2010 Diary week 41
Predicting the future
Book Review
These are some snippets from the review of Useless Arithmetic: Why Environmental Scientists Can’t Predict the Future: “The mother of all environmental impact predictions is the required assurance of 10,000 years of safety from the Yucca Mountain repository of the nation’s radioactive waste.” “Agencies that depend upon project approvals for their survival can and frequently do find ways to adjust models to come up with correct answers that will ensure project funding.” “It became clear that beach modelers used models that had no demonstrable basis in nature. They employed ‘coefficients’ that in reality were fudge factors to assure that the ‘correct’ answer could be found, and no one looked back to see if the models actually worked. Neither the public nor the politicians knew or particularly cared, since the models were providing them with federal funds to stop beach erosion.” “The causes of the ice ages and their huge sea-level changes are earth orbital changes, such as the tilt of the axis of spin and the eccentricity of the orbit around the sun. These changes are responsible for changes in the location and intensity of solar radiation on the surface, which in turn determines global climates.” “The sea level along the entire western margin of Alaska’s Kenai Peninsula rose 2 to 3 feet in an instant, as the land subsided during the Good Friday Earthquake of 1964. Along the Pacific coast of Colombia, earthquakes (accompanied by tsunamis) cause the shorelines to sink 3 to 4 feet at a time, resulting in some astounding local sea-level-rise rates of as much as 10 feet per century.” “90% of the world’s ice resides on the continent of Antarctica. The potential for sea-level rise is huge. If all the ice on that continent melted, sea level would rise by 170 feet. The West Antarctic Ice Sheet could produce a 13-foot rise and the Greenland ice cap has a 20-foot sea-level rise potential.” “One IPCC panel predicted that Antarctica could gain ice because higher temperatures could lead to more snowfall, while a 2006 report in Science magazine reported that the West Antarctic Ice Sheet has lost 36 cubic miles of ice per year.”
USELESS ARITHMETIC
WHY ENVIRONMENTAL SCIENTISTS CAN’T PREDICT THE FUTURE
ORRIN H. PILKEY & LINDA PILKEY-JARVIS
COLUMBIA UNIVERSITY PRESS 2007
Preface
• The widespread availability of computers, the requirement for environmental impact statements and cost-benefit ratios, and the dawn of mathematical models all arrived on the scene simultaneously in the final quarter of the 20th century.
• The mother of all environmental impact predictions is the required assurance of 10,000 years of safety from the Yucca Mountain repository of the nation’s radioactive waste. Billions of dollars have been spent on the unrealistic goal of predicting what the climate and groundwater flow will be thousands of years from now.
• Models act as convenient fig leaves for politicians, allowing them to put off needed action on controversial issues. Fishery models provided the fig leaf for Canadian politicians to ignore the Grand banks cod fishery.
• Agencies that depend upon project approvals for their survival can and frequently do find ways to adjust models to come up with correct answers that will ensure project funding.
• Professor Orrin of Duke University organized a seminar to look at mathematical models used in coastal geology. It became clear that beach modelers used models that had no demonstrable basis in nature. They employed ‘coefficients’ that in reality were fudge factors to assure that the ‘correct’ answer could be found, and no one looked back to see if the models actually worked. Neither the public nor the politicians knew or particularly cared, since the models were providing them with federal funds to stop beach erosion.
• In this book we are concerned with the quantitative, ‘accurate’ predictions made by mathematical models that are applied to societally important issues involving natural surface events on the earth. Without resorting to mathematics, we make our point that applied quantitative mathematical models of earth processes cannot produce accurate answers.
Chapter 1: Mathematical Fishing
Chapter 2: Mathematical Models: Escaping from Reality
Chapter 3: Yucca Mountain: A Million Years of Certainty
Chapter 4: How Fast the Rising Sea?
• Sometime around 4 billion years ago, Earth cooled and allowed water to amass instead of boiling away. By one billion years ago, the volume of water that makes up our oceans had largely been accumulated.
• Earth’s lighter granitic materials and heavier basaltic lava-like materials segregated into continents and oceans, respectively. The light material formed continents that float like icebergs above the heavier material of the ocean basins.
• The continents drifted about; ocean basins expanded and contracted; the sea level relative to the continents went up and down like a slow yo-yo. Since the beginning of time, the level of the sea has been in a constant state of change.
• All sea level changes are either eustatic or isostatic. Eustacy refers to sea-level changes that happen because of variations in the water volume. Isostacy refers to changes in sea level that result from the moving up and down of the earth’s surface, caused because of local mountain building forces, subsidence caused by the weight of glaciers, or the compaction of sediments on deltas.
• When the volume of the ocean basin gets smaller, global sea level rises and the water sloshes onto the continents. Conversely, if the ocean basin volume increases, sea level drops and ocean waters withdraw from the continental land surface.
• An ice age is a time that alternates between cold periods of peak glaciation and warmer periods, like today, when the world is mostly free of ice (except for Greenland and Antarctica).
• Today we are a couple of million years into the middle of an ice age known as the Pleistocene epoch. Large tongues and sheets of ice pushed down from the high latitudes in at least 9 major and many more small separate episodes, covering at their peak as much as 30% of the area of the continents.
• The miles-thick glaciers accumulated snowflake by snowflake, capturing huge volumes of water. During times of peak glaciation, the exchange of water caused the sea level to drop by as much as 350 feet or more (eustatic change).
• The causes of the ice ages and their huge sea-level changes are earth orbital changes, such as the tilt of the axis of spin and the eccentricity of the orbit around the sun. These changes are responsible for changes in the location and intensity of solar radiation on the surface, which in turn determines global climates.
• When glaciers decay and retreat, the land rebounds and the sea falls back. A present-day example of this phenomenon is Juneau, Alaska, where because of the removal of the weight of the retreating Mendehall Glacier, the land is rising and the sea level is dropping.
• Sea-level fluctuations related to the advance or retreat of glaciers cause alternate flooding and draining of the continental shelves. When the water level is up, as it is today, the water’s weight slightly depresses the edge of the continents. This is one of the mechanisms responsible for today’s sea-level rise on both the east Coast and the Gulf Coast of the US.
• It was thought that the warming of the oceans was probably a more important cause of sea-level rise than the melting of glaciers and polar ice caps or crustal depression. As water warms up, it expands ever so slightly. In 2004, Walter Munk argued that the melting of glacial ice is more important.
• The sea level along the entire western margin of Alaska’s Kenai Peninsula rose 2 to 3 feet in an instant, as the land subsided during the Good Friday Earthquake of 1964. Along the Pacific coast of Colombia, earthquakes (accompanied by tsunamis) cause the shorelines to sink 3 to 4 feet at a time, resulting in some astounding local sea-level-rise rates of as much as 10 feet per century.
• Extraction of oil and water causes the land to sink on the Mississippi Delta, along the North Sea, on the Nile Delta in Egypt, and on the Niger Delta in Nigeria.
• Major ocean surface flows such as the equatorial currents pile up water on one side of continents and lower sea level on the other side. The level of the sea is about a foot higher on the Pacific side of the Panama Canal than on the Atlantic side because of a combination of lower water density and weather conditions on the Pacific side.
• 20,000 years ago, eustatic sea level rose 350 feet in mid-latitudes as the ice melted. Between 15,000 and 6,000 years ago, the rise rate was 3 feet per century, although at times it was 10 feet per century.
• Between 6,000 and 3,000 years ago, the overall rate of rise was around 1.5 feet per century. For the last 3,000 years the rate has been less than 4 inches per century.
• 100 years ago the rate of sea level rise suddenly accelerated to between 1 and 1.5 feet per century. Adding the sinking of the Louisiana sea floor to the extant rising of the sea leads to a combined rise of 4 feet per century on the Mississippi Delta.
• Coastal geologists are engaged in a raging controversy regarding the last 6,000 years of sea-level history. How can the sea-level history of the east coast of the United States be so different from Brazil’s east coast during the last 6,000 years? After all, it’s all the same ocean.
• Sea level is rising along most tectonically stable coasts of the world, and along with that rise we can expect that storm waves and floods will reach higher levels and more inland locations than ever before. This could be a potential tragedy for modern human kind that crowds together at the shore.
Modeling global sea level rise
• Climate variations will cause most of the changes in the level of the sea in the coming decades and centuries. Prediction of climate changes are important because of their possible impact on agriculture, fisheries, tourism, invasive plants and animals, natural hazards, quality of life and sea-level rise.
• The current most widely accepted prediction of sea-level rise is that its rate will be 2 to 4 times the present rate by the year 2100, and the sea level will be 2 to 3 feet above its present state. Atmospheric temperatures will rise 4 to 5 degrees Fahrenheit. But these are numbers with a lot of leeway.
• The predictions of the Intergovernmental Panel on Climate Change (IPCC) are packed with vast uncertainties and vulnerable to criticism.
• The December 26, 2004, Indian Ocean tsunami, the greatest natural disaster in recorded human history, provided a disheartening measure of the concentration of human souls at low elevations next to Asian shorelines.
• Global change modelers usually employ a bottom-up modeling approach, starting with the smallest elements – say a melting glacier – and integrates other processes and events, using a super computer. Assumptions are made at each stage. An initial error created by weak assumptions and uncertainties are ever magnified.
• Top-down models start with the largest elements – the Atlantic Ocean, the Greenland icecap – and hope to bypass the minutiae, relying more on observation and leaving gaps that can be hazardous to the accuracy of predictions.
• It is important to note that we are examining the quantitative models that will predict sea-level rise with sufficient accuracy to help society plan for the future. What to do about the Pacific Islands? Bangladesh? Manhattan? The models must involve an accurate characterization of everything that plays a significant role in sea-level rise.
• The greenhouse effect is said to be due to carbon dioxide accumulating in the atmosphere faster than it can be absorbed by the oceans and by vegetation. The most direct evidence of the increased CO2 concentration in the atmosphere is provided by the Mauna Loa Observatory in Hawaii. The 1955 concentration was 315 parts per million compared to today’s 379ppm and 289ppm in pre-Industrial Revolution glacial ice.
• Important questions are: how rapidly does the ocean absorb CO2? How much excess will humans produce in the future? How will global warming affect cloud cover? What will global warming do to ocean circulation? How will global climate change affect local climates?
• Human behavior, the hardest variable of all to model, is central to the future of climate and sea-level prediction.
• 90% of the world’s ice resides on the continent of Antarctica. The potential for sea-level rise is huge. If all the ice on that continent melted, sea level would rise by 170 feet. The West Antarctic Ice Sheet could produce a 13-foot rise and the Greenland ice cap has a 20-foot sea-level rise potential.
• One IPCC panel predicted that Antarctica could gain ice because higher temperatures could lead to more snowfall, while a 2006 report in Science magazine reported that the West Antarctic Ice Sheet has lost 36 cubic miles of ice per year.
• Melting of the Arctic Ocean ice cover would not add to global sea level change in any significant way as it floats on the surface.
• Reflectivity of solar radiation from ice and snow is very high, while that of ocean water is very low. As warming creates more open ocean water, more heating occurs leading to more open water.
• The Gulf Stream pushes warm water north with the counterflow requirement satisfied by cold water with a higher-than-normal salt content hugging the sea floor flowing from the Arctic Ocean to the Atlantic.
• Due to warming the Arctic it is likely that the counterflow of south-flowing water has been reduced in volume. Because it is possible that the Gulf Stream could be halted in a few decades, Henry Pollack in Uncertain Science … Uncertain World, describes the cessation of large-scale North Atlantic circulation as a hidden cliff edge. We’re probably close to the edge now, but no one knows where it is or when we will step over it.
• The IPCC approach is a refreshing sort of modeling. Their publications are filled with long discussions about error, uncertainties, and missing data but the final sentence in the 2001 IPCC report says: ‘We recognize that it is important to assign probabilities to sea-level rise projections, but this requires a more critical and quantitative assessment of model uncertainties than is possible at present.’
• What is said in the 875-page report and what is said out on the street are two different things; complexities are downplayed and ‘real’ predictions are made.
• Today there are probably 15 major climate models in use by various climate groups. Each model has its own set of unknowns and uncertainties, which feed into the next model and the next and the next. At the top of the pyramid are the models that put it all together.
• Assumption upon assumption, uncertainty upon uncertainty, and simplification upon simplification are combined to give an ultimate and inevitably shaky answer, which is then scaled up beyond the persistence time to make the long-term predictions of the future of sea-level rise.
• One of the long-held criticisms of quantitative mathematical models is the use of corrections, referred to various names such as ‘coefficient,’ ‘adjustments,’ and ‘constants.’ These bring the results into line with perceived reality but are invisible to the policymakers and decision makers who use the results.
• Raynor suggests that an example of fudge factors is the anticipated change in global temperatures that results from a doubling of carbon dioxide. The range of 1.5 to 4.5 degrees Centigrade is not empirically, experimentally, or model derived but is ‘the result of diffuse, expert judgment and negotiation among climate modelers.’
• When predicted numbers reach politicians, policymakers, and other users, they are usually unencumbered by any mention of assumptions, uncertainties, and simplifications.
• All is not peace within the IPCC family. In 2005, hurricane expert Chris Landsea resigned from the IPCC, saying that the panel writing up the section on the relationship between hurricane activity and global warming was contaminated by unsound science and a preconceived agenda.
• Accurate prediction of future sea-level change is clearly impossible, but predicting the direction and general magnitude of changes is within our capabilities. Qualitative global change models can play a very important role here.
• Global change modelers fall into two categories. There are the true believers who take no prisoners, believe every word, every model prediction, and feel that criticism is unwarranted. A much larger group, when pressed to the wall, admits the unlikelihood of providing the accurate prediction that society has grown to expect. However, the juggernaut that has risen to answer the questions about global climate change, global warming, sea level rise, and all their ramifications, has unstoppable momentum.
• The logical next step should be to turn toward more data-rich, qualitative modeling and to seek answers of a more general nature, to seek likely trends for the future, to example all the possible scenarios, the worst and best cases.
• But the leaders of global change studies tend to view as a primary task the maintenance of funding for the modeling juggernaut. In this effort they are no different from most of the long line of supplicants who appear before Congress to ask for money to solve some social ill or technical or military problem.
Senator Inhofe’s Fig Leaf
Chapter 5: Following a Wayward Rule
Chapter 6: Beaches in an Expected Universe
Chapter 7: Giant Cups of Poison
Chapter 8: Invasive Plants: An Environmental Apocalypse
Chapter 9: A Promise Unfilled
Appendix
References
Index