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Über dieses Buch

This book is a thorough introduction to climate science and global change. The author is a geologist who has spent much of his life investigating the climate of Earth from a time when it was warm and dinosaurs roamed the land, to today's changing climate. Bill Hay takes you on a journey to understand how the climate system works. He explores how humans are unintentionally conducting a grand uncontrolled experiment which is leading to unanticipated changes. We follow the twisting path of seemingly unrelated discoveries in physics, chemistry, biology, geology, and even mathematics to learn how they led to our present knowledge of how our planet works. He explains why the weather is becoming increasingly chaotic as our planet warms at a rate far faster than at any time in its geologic past. He speculates on possible future outcomes, and suggests that nature itself may make some unexpected course corrections. Although the book is written for the layman with little knowledge of science or mathematics, it includes information from many diverse fields to provide even those actively working in the field of climatology with a broader view of this developing drama. Experimenting on a Small Planet is a must read for anyone having more than a casual interest in global warming and climate change - one of the most important and challenging issues of our time.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
At a meeting of US and Soviet climatologists in Leningrad in 1982 I became aware of the sensitivity of the Arctic to climate change resulting from increasing the concentration of carbon dioxide in Earth’s atmosphere by burning fossil fuels. The eminent Soviet climate specialist, Mikhail Budyko, suggested that we had set in motion a sequence of events that would lead to melting of the Arctic ice pack by 2100, and that would have grave consequences for the entire planet. But what is happening is not gradual warming, and the increasing number of weather events suggest that our planet is beginning to move from one climate state to another. Rather than ‘Global Warming’ we should speak of ‘Global Weirding.’ I have been a life-long academic. I started out my research as a micropaleontologist, studying tiny microscopic fossils. Then I became interested in oceanography and finally in Earth’s past climate. I have spent the last 40 years trying to understand the warm climate of the Cretaceous period, when dinosaurs roamed the Earth. Science is a search for the truth, wherever it may lead. There is no good or evil in such a search. There are two different kinds of scientific investigation. One group of sciences, physics, chemistry, and biology, performs and evaluates the results of experiments. Geology and astronomy are different in that they must rely largely on interpretation of observations. In both cases, the results of the investigations lead to ideas that can be tested, either by new experiments or by observations. These preliminary explanations are termed ‘hypotheses.’ If they stand the test of time and intensive experimentation, they become theories. ‘Occam’s razor’ is the principle that the simplest explanation is the most likely to be correct. And if it is concluded that a theory is absolutely correct, it is termed a Law. Note that the general public often uses the term ‘theory’ to correspond to a scientists ‘hypothesis.’
William W. Hay

Chapter 2. The Language of Science

Abstract
This chapter is devoted to the background information necessary to understand scientific arguments. Geometry is basic to locating things in space. Trigonometry explores geometric relationships. Much of our knowledge of our planet is presented on maps, but showing a spherical surface on a flat sheet of paper is not so simple. Different map projections have different uses, but some have distortions that give false impressions. Measurement in science involves the ‘Metric System’ where all measurements are based on the numbers 1,10,100 etc. It was developed in France around the time of the Revolution, and was spread throughout Europe by Napoleon. The United States is the last holdout, still using the old English imperial system of inches, feet, miles, etc. Describing things in terms of powers of ten (‘orders of magnitude’) allows us to conveniently describe things on the level both of atoms and of the universe. Very different sizes are easily expressed though using the shorthand of exponents and logarithms. Understanding the implications of exponential growth and decay is essential to making rational decisions, but tends to be poorly understood by the general public. This chapter also introduces the reader to the precise definitions of many words in common use.
William W. Hay

Chapter 3. Geologic Time

Abstract
In the seventeenth century the age of the Earth, based on biblical sources, was estimated to be 6,000 years. Looking at the rock record on the coast, Scottish geologist James Hutton realized that the Earth was very much older; there was literally an abyss of time. The geologic record in the Paris Basin suggested that there had been not one, but a series of ‘Creations’ each ended by a catastrophe. In the early nineteenth century Charles Lyell realized that the same geologic processes operating today had been at work in the past, and that geologic change was imperceptibly slow. This concept became known as ‘Uniformitarianism.’ The sequence of rocks and a relative geologic time scale based on superposition was worked out during the nineteenth century. Two major discoveries indicated that conditions in the past had been very different from those of today: the Ice Age and warm Polar Regions. Americans championed the idea of permanence of continents and ocean basins; Europeans suggested the Earth’s crust was mobile, and even that the continents had drifted apart with time. It was recognized that life on the planet had experienced a number of extinction events.
William W. Hay

Chapter 4. Putting Numbers on Geologic Ages

Abstract
While geologists knew simply that the Earth was very old, physicist Lord Kelvin calculated its age to be about 100 million years. On the basis of the rate of delivery of salt to the ocean by rivers, the Earth’s age was calculated to be 90 million years. Many geologists felt that these ages were too short to account for everything that had happened. A major breakthrough came at the end of the nineteenth century with the discovery of radioactive decay of heavy elements. Also, at the end of the century Svante Arrhenius noted that the carbon dioxide being introduced into the atmosphere from burning fossil fuels would warm the planet. It was soon realized that the rates of decay of radioactive elements could be used to date rocks. The Earth’s age turned out to be measured in billions, not millions, of years. By 1920, a numerical age framework similar to the one we have today had been established.
William W. Hay

Chapter 5. Documenting Past Climate Change

Abstract
To eliminate the variability inherent in the weather, ‘Climate’ is taken to be a 30-year average of temperature, precipitation and other factors. As the old saying goes, ‘The climate is what you expect; the weather is what you get.’ Earth’s climate has varied between two major states, ‘greenhouse,’ where there is no ice in the polar regions and equator–pole temperature gradients are small, and ‘icehouse,’ where the polar regions are covered by ice and the latitudinal temperature gradient is large. During the icehouse state, the climate oscillates between glacials when the polar ice expands down to the mid-latitudes, and interglacials when it is restricted to high latitudes. The last change from greenhouse to icehouse occurred about 35 million years ago. For the past 800,000 years, glacials have lasted about 80,000 years, followed by a deglaciation lasting 10,000 years and an interglacial lasting 10,000 years. Determination of changing geologic process rates has become possible through the development of more sophisticated techniques involving potassium–argon dating, reversals of Earth’s magnetic field, fission track dating, astronomical dating, and tritium, carbon-14, and beryllium-10 dating techniques. Human activities have greatly accelerated the rates of geologic change. The climate of the past 6,000 years, during which civilization has developed, is the longest period of stability in the past few million years.
William W. Hay

Chapter 6. The Nature of Energy Received from the Sun: The Analogies with Water Waves and Sound

Abstract
The nature of the energy received from the Sun was a mystery. Analogies were sought in better understood phenomena: water waves and sound. Water waves produce an up and down motion of the surface, but do not move the water except in the special circumstances of the very long waves known as the tides and tsunamis. The speeds of different kinds of waves could be readily determined. However, they can be used as analogs to visualize what happens in other kinds of wave. Sound waves are compression waves in the air. The speed of sound in air was also readily determined. Although sound waves cannot be seen, they have properties that can be used in trying to understand light.
William W. Hay

Chapter 7. The Nature of Energy Received from the Sun: Figuring out What Light Really is

Abstract
Light has many peculiar properties, some with analogs in water waves, some with analogs in sound waves, and some that are unique. It was discovered that ‘white’ light passing though a glass prism is split into a spectrum showing all of the colors of the rainbow. These can be recombined to make white light. Some thought that light traveled instantaneously through space, but measurement of its speed, already close to the modern value, was made in the Seventeenth Century. It was discovered that there was invisible radiation coming from the Sun, beyond the red (infrared) and violet (ultraviolet) ends of the spectrum. Light had many strange properties: reflection, refraction, dispersion, diffraction, and polarization. It was discovered that the colors travel at different speeds through media like minerals or glass. While investigating the relation between electricity and magnetism, James Clark Maxwell realized that light was an electromagnetic wave. It was thought to be moving through the ‘luminiferous æther’ that filled all of space. But attempts to detect the ‘æther’ failed. Empty space was truly empty!
William W. Hay

Chapter 8. Exploring The Electromagnetic Spectrum

Abstract
Upon detailed examination, the spectra of sunlight were found not to be continuous but rather to be interrupted by dark lines. It was discovered that when burned, chemicals often gave off light at very specific wavelengths. It became possible to determine the elements present in a compound by examination of the spectrum. The element helium was discovered in the spectrum of the Sun’s corona during an eclipse 30 years before it was discovered trapped in minerals on Earth. It was found that spectral lines are mathematically related. Heinrich Hertz confirmed Maxwell’s ideas about electromagnetic radiation by generating it in his laboratory. He did not realize the implications of his discovery. Giuseppe Marconi made the electromagnetic spectrum a tool for civilization, developing radio transmission. Human use of the electromagnetic spectrum has expanded to include FM radio, television, radar, and even microwave cooking.
William W. Hay

Chapter 9. The Origins of Climate Science: The Idea of Energy Balance

Abstract
Heat is the kinetic motion of atoms or molecules. The Laws of Thermodynamics were developed in the middle of the nineteenth century. These laws state that energy cannot be created or destroyed, it can only change form; that two nearby systems, each internally in thermodynamic equilibrium, but not in equilibrium with each other, will exchange matter or energy and reach a mutual thermodynamic equilibrium; and, as the temperature approaches absolute zero, the entropy of a system approaches a minimum. Entropy is energy that is no longer available for doing mechanical work; it is the random motion of atoms or molecules; it is waste heat; it cannot be used to do anything: it is Mother Nature’s tax on everything. The ability of some gases to absorb and reradiate energy and to heat the air was discovered and measured in the middle of the nineteenth century. The idea of the climate being the result of a balance between the energy received and emitted by the Earth arose but lacked a formal analysis. The concept of a ‘black body,’ a perfect absorber and emitter of energy was developed in the latter half of that century. It formed the basis for understanding the energy balance of incoming radiation from the Sun and outgoing radiation from the Earth, and hence the planetary temperature.
William W. Hay

Chapter 10. The Climate System

Abstract
Insolation is the incoming energy from the Sun. It is at shorter wavelengths of ultraviolet, the visible spectrum, and the near infrared. Albedo is the reflection of incoming energy back into space by the planet. To maintain a given temperature, the Earth radiates energy back into space at invisible infrared wavelengths. In doing so, it must redistribute the energy. But the weather is inherently chaotic. The major components of Earth’s climate system are air, earth, ice, and water: the atmosphere, hydrosphere, cryosphere, and land. Climatic regions are commonly classified by their vegetation, which integrates the climate signal over time. Some uncertainties in the components of the climate scheme remain.
William W. Hay

Chapter 11. What’s at the Bottom of Alice’s Rabbit Hole

Abstract
Measurements of black body radiation could not be duplicated with simple mathematical formulations. A curve fit to the short wavelengths did not fit the shorter wavelengths and vice versa. Max Planck found a solution by assuming the energy is not continuous but comes in discrete particles, known as quanta. This explained the photoelectric effect. Niels Bohr produced a new model for the structure of the atom using quantum physics. This had major implications for understanding the periodic table of the elements. It was realized that waves have a particulate nature and vice versa, ushering in the second quantum revolution. It was discovered that atoms can undergo spontaneous nuclear fission.
William W. Hay

Chapter 12. Energy from the Sun: Long-Term Variations

Abstract
The evolutionary history of the Sun indicated that it had originally been much fainter than at present. But the Earth had liquid oceans shortly after its formation. The Faint Young Sun Paradox was solved by assuming that Earth’s early atmosphere had much higher greenhouse gas concentrations. The amount of energy received by Earth varies as our planet’s orbital configuration changes. Calculations of the Earth’s orbit in the past suggested that this was the cause of the ice ages. However, the orbital calculations suggested that there must have been many ice ages but only four were known to geologists. Study of river terraces and deep sea cores suggested that there had been many ice ages. Studies of sedimentary rocks indicated that the orbital changes had affected Earth’s climate even in times when there was no polar ice.
William W. Hay

Chapter 13. Solar Variability and Cosmic Rays

Abstract
The Sun is a variable star, as evidenced by its 11-year sunspot cycles, but the changes in its radiative output are so small as to have no unambiguous effect on climate. Longer term variability is uncertain. Expulsion of solar matter in ‘coronal mass ejections’ produces space weather which may affect electrical devices. In the latter part of the twenty-ninth century it was discovered that the flux of neutrinos from the sun was lower that it should be. The neutrino problem was solved when it was discovered that neutrinos can change between their different forms. Satellites have shown that although the change in radiation in the visible and infra-red parts of the spectrum during the sunspot cycles is small, there are large variations in the ultraviolet. Cosmic rays are high energy particles coming in from outer space. They can interact with Earth’s atmosphere to produce carbon-14 and beryllium-10. It has been suggested that they can affect cloudiness, but detailed analysis of satellite records indicates this is not the case.
William W. Hay

Chapter 14. Albedo

Abstract
Albedo is the Earth’s reflectivity; about 30 % of the incoming solar radiation is reflected back into space. The reflectivity of different surfaces is highly variable. Forests absorb most of the incoming radiation; ice and snow reflect it. Most of the Earth’s reflectivity is from clouds. It was suspected that cloudiness might be a global thermostat ameliorating the effects of global warming, but this has turned out not to be the case. Volcanic ash and sulfur dioxide, as well as dust enhance planetary albedo as does anthropogenic pollution. This may be the cause of the leveling off of northern hemisphere temperatures from 1950 to 1970. Because of more extensive ice cover and during the Last Glacial Maximum, the planetary albedo was higher then.
William W. Hay

Chapter 15. Air

Abstract
Air is composed of the molecules of the diatomic gases nitrogen and oxygen, a very small amount of atomic argon, and multi atomic trace gases such as CO2, CH4, and N2O, which can absorb and reradiate energy. The atmosphere is filled with photons representing the incoming and outgoing radiation. It is the kinetic motion of air molecules we recognize as sensible (measurable) heat. But the molecules have other motions, vibration, and rotation. Photons can interact with the major gases to impart kinetic energy, and in extreme instances to cause ionization. Interaction of photons with oxygen and nitrogen molecules scatters the light to produce the blue sky. Interactions between molecules of air in the upper atmosphere with cosmic rays can cause showers of subatomic particles.
William W. Hay

Chapter 16. HOH: The Keystone of Earth’s Climate

Abstract
Water has the structure HOH, whereby the hydrogen atoms are separated by about 104°; as a result the water molecule is more electrically positive on one side, negative on the other. This makes water molecules ‘stick’ and gives this common substance many unique properties. Water exists in three phases, gas (vapor), liquid (water), and solid (ice) on and near the surface of the Earth. Very large amounts of energy are involved in the change from one phase to another. Most of the water on Earth contains salt. Fresh and sea water behave differently as their temperature changes. Fresh water reaches its maximum density at about 4 °C, and becomes less dense as it approaches the freezing point. At a salinity of 27.4 ‰ the temperature of maximum density and the freezing point coincide. The average salinity of ocean water is about 34.5 ‰, so it gets denser and denser as it approaches the freezing point. Sea ice forms by snowflakes diluting a tiny amount of seawater so it can float and freeze. Ice, the sold phase, is less dense than water, the liquid phase. Ice covers the polar regions of Earth and is a powerful stabilizer of climate. Ice cores from Greenland and Antarctic contain not only an isotopic record of climate change, but bubbles containing the ancient atmosphere. Ice cores in Greenland go back about 100,000 years, in Antarctica about 700,000 years.
William W. Hay

Chapter 17. The Atmosphere

Abstract
Atmospheric pressure declines with altitude following an exponential curve. Earth’s atmosphere is stratified. The lowest layer, the troposphere convects; the temperature of the air declines with height as the pressure decreases. In the next layer, the stratosphere the temperature increases with height preventing convection. The increase in temperature is due to ozone, a greenhouse gas intercepting energy from the Sun and heating the air. Ozone is concentrated at the base of the stratosphere. The temperature declines again in the mesosphere, and increases in the extreme outer layer, the thermosphere. There is no top to the atmosphere; air molecules simply become increasingly rare.
William W. Hay

Chapter 18. Oxygen and Ozone: Products and Protectors of Life

Abstract
Diatomic oxygen, O2, can be produced by dissociation of water vapor in the outer atmosphere, but almost all of the oxygen in the atmosphere today has been produced through photosynthesis, fixing carbon and water to make organic matter and release oxygen. If the organic matter is buried and does not decay, oxygen is left behind in the atmosphere. Triatomic Oxygen, O3, or Ozone is created by the interactions of diatomic oxygen molecules and energetic photons in the upper atmosphere. It settles gravitationally to the base of the stratosphere. It absorbs ultraviolet radiation and protects life on the planet’s surface from those harmful rays. It is decomposed by other compounds, but particularly by some man-made gases, such as chlorofluorocarbons. An international agreement, the Montreal Protocol, is succeeding in phasing out the production of most anthropogenic agents destroying ozone.
William W. Hay

Chapter 19. Water Vapor: The Major Greenhouse Gas

Abstract
Water vapor is a powerful greenhouse gas. The amount of water vapor in the air depends on temperature. Its saturation level doubles with every 10 °C increase in temperature. Its concentration also depends on availability of sources such as water surfaces and vegetation. Because of its strong temperature dependence its role as a greenhouse gas is limited to the equatorial region and the tropics diminishing to nil in the polar regions.
William W. Hay

Chapter 20. Carbon Dioxide

Abstract
The ultimate source of CO2 is thought to be volcanic emissions. However, most CO2 is continuously recycled as part of the carbon cycle. CO2 is taken up by plants, and through photosynthesis is fixed as organic matter. The organic matter is then used by plant or animals to obtain energy, releasing the CO2 back into the atmosphere. CO2 is a greenhouse gas, intercepting and re-emitting the radiation from Earth back into space. It is thought that CO2 has been the Earth’s major thermostat mechanism through time. Higher levels result in a greenhouse condition, lower levels an icehouse state. CO2 is ultimately removed from the system by the weathering of silicate minerals, an exceedingly slow process. Because CO2 reacts with water to form carbonate and bicarbonate ions it is thousands of times more soluble than oxygen. Although the changes in the icehouse state from glacial to interglacial are forced by variations in Earth’s orbit, atmospheric CO2 levels follow, acting as a positive feedback. Since the Industrial Era, there has been an almost exponential increase in the amount of CO2 in the atmosphere, almost all from the burning of fossil fuels. Today’s atmospheric concentrations are as much higher than pre-industrial levels as those were above the levels of the Last Glacial Maximum. CO2 is the major greenhouse gas in the polar regions, concentrating global warming in the high latitudes.
William W. Hay

Chapter 21. Other Greenhouse Gases

Abstract
Methane, CH4 is a more powerful greenhouse gas than CO2 but its concentration is much less. It is produced by anaerobic bacteria. These occur in bogs and rice paddies, but also in the intestines of ruminant animals (cattle) and termites. Before oxygen appeared in Earth’s atmosphere methane may have been the most important greenhouse gas. The dominant sites of production of methane are low-latitude wetlands, but with warming of the Earth, increasing amounts of methane are being released from Arctic bogs. Methane can combine with water to form an ice, termed a clathrate. These ices form under the pressure of a few hundred meters of seawater at temperatures well above the freezing point of the water itself. Clathrates cement sediment grains together, acting in some areas to stabilize continental slopes. Warming of the ocean may decompose clathrates releasing methane into the seawater or atmosphere and resulting in tsunami-producing slope failure on the continental margins. Nitrous Oxide, N2O, is another powerful greenhouse gas released into the atmosphere from decaying vegetation. Since the middle of the last century, it has been artificially produced for munitions and then fertilizer but through overuse it has become an anthropogenic pollutant. It is becoming the most effective destroyer of ozone in the twenty-first century.
William W. Hay

Chapter 22. The Circulation of Earth’s Atmosphere and Ocean

Abstract
The modern atmospheric circulation reflects the state of the planet with ice on both poles. Warm air rises in the equatorial region and sinks in the polar regions. But the rotation of the earth causes equatorward flowing air to appear to be turned to the right in the northern hemisphere and to the left in the southern hemisphere. The result is three cells per hemisphere. Those on either side of the equator are the Hadley cells, those in the polar regions are the Polar cells; these drive an intermediate pair of cells, the Ferrell cells. The winds drive the ocean currents; the water moves to the right of the wind in the northern hemisphere, and to the left in the southern hemisphere. The winds set up large anticyclonic gyres between the equator and a latitude of about 60 ̊N and S. These warm water gyres overlie cold water that sinks in the polar region. The waters between these two masses in which the temperature declines rapidly with depth are known as thermocline and intermediate waters. They sink into the ocean along the Subtropical and Polar frontal system that border the great gyres. The deep waters of the ocean form a ‘Great Conveyor.’ Cold saline waters sink in the Greenland–Iceland–Norwegian (GIN) Sea and overflow the Greenland–Scotland Ridge into the North Atlantic Basin. There they mix with warm saline Mediterranean outflow waters, and flow southward as North Atlantic deep water. Some of this wells up near the Weddell Sea, is chilled, and sinks again as Antarctic Bottom Water, flowing eastward to end up in the Pacific. Slow upwelling of deep waters occurs throughout the lower latitude ocean, but more rapid upwelling occurs along the eastern margins of the ocean basins where equatorward blowing winds drive the surface water offshore. Special disturbances of the general circulation occur periodically in the Pacific (El Niño - La Niña, The Southern Oscillation) and the Atlantic (North Atlantic Oscillation) Ocean circulation on the warmer Earth of the Cretaceous was very different from that of today. Atmospheric pressure systems at the poles reversed with the seasons, winds were inconstant, and the great ocean gyres were replaced by myriads of eddies.
William W. Hay

Chapter 23. The Biological Interactions

Abstract
The earliest life forms on Earth were chemoautotrophs, manipulating the chemistry of compounds to obtain energy. Photosynthesis and the ability to use the energy from the Sun evolved about 2 billion years ago. Over the ages living organisms have modified the surface of the planet. Life forms a thin veneer on the surface of the land, with plants consuming nutrients, water, and CO2 for photosynthesis to produce sugars and other compounds that they and animals ultimately use for energy. Two major categories of plants, C3 and C4 use different pathways for photosynthesis. C4 plants are thought to have evolved as an adaptation to the lower levels of atmospheric CO2 that characterize the icehouse climate. They conserve water and do not return as much of it to the atmosphere as C3 plants. Humans use many C4 plants for food and have spread them over many areas formerly covered by C3 plants. Growth of some plants is enhanced by higher levels of CO2 but others are inhibited. Whereas plants are the obvious life forms on land, animals are the large life forms in the sea. Most marine plants are microscopic. There is little free CO2 dissolved in the ocean so many marine algae obtain their CO2 through photosynthesis from the bicarbonate ion. Many of them get rid of excess CO2 by combining it with the calcium ion to make calcium carbonate. Small animals eat the microscopic plants and produce fecal pellets that sink into the deep ocean. As more CO2 enters the ocean, it becomes increasingly acidic, affecting the ability of many organisms to secrete carbonate.
William W. Hay

Chapter 24. Sea Level

Abstract
Sea level is a long-term average of the heights of high and low tides. It is a function of the volume of water in the ocean. The volume depends on the mass of H2O in the ocean, the salinity, and the temperature. Although the ocean is by far the largest reservoir of H2O the masses in groundwater and ice are also significant. Thermal expansion as the ocean warms can produce sea level changes of tens of meters. Sea level at any particular place also depends on motions of the earth’s solid surface changes in the speed of earth’s rotation, the effect of winds, atmospheric pressure systems and the evaporation-precipitation balance. During the Last Glacial Maximum seal level was about 135 meters lower than today. During the deglaciation sea level rose to its present level in about 11,000 years. Because of the interaction between the increasing volume of water and the motions of Earth’s solid surface sea level records for different places can look very different. During the last 8,000 years global sea level has been stable, but a slow rise has been observed over the past few centuries.
William W. Hay

Chapter 25. Global Climate Change: The Immediate Past

Abstract
The climate changes during the last deglaciation were very large. Conditions for the growth of trees often changed faster than the plants could migrate resulting in forest types with no modern analog. Ice cores from Greenland show sudden short-term temperature changes called ‘Dansgaard-Oeschger events’ that affected the northern North Atlantic. Massive iceberg discharges into the North Atlantic through the Labrador Sea, ‘Heinrich events’ occurred periodically. Attempts to reconstruct the Earth’s temperature history over the past two millennia that showed the warming taking place in the last century were greeted with skepticism by politicians, as exemplified by the ‘hockey stick controversy’ which bore uncanny resemblance to the trial of Galileo Galilei.
William W. Hay

Chapter 26. Is There an Analog for the Future Climate?

Abstract
The Eemian, the Last Interglacial, was very different from that of today. Climate variability was much higher and there were significant changes of sea level in hundreds to a few thousand years. The same is true of the older interglacials. The modern interglacial is unique in having had a 6,000 year history of climate stability that allowed human civilization to develop.
William W. Hay

Chapter 27. The Instrumental Temperature Record

Abstract
The thermometer, a device for measuring temperature, was developed in the seventeenth century but proper calibration and the development of systematic records did not occur until the nineteenth century. The World Meteorological Organization set up a system for collecting temperature measurements on a global scale early in the twentieth century. Data collection and homogenization have become ever more sophisticated. Records from single sites reflect the chaos of the weather, but when combined into regional analyses show distinct trends. North America appears to be a special case, showing a rise in the first half of the twentieth century, a plateau until about 1970, and a subsequent rise. The same patterns can be seen, but not so distinctly, in European records. It is thought that the rises reflect the increasing levels of atmospheric CO2, and the plateau the industrial pollution of the middle of the century. Records from the tropics show the slowest upward trend, but higher latitude records show more pronounced upward trends.
William W. Hay

Chapter 28. The Future

Abstract
The anthropogenic factors causing Earth’s climate and environment to change include increases in atmospheric greenhouse gas concentrations, changes in land use, urbanization, mining, and other alterations ultimately resulting from the growth of the human population. Projections of future change by the Intergovernmental Panel on Climate Change (IPCC) are very conservative, and modern trends generally exceed their ‘worst case’ scenarios from their 2007 report. Although many countries are making efforts to reduce their greenhouse gas emissions, a few countries, most notably the United States refuse to participate. It is recognized that there are tipping points in the climate system. Unfortunately, a tipping point cannot be identified with certainty until one is far enough past it so that there is no possibility of return. For me the great Arctic ice meltback of 2007 indicated we had gone past a tipping point. This event wasn’t expected until the end of the 21st century. A number of changes are accelerating: melting of the Greenland ice sheet, breakup of the ice shelves of the Antarctic, and slowing of the thermohaline circulation. Other changes are occurring with El Niño and the Southern Oscillation, the Indian summer monsoon, in the Sahara and Sahel, and in Amazonia. Changes in the boreal forest, tundra, and permafrost are beginning to appear. Sea level rise is accelerating. The potential release of methane from clathrates and a possible die-off of marine plankton would be catastrophic. Mother Nature may impose her own remedy.
William W. Hay

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