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Last Updated: 2:47 PM GMT on May 16, 2013
— Last Comment: 4:51 AM GMT on May 19, 2013
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Records and Patterns
It is hot in Phoenix, Arizona, where the record was just broken for the number of consecutive days above 110 degrees F. Here's a story or two. Christian Science Monitor Washington Post Both of these stories talk about the urban heat island effect, and mention CO2 global warming as well. Phoenix is one of the places where the heat island effect is most obvious. There have been huge increases in the nighttime temperatures. Here is the link to the National Climatic Data Center's Summary Report for the U.S. in July 2007. Here is the dot diagram of the July 2007 temperature anomalies.  The eastern half of the U.S. was cooler than normal, which provided the core for some of the Rush Limbaugh discussion in early August. The western half of the U.S. was very hot, especially in the states of Idaho-Montana. Taken as a average, the country was above the long-term average, the 15th warmest July since 1895. (This is based on preliminary data.) This sort of warm-cold pattern is familiar to those who look at atmospheric observations. The patterns are related to high and low pressure centers, and are often best described as a wave. The highs and lows are the peaks and troughs of the wave. Much of the weather in the U.S. is due to waves that are traveling from, approximately, west to east. There are many types of waves in the atmosphere. One type of wave has a very long wavelength, with only 1 - 3 ups and downs making a belt around the Earth. These are called planetary waves. The shorter waves directly responsible for the weather travel along these very long waves; weather is, approximately of course, steered by these very long waves. On TV and in weather forecasting the "jet stream" is often used to describe weather patterns. The jet stream is related to the planetary wave patterns, and when it gets down to modeling the weather patterns it is wave theory that works best. When you see a pattern like in the July figure above, it says that the wave is stationary, rather than moving from west to east. When you get a persistent pattern, and that pattern lasts for a very long time, then you are likely to get heat waves and cold snaps, and droughts and floods. The question becomes, then, what causes these persistent patterns? Not an easy question to answer, but some insight can be gained by thinking about planetary waves and what causes them. Planetary waves arise because in middle latitudes the wind flows primarily from west to east, and when this flow encounters mountains or because of temperature differences between land and ocean, a wave is set up. These waves are said to be forced. They usually wiggle a little, keeping the hot and cold, the wet and the dry, from becoming extreme. But if they don't wiggle, for whatever reason, then the extremes can develop. Every year sees extremes. What about climate and climate change? One way to think of climate change is - are the extremes more intense? Is the heat wave exceptional? Is the drought worse because the temperature is warming? Another way is to think about the waves. With climate change, the mountains stay the same, but the land-ocean temperature difference, which also forces the waves in the atmosphere, changes. It is intuitive, that if this forcing becomes more prominent and dominant in a warmer climate, then stationary wave patterns will be more prevalent. The waves lose their ability to wiggle. Long waves. The Arctic Oscillation. The Bermuda High. Yes these are sources of variability, but they are not independent of the climate. The variability associated with these waves does not stand in contradiction to climate change; it confounds attribution. View (58) Comments For This Post
Heat, Flood, and Fire
The Atlanta Journal Constitution, today, reported that much of Georgia was now in exceptional drought. "Exceptional", in this case, means once in one hundred years.  Figure 1: Drought Index, just to be different, from the U.S. Forest Service. Much of the South in the U.S. is in the midst of a heat wave. This year we have seen heat waves of note in India, Europe and the United States. We have seen severe floods in Texas-Oklahoma-Kansas, England, southern and eastern Asia, and now the upper Midwest. This has been another year of severe wild fires in the U.S. West, and earlier in the U.S. South. What do all of these things mean? How do we put it into perspective? To be sure, we have more access to information from around the world. Therefore, we hear about these things. Also, there are more people impacted by the weather. We are all sensitized about climate. As scientists and observers of the atmosphere, we know that there have been droughts and floods and heat waves before. It�s the nature of the beast; is the beast changing? First, heat waves: Public health experts will tell you that heat waves are responsible for more deaths than any other weather-climate hazard. Heat waves are complex events; often it is not the absolute temperature that is the most important variable for predicting a dangerous heat wave. People acclimate to heat. The same temperature late in the spring and early in the summer is much more dangerous than in August. A dangerous heat wave in Montreal is a normal summer day in Houston. This interaction of the environment and human physiology blends physical and biological science. Among other things we know about heat waves, when it stays warm at night for several nights in a row, the heat wave gets much more dangerous. Heat waves, or at least the direct impact on human health, are often viewed as an urban problem. All of those issues of the urban heat island come up. Meehl and Tebaldi (Science, 2004) have projected that heat waves will become longer, more intense, and more frequent in the next 100 years. Given that urban heat waves are already a significant public health problem, a warming planet would amplify this problem. Second, drought and fires: We do know that drought and floods, heat waves and cold snaps are all part of nature. Like the problem of urban heat waves, we have an event that already exists, and there should be a change associated with global warming. I have already mentioned that some studies have attributed the pinyon pine die off in the U.S. Southwest to the fact that the temperature in the recent drought years is higher than in previous droughts. Therefore, ground water is reduced; there is more stress on the plants. (And perhaps it is really the warmer nighttime temperatures that matter?) There have also been papers which make a compelling argument that wild fires in the western U.S. are increasing in intensity and duration. In the paper of Westerling et al. (Science, 2006), the conclusion is drawn that this is directly related to snow melt occurring earlier in the year, a hotter and drier forest, and hence, a longer burning season. Plus they isolate the impact to be at mid-elevations in the Rockies, and hence, relatively free of land-use changes. While many newspapers reported that this work showed an increase of wild fires due to climate change, I quote directly from their paper: "Whether the changes observed in western hydroclimate and wildfire are the result of greenhouse gas-induced global warming or only an unusual natural fluctuation is beyond the scope of this work". In the examples discussed above, we have existing events, heat waves, droughts, floods, and wildfires. Casually, one can look at our history and conclude that all of these things have been around forever, and hence, they are not evidence of climate change. Alternatively, with our current sensitivity to climate change, the casual observer can see each of these events as another brick in the wall. The scientists approach to this work is to look how the characteristics of these existing events are changing, not whether or not they exist. Then those changes have to be considered in light of other sources of change--land-use, population, climate, etc. The question, the argument, then focuses on how do we determine cause and effect? View (30) Comments For This Post
Temperature Data and Urban Heat Islands
I am going to start this entry with the end of the last entry. Two things I want to talk about are the temperature data set and the urban heat island. I introduced the graph of the Central England observations and said that it was for the purists. These are data made with thermometers, and the thermometers are "rural." For sure there have been changes over the years, but in some sense the spirit of this data set is one of a consistent simplicity for a very long time. Here is that plot again, and if you follow the links you will find references and discussions. Temperature measurements from Central England.  Figure 1, Central England Temperatures, 1772 --> present. I asked what people saw in this figure. Here is how I would analyze this figure. First, this is a figure that is a difference from some average; therefore, what is the averaging time, which is according to the reference, 1961-1990. Given this, you can look at that time in the graph, and over that time the positives and minuses should balance each other. If not, well there is a problem. (If there is a strong trend during the averaging time, that would show up in the differences, and suggest a choice of a different averaging time.) Next, I would notice that there have been times of sustained difference from the average. In the past, before 1900, there were a number of times where it was cooler than the average, and very few times where warmer than average was sustained. There were a few very cold years, and a number of years that were nearly as warm as the most recent years. The recent warm time is the longest sustained warm time, but there are a number of cool times of comparable length. For this time record, the recent years are definitely the warmest. This does not establish cause and effect. If you were to look at the time series closest to the averaging span, then this is when there is the most oscillation above and below the average. Going into the past, again before 1900, the temperature lies mostly below zero. If you calculated a trend between most any average before 1900 and today, it would show warming. The questions that arise about this graph: What is the impact of changing the averaging length? What is sensitivity to the choice of time span for the average? Of course there are questions of data quality and how representative are they of the temperature in the region that they cover. As a reminder, this time series is made up of only a small number of thermometers in a part of central England. This is not meant to represent the globe. In terms of understanding cause and effect, this is most accurately thought of in terms of what meteorologists call the thermodynamic equation, which is an equation that describes the behavior of temperature in time. Most simply, the temperature can change based on heating, cooling, and variability associated with changing weather patterns, like the North Atlantic Oscillation. This being a plot of regional temperatures it is likely sensitive to changes in weather patterns. In terms of heating and cooling, one would look at, for instance, solar variability, volcanic activities, changes in composition, and changes in local environment of the measurements, and of course the accuracy and precision of the measurement instrumentation. It has been long recognized that changes in the local environment impact the measurement of temperature. This makes the job of defining trends and determining cause and effect difficult. This is a challenge for all observing systems. All. Clearly, any measurements of the last 100 years would have to consider the role of urbanization in the temperature record. There is a correlation, but again, correlation does not determine cause and effect. Some have written in response to this blog as if urban effects have not been considered. Or if it has been considered, then it has been considered in either an inaccurate or a disingenuous way. The impact of urban heat islands is a problem that has definitely been considered. Typing "urban heat island" into the Web of Science, the old Science Citation Index, finds 63 pages of peer-reviewed references. (Most big libraries have a subscription to Web of Science.) Here is a link to a paper from the American Meteorological Society's Journal of Climate. (Parker, 2006, A Demonstration that Large-scale warming is not urban.) Here so you can read what is done in the GISS analysis of temperature is Hansen et al., 1999, GISS Analysis of Surface Temperature Change. You will see that in these papers the authors take some trouble to account for difficulties in the data sets. Further, they provide a list of references that show how others have tried to address the problem. It is fair and legitimate to read these papers and to challenge the methods and the conclusions. (In fact, this is taught formally in graduate school. Students are given such papers and asked to analyze and evaluate methods and the conclusions.) I don't think that there is any justification in stating the scientists have been negligent in considering, for instance, the impact of urban heat islands. Nor is there justification in saying that there is some attempt to hide methodology. It is not in the best interest of science or scientists. (Seriously, if you think it is in the best interest, tell me why.) Now back to the temperature data. I expect that there will be more errors found in all of the data records. I can think of very few things that if one continues to revisit over and over whose perfection stands up to such scrutiny. Each of the corrections will be incorporated and the quality of the data record will be improved. The question arises - are there errors in the observations or the analysis that will challenge the basic conclusion that the Earth is currently in a sustained period of warm climate? Or are we only refining the accuracy of that conclusion? I personally do not think that we will find any systematic error in the observations or the analysis that will change the conclusion. And if there is something from a single observation that changes it all --- well, I think that would be magic, and there is no magic. View (24) Comments For This Post
Hi, I am back for a blog or two. Some interesting things going on --- in the world of blogs, a lot of discussion about the error in the GISS temperature data set.
In a couple of my early blogs I talked about the scientific process and how part of the process was challenging the conclusions. Also important was the idea of validation and especially validation by independent investigators. Here are links to my old blogs. A Belief in Science. Incoherent Surface Temperatures. Steve McIntyre of ClimateAudit.org played a role in finding this error. He has written a blog on finding the error and the significance of the error, which appeared on the Watts Up with That web site. To me, this is first and foremost an example of the scientific process working. Given observations, examination, and validation, the result of the investigation was incorporated into the accepted knowledge. And the result changed the data record in a detectable way. Does it change the basic conclusions about a warming Earth? No. There is an amplified response to the change because so many people are attuned to climate change. The climate data records are continuously being processed and reprocessed. This arises because so many of our observing systems were not originally designed with the stability and calibration to determine climate trends. Therefore, we have had build these climate records and take into account thermometer locations, equipment manufacturers, etc., etc. This has also been true with satellite observations, which suffer tremendous calibration challenges with launches and solar wind and all of that. People have talked about how to correct bad data, like it is almost by definition an impossible thing to do. It is possible to correct "bad" data if, for instance, you know why the data is bad. There could be an alignment problem which, if quantified, might be accounted for almost exactly. It is possible to correct "bad" data, if you know that an instrument is biased. A lot of us know (or hope) that our scales weigh five pounds over. We determine this by using scales of known calibration. And this leads to another way to correct "bad" data, if we have other instruments for comparison. Many of you probably do not know that every single observation used in a weather forecast undergoes quality control by comparison with a very short-term forecast and all nearby observations (buddy check) before it is used to initialize a weather forecast. Sometimes data are "corrected;" for instance, a balloon sounding that has been reported upside down. This is a problem faced with every measurement, in every science, including the tests that determine your cholesterol. This is one reason why multiple data sets and multiple analyses is so important. In this case the data set produced by the Hadley Center is an example ... HadCRUT3 data sets. For you purists, here is perhaps the most consistent data set available, the temperature measurements from Central England. Figure 1, Central England Temperatures, 1772 --> present. Tell me what you see in this figure.A final point I would like to make. A lot of people say this data is "not available." It is there for all to get, and that is why McIntyre's analysis was possible. That's part of science as well, the data are available for independent analysis. r (With all of these blogs, I must be treading on the edge of the blogosphere. Why haven't I shown up in wikipedia yet. I am neither the late wrestler or the violinist.) View (50) Comments For This Post
From the Gulf, we wandered across Alabama to Selma, then a night in Memphis, Ponca City, and finally back to Boulder. We passed through an arch of lightening and thunderstorms in the Colorado Plains and, once through, saw the most brilliant and complete rainbow ever. A couple of pictures in "My Recent Photos."
Still in the spirit of the road trip --- if there is climate discussion on the road it is how wet it has been in Texas and Kansas, and how dry it is in northern Alabama and Tennessee. With all of the discussion of how climate change will impact severe weather and flood and drought cycles, some are seeing this as another part of the accumulation of evidence. Others, of course, point to the historical variability and say that we have seen such extremes before and, hence attribution to climate change is unjustified. As was commented in the last blog, this discussion has moved beyond science and out into the public. People will start to re-frame the discussion. Knowledge and belief will become more entwined. For the sake of completeness and discussion here is the rainfall anomaly chart.  Figure 1: Rainfall anomaly from National Climate Data Center. What is perhaps of more interest from a climate change point of view is the continued drought in the western third of the nation. There has been a lot of pretty good research that shows that this drought in combination with warmer temperatures is having impacts on eco-systems and wildfires beyond any ever realized before. Here's an aging link to pinyon pine die off. As you drive across the agricultural parts of the country there is an increasing discussion of ethanol. A lot of corn has been planted. The discussion is beginning to move to the rationality of corn-based ethanol. There is some potential of realizing some energy independence, but (in my opinion) this is largely symbolic. From a climate point of view ethanol production does not make a lot of sense, especially if the extra stress on water is considered. What is most interesting to me about the discussion on the agricultural radio stations is the quick impact that the diversion of corn to ethanol is having on the beef industry, the food industry in general (corn syrup), and the link to the increase in milk prices. This is not to mention the impact on, say, supplying food to other nations--something that is important from both a humanitarian and international stability point of view. Then there are the links back to myriad existing policies. The interdependencies are emerging quickly. Perhaps on the opposite side of politics from last blog's link to Rush--here is a link to a article I was surprised to see in the Rolling Stone on ethanol. So again some thoughts from the road--next time I will ask for local restaurant recommendations. Plus, tell me what to do about the speed trap in Loan Oak, Texas. r View (29) Comments For This Post
Work and vacation has brought me to the Gulf Coast - stayed in Slidell, LA for a couple of nights--now in Mobile. I've placed a picture of a small fortification on the banks of the Bayou in My Recent Photos. This is on US 11 as it gets close to its end at US 90 - in Irish Bayou. US 90 is the old US highway that runs along the Gulf Coast.
There is a lot of rebuilding along the Gulf. Some houses, some bridges, and the Waffle House and casinos seem more than committed to the area. A lot of property for sale. The houses are built a little higher. There are still heaps of rubble. I spent many of my younger years struggling with hurricanes along the NC coast. My father loved building cabins along the coast out of old train bridges and phone poles. We viewed everything as ephemeral. Those piles of rubble, the urge to rebuild, the irrationality of rebuilding are all very close to me. Compared to earlier in the year climate change is moving away from the radio. I did listen to Rush Limbaugh for a while, who provided his global warming update. I was interested in his statement that he was confident that in 3-4 years the "hoax" could be revealed. I am curious about the idea that there is an organized hoax, some sort of desire it seems to tell people how to live, what to buy. Perhaps someone can explain to me the rationale. Just some thoughts from the road, r View (29) Comments For This Post
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