By Judith Curry
The American Meteorological Society (AMS) has just published its new statement on Climate Change.
The statement is billed as an ‘Information Statement’ of the AMS. This statement is part of the AMS series of Policy Statements, see this link for Guidelines for Statements of the AMS. From the Guidelines:
The American Meteorological Society (AMS) promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications.
Information Statements are intended to provide a trustworthy, objective and scientifically up-to- date explanation of scientific issues of concern to the public at large. They are informational only and do not make recommendations or take positions on issues. Information Statements should use language easily understood by a lay reader and avoid technical terminology and jargon. Information statements are typically no longer than 2000 words.
The AMS wrote a previous statement on climate change in 2007 [link].
The link to the new statement can be found here [link].
Excerpts from the statement are appended below, providing a sense of the overall content:
Background
This statement provides a brief overview of how and why global climate has changed over the past century and will continue to change in the future. It is based on the peer-reviewed scientific literature and is consistent with the vast weight of current scientific understanding as expressed in assessments and reports from the Intergovernmental Panel on Climate Change, the U.S. National Academy of Sciences, and the U.S. Global Change Research Program.
How is climate changing?
Warming of the climate system now is unequivocal, according to many different kinds of evidence. Due to natural variability, not every year is warmer than the preceding year globally. Nevertheless, all of the 10 warmest years in the global temperature records up to 2011 have occurred since 1997, with 2005 and 2010 being the warmest two years in more than a century of global records. The warming trend is greatest in northern high latitudes and over land.
Why is climate changing?
Climate is always changing. However, many of the observed changes noted above are beyond what can be explained by the natural variability of the climate. It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide. The most important of these over the long term is CO2, whose concentration in the atmosphere is rising principally as a result of fossil-fuel combustion and deforestation.
Human activity also affects climate through changes in the number and physical properties of tiny solid particles and liquid droplets in the atmosphere, known collectively as atmospheric aerosols. Examples of aerosols include dust, sea salt, and sulfates from air pollution.
Land surface changes can also affect the surface exchanges of water and energy with the atmosphere. Humans alter land surface characteristics by carrying out irrigation, removing and introducing forests, changing vegetative land cover through agriculture, and building cities and reservoirs. These changes can have significant effects on local-to-regional climate patterns, which adds up to a small impact on the global energy balance as well.
How is the climate expected to change in the future?
Future warming of the climate is inevitable for many years due to the greenhouse gases already added to the atmosphere and the heat that has been taken up by the oceans.
In general, many of the climate-system trends observed in recent decades are projected to continue. Those projections, and others in this section, are largely based on simulations conducted with climate models, and assume that the amount of greenhouse gas in the atmosphere will continue to increase due to human activity. Global efforts to slow greenhouse gas emissions have been unsuccessful so far. However, were future technologies and policies able to achieve a rapid reduction of greenhouse gas emissions - an approach termed “mitigation” - this would greatly lessen future global warming and its impacts.
Confidence in the projections is higher for temperature than for other climate elements such as precipitation, and higher at the global and continental scales than for the regional and local scales. The model projections show that the largest warming will occur in northern polar regions, over land areas, and in the winter season, consistent with observed trends.
In the 21st century, global sea level also will continue to rise although the rise will not be uniform at all locations. With its large mass and high capacity for heat storage, the ocean will continue to slowly warm and thus thermally expand for several centuries. Model simulations project about 27 cm (10 inches) to 71 cm (28 inches) of global sea level rise due to thermal expansion and melting of ice in the 21st century. Moreover, paleoclimatic observations and ice-sheet modeling indicate that melting of the Greenland and the West Antarctic ice sheets will eventually cause global sea level to rise several additional meters by 2500 if warming continues at its present rate beyond the 21st century.
Atmospheric water content will increase globally, consistent with warmer temperatures, and consequently the global hydrological cycle will continue to accelerate. For many areas, model simulations suggest there will be a tendency towards more intense rain and snow events separated by longer periods without precipitation. However, changes in precipitation patterns are expected to differ considerably by region and by season. In some regions, the accelerated hydrological cycle will likely reinforce existing patterns of precipitation, leading to more severe droughts and floods. Further poleward, the greater warming at high latitudes and over land likely will change the large-scale atmospheric circulation, leading to significant regional shifts in precipitation patterns. For example, the model simulations suggest that precipitation will increase in the far northern parts of North America, and decrease in the southwest and south-central United States where more droughts will occur.
Climate-model simulations further project that heavy precipitation events will continue to become more intense and frequent, leading to increased precipitation totals from the strongest storms. This projection has important implications for water-resource management and flood control. The simulations also indicate the likelihood of longer dry spells between precipitation events in the subtropics and lower-middle latitudes, with shorter dry spells projected for higher latitudes where mean precipitation is expected to increase. Continued warming also implies a reduction of winter snow accumulations in favor of rain in many places, and thus a reduced spring snowpack. Rivers now fed by snowmelt will experience earlier spring peaks and reduced warm-season flows. Widespread retreat of mountain glaciers is expected to eventually lead to reduced dry season flows for glacier-fed rivers. Drought is projected to increase over Africa, Europe, and much of the North American continental interior, and particularly the southwest United States. However, natural variations in world ocean conditions at decadal scale, such as those in the North Pacific and North Atlantic basins, could offset or enhance such changes in the next few decades. For the longer term, paleoclimatic observations suggest that droughts lasting decades are possible and that these prolonged droughts could occur with little warning.
Weather patterns will continue to vary from day to day and from season to season, but the frequency of particular patterns and extreme weather and climate events may change as a result of global warming. Model simulations project an increased proportion of global hurricanes that are in the strongest categories, namely 4 and 5 on the Saffir-Simpson scale, although the total counts of hurricanes may not change or may even decrease. Some regional variations in these trends are possible. Simulations also indicate that midlatitude storm tracks will shift poleward. Interannual variations of important large-scale climate conditions (such as El Nino and La Nina) will also continue to occur, but there may be changes in their intensity, frequency, and other characteristics, resulting in different responses by the atmosphere. Heat waves and cold snaps and their associated weather conditions will continue to occur, but proportionately more extreme warm periods and fewer cold periods are expected. Indeed, what many people traditionally consider a cold wave is already changing toward less severe conditions. Frost days (those with minimum temperature below freezing) will be fewer and growing seasons longer. Drier conditions in summer, such as those anticipated for the southern United States and southern Europe, are expected to contribute to more severe episodes of extreme heat. Critical thresholds of daily maximum temperature, above which ecosystems and crop systems (e.g., food crops such as rice, corn, and wheat) suffer increasingly severe damage, are likely to be exceeded more frequently.
Final remarks
There is unequivocal evidence that Earth’s lower atmosphere, ocean, and land surface are warming; sea level is rising; and snow cover, mountain glaciers, and Arctic sea ice are shrinking. The dominant cause of the warming since the 1950s is human activities. This scientific finding is based on a large and persuasive body of research. The observed warming will be irreversible for many years into the future, and even larger temperature increases will occur as greenhouse gases continue to accumulate in the atmosphere. Avoiding this future warming will require a large and rapid reduction in global greenhouse gas emissions. The ongoing warming will increase risks and stresses to human societies, economies, ecosystems, and wildlife through the 21st century and beyond, making it imperative that society respond to a changing climate. To inform decisions on adaptation and mitigation, it is critical that we improve our understanding of the global climate system and our ability to project future climate through continued and improved monitoring and research. This is especially true for smaller (seasonal and regional) scales and weather and climate extremes, and for important hydroclimatic variables such as precipitation and water availability.
Technological, economic, and policy choices in the near future will determine the extent of future impacts of climate change. Science-based decisions are seldom made in a context of absolute certainty. National and international policy discussions should include consideration of the best ways to both adapt to and mitigate climate change. Mitigation will reduce the amount of future climate change and the risk of impacts that are potentially large and dangerous. At the same time, some continued climate change is inevitable, and policy responses should include adaptation to climate change. Prudence dictates extreme care in accounting for our relationship with the only planet known to be capable of sustaining human life.
[This statement is considered in force until August 2017 unless superseded by a new statement issued by the AMS Council before this date.]
Update: Bill Hooke has some additional background on the AMS statement:
JC comments:
My strong objections to this type of statement by professional societies has been voiced previously. This statement is worse than the previous AMS statement, and much worse than the statement by the Royal Society, which is probably the most credible statement on this topic made by a professional society.
So who is responsible for this statement? Current members of the AMS Council can be found [here]. It is not clear who authored the statement, but I suspect it was the members of the AMS Committee on Climate Variability and Change (for membership list, see here). After reading this list of names, I recognize some, but less than half. Does this group of people inspire my confidence in making an assessment of climate change? In a word, NO.
Several months ago, I recall receiving an email asking for comments on the draft statement (apparently a mass mailing to the AMS membership). I tried to access it but didn’t have my site login info handy at the time. So I am seeing this statement today for the first time. I suspect that there will be a lot of AMS members that are unhappy with this statement.
Apart from the broader issue of whether or not professional societies should make such statements, the main question that I have is why write a new statement now? It appears that each statement has a life time of 5 years. Why not wait another year or two until the IPCC AR5 is out? It seems that there is little in the AMS statement that is associated with more recent publications (since the AR4). As the CMIP5 climate model simulations show a broader range of uncertainty than the simulations used in the AR4, what is the basis for making a more confident statement on attribution (which seems to be based wholly on models) than was made in the AR4?
As far as I can tell, this statement is a naive example of Michael Kelly’s invisible hand (quote from my no consensus paper):
Kelly (2005) describes an additional source of confirmation bias in the consensus building process: “As more and more peers weigh in on a given issue, the proportion of the total evidence which consists of higher order psychological evidence [of what other people believe] increases, and the proportion of the total evidence which consists of first order evidence decreases . . . At some point, when the number of peers grows large enough, the higher order psychological evidence will swamp the first order evidence into virtual insignificance.”
In other words, consensus statements get parroted without any actual intellectual examination. In this case, what is the point of the AMS statement? Apparently, to ‘inform the public’ on this controversial issue by appealing to the ‘authority’ of the society.
JC note to AMS: read my paper No consensus on consensus.
With this newspaper arguing that our planet is in peril and that its remedies should be followed, global warming has again arisen as a hot political and pseudo-religious topic. Even professors from the University of Kentucky bear witness to their faith, professors who should know that science has nothing to do with faith or claims of consensus. Objective science is about logic and evidence only.
Albert Einstein understood this when his Theory of Relativity turned the classical physics world upside-down in 1905. He patiently waited decades for experimental confirmation, emphasizing that “one man can prove me wrong.” What a contrast with global warming, where proponents offer popularity, authority and peer-review as definitive substitutes for real science.
What do we mean by “global warming?” It is not “climate change,” “climate disruption” or whatever truism propagandists invent. We mean the theory that man-made carbon dioxide is catastrophically warming the Earth.
Nobel Laureate in physics Ivar Giaever says that the tiny observed increase of 0.8 degree Centigrade over the 20th century indicates remarkable stability and no cause for alarm.
Meteorologist and staunch Democrat Martin Hertzberg points out that we experimented with carbon reduction schemes in the 1930s. These reduced fossil fuel usage by 20 percent and went by the memorable name Great Depression. Mother Nature had the last laugh as temperatures and CO2 levels continued upward, proving that man is not as important as he thinks.
After World War II, the post-war boom saw an expansion of human CO2 emissions but a decline in the global temperature. After the Great Pacific Climate Shift of 1977, when the Pacific Ocean shifted to its warm phase, we finally saw temperatures rise in concert with man-made CO2.
What has especially confused climate alarmists has been the abrupt cessation of warming since 1998, as shown by NASA satellite measurements, the best global temperature measurements we have.
For advocates to prove that increasing carbon dioxide has any effect on temperature, they need to find a unique signature that would be expected only from carbon dioxide and not from ocean or solar cycles.
The notorious climate codes which erroneously forecast rapidly rising temperatures predict such a signature developing in the tropical troposphere. But the “hot spot” is not observed. This says that late 20th-century warming had at most a small greenhouse gas component.
Because the high quality temperature reconstructions from polar ice cores show far greater temperature variations in the past than seen recently, there is no way a rational person can argue that anything unusual is happening today. Previous warm periods (Minoan, Roman and Medieval) were all warmer than today and ramped up in similar fashion.
During this Holocene interglacial period, the overall temperature trend has been downward as the Earth’s closest approach to the Sun has shifted from the Northern to Southern Hemisphere summer over 10,000 years. This is part of the Milankovitch Cycles known to dominate the Earth’s climate for at least the last half million years.
The enormous shift of 85 watts/m2 of sunlight from July to January is what brings us to the brink of another Ice Age. But don’t trade your swimsuit for a heavy winter parka just yet, because our oceans contain the vast majority of mobile heat on this planet and will prevent a precipitous plunge into another Ice Age.
With ocean cycles now negative or heading negative, and with the abrupt decrease in solar activity reminiscent of the cold Maunder Minimum of the 17th century, a cooler future appears inevitable.
The expected cooling should slow or slightly reverse in 50 to 100 years, according to Habibullo Abdussamatov, a top Russian astrophysicist. However another warm period happens only once every 1,000-plus years. If we plunge into an ice age first, you will have to wait about 100,000 years. Massive ice sheets reach south of Indianapolis during ice ages.
Will carbon-dioxide warming save us? Harvard-Smithsonian astrophysicist Willie Soon gives a blunt answer: “It’s the sun, stupid.”
While Kentuckians may seek supernatural explanations for their brutal summer weather, they should realize that many did not see a hot June and July. We in the Pacific Northwest and many in Europe were complaining of unusual cold.
The ancient Egyptians had it right 3,500 years before the dawn of modern science. The primary Climate God is Amon Ra, the God of the Sun. The God of Carbon Dioxide, Al Gore, is but a minor contender.
From the American Geophysical Union
WASHINGTON - Scientists have long suspected that the Sun’s 11-year cycle influences climate of certain regions on Earth. Yet records of average, seasonal temperatures do not date back far enough to confirm any patterns. Now, armed with a unique proxy, an international team of researchers show that unusually cold winters in Central Europe are related to low solar activity - when sunspot numbers are minimal. The freezing of Germany’s largest river, the Rhine, is the key.
Although the Earth’s surface overall continues to warm, the new analysis has revealed a correlation between periods of low activity of the Sun and of some cooling - on a limited, regional scale in Central Europe, along the Rhine.
“The advantage with studying the Rhine is because it’s a very simple measurement,” said Frank Sirocko lead author of a paper on the study and professor of Sedimentology and Paleoclimatology at the Institute of Geosciences of Johannes Gutenberg University in Mainz, Germany. “Freezing is special in that it’s like an on-off mode. Either there is ice or there is no ice.”
From the early 19th through mid-20th centuries, riverboat men used the Rhine for cargo transport. And so docks along the river have annual records of when ice clogged the waterway and stymied shipping. The scientists used these easily-accessible documents, as well as additional historical accounts, to determine the number of freezing episodes since 1780.
Sirocko and his colleagues found that between 1780 and 1963, the Rhine froze in multiple places 14 different times. The sheer size of the river means it takes extremely cold temperatures to freeze over making freezing episodes a good proxy for very cold winters in the region, Sirocko said.
Mapping the freezing episodes against the solar activity’s 11-year cycle - a cycle of the Sun’s varying magnetic strength and thus total radiation output - Sirocko and his colleagues determined that ten of the fourteen freezes occurred during years around when the Sun had minimal sunspots. Using statistical methods, the scientists calculated that there is a 99 percent chance that extremely cold Central European winters and low solar activity are inherently linked.
“We provide, for the first time, statistically robust evidence that the succession of cold winters during the last 230 years in Central Europe has a common cause,” Sirocko said.
With the new paper, Sirocko and his colleagues have added to the research linking solar variability with climate, said Thomas Crowley, Director of the Scottish Alliance for Geoscience, Environment, and Society, who was not involved with the study.
“There is some suspension of belief in this link,” Crowley said, “and this study tilts the argument more towards thinking there really is something to this link. If you have more statistical evidence to support this explanation, one is more likely to say it’s true.”
The study, conducted by researchers at Johannes Gutenberg and the Institute for Atmospheric and Climate Science in Zurich, Switzerland, is set to be published August 25 in Geophysical Research Letters, a journal of the American Geophysical Union.
When sunspot numbers are down, the Sun emits less ultraviolet radiation. Less radiation means less heating of Earth’s atmosphere, which sparks a change in the circulation patterns of the two lowest atmospheric levels, the troposphere and stratosphere. Such changes lead to climatic phenomena such as the North Atlantic Oscillation, a pattern of atmospheric pressure variations that influences wind patterns in the North Atlantic and weather behavior in regions in and around Europe.
“Due to this indirect effect, the solar cycle does not impact hemispherically averaged temperatures, but only leads to regional temperature anomalies,” said Stephan Pfahl, a co-author of the study who is now at the Institute for Atmospheric and Climate Science in Zurich.
The authors show that this change in atmospheric circulation leads to cooling in parts of Central Europe but warming in other European countries, such as Iceland. So, sunspots don’t necessarily cool the entire globe - their cooling effect is more localized, Sirocko said.
In fact, studies have suggested that the extremely cold European winters of 2010 and 2011 were the result of the North Atlantic Oscillation, which Sirocko and his team now link to the low solar activity during that time.
The 2010 and 2011 European winters were so cold that they resulted in record lows for the month of November in certain countries. Some who dispute the occurrence of anthropogenic climate change argue that this two-year period shows that Earth’s climate is not getting any warmer. But climate is a complex system, Sirocko said. And a short-term, localized dip in temperatures only temporarily masks the effects of a warming world.
“Climate is not ruled by one variable,” said Sirocko. “In fact, it has [at least] five or six variables. Carbon dioxide is certainly one, but solar activity is also one.”
Moreover, the researchers also point out that, despite Central Europe’s prospect to suffer colder winters every 11 years or so, the average temperature of those winters is increasing and has been for the past three decades. As one piece of evidence of that warming, the Rhine River has not frozen over since 1963. Sirocko said such warming results, in part, from climate change.
To establish a more complete record of past temperature dips, the researchers are looking to other proxies, such as the spread of disease and migratory habits.
“Disease can be transported by insects and rats, but during a strong freezing year that is not likely,” said Sirocko. “Also, Romans used the Rhine to defend against the Germanics, but as soon as the river froze people could move across it. The freezing of the Rhine is very important on historical timescales.”
It wasn’t, however, the Rhine that first got Sirocko to thinking about the connection between freezing rivers and sunspot activity. In fact, it was a 125-mile ice-skating race he attended over 20 years ago in the Netherlands that sparked the scientist’s idea.
“Skaters can only do this race every 10 or 11 years because that’s when the rivers freeze up,” Sirocko said. “I thought to myself, ‘There must be a reason for this,’ and it turns out there is.”
Title:
“Solar influence on winter severity in central Europe”
Abstract:
The last two winters in central Europe were unusually cold in comparison to the years before. Meteorological data, mainly from the last 50 years, and modelling studies have suggested that both solar activity and El Niño strength may influence such central European winter coldness. To investigate the mechanisms behind this in a statistically robust way and to test which of the two factors was more important during the last 230 years back into the Little Ice Age, we use historical reports of freezing of the river Rhine. The historical data show that 10 of the 14 freeze years occurred close to sunspot minima and only one during a year of moderate El Niño. This solar influence is underpinned by corresponding atmospheric circulation anomalies in reanalysis data covering the period 1871 to 2008. Accordingly, weak solar activity is empirically related to extremely cold winter conditions in Europe also on such long time scales. This relationship still holds today, however the average winter temperatures have been rising during the last decades.
Authors:
Frank Sirocko and Heiko Brunck: Institute of Geosciences, Johannes Gutenberg University Mainz;
Stephan Pfahl: Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland
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UPDATE: Dr. Leif Svalgaard provides the paper, as did the AGU press agent Kate Ramsayer per my emailed request, along with a copyright admonishment. Thank you both. Figure 6a and 6b are interesting:
