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Last Updated: 2:47 PM GMT on May 16, 2013
— Last Comment: 8:10 PM GMT on May 21, 2013
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Drought in the South
The Atlanta Journal Constitution recently reported that Georgia was losing billions of dollars because of the continuing drought in the Southeast. The governor of Georgia has asked for federal aid, and in his remarks he talks about this being, at least in part, a man-made crisis. The man-made part is not due to climate change; it is due to water policy. The severity of the situation highlights our stress on water resources. There are agreements about the release of water from North Georgia reservoirs to communities downstream in Alabama and Florida. Some of these releases are for the protection of endangered species - a cause that always comes under pressure when in conflict with the economy or human welfare. What I find most portending is the release of water from reservoirs to cool the rivers after the river water has been used to cool power plants. Energy production requires vast amounts of water. What is the relation of climate change to this drought its impact? I have written previously that because of consumption and population pressure, we have already stressed our environment. In many cases, the projected climate change amplifies these stresses. What is happening in the Southeast (and the Southwest) is the type of crisis that we are likely to see more of. There is a need for water policy, efficient use of water, and anticipation of how climate change will impact water resouces. Exactly two months ago I first wrote about this drought. There had been, at that time, sustained localized drought, especially in North Alabama. It has grown since then. In the figure, below, the drought in the Southeast and the continued wetness in Texas form an interesting couplet. Much of Texas had been in a major drought prior for the past few years.  Figure 1: Palmer Drought Index from National Climatic Data Center. ( Here’s an animation of the last few months. ) A basic requirement for climate models should be the ability to simulate the processes which maintain the moisture budgets over the continents. For the eastern United States, in the summer, the high pressure system, known as the Bermuda High, is one of the critical features. The Bermuda High is of different intensities and stubbornness from year to year. This year, the Bermuda High has pushed into the Southeast, and it has been very stable. In the center of a high pressure system there is usually the downward movement of air, and therefore, no rain. When a system like this is stuck over a region there is drought. More generally, the summertime moisture budget of the United States, east of the Rockies, is strongly related to the Bermuda High and the Rockies. Moist streams of air move northward from the Gulf of Mexico. These rivers or air are often close to the surface. On their westward edge, they are guided by the elevation of the land and, ultimately, channeled by the Rockies. The impact of the stubborn Bermuda High steering moisture over Texas and the lower Midwest is clear in the figure. In a year where the Bermuda High is more variable, the moisture flux fans out over the southern coast of the U.S. Often droughts in the Southeast of the U.S. are broken with a hurricane or two. This has not happened this year. The Bermuda High helped to steer the hurricanes into Central America and Mexico. There is not much chance of a hurricane breaking the drought this year – the drought is likely to continue. Here’s a link to a couple of related blogs ... The persistence of patterns and climate change. Droughts, heat waves and fires. r California Fires: In the past two days I have been called by CNN and ABC about whether or not the wildfires in California are part of climate change. Exactly how they decided to call me is an algorithm that I am not sure I could figure out, but I blog, so I clearly will talk about anything. The Santa Ana winds are not being caused by climate change. They’ve been around longer than Santa Ana. It’s wind falling down a hill, which warms the air, lowers the relative humidity, and sucks up moisture from the ground. Bad stuff for fire fighters. The fact that the fires are so damaging is that they are in places where people have built in very dry and very vulnerable places. And for the most part, people seem to set the fires one way or another. It’s mostly a land-use and land-management issue. If, if, if there is anything to do with climate change it would be that the extended drought has warmer temperatures than similar droughts in the past, and hence, drying is worse. I cited some research earlier that made such a argument in a way that has some substance. (Droughts, heat waves and fires.) In answering the question, I did come across two recent papers. One that showed that there is an El Nino – La Nina cycle in Santa Ana winds in March. The other showed that in a global warming forecast, the frequency and the seasonality of the Santa Ana winds would change. Here are the links to those titles. Finley and Raphael, Santa Ana winds and El Nino (Professional Geographer) or Finley and Raphael, Santa Ana winds and El Nino Miller and Schlegel, Santa Ana winds and climate change (Geophysical Research Letters) and Miller and Schlegel, Santa Ana winds and climate change (Lawrence Berkley National Laboratory)  Figure 2: Smoke from multiple wildfires burning in Southern California, together with dust in Southern California, Baja California and mainland Mexico, swirl out into the Pacific and Gulf of California, respectively, in this false-color visible image from the Atmospheric Infrared Sounder on NASA's Aqua satellite, acquired at about 7 p.m. Eastern Time on October 22. More pictures of the SoCal fires from NASA’s Earth Observatory View (27) Comments For This Post
Nobel, Stories, Sea Ice North – The End
First I will finish the northern sea ice, then below, I have a question that I need help with, and I can’t ignore the Nobel Prize. The last two blogs have been about the sea ice in the northern and southern oceans. I started down the path because of the discussion in earlier blog comments that suggested the observations of sea ice stability and growth in the southern hemisphere challenged the basic ideas of global warming. This will be the last blog on the North, and I think I’ll wait awhile for the South. The carry away points – the summer trend of melting in the northern summer is strongly correlated with increased infrared radiation, which is associated with more moisture in the air, and warmer temperatures. Other points were how the balance of sea ice and sea water were related to more than just air temperature. The links to the old blogs are at the end. This blog is a little more about the idea of whether or not there is a tipping point. One significant event would be if the sea is warmed enough in the summer that ice formation in the winter was reduced. Then spring and summer would see less ice, more water would be exposed, and because water absorbs more solar radiation than ice, the sea warms. Going into the winter the sea water is warmer, ice formation is delayed, and there is less ice in the winter. Because the ocean is good at holding heat, it would take a long time to recover from this. As reported by Walter Meier, Julienne Stroeve, Florence Fetterer, and Ken Knowles, of the National Snow and Ice Data Center, in the September 9, 2005, EOS, Transactions of the American Geophysical Union, there is, recently, a trend in the winter sea ice. They also report that the wintertime ice reductions occur in the entire Arctic basin, on both the Atlantic and Pacific sides. The occurrence of the reductions throughout the basin is a piece of evidence that the reductions are not due to some sort of atmospheric circulation anomaly, such as the Arctic Oscillation. (Yes, 2007 was not another winter record low, but it would be hard to say it started a recovery. See here.)  Figure 1: Wintertime Growth of Arctic Sea Ice There is substantial evidence that the decrease of the Arctic sea ice is due to a systematic warming of the northern high latitudes. Because the northern pole is covered with water, not land, it is especially sensitive to global warming. Both the ocean and the atmosphere are able to carry heat to the pole. This balance of sea ice and sea water is complex, and it is susceptible of change. Once the balance is shifted away from ice towards water, sea water absorbs heat that sea ice would reflect and the warming is further accelerated. The fact that the north pole is, first and foremost, a maritime environment explains the large difference in the predictions for the north and the south. It also means that to think of the north and south as analogues to be compared for consistency is not a justified assumption. Changing Subjects: I have this idea that I have been promoting and getting some traction. Climate Stories. It is a collection of personal stories, perhaps, oral histories. This is a nuance of the traditional folk history, because rather than looking to the past at something that is disappearing, we are acting on a prediction of big changes. And – at the same time our parents, grandparents, and we have lived through a heap of CO2 increase and temperature increase. We have a lot to talk about. I need some test stories for the person developing the collection software. The farther away and the more remote, the better. Hoping to find a few through the blog here. Don’t be shy. Nobel Prize: Everyone has talked about the Nobel Prize – and you know I don’t usually talk about what everyone is talking about. A couple of things. Almost exactly two years ago, I spent some time with Al Gore. What struck me was his true passion about climate change, the environment in general, and his sense of humor. Every one walked out of the room thinking this was a different man than the one we saw campaigning. He and his organization consume information from all aspects of climate science and climate change. They do a good job of turning it in the material that they produce. People with such passion are a marvel to me. As for the IPCC, in my earliest blogs I talked about the breadth and the rigor of the IPCC. Yes, the Nobel Prizes often make a statement. They are always made with merit. This is more than a significant honor. The Sea Ice Blog Collection Sea Ice in the North Sea Ice North and South Links to some relevant old blogs The End of Ice Fast Ice 1 Warm Snow View (24) Comments For This Post
Sea Ice Arctic
In my last blog I introduced the idea that sea ice production and loss was more complex than just the temperature of the air. There is this stew of processes which include water temperature, air temperature, saltiness, and both solar and infrared radiation. One point I tried to get across was that in our current climate, and in the recent pass, sea ice exists on the edge. It is balance of all of these ways of heating and cooling. This blog, I want to get a little more precise. First, I posed a couple of questions about fresh water at the end of the last blog. The first question was about what happens if fresh water collects around sea ice. Fresh water is lighter than salt water, so if there is fresh water around sea ice then it tends to “float” on top of the more dense salt water underneath. The fresh water also freezes at a warmer temperature than salt water. This ice is even less dense. So fresh water on top of salt water is “stable;” it could be viewed as the sea-water equivalent of “hot (less dense) air rises.” Salty water tends to sink and start a circulation. The other question I posed was about where would fresh water come from. It could come from rain and snow, and it can also come from rivers. Therefore, what happens in the northern and southern hemisphere is different because of the distribution of land and rivers and precipitation. In addition as the sea freezes and thaws, there is a change in the salt content. When sea water freezes there is a separation of salt from the ice. So the ice is fresher than the sea water that started to freeze. In the short term the water that is extruded from the ice is more saline and the sea around the ice is saltier. Within the ice are bubbles of very salty water, which sink through the ice and contribute to melting. When the bulk of the ice melts, it makes the sea fresher for a while. This cycle of salt changes the density of water and helps create a stirring of water down and up. So what happens in the Arctic? There was an interesting paper in the 14 November 2006, EOS, Transactions America Geophysical Union (J.A. Francis and E. Hunter). This study looked at the energy budget at the edges of the Arctic sea ice. What they found is that where the sea ice loss is greatest, there is increased downward flux of infrared radiation. The melting is strongly related to cloudiness and the increase of water vapor. This increases the amount of time that terrestrial heat is held near the surface of the Earth; this is the greenhouse effect. Increasing water vapor? That comes from increasing atmospheric temperature; warm air holds more water. What we have, approximately, in the northern hemisphere is a situation where sea ice is formed at the bottom and melted at the top. I have tried to represent this in the figure. Also in the figure I represent the radiative balance and what has changed. For more details of the radiative balance see this blog. Clouds Cool and Warm  Figure 1: Simplistic summary of Arctic sea ice Two things: I would like to thank Dr. Elizabeth Hunke from Los Alamos for teaching me in the last few much of what I do know about sea ice. And I have a new piece on BBQ published here. Link to Francis and Hunter: New Insight into the Disappearing Arctic Sea Ice. Recent sea ice trends Sea ice data LINKS TO MY OLD BLOGS The End of Ice Fast Ice 1 Warm Snow View (14) Comments For This Post
Sea Ice North and South
If you follow the links in this there is a lot of interesting reading! There was a lot of discussion about melting sea ice in the Arctic and, perhaps, no melting sea ice in the Antarctic. In his blog, Jeff Masters has been regularly visiting the sea ice in the Northern Hemisphere and talking about its record decline. Some of you may recall that I had a series of blogs (Links at the end) on ice melting, and how when you consider the interaction of water with ice, ice can melt much faster than when it is just a dripping block. It’s like stirring your ice rather than just letting it sit there. In 2004 when I went on sabbatical, I thought that sea ice and sea ice modeling must be simple. There is transport of ice and there is melting of ice. By coincidence, I started to diagnose an excess of sea ice in a new configuration of a climate model. I was surprised to learn the immense complexity of the physics of sea ice. Here is a link to one of the world’s most used sea ice models. CICE at Los Alamos In this blog I will summarize some of the elements of the physics of sea ice. This is to get you thinking about the problem beyond whether it is just hot or cold. Here is a nice essay from NOAA on sea ice. Here is a link to a story about my friend David Barber, who does all sorts of things with sea ice and polar bears. First, remember that by definition, sea ice exists at the edge. It exists at the edge of freezing and thawing. Sea-ice is made by the freezing of sea water. Intuitively, it is formed in the winter. What happens in the summer? There is in general a decline of sea ice in the summer; there is melting for various reasons. Since sea ice sits on the edge of a phase transition (freezing and thawing) its distribution is sensitive to small changes in the environment. I was diligent to avoid, in the previous sentence, saying that the sea ice was sensitive to small changes in “temperature.” Sea ice depends on far more than temperature. Remember the sea is salty and all of us who sprinkle salt on our icy sidewalks know that salt melts ice. Therefore, 1) sea-ice forms a little below, about - 1.8 C, our normal idea of freezing (0 C, 32 F), and conversely, 2) sea ice is sensitive to the salinity of the water. To make it more complex as sea ice freezes and thaws it changes the salinity, and if the salinity is different, then its thaw-freeze temperature is different. What about the temperature? The sea ice is sensitive to the air temperature and the water temperature. It is also sensitive to the absorption of solar and infrared energy. If the ice is dirty and dark, then it absorbs more solar energy in summer. If the ice is cracked and there is sea water in the cracks, then the water is dark and absorbs heat. If there is fresh white snow, sea ice is insulated from both air and the sun. And that air and water temperature: Sea ice does not just melt because the air temperature is warm or the sun is shining on it, sea ice is also melted from below by the unfrozen sea water. Sea ice exists on the edge in every direction, up, down, north, south, east and west. Going back to those blogs on ice melting - once there are pools of water on the ice, it starts to flow and can accelerate the melting. Then there is that salinity again. The salinity changes the density of the sea water. Therefore, salinity helps to determine how the water circulates. Remember if more dense water sits on top of less dense water, it will sink, and other, perhaps warmer, water will come to the surface. To make it even more complex – what happens when fresh water freezes and makes ice? It expands. What happens if water is heated towards boiling? It expands? Water is odd; it is expanding with both heating and cooling – at least close to freezing and boiling. Putting enough salt in water completely changes this behavior. And, this messes with the density, and then the dynamics. A point: When you think about the northern and southern hemisphere, you have to think about much more than the atmospheric temperature. You have to think about the radiation budget, the cleanliness and the dirtiness of ice, snow on the ice surface, the ocean temperature and the ocean circulation. You have to think about how the wind blows the ice around – does it bunch it next to the coast or blow it into open warmish water. And, in many cases what might be most important is salinity, and the density changes and freezing temperatures associated with differing salinity. What if there was fresh water collecting around the sea ice? Where could fresh water come from? Recent sea ice trends Sea ice data LINKS TO MY OLD BLOGS The End of Ice Fast Ice 1 Warm Snow View (32) Comments For This Post
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