Climate Change Luc Ikelle 2011.

Climate Change Luc Ikelle 2011

Motivations Earth is the place where we live – Climate change.
It provides food through the farming of its soils. It provides energy resources (e.g., oil, gas, and coal) and minerals (e.g., gold, diamonds, uranium, and thorium) – Energy resources.

Motivations Yes, Earth also kills, even more frequently these days; earthquakes and volcanic eruptions are the major sources. – Earthquakes and volcanoes.

Key References Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K., Tignor, M., and Miller, H., 2007, Climate change 2007: The physical science basis: Cambridge University Press, New York, NY. National Research Council, 2002: Abrupt climate change, inevitable surprise: National Academy Press, Washington, DC. European parliament report: Scientific evidence of a possible relation between recent natural disasters and climate change (IP/A/ENVI/FWC/ ).

Key References Reynolds, S.J., Johnson, J.K., Kelly, M.M., Morin, P.J., Carter, C.M., 2010, Exploring geology, 2nd edition, McGraw-Hill Company Inc, New York, NY. Bloom, A.J., 2010, Global climate change: Convergence of disciplines, Sinauer Asspciates, Inc., Sunderland, Ma. Emanuel, K., 2007, What we know about climate, The MIT Press, Cambridge, Ma.

Key References Stott, P.A., Stone, D.A. and Allen, M.R. 2004: Human contribution to the European Heatwave of 2003, Nature, 432, pp Trenberth, K., 2005, Uncertainty in Hurricanes and Global Warming, Science, 308, 17. Travis, D.J., Carleton, A.M., and Lauritsen, R.G., 2002, Climatology: Contrails reduce daily temperature range, Nature, 418, 601.

“Climate is what we expect; weather is what we get.” Mark Twain (1897)

Weather Weather refers to hour-to-hour and day-to-day changes in temperature, plus cloudiness, precipitation, and other meteorological conditions. The weather pages in The Eagle newspaper includes information on daily maximum and minimum temperatures, humidity, precipitation, and wind speed and direction. The accuracy of weather forecasts can be confirmed by observing the actual weather.

Climate Long-term averages of meteorological conditions (e.g., temperatures, humidity, precipitation, wind speed and direction) define the climate in your area. In other words, long-term weather patterns characterize the climate. For example, a Mediterranean climate is characterized by relatively hot, dry summers and cool, wet winters.

Climate Change Plate tectonic theory has just taught us that Earth’s surface changes with space and time. Climate is not infinitely stable, either; it changes with time and space. Climate changes are not caused just by human actions; climates also change naturally.

Climate Change Climate changes naturally on a range of spatial scales, from local and regional to global, on a range of time scales: decadal (10s of years), centennial (100s of years), millennial (1000s of years), and longer (glacial cycles, e.g., ice ages). For example, a longer winter characterizes climate change in time, and the monsoon rains occurring farther south characterize climate change in space. 11

Climate Change Within the past three million years or so, our climate has swung between mild states, like today’s, and lasting from 10,000 to 20,000 years; and periods of 100,000 years or so in which giant ice sheets, in some places several miles thick, covered northern continents. Moreover, climate changes between cycles are often sudden, especially as the climate recovers from glacial eras. 12

Climate Change Around 50 million years ago, the earth was free of ice, and giant trees grew on islands near the North Pole, where the annual mean temperature was about 60 degrees Fahrenheit, far warmer than today’s mean of about 30. There is also evidence that the earth was almost entirely covered with ice at various times around 500 million years ago; in between, the planet was exceptionally hot.

Why Should We Be Interested in Climate Change?
Climate determines the type and location of human-managed ecosystems, such as agricultural farmlands. For example, changes in climate will impact on crops and livestock. Rising temperatures cause a shift in budburst, shorter growing seasons, earlier harvest dates, lower crop quality, and changes in soil temperatures. Climate determines the quantity and quality of water available for human use.

Why Should We Be Interested in Climate Change?
A warming of 1°C is sufficient to move climate belts about 150 km south. A regional temperature change of 2°C likely to have a serious impact on most life forms and on most ecosystems and agricultural areas. Some climate changes are abrupt—that is, rapid and unpredictable. In the past, the average global temperature has risen or fallen > 6º C in less than 10 years. Abrupt climate change : inevitable surprises / Committee on Abrupt Climate Change, Ocean Studies Board, Polar Research Board, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, National Research Council.

How About Recent Extreme Weather Events?
The 2010 Pakistan floods began in July 2010 following heavy monsoon rains in the Khyber Pakhtunkhwa, Sindh, Punjab and Balochistan regions of Pakistan. Present estimates are that more than 2,000 people have died and more than a million homes have been destroyed. Hurricane Katrina, which took place during the Atlantic hurricane season, was the costliest natural disaster and one of the five deadliest hurricanes, in the history of the United States. At least 1,836 people lost their lives in the hurricane and the subsequent floods.

How About Recent Extreme Weather Events?
The European heat wave in the summer of 2003 caused massive loss of life; the deaths of at least 22,146 people have been attributed to the heat. Hurricane Mitch in 1998 killed more than 10,000 people in Central America. The 1970 Bhola cyclone was a devastating tropical cyclone that struck East Pakistan (now Bangladesh) and India's West Bengal on November 12, It was the deadliest tropical cyclone ever recorded and one of the deadliest natural disasters in modern times. Up to 500,000 people lost their lives in the storm, primarily as a result of the storm surge.

Natural Hazards Geosphere (Chapter 1):
Earthquakes (fire, floods, etc.) Volcanic eruptions Landslides Tsunamis Atmosphere (Chapter 3): Hurricanes Cyclones Droughts Wildfires

Plan Basic physics of the atmosphere Glaciers and ice ages
Tools of climate sciences Natural forcing factors Human forcing factors Global climate model and global warming Climate change and natural disasters Abrupt climate change Mitigation and adaptation

Terminology A monsoon is caused by winds that reverse direction, depending on the season. In some areas, the changing wind patterns cause torrential rainstorms. Tropical hurricanes, typhoons, and cyclones are all names for immense storms that form primarily in the warm waters of the Atlantic, Pacific, and Indian oceans, respectively. They are characterized by swirling high-velocity winds, heavy rain, and high storm surges that cause high waves and flooding ahead of the storm.

Terminology Molecules. A molecule is a stable group of two or more atoms held together by strong chemical bonds. A molecule may consist of atoms of a single chemical element, such as oxygen (O2), or of different elements, such as water (H2O), methane (CH4), and carbon dioxide (CO2). Isotopes are different types of atoms (nuclides) of the same chemical element, each having a different number of neutrons. Isotopes differ in mass number (or number of nucleons) but never in atomic number (e.g., 16O, 17O, and 18O).

Terminology IPCC refers to the Intergovernmental Panel on Climate Change. SRES refers to the Special Report on Emissions Scenarios (SRES) prepared by the IPCC. CAFE refers to Corporate Average Fuel Economy. In the aftermath of the 1973 oil embargo, the U.S. Congress enacted the CAFE regulations. The regulations established the average fuel economy of passenger cars in a manufacturer’s U.S. fleet in order to spur the development of more fuel-efficient technologies.

Atmosphere Atmosphere: N2, O2, H2O, and a little CO2
Mean temperature: + 15o C Photo

Earth’s Atmospheric Gases
Nitrogen (N2) Oxygen (O2) Non-greenhouse Gases > 99% Argon (Ar) Water (H2O) Carbon Dioxide (CO2) Greenhouse Gases Methane (CH4) < 1%

Greenhouse Gases Nitrous oxide Methane Sulfur hexafluoride
Carbon dioxide Water Methane Nitrous oxide Sulfur hexafluoride

Major Greenhouse Gases
Concentration (ppb) Lifetime (years) Warming potential Carbon dioxide , Methane , Nitrous oxide Carbon monoxide Sulfur hexafluoride , ,800 ppb: parts per billion. warming potential: Total radioative effect per molecule over 100 years relative to C02 Source: IPCC 2001; Forster et al. (2007)

One Part Per Million Parts (ppm)
The expression “1 ppm” means a given solute exists at a concentration of one part per million parts of the solution. One-millionth of a gram per gram of sample solution One gram of solute per million grams of sample solution Notice that ‘gram’ is used just above. This is because ‘gram’ is used almost exclusively when the term “parts per million” is used.

One Part Per Million Parts (ppm)
Pollutants in air and water are frequently measured in parts per million (ppm) or parts per billion (ppb). One part per million would mean that there is one gram of the pollutant in every one million grams of air. At ordinary temperature and pressure, air has a density of gram per cubic centimeter.

Atmospheric Composition
Air is a mixture of many discrete gases. Dry air is composed almost entirely of two gases: 78% nitrogen and 21% oxygen. These gases are important for life on Earth but have no significant effect on weather and climate changes.

The remaining 1 percent of dry air is mostly inert gas (0.93 percent) plus a number of other gases. Carbon dioxide (0.038 percent) is an important constituent of air because it has the ability to absorb heat energy radiated by Earth and thus to heat the atmosphere. Air includes many gases and particles that vary significantly from time to time and from place to place. Important examples include water vapor and tiny solid and liquid particles.

The amount of water vapor in the air varies considerably, from practically none at all up 4 percent by volume. Water vapor is the source of clouds and precipitation. It has the ability to absorb heat energy given off by Earth as well as some solar energy. Water vapor is therefore important when we examine the warming of the atmosphere.

Climate science IPCC FAQs 1.3 Fig 1
GHGs next slide Pic IPCC FAQs 1.3 Fig 1 IPCC FAQs 1.3 Fig 1

Greenhouses Natural-produced greenhouse gases
Naturally produced Natural-produced greenhouse gases (water vapor, carbon dioxide, etc.) Human-produced greenhouse gases (carbon dioxide, methane, etc.) Human produced Human produced Source: NewSci, National Academy of Sciences

Electromagnetic Radiation
The greenhouse effect has to do with radiation, which in this context refers to energy carried by electromagnetic waves, which include such phenomena as visible light, radio waves, and infrared radiation. All matter with temperatures above absolute zero emits radiation.

The Electromagnetic Spectrum (Range of Wavelengths)
Visible light is part of the electromagnetic spectrum. Its wavelength is a little less than a millionth of a meter.

The hotter the substance, the more radiation it emits, and the shorter the average wavelength of the radiation emitted. The same object can emit and absorb radiation: when an object emits radiation, it loses energy, and this has the effect of cooling it; absorption, on the other hand, heats an object. Most solids and liquids absorb much of the radiation they intercept, and they also emit radiation rather easily.

A fairly narrow range of wavelengths constitutes visible light. The average surface temperature of the sun is about 10,000 degrees Fahrenheit. It emits much of its radiation as visible light of about half a micron. The earth’s atmosphere’s average temperature is around 0 degrees Fahrenheit. It emits radiation at an average wavelength of 15 microns.

The Electromagnetic Spectrum
All objects at any temperature emit electromagnetic radiation. Hot objects radiate infrared (which we feel as heat), and even hotter ones glow with visible electromagnetic radiation.

Solar Radiation Solar radiation consists of a range of light at different wavelengths (spectrum): Ultraviolet – largely absorbed by ozone in the stratosphere (high altitude) Visible – sunlight, the easiest to reach the ground Infrared (heat) – absorbed and trapped by water vapor and certain gases, such as carbon dioxide

Solar Radiation Visible light is absorbed by the soil, oceans, and plants. A percentage of this infrared radiation is kept from escaping back into space by greenhouse gases. If greenhouse gases increase in concentration, more infrared radiation is trapped, and global temperatures rise.

Absorption Spectra for Greenhouse Gases
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CO2 42

CO2 CH4 That means that even if the atmosphere is saturated with water vapor a lot of infrared still gets through. CO2 and CH4 absorb IR wavelengths that H2O doesn’t. 43

How Are Glaciers Formed?
Margin of the Greenland Ice Sheet. 45

The Formation of Glaciers
Glaciers are formed from layers of snow that collect in cold areas. More snow is collected than is melting each year, so it piles up. The snow on the bottom is compressed into ice. Before long there is an expanding field of ice that covers the ground. 46

Types of Glaciers Continental glaciers (ice sheets)
96% of all glaciers Found in Antarctica and Greenland Covered most of Canada and the northern USA during the last ice age (up until about 18,000 years ago) Mountain or valley glaciers Found in the valleys of some mountains Rivers of ice Teachers guide to glaciers of the New England at 47

Continental Glaciers Continental glaciers are very large ice sheets that spread outward in all directions like pancake batter. Ice caps are very large continental glaciers. Some examples: Antarctica, Greenland Ice Sheet on Ellesmere Island, Canada Photo credit: Geological Survey of Canada 48

Mountain Glaciers Mountain or valley glaciers begin in the mountains at high altitudes. As they thicken, they flow downhill, following the shape of the valley. Donjek Glacier in the Saint Elias Range, Yukon Territory, Canada. (Source: Natural Resources Canada. Photograph by Douglas Hodgson. Copyright Terrain Sciences Division, Geological Survey of Canada.) 49

What Is an Ice Age? An "ice age" or, more precisely, "glacial age" is a period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers. Within a long-term ice age, individual pulses of extra cold climate are termed "glacial periods" and intermittent warm periods are called "interglacials". 50

Ice Ages The earth has experienced warm and cold spells.
Successive years of cold weather constitute an ice age. Glaciers are formed during years of cold weather. In the past million years, the earth has seen some dramatic climate flux. 5 major glaciations 30 minor glaciations 51

Recent Climate Change The past 15,000 years (the Holocene)
Warming led to deglaciation, yet temperatures still fluctuate. Several cold periods have punctuated this interglacial period. Duan (2009)

Recent Climate Change Holocene is the name given to the last 15,000 years or so of the earth's history; the time since the end of the last major ice age. Since then, there have been small-scale climate shifts—notably the “Little Ice Age” between about 1200 and 1700 A.D. –but in general, the Holocene has been a relatively warm period in between ice ages.

Recent Climate Change Several ice ages have caused the northern United States to be covered with glaciers. The last ice age was at its maximum approximately 25,000 years ago. Glaciers 1 to 2 kilometers thick covered the mountain peaks of New England. By 15,000 years ago, the ice had all melted and retreated, leaving behind a changed landscape. Teachers guide to glaciers of the New England at 54

Thermometer Records Thermometers provide a means of direct measurement of air temperature. The record shows average global variations in temperature for the past 150 years. It appears that average temperatures have increased over the last century. Before 1940, the data show a relatively cool period. Modest (0.5o C) global warming substantially increases the risk of extreme weather events.

Thermometer Record

Borehole Temperatures
Temperatures deep in the ground respond to changes near the surface. For example, a sustained heat wave at the surface will cause warming to propagate slowly downward, taking roughly 100 years for the perturbation to reach a depth of 150 m. Therefore, the vertical distribution of temperatures in boreholes from drilling operations contains information about past air temperatures.

There are thousands of boreholes around the world, and measurements of temperature with depth are compared to predicted subsurface temperatures to infer temperatures. This approach has the advantage of measuring temperature directly. The disadvantage is that various soils and rocks differ in how they transfer heat and distort the temperature signal from the surface, so the precision of temperature measurement declines rapidly with depth.

Reynolds et al. (2010)

Glacier Length Quantitative assessments of the size of glaciers for the past 400 years are available. Glaciers flow from areas of snow accumulation to lower elevations. The dynamics and energy flow of glacier movement and retreat are well understood. A simple relationship exists between glacier length and average air temperature.

Glacier Length Reynolds et al. (2010)

So where are the proofs of the climate changes going back thousands and millions of years ago that we have described in the previous slides?

Tools of Climate Sciences
The problem with accurately assessing climate change is that historical records of most meteorological variables go back, at best, only 160 years or so (to about 1850). The length of this record is just too small to describe the range of natural climate variability over thousand- and million-year periods.

Also, the data that we do have are not necessarily consistent, as issues such as changes in instruments, urbanization, and the advent of satellite data complicate the matter significantly. Yet to understand fully the behavior of the atmosphere and to anticipate future climate change, we must somehow discover how climate has changed over broad expanses of time. 65

To overcome the lack of direct measurements, scientists have turned to indirect measurements to reconstruct past climates. Such proxy data come from natural recorders of climate such as glacial ice, tree-growth rings, coral reefs, seafloor sediments, etc.

Tools of Climate Sciences: Ice Cores
Ice cores allow us to reconstruct past climates. Cores taken from Greenland and Antarctic ice sheets have changed our basic understanding of how the climate system works. Scientists collect samples with a drilling rig like a small version of an oil drill. A hollow shaft follows the drill head into the ice, and ice cores are extracted.

Ice cores provide a detailed record of changing air temperatures and snowfall. Air bubbles in the ice record variations in atmospheric composition. Changes in carbon dioxide and methane are linked to fluctuating temperatures. The core information also includes atmospheric fallout such as windblown dust, volcanic ash, pollen, and modern-day pollution. 68

National Ice Laboratory
69

Ice cores from Antarctica tell us that the current polar climate is warmer than it has been at any time in the past 250,000 years.

Tools of Climate Sciences: Tree Rings
Every year, trees in temperate regions add a layer of new wood under the bark. Characteristics of each tree ring, such as size and density, reflect the environmental conditions that prevailed during the year when the ring formed. Favorable growth conditions produce a wide ring; unfavorable ones produce a narrow ring. Trees growing at the same time in the same region show similar tree-ring patterns.

Annual tree rings indicate not only tree age; the ring width indicates growth spurts due to warmer temperatures.

Tools of Climate Sciences: Coral Reefs
Corals are marine animals that form exoskeletons of calcium carbonate. Colonies of corals produce reefs in clear, shallow waters. These animals generate denser layers in their exoskeletons during months with severe weather and less-dense layers during months with more- benign weather. As a result, corals develop discernible annual bands that can be counted to establish the age of a sample.

Useful information on past climate conditions is gathered by analyzing the changing chemistry of coral reefs with depth. The ratio of heavy to light oxygen isotopes in shells of marine organisms decreases with the temperature of the surrounding seawater. The strontium/calcium ratio in coral skeletons decreases with temperature.

Fiji coral reefs

Tools of Climate Sciences: Sea Level
Global sea levels rise and fall depending on the volume of the ocean basins versus the water in them. Changes in the volume of ocean basins occur over million of years and are not directly related to climate (plate tectonics). However, changes in water volume may occur relatively rapidly (in less than 100,000 years) and depend on global temperatures.

Tools of Climate Sciences: Seafloor Sediments
Seafloor sediments are useful recorders of worldwide climate change because the numbers and types of organisms living near the sea surface change with the climate. 82

Comparing Temperature Reconstructions
83

Causes of Climate Change
What cause climate change? Humans started emitting greenhouse gases only after the advent of the industrial era, which began in the late 1700s. Given that there are fairly large temperature fluctuations in the proxy data well before the 1700s, what are the reasons for these climate changes?

Natural Causes of Climate Change
The sun is Earth’s main energy source. The sun’s output is nearly constant, but small changes over an extended period of time can lead to climate changes. In addition, small changes in the earth’s orbit affect how the sun’s energy is distributed across the planet, giving rise to ice ages and other long-term climate fluctuations over many thousands of years. Our objectives here is to describe how the sun’s output affects climate change as well as other natural processes that may influence climate change.

Forcing Factors The earth’s temperature is influenced by many factors. These factors are known as climate forcings. Prediction of the future of Earth’s climate requires a thorough understanding of these factors. There are two categories of forcing factors: external (outside of Earth and its atmosphere; e.g., solar energy) and internal (factors originated on Earth; e.g., greenhouse gases in Earth’s atmosphere).

Natural Forcing Factors
Some of the internal forcing factors are due to human actions, and others occur naturally. All external forcings occur naturally. These include galactic variations, orbital variations, and sunspots. We will first focus on naturally occurring forcing factors; that is, external forcings and natural internal forcings.

External Forcing Factors: Galactic Variations
Our sun lies in the Milky Way, a swirling spiral galaxy of more than 200 billion stars. Every 150 million years or so, our solar system rotates around the Milky Way. The quality and quantity of energy reaching Earth from nearby star systems and from the gases and dust that pervade interstellar space vary during this rotation.

External Forcing Factors: Galactic Variations
The cyclical fluctuations in this energy are so long and so uncertain that they obscure the influence of galactic rotation on Earth’s climate. Nonetheless, several major climatic events, such as tropical temperature changes, are separated by about 150 million years and therefore may be related to the period of galactic rotation. Since 1979, when we began taking measurements from space, the data show no long-term change in total solar energy, even though Earth has been warming.

External Forcing Factors: Orbital Variations
Relying on ice cores and sediment cores from the deep ocean, scientists have learned that the ice-age cycles of the past three million years are caused by periodic oscillations of the earth’s orbit. These oscillations do not greatly affect the amount of sunlight that reaches the earth, but they do change the distribution of sunlight with latitude.

The distribution matters because land and water absorb and reflect sunlight differently, and the distribution of land and water is quite different in the northern and southern hemispheres. Ice ages occur when, as a result of orbital variations, the Arctic regions intercept relatively little summer sunlight, and ice and snow do not melt as much.

Orbital variations are characterized by their eccentricity, obliquity, and precession.

External Forcing Factors: Orbital Variations (Eccentricity)
The elliptical shape of Earth’s orbit around the sun is characterized its eccentricity, a measure of the deviation of an orbit from a perfect circle. The red line is a near-circular orbit, and the blue line is an elliptical orbit. Reynolds et al. (2010)

External Forcing Factors: Orbital Variations (Eccentricity)
Eccentricity: 100,000 years

External Forcing Factors: Orbital Variations (Tilt)
Earth’s daily rotation around its own axis has an angle with respect to its orbital plane around the sun. This angle is called the axial tilt or obliquity. Reynolds et al. (2010)

Maximum tilt angle Present-day tilt angle Minimum tilt angle Reynolds et al. (2010)

External Forcing Factors: Orbital Variations (Tilt)
Obliquity: 41,000 years

External Forcing Factors: Orbital Variations (Precession)
Earth behaves like a wobbling top, and its precession, the alignment of its axis of diurnal with its distance from the sun, oscillates with an average period of about 21,000 years. Due to this wobble, a climatically significant alteration must take place. The tilt toward Vega means that the Northern Hemisphere will experience winter when the earth is farthest from the sun and will experience summer when the earth is closest to the sun. This coincidence will result in greater seasonal contrasts. Reynolds et al. (2010)

Orbital variations vs. Temperature
Age (kya) 1000 900 800 700 600 500 400 300 200 100 Eccentricity (100 ky) Temperature Obliquity (41 ky) Precession (21 ky)

External Forcing Factors: Milankovitch Theory
The episodic nature of the earth’s glacial and interglacial periods within an ice age is caused primarily by cyclical changes in the earth’s circumnavigation of the sun. Variations in the earth’s eccentricity, axial tilt, and precession comprise the three dominant cycles, collectively known as the Milankovitch cycles. They are named for Milutin Milankovitch, the Serbian astronomer who is generally credited with calculating their magnitude.

External Forcing Factors: Milankovitch Theory
Taken together, the variations in these three cycles create alterations in the seasonality of solar radiation reaching the earth’s surface. These times of increased or decreased solar radiation directly influence the earth’s climate system, thus impacting the advance and retreat of the earth’s glaciers.

External Forcing Factors: Orbital Variations (Good News)
Currently the obliquity of Earth’s orbit is intermediate, its eccentricity is small, and its processional alignment is such that Earth is farthest from the sun during June and July. If the orbital variations were the sole forcing factors, Earth’s climate would remain about the same for the next 40,000 years or so.

External Forcing Factors: Sunspots
Each of these sunspots spanned an area several times that of Earth.

Periodic changes in the alignment between the sun’s rotational axis and the gravitational center of the solar system produce intense fluctuations in the vertical magnetic fields of the sun. These divert heat flow from deeper layers in the sun and generate patches of fluctuating temperatures on the surface that manifest as sunspots. Optical telescopes can be used to detect sunspots.

The number of sunspots varies. There is an approximately 11-year period as well as a less-predictable longer cycle. Solar energy reaching Earth increases during the time of high sunspot activity, therefore increasing the earth’s surface temperature. However, the sunspots accounts for only a degree Celsius variation in global temperature.

Internal Forcing Factors: Plate Tectonics
Orogeny is the process by which tectonic movements of Earth’s crust or volcanic activities form mountains. Mountains disrupt global atmospheric circulation. Mountains tend to accumulate ice and snow that increase the percentage of solar energy reflected by the earth The uplifting of mountains also exposes rocks that undergo chemical weathering and absorb carbon dioxide. In the distant past, drifting continents make a big difference in climate over millions of years by changing ice caps at the poles and by altering ocean currents, which transport heat and cold throughout the ocean depths.

Times of relatively rapid mountain building (say, from 40 million years ago, when the Himalayas and the Sierra Nevada first arose, until today, as these ranges continue to uplift) are usually cooler periods. Last Hope Sound, Chile Mountain ranges intercept wind and water vapor, causing rain shadows, concentrated rainfall, and other climatic effects. Tectonic uplift also exposes land to chemical weathering, which removes carbon dioxide from the atmosphere. Reynolds et al. (2010)

Epeirogeny is the formation of continents and ocean basins through deformations of Earth’s tectonic plates. The global distribution of landmass determines the amplitude of glacial-interglacial cycles. Mid-ocean ridges release large amounts of energy and greenhouse gases. The sea level rises and falls as new plate materials modify the shape of ocean basins.

Internal Forcing Factors: Volcanism
Volcanic activity releases carbon dioxide and water vapor, which cause atmosphere warning. Volcanic ash and sulfur dioxide gas from volcanoes reflect solar radiation, causing regional or global cooling. Reynolds et al. (2010)

The June 1991 eruption of Mount Pinatubo had a global impact. The sulfur dioxide (SO2 ) in this cloud – about 22 million tons – combined with water to form droplets of sulfuric acid, blocking some of the sunlight from reaching the earth and thereby cooling temperatures in some regions by as much as 0.5 degrees C. An eruption the size of Mount Pinatubo could affect the weather for several years.

In April 1815, the cataclysmic eruption of Tambora volcano in Indonesia was the most powerful eruption in recorded history. Tambora’s volcanic cloud lowered global temperatures by as much as 3 degrees C. Even a year after the eruption, most of the northern hemisphere experienced sharply cooler temperatures during the summer months. In parts of Europe and North America, 1816 was known as “the year without a summer.”

Internal Forcing Factors: Natural Albedo
Albedo is the percentage of solar energy reflected by Earth. The albedo of various materials ranges from about 85% for pure, fresh snow to 5% for asphalt parking lots or deep, still water. The global average is about 29%. Deserts and snow-covered regions have a high albedo, whereas forests have a low albedo.

Source: OSTP The “natural” Greenhouse Effect and Global Warming
The “natural” greenhouse effect: The Earth is covered by a blanket of gases which allow light energy from the sun to pass through to the Earth’s surface where it is converted to heat energy. This heat is re-radiated back out to space and some of it is trapped by the gases in the atmosphere. By trapping this outgoing heat, the gases keep the Earth’s surface warm— in much the same way that a blanket keeps us warm underneath it. Water vapor and carbon dioxide (CO2) are the two most abundant natural heat-trapping gases in our atmosphere. These and other gases keep the Earth’s surface about 60°F (33 °C) warmer than it otherwise would be. Without this natural greenhouse or blanket effect, life as we know it would not be possible. Global warming: Humans have been releasing carbon dioxide and other heat-trapping gases into the atmosphere, altering the natural concentration. These gases mix in the atmosphere and warm the Earth by trapping outgoing heat. The more heat-trapping gases we release into the atmosphere, the thicker the heat-trapping “blanket” gets, and the more the globe warms up. [Note on analogies: The “greenhouse” analogy comes from the fact that sunlight goes through the glass of the greenhouse and the heat is trapped inside. In our explanation above we have used the “blanket of heat-trapping gases” analogy, which is often a simpler concept for people to understand.] Reflection/absorption, Changes in the concentration of greenhouse gases, which occur both naturally and as a result of human activities, also influence Earth’s climate. Source: OSTP 114

Internal Forcing Factors: Natural Greenhouse Effect
A significant amount of greenhouse gases in the atmosphere is due to past natural forcings and is not the result of human actions.

The greenhouse effect plays a critical role in the earth’s climate. The greenhouse effect has to do with radiation, which in this context refers to energy carried by electromagnetic waves, which include such phenomena as visible light, radio waves, and infrared radiation.

Greenhouse gases absorb much of the long wavelength, the infrared radiation that passes through them. To compensate for the heating that this absorption causes, greenhouse gases must also emit radiation, and each layer of the atmosphere thus emits infrared radiation upward and downward.

The hotter the substance, the more radiation it emits, and the shorter the average wavelength of the radiation emitted. The same object can emit and absorb radiation: when an object emits radiation, it loses energy, and this has the effect of cooling it; absorption, on the other hand, heats an object. Most solids and liquids absorb much of the radiation they intercept, and they also emit radiation rather easily.

The surface of Earth receives radiation from the atmosphere as well as from the sun. Actually, the surface receives more radiation from the atmosphere than directly from the sun. To balance this extra input of radiation, the earth must warm up and thereby emit more radiation itself. This is the essence of the greenhouse effect.

Source: OSTP The “natural” Greenhouse Effect and Global Warming
The “natural” greenhouse effect: The Earth is covered by a blanket of gases which allow light energy from the sun to pass through to the Earth’s surface where it is converted to heat energy. This heat is re-radiated back out to space and some of it is trapped by the gases in the atmosphere. By trapping this outgoing heat, the gases keep the Earth’s surface warm— in much the same way that a blanket keeps us warm underneath it. Water vapor and carbon dioxide (CO2) are the two most abundant natural heat-trapping gases in our atmosphere. These and other gases keep the Earth’s surface about 60°F (33 °C) warmer than it otherwise would be. Without this natural greenhouse or blanket effect, life as we know it would not be possible. Global warming: Humans have been releasing carbon dioxide and other heat-trapping gases into the atmosphere, altering the natural concentration. These gases mix in the atmosphere and warm the Earth by trapping outgoing heat. The more heat-trapping gases we release into the atmosphere, the thicker the heat-trapping “blanket” gets, and the more the globe warms up. [Note on analogies: The “greenhouse” analogy comes from the fact that sunlight goes through the glass of the greenhouse and the heat is trapped inside. In our explanation above we have used the “blanket of heat-trapping gases” analogy, which is often a simpler concept for people to understand.] Source: OSTP 120

Internal Forcing Factors: Clouds
The amount of water vapor in the air varies considerably, from practically none at all to as much as 4 percent by volume. Water vapor is the source of clouds and precipitation. It has the ability to absorb heat energy given off by Earth as well as some solar energy. Water vapor is therefore important when we examine the warming of the atmosphere.

Internal Forcing Factors: Clouds
Clouds reflect sunlight back to space and also act like a greenhouse gas by absorbing heat leaving the earth’s surface. Low clouds tend to cool (reflect more energy than they trap) while high clouds tend to warm (trap more energy than they reflect). The net effect of cloudiness on surface temperatures depends on how and where the cloud cover changes. This is one of the largest uncertainties in projections of future climate change.

Internal Forcing Factors: Ocean Currents
One major pattern of ocean currents, the thermohaline circulation or global consurface belt, involves the northward flow of warm surface waters from the Caribbean along the Atlantic coast of the United States. It is known as the Gulf Stream. Reynolds et al. (2010)

Internal Forcing Factors: Ocean Currents
Ocean waters circulate around the globe in established patterns or currents that derive from different factors: - Differences in solar energy received by the equator and the poles - Topography of the sea floor and coastal landmasses - Changes in seawater density - Rotation of Earth around its axis - Atmospheric winds

Internal Forcing Factors: Storms
There are six conditions for major tropical storms: (i) Sea temperatures must be above 26.5 degrees Celsius to a depth of 50 m. (ii) Air temperatures must cool rapidly with the altitude. (iii) The relative humidity must be high. (iv) A location must be more than 500 km away from the equator. (v) Vertical wind shears between the sea surface and the middle atmosphere must be less than 10 m/s. (vi) A storm must already be brewing.

Summary on Ice Ages The timing of the ice ages is essentially the result of the earth’s orbit. But the orbital variations do not explain either the slow pace of the earth’s descent into the cold phases of the cycle or the abrupt recovery to interglacial warmth. Large climate swings – from glacial to interglacial and back – are caused by relatively small changes in the distribution of sunlight with latitude.

Summary on Natural Forcings
Variations in the energy output of the sun Variations in Earth’s orbit and tilt Plate tectonics Changes in atmospheric composition from volcanoes, biological activity, and weathering of rocks Ocean currents

Greenhouse Gases Many chemical compounds found in the earth’s atmosphere act as greenhouse gases. These gases allow sunlight to enter the atmosphere freely. When sunlight strikes the earth’s surface, some of it is reflected back toward space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere.

Human Forcings: Anthropogenic Changes
Over time, the amount of energy sent from the sun to the earth’s surface should be about the same as the amount of energy radiated back into space, leaving the temperature of the earth’s surface roughly constant. In other words, over time, there is a natural balance between positive (warming factors) and negative (cooling factors) forcings. Human actions are introducing forcings into the climate system which are altering this balance and thus causing a change in the earth’s temperature. We characterize these forcings as human.

Anthropogenic Changes
Human Forcings: Anthropogenic Changes Rising concentration of greenhouse gases from deforestation, agricultural practices, and fossil-fuel burning (greenhouse effect; H2O, C02, CH4, CFC, ..) Rising concentration of particulate matter from agricultural burning, cultivation, and fossil-fuel burning (aerosols; ) Alteration of Earth’s surface reflectivity by deforestation and desertification (albedo) Increase in high cloudiness, caused by aircraft contrails (clouds) 131

Because human actions affecting climate change originate on Earth, we can consider human forcing as internal. Our objective now is to describe human forcing factors (anthropogenic factors).

Greenhouse Effect: Water Vapor
Human-added H2O is not a big problem – it soon rains out again. Water vapor goes in and out of the atmosphere very quickly, in a few days on average. When there is too much, it rains out. Also, more water vapor implies more clouds, which reflect sunlight and reduce the warming effect.

Greenhouse Effect: CO2 Carbon dioxide (CO2) has both natural and human sources, but CO2 levels are increasing, primarily because of the use of fossil fuels, deforestation, and other land-use changes. The increase in carbon dioxide is the single-largest climate forcing contributing to global warming. Only about 50% of the increased CO2 stays in the atmosphere. The rest is absorbed by the oceans and other sinks.

Greenhouse Effect: CO2 A percentage of the infrared radiation emitted by Earth is kept from escaping back into space by greenhouse gases. More CO2 concentration implies more warming. More infrared radiation is trapped; therefore global temperatures rise. Carbon dioxide molecules remain in the air for ~ 120 years.

Greenhouse Effect: CO2 . 136

Greenhouse Effect: CH4 Methane (CH4) is another greenhouse gas with both human and natural sources. The levels of methane have risen significantly since pre-industrial times due to human activities such as raising livestock, growing rice, filling landfills, and using natural gas (which releases methane when it is extracted and transported). Methane dioxide can remain in the air for ~ 12 years.

Greenhouse Effect: CO2 and CH4
Hansen,Clim.Change 68, 2005 Four hundred thousand years of greenhouse-gas and temperature history is based on bubbles trapped in Antarctic ice. The time scale has been expanded for the last 150 years (right side of diagram). CO2 and CH4 levels are far above the range of natural variation in the current geologic era. The last time CO2 was > 300 ppm was about 25 Million year ago.

Greenhouse Effect: N2O and O3
Nitrous oxide (N2O) concentrations have primarily risen because of agricultural activities and land-use changes. Ozone (O3) forms naturally in the upper atmosphere, where it creates a protective shield that intercepts damaging ultraviolet radiation from the sun. However, ozone produced near the earth’s surface via reactions involving carbon monoxide, hydrocarbons, nitrogen oxide, and other pollutants is harmful to both animals and plants and has a warming effect. The concentration of O3 in the lower atmosphere is increasing as a result of human activities.

Greenhouse Effect: Soot and CFC
Black carbon particles or “soot,” which is produced when fossil fuels or vegetation is burned, generally have a warming effect because they absorb incoming solar radiation. Black carbon particles settling on snow or ice are a particularly potent warmer. Halocarbons, including chlorofluorocarbons (CFCs), are chemicals that have been used for a variety of applications, such as refrigerants. In addition to being potent greenhouse gases, CFCs also damage the ozone layer. The production of most CFCs is now banned, so their concentrations are starting to decline.

Human-Enhanced Albedo
Deforestation and other changes in land use modify the amount of sunlight reflected back to space from the earth’s surface. Changes in land use can lead to positive and negative climate forcing locally, but the net global effect is a slight cooling. Reynolds et al. (2010)

Aerosols Most aerosols (airborne particles and droplets), such as sulfate (SO4), cool the planet by reflecting sunlight back to space. Some aerosols also cool the earth indirectly by increasing the amount of sunlight reflected by clouds. Human activities such as industrial processes produce many kinds of aerosols. The total cooling that these aerosols produce is one of the greatest remaining uncertainties in understanding present and future climate change.

Aircraft Contrails Contrails over Paris rooftops Source: IPCC

Aircraft Contrails Jet airplanes flying at high altitudes generate contrails. These behave like clouds in that they reflect incoming solar radiation and decrease daytime temperature maximums but absorb long-wave radiations from Earth’s surface and increase nighttime temperature minimums. Contrails have the potential to diminish temperature differentials between day and night.

Aircraft Contrails Commercial air traffic was shut down in the United States for three days on September 11-13, During this interval, day-night temperature differentials in the continent United States jumped by 1.8o C above during the 3-day periods immediately before or after (Travis et al., 2002). The change was significantly greater in the regions where contrails are most abundant.

NOTE 2000, next 2005 IPCC SynRep 146

History and Projections
1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 Carbon Intensity (tC/toe) Source: National Academy of Engineering, 1997 1900 1920 1940 1960 1980 2000 Carbon Intensity of: Wood = 1.25 Coal = 1.08 Oil = 0.84 Gas = 0.64 2020 2040 2050

Human Forcings: Summary

Global Warming source:

Human Forcings: Summary

Tools of climate sciences Natural forcing factors Human forcing factors Global climate model and global warming Climate change and natural disasters Abrupt climate change Mitigation and adaptation The models project possible climates based on scenarios that cover a range of assumptions about global population, greenhouse gas emissions, technologies, fuel sources, etc. The model results provide a range of possible impacts based on these assumptions.

A climate system includes the atmosphere, hydrosphere, lithosphere, biosphere, and cryosphere (cryosphere refers to the ice and snow that exist at the Earth’s surface). The climate system involves the exchanges of energy and moisture that occur among the five spheres.

Global Climate Model (GCM)
Climate models are computer-based simulations that use mathematical formulas to re-create the chemical and physical processes that drive Earth’s climate. To “run” a model, scientists divide the planet into a three-dimensional grid, apply the basic equations, and evaluate the results. Basic equations are conservation of momentum (also known as Newton’s second law; force = mass x acceleration), conservation of mass, and heat flows between systems.

Global Climate Model (GCM)
Models are tested to see if they generate past known climate patterns. Atmospheric models calculate winds, heat transfer, radiation, relative humidity, and surface hydrology within each grid and evaluate interactions with neighboring points. Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice.

SERS Emission Scenarios
A1 - a future world of very rapid economic growth, global population that peaks in mid-century and declines thereafter, and the rapid introduction of new and more-efficient technologies. Three subgroups: fossil-intensive (A1FI), non-fossil energy sources (A1T), or a balance across all sources (A1B). A2 - A very heterogeneous world. The underlying theme is that of strengthening regional cultural identities, with an emphasis on family values and local traditions, high population growth, and less concern for rapid economic development.

SERS Emission Scenarios
B1 - a convergent world with the same global population, which peaks in mid-century and declines thereafter, as in the A1 storyline. B2 - a world in which the emphasis is on local solutions to economic, social, and environmental sustainability.

Prediction of Temperature Increase
Source: IPCC

Prediction of Sea-Level Rise
Source: IPCC

Other Modeling Results
Unless measures are taken to reduce greenhouse-gas production, Rainfall will continue to become concentrated in increasingly heavy but less- frequent events. The incidence, intensity, and duration of both floods and droughts will increase. The intensity of hurricanes will continue to increase, though their frequency may dwindle.

Where Has the Ice Gone? Sunday Times, 2007

Some Issues with GCM Uncertainties on climate system sensitivity to clouds, water vapor, and snow. Need to improve understanding of whether and how human impacts may alter natural climate variability. Uncertainties on abrupt climate changes. Insufficient understanding of effects of anthropogenic forcings on extreme weather events. Limited capabilities at regional scales.

Human Attribution Recent modeling attempts have tried to isolate the impact of anthropogenic versus natural forcing. Continued greenhouse gase emissions at or above current rates can cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century.” Warming of the climate system is clear. Human-caused warming over last 40 years has is visible. Source: IPCC

Human Attribution Forecasting the future is a very difficult and dangerous exercise; erroneous forecasts can have catastrophic effects. In 1997, experts claimed that oil prices would neither fall below $15/barrel nor increase to more than $25/barrel, at least until the demand exceeded 80 million barrels of oil production per day. However, by the end of 1998, oil prices had plunged to as low as $10/barrel, resulting in huge layoffs in the oil and gas industry. The low oil price was due to a 1 percent overproduction, and its increase to $26/barrel in late 1999 was related to about a 1.5 percent reduction in world production.

Human Attribution In the context of reducing human forcings, forecasting future challenges does not have similar consequences. If the forecast global climate model (GCM) turns out to be too conservative, we will have at least started reducing human responsibility for climate change. If the GCM forecast is overstated and the whole exercise of reducing human forcings was futile, we will at least have taken our responsibility for future generations seriously, and we will be better prepared for peak-fossil fuels. Scientists are still working on the GCM. The IPCC’s 5th report is planned for Climate models are being improved, more data is being collected.

2009 Carbon Emissions Fall Smaller Than Expected
Carbon emissions fell in 2009 due to the recession - but not by as much as predicted, suggesting the fast upward trend will soon be resumed. Those are the key findings from an analysis of 2009 emissions data issued in the journal Nature Geoscience a week before the UN climate summit opens. Industrialised nations saw big falls in emissions - but major developing countries saw a continued rise. Environment correspondent, BBC News,

Extreme Weather Events: Mt. Kilimanjaro

Extreme Weather Events: Drought: Lake Chad
Adapted from Bloom (2010)

Extreme Weather Events: 2005 Hurricane Katrina Crossing the Gulf of Mexico

Extreme Weather Events: Summer 2003 Temperatures
From NASA’s Moderate Resolution Imaging Spectrometer, courtesy of Reto Stöckli Climateprediction.net

2003 European Heat Wave U.K.: Train rails buckle
Germany: Lowest river levels this century Switzerland: Melting glaciers, avalanches France: >14,000 deaths Portugal: Forest fires U.K.: Train rails buckle

Extreme Weather Events: Pakistan Floods July-August 2010

Climate Change and Natural Disasters
Climate change is predicted to have a range of serious consequences, some of which will have impact over the longer term, like sea-level rise, while some have immediate impacts, such as intense rain and flooding. The latter are obvious and easily grasped by the public at large, thanks to the Internet, which makes the images of these events available to the four corners of the globe in a matter of minutes or hours.

Recent examples of extreme weather events include the 2010 Pakistan flood (more than 2,000 deaths), the 2005 Hurricane Katrina (more than 1,600 deaths), the summer 2003 heat wave in western Europe (more than 22,000 deaths). The question about these extreme weather events is whether they are caused by natural climate forcings or human forcings.

In other words, can the global climate model (GCM) shed light on possible links between these events and anthropogenic greenhouse gas emissions?

Before we attempt to answer this question, let us group extreme weather events into three categories: Extreme temperature highs – heat waves High levels of precipitation and associated flooding; lack of precipitation and associated drought Storms, including windstorms, hurricanes, etc.

Climate Change and Natural Disasters: Heat Waves
Increasing high-temperature extremes are among the easiest to identify. The GCM suggests that cold and warm extreme temperatures are rising globally. In Europe, daily high temperatures are rising more in summer than in winter, and warm extreme temperatures are rising twice as fast as cold extremes are warming. There are fewer deaths from cold and more from heat.

The magnitude of the rise in mean temperatures and the existence of severe extremes, such as the European heat wave in the summer of 2003, are inconsistent with natural cycles, and the most plausible explanation is climate change. These changes are consistent with the modeled influence of anthropogenic greenhouse gases, enhancing confidence that the phenomenon is indeed largely attributable to human forcings. There will always be natural variability, and some places and some years will be warmer or cooler than average. In general, however, summers will get hotter, not only because of higher temperatures but also because humidities will increase. That means that heat waves, like the one that killed over 20,000 people in Europe in 2003, will become more common. On the plus side, winters will be warmer in many places, reducing heating bills. And the number of days with frosts is likely to decrease.

The analysis of Stott et al. (2004), suggests that it is very likely that human forcings have already at least doubled the risk of the 2003 heat wave occurring again. June-July-August temperature in France (°C)

Climate Change and Natural Disasters: Floods
Providing the link between climate change and precipitation levels, and the resulting flooding or contribution to drought, is more difficult than for heat waves. Precipitation and flooding are periodic phenomena, making patterns in extreme events harder to model. Recent global-climate-modeling attempts are capable of isolating the impact of anthropogenic versus “natural forcing.” Isolating water-vapor forcing may shed some light here.

Climate Change and Natural Disasters: Droughts
Drought is very easy to recognize, but only recent global climate models are able to distinguish climate-change trends from natural variability. Precipitation changes imply droughts. Droughts are cyclical, and severe events can be expected every 10 years, with very severe events recurring, on average, every 40 years.

Climate Change and Natural Disasters: Droughts
The North Atlantic Oscillation is strongly influential. When in its negative phase, as it is now, it causes dryer winter weather and hence less recharging of rivers and reservoirs, exacerbating summer droughts. Recent studies suggest that the land area of the world affected by severe drought has doubled since the early 1970s. Half of this trend is estimated to be due to changes in precipitation, and half due to warmer weather.

Climate Change and Natural Disasters: Windstorms
While trends for temperature and precipitation are somewhat more clear, the picture for the intensity of windstorms is just emerging, and results seem to vary in different regions of the world. Recent studies indicate that the increased frequency of storms is still probably due to natural cyclical variation. Measurements show a noticeable rise in sea-surface temperatures, which are a main determinant of the strength of storms as well as the total column water vapor and the available convective potential energy (Trenberth, 2005).

Climate change and Natural Disasters: Hurricanes
Studies show that the total number of hurricanes has not changed. However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones). This change is probably due to higher sea- surface temperatures (more energy). It is difficult to know whether this trend will continue.

Abrupt Climate Change Some large natural climate changes have occurred abruptly. In some instances, the average global temperature has risen or fallen > 8º C in less than 10 years, and at least one in as few as five years. An increase of 6° C in this century would be considered an abrupt climate change. The trigger for the abrupt temperature rises is not well understood, but it probably involves a catastrophic release of methane and carbon dioxide.

Younger Dryas The best-known abrupt climate change is called the Younger Dryas. It is also the best-studied abrupt climate change. It began abruptly about 12,800 years ago and ended even more suddenly about 11,600 years ago. 189

Climate Change and Human History
Medieval Warm Period The above graphic, derived from sampling of an ice core in Greenland, shows a historical tendency for particular regions to experience periods of abrupt cooling within periods of general warming. R.B. Alley, from The Two Mile Time Machine, 2000

Abrupt Younger Dryas Climate Change

The Younger Dryas at About 12 kyBP
Source: Younger Dryas, Oceanographic Cruise off N. NovaScotia-July10Kybp

The Younger Dryas The Younger Dryas saw a rapid return to glacial conditions in the higher latitudes of the Northern Hemisphere between 12,800 and 11,600 years ago, in sharp contrast to the warming of the preceding interstadial deglaciation. Each of the transitions occurred over a period of a decade or so.

The Younger Dryas The mean temperature in the UK dropped to approximately -5° C, and periglacial conditions prevailed in lowland areas, while icefields and glaciers formed in upland areas. Nothing of the size, extent, or rapidity of this period of abrupt climate change has been experienced since.

The Younger Dryas Pre-Younger Dryas Warm Glacial Sediments
Younger Dryas Cold Period Pre-Younger Dryas Warm Glacial Sediments Source: Younger Dryas, Oceanographic Cruise off N. NovaScotia-July10Kybp

Younger Dryas Oceanographic Cruise off N. Nova Scotia - July 10 Kybp
Source: Younger Dryas, Oceanographic Cruise off N. NovaScotia-July10Kybp

28,000 years ago Today Reynolds et al. (2010)

Mitigation and Adaptation
Mitigation here refers to measures to reduce the pace and magnitude of the changes in global climate being caused by human activities. Adaptation here means measures to reduce the adverse impacts on human well-being resulting from the changes in climate that do occur. Mitigation and adaptation are both very important.

Mitigation Halt deforestation; e.g., increase forest planting.
Reduce energy needs and encourage recycling. Accelerate the development of alternate energy sources with very little or no carbon (wind, geothermal, hydro, solar, biomass, etc.); e.g., increase solar capacity 1,000 times. Capture and sequestrate CO2 when fossil fuels are converted or burned. Halt deforestation; e.g., increase forest planting. Accelerate the development of the fuel efficiency of cars, trucks, buses, trains, and aircraft; e.g., double car fuel efficiency from 30 miles per gallon to 60 miles per gallon.

Mitigation Increasing the atmosphere’s reflectivity by injecting reflecting particles into the stratosphere might be affordable (& reversible), but would be likely to deplete stratospheric ozone. Placing reflecting materials or mirrors in Earth orbit (or at the Lagrangian equilibration point between the Sun and the Earth) would be staggeringly expensive. Develop technological ways of cleaning CO2 out of the air? Add your own recommendations (no giant space umbrella).

Adaptation Avoid new ocean coastal development. Ocean coastal properties cannot be expected to survive routine future hurricanes. Avoid structures elevated below 28 feet above sea level. These structures are at risk of destruction by a storm surge. Locate new development higher than 110 feet above sea level because 80 feet of sea-level rise is likely. Also, as aquifer withdrawal continues to negatively impact irrigated landforms and sea levels rise due to icecap melt and/or water/thermal expansion, these storm surges will ride higher over time. 202

Adaptation Increase the use of light personal electromagnetic flying rigs. Increase the use of electromagnetic power trains for transit shipment and transport options. Add your own regulations.

2009 Carbon Emissions Fall Smaller Than Expected
Carbon emissions fell in 2009 due to the recession - but not by as much as predicted, suggesting the fast upward trend will soon be resumed. Those are the key findings from an analysis of 2009 emissions data issued in the journal Nature Geoscience a week before the UN climate summit opens. Industrialised nations saw big falls in emissions - but major developing countries saw a continued rise. Environment correspondent, BBC News,

CO2 Sequestration The aim of CO2 sequestration in sub-seabed geological formations is: permanent isolation. The major steps are: (i) CO2 separation, capture, and compression; (ii) Transport to injection site; (iii) Injection into peep geologic formation (> 2500 feet); (iv) Measurement, monitoring, and verification. CO2 requires better seals than other fluids for a particular column (flat-lying strata, no faults, no folds).

CO2 Sequestration To date, no leakage has been detected. However, the study has shown that after the carbon dioxide is sequestered, the chemical properties of the water and the dissolved inorganic carbon change. Changes include: (i) sharp drops in pH, (ii) pronounced increases in alkalinity, (ii) significant shifts in the isotopic compositions. Also, it has shown that the CO2 can degrade carbonate substances in the rock.

Steps in the CO2-Sequestration Process
Image copyrighted by Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC)

CO2 Sequestration

Problems (1) Over the last 150 years, global average temperatures have (a) cooled about 1.5 degrees Celsius, (b) cooled about 0.5 degrees Celsius, (c) not changed, (d) warmed by 0.5 degrees Celsius, (e) warmed by 2.1 degrees Celsius. Select one answer. Which one of the following measurements serves as proxy measurements of temperature? (a) tree rings, (b) relative amount of oxygen isotopes in water, (c) relative amount of oxygen isotopes in marine shells.

Problems (2) Which of the following factors contributes to climate variability? (i) volcanoes, (ii) solar luminosity, (iii) cloud cover, (iv) greenhouse gases, (v) all of the above As the eccentricity of Earth’s orbit increases, (a) the amount of solar energy reaching Earth will fluctuate more from summer to winter, (b) the Arctic ice cap will completely melt, (c) the Northern Hemisphere will retreat into darkness. What is a proxy measurement?

Problems (3) List three greenhouse gases associated with natural forcings. List three human-produced greenhouse gases. Preindustrial concentration of carbon dioxide in Earth’s atmosphere was about (a) 200 ppm, (b) 270 ppm, (c) 430 ppm, (d) 550 ppm, (e) 970 ppm. What is GCM in the context of climate change? What is CO2 sequestration? Why is human-added H2O in the earth’s atmosphere not a major problem as far as global warming is concerned?

Problems (4) Describe three evidences of a warming world.
List three natural forcing factors that affect global climate change. List four human forcing factors that affect global climate. List two causes of the CO2 build-up in the Earth’s atmosphere in the last 150 years.

Problems (5) List four sources of anthropogenic methane (CH4) in the atmosphere. List two sources of anthropogenic soot in the atmosphere. Here are five major climate forcings: (i) the sun’s output, (2) Earth’s orbit, (3) drifting continents, (4) volcanic eruptions, (5) greenhouse gases. Classify them as internal or external and as natural or anthropogenic.

Problems (6) Based on direct and proxy measurements, the earth is getting warmer. The temperature has been well above normal for more than 25 years. (i) Define the normal temperature. (ii) Define the range of this increase by various measurements. (iii) Compare the warming of land and oceans. (iv) Compare the warming in higher latitudes as opposed to warming in the tropics. Cloud covers (a) tend to warm Earth more than they cool it, (b) absorb electromagnetic radiation emitted from Earth’s surface.

Problems (7) Scientists learn about past climate conditions from such things as tree ring analysis, fossil evidence, and analysis of patterns and chemical compositions of coral skeletons and ice cores. Are these direct temperature measurements or proxy temperature measurements, or neither of the above? Explain. What does IPCC stand for in the context of climate change? What is the difference between IPCC and the World Meteorological Organization (WMO). What are the products of IPCC?

Problems (8) The main tools for both past and present climate analyses are computer climate models. Climate models simulate the climate system with a 3-dimensional grid that extends through the land, ocean, and atmosphere. The models project possible climates based on scenarios that cover a range of assumptions. List four of these assumptions.

Problems (9) A common critique of climate predictions is, “If weather model forecasts aren’t reliable more than a week out, how can models predict climate decades in the future?” (i) Propose an explanation of this critique. (ii) How can we establish confidence in our climate models? How can we use climate models to differentiate the effects of natural forcings and those of anthropogenic forcings on global temperatures?

Climate Change Luc Ikelle 2011.

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