the glacial outwash to the north the glacier. You can see from the picture at the top of this page that most of the outwash is sand. If the lava flows on top of it, the tributaries will just shift farther east. You can better see what’s happening on this map I put up a few days ago outlining the flow:

 

The flow is barely a kilometer away from reaching Vaðalda mountain, which is also volcanic. It looks to me like the river can still move farther to the east, although the geologists on the ground say that the river has nowhere else to go. It certainly has cut off all the drainage coming down off Askja, which is not insubstantial, include the following waterfall Drekafoss (“dragon-falls”):

If you look back at earlier maps I’ve posted, the map above no longer shows the braided western channels leading to the Jökulsá á Fjöllum. If the eruption stops soon, we’ll probably see at least some water pooling on the west. If we see a major eruption of Bárðarbunga which melts some or all of the 600 meters of ice, we’ll be seeing a major flood that may simply erode away much of the Holuhraun addition to Iceland….but we’ll be so focused on the air-traffic disruption that we probably won’t get to see the original site for weeks.

Update on Iceland

I’m mildly surprised that nothing has appeared in mainstream media about the Icelandic eruptions, especially since significantly more lava has been erupted than any eruption in Iceland since the Askja caldera collapsed in 1875. Here’s what we do know, besides that fact that the amount of lava is big, big, big.

First, the sulfur dioxide emissions have continued to the point where people with respiratory difficulties are urged to stay inside, and travel to the fissure requires wearing a gas mask and taking gas-sensing equipment. I haven’t found anybody who’s talking about how much SO2 is getting injected into the atmosphere, other than it’s more than any modern eruption. Sulfur dioxide is, to my mind, the matter of most concern, as if there’s enough of it, it will unquestionably cause some world-wide cooling by forming a sulfuric-acid aerosol high in the atmosphere that will reflect incoming sunlight.

BTW, don’t assume that that means we’ll get a break in the drought in the American West, although we might. There have been cooler time periods in history–the Younger Dryas millennium around 10,000 BCE, for example–which were characterized by major droughts in important areas of the world. (Brian Fagan thinks that the drought led people in the Middle East to turn from hunting-and-gathering to agriculture.)

Second, the lava has reached the Jökulsá á Fjöllum glacial river and is slowly crossing it, as seen in the pciture in this post. Oddly, the lava has not caused any ashfall, which often happens (“phreatic” reaction of lava and water is the fancy geological term if you think that will impress people; my experience is that using fancy scientific words makes Americans flee in terror into the night). In some ways, this isn’t surprising, because it looks to me like the lava has lost most of its dissolved gasses by the edge of the flow and looks like it’s a’a, which is very slow moving and solid.

The real question for immediate impact (and lots more pictures) is what’s happening with Bárðarbunga. As the lava has moved and started erupting at Holuhraun, the number of quakes on Bárðarbunga has gone down significantly from nearly 2,000 to 100-200 and even lower. On the other hand, the intensity of those quakes is increasing, with quakes of magnitude M5 occurring daily. More ominously, the caldera at Bárðarbunga continues to subside. An eruption here has up to 600 meters (about 2,000 feet) of ice to melt, and would cause a huge jökulhlaup that would be quite something to watch. This area is one of the least densely populated areas of Iceland and hard to get to, so while we would get dramatic footage and have all sorts of fun in seeing what a flood of Biblical proportions can do, the world impact outside pictures of such a flood would be minor. If accompanied by great quantities of sulfur dioxide, however, it could be significant, and a lot of ash would ground air transportation between Europe and North America, and possibly within Europe itself.

As always, stay tuned.

“Supermoons”: the glories of an elliptical orbit

All celestial bodies orbit their star or planet in an elliptical path. That means they have moments when they are closest to the parent body (apogee) and times when they are farthest (perigee). The earth, for example, is about 5 million miles closer to the sun on January 5 than it is at perigee during July. This is a delightful source of confusion for astronomy students, who assume that the proximity of the earth to the sun determines the seasons, which it does not. (Stay tuned for the correct explanation. No extra points will be awarded, but your instructor, having warned you, will be quite irritated if you don’t get the correct answer after the post in about 10 days on the equinox.)

On September 8 or 9, 2014, a full moon that is close to a “supersize” moon will appear. I’ve never been able to tell the difference between full moons that appear when the moon is closest to earth at apogee (‘supermoons”) and those that appear when the moon is close to being farthest from earth close to perigee (“micromoons”). Your visual perspicacity (as Noam Chomsky says, “you can look it up”) may be better than mine; I really can’t tell the difference, and a full moon is a thing of beauty in any case.But go out tomorrow night and observe a “supermoon.” Lest you think you’re watching something unique, though, there will be another close contender in about a year on August 30, 2015. You heard it here first.

What’s happening in Iceland?

The real answer: we don’t know for sure.

As the map above shows clearly, the lava stream from the Holuhraun fissure continues to flow, and is now within a kilometer (0.6 mile) of the river Jökulsá á Fjöllum. There’s some indication that conductivity is increasing in the river, which, combined with depressions along the top of  the Dyngjujökull outlet glacier to the south of the Holuhraun fissure, is an sign of possible subglacial eruptions. But the ice is thick, and we don’t know for sure.

On Bárðarbunga, there is now significant subsidence, up to 45 meters. That’s a collapse in the caldera equivalent to a building more than 10 stories tall. Eruption? Subsidence because of the eruption on the fissures to the north? We don’t know….yet. Here’s a map of the subsidence:

But enjoy this picture of the eruptions, taken by Jon Gustafsson, an Icelandic documentary maker and artist:

VOLCANO ICELAND 2014

New fissure eruptions closer to Vatnajökull ice cap

The Icelandic Met (short for Meteorological) Office has released a new map showing a smaller but ongoing fissure eruption that has started south of the main fissure at close to the glacier. The location is marked by the triangle in the map. The lava on the main fissure continues to advance toward the river, as marked by the circle in the upper right of the map. The numbers are the days–day first, followed by the month–of the lava flow.

NASA composite picture of Holuhraun

In science, what’s true and accurate isn’t necessarily what you can see. This splendid picture from NASA is a composite of an night infrared shot of the Holuhraun fissure eruption overlaid on a natural light (4oo to 700 nanometer wavelength) photograph of the area. It’s accurate, stunning…and something you’d never see in real time. Doesn’t mean it’s not a great and helpful picture. The false color lets you see the fissure, the vapor plume, and the lava flow, all overlying a picture that gives you the topography and the relationship to the Dyngjujökull glacier coming off the Vatnajökull ice cap. Well done, NASA!

Map of Holuhraun fissure eruptions

Thus far the eruptions in Iceland have been limited to fissure eruptions at Holuhraun, an area between the Dyngjujökull outlet glacier on the northern border of Vatnajökull, and Askja,, a volcano about 25 kilometers to the north of Vatnajökull. The University of Iceland has published a nice map, reproduced above, showing the exact spot of the eruptions, something I hadn’t been able to find elsewhere. This map also has a nice representation of the Askja caldera lake, which was formed much like much like Crater Lake in Oregon,when the magma chamber beneath the volcano collapsed after erupting out most of its magma.