Why is there no symmetry in pigmentation when comparing people north and south of the equator?

Why is there no symmetry in pigmentation when comparing people north and south of the equator?

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If you are at the equator and start moving north, the further you travel, the lighter the skin of the indigenous peoples. Considering that we live on a ball, why do we not find the same traveling south from the equator? This relationship does not hold for individuals as you move south from the equator. At the very least, one could say there are no blond hair blue eyed peoples south of the equator.

I rather would say that the lack of North/South Symmetry in pigmentation is that we forget how quickly human beings have spread. In prehistory, people have come to populate every continent over perhaps the last 60,000 years.

While in that time its clear that several mutations have popped up to influence skin color, they are pretty rare compared to the speed with which we migrated over the globe. The dark color of our earliest ancestors has been lost and regained more than once, but not so often that the selection pressure of latitude have made indigenous in the tropics of south america or south east asia uniformly as dark as africans. Or for that matter have lightened the skin of pre-colonial South Africans.

One might guess that clothing and shelter have reduced the selection pressure on pigmentation further over the past few thousand years.

Individual cases should be studied - this is just a sketch - but the general thought here is that the pigmentation of human beings have more to do with where they have been and how quickly they have recently come from in their migrations.

Summarizing the comments below: There is a correlation between pigmentation and latitude. The answer is really a combination of latitude, how long a people has been there, and the speed at which pigmentation mutants show up. It doesn't change so quickly that all people are equally dark at the same latitude or so slowly that you find completely pale people at the equator.

Distance and Displacement

I've got to assume that everybody reading this has an idea of what distance is. It's one of those innate concepts that doesn't seem to require explanation. Nevertheless I've come up with a preliminary definition that I think is rather good. Distance is a measure of the interval between two locations. (This is not the final definition.) The "distance" is the answer to the question, "How far is it from this to that or between this and that?"

How far is it?
how far is it possible answer standard answer
Earth to sun 1 a stronomical u nit 1.5 × 10 11 m
66th to 86th Street in NYC 1 mile 1.6 × 10 3 m
heel to toe on a man's foot 1 foot 3.0 × 10 𕒵 m

You get the idea. The odd thing is that sometimes we state distances as times.

How far is it?
how far is it possible answer standard answer
International Space Station 90 minutes per orbit 40,000,000 m
Chicago to Milwaukee 90 minutes by train 00, 150,000 m
Central Park to Battery Park 90 minutes on foot 00,0 10,000 m

They're all ninety minutes, but nobody would say they were all the same distance. What's being described in these examples is not distance, but time. In casual conversation, it's often all right to state distances this way, but in most of physics this is unacceptable.

That being said, let me deconstruct the definition of distance I just gave you. Every year in class, I do the same moronic demonstration where I start at one side of the lecture table and walk to the other side and then ask "How far have I gone?" Look at the diagram below and then answer the question.

There are two ways to answer this question. On the one hand, there's the sum of the smaller motions that I made: two meters east, two meters south, two meters west resulting in a total walk of six meters. On the other hand, the end point of my walk is two meters to the south of my starting point. So which answer is correct? Well, both. The question is ambiguous and depends on whether the questioner meant to ask for the distance or displacement.

Let's clarify by defining each of these words more precisely. is a scalar measure of the interval between two locations measured along the actual path connecting them. is a vector measure of the interval between two locations measured along the shortest path connecting them.

How far does the Earth travel in one year? In terms of distance, quite far (the circumference of the Earth's orbit is nearly one trillion meters), but in terms of displacement, not far at all (in some respects, zero). At the end of a year's time the Earth is right back where it started from. It hasn't gone anywhere.

Your humble author occasionally rides his bicycle from Manhattan to New Jersey in search of discount そば (soba) and さけ (sake) at a large Japanese grocery store on the other side of the Hudson River. Getting there is a three step process.

  1. Follow the Hudson River 8.2 km upriver.
  2. Cross using the George Washington Bridge (1.8 km between anchorages).
  3. Reverse direction and head downriver for 4.5 km.

The distance traveled is a reasonable 14 km, but the resultant displacement is a mere 2.7 km north. The end of this journey is actually visible from the start. Maybe I should buy a canoe.

Distance and displacement are different quantities, but they are related. If you take the first example of the walk around the desk, it should be apparent that sometimes the distance is the same as the magnitude of the displacement. This is the case for any of the one meter segments but is not always the case for groups of segments. As I trace my steps completely around the desk the distance and displacement of my journey soon begin to diverge. The distance traveled increases uniformly, but the displacement fluctuates before it eventually returns to zero.

This artificial example shows that distance and displacement have the same size only when we consider small intervals. Since the displacement is measured along the shortest path between two points, its magnitude is always less than or equal to the distance.

How small is small? The answer to this question is, "It depends". There is no hard and fast rule that can be used to distinguish large from small. DNA is a large molecule, but you still can't see it without the aid of a microscope. Compact cars are small, but you couldn't fit one in your pocket. What is small in one context may be large in another. Mathematics has developed a more formal way of dealing with the notion of smallness and that is through the use of limits. In the language of limits, distance approaches the magnitude of displacement as distance approaches zero. In symbols, that statement looks like this.

s → 0 s → |∆s|


What would be a good symbol for distance? Hmm, I don't know. How about d? Well, that's a fine symbol for us Anglophones, but what about the rest of the planet? (Actually, distance in French is spelled the same as it is in English, but pronounced differently, so there may be a reason to choose d after all.) In the current era, English is the dominant language of science, which means that many of our symbols are based on English words used to describe the associated concept. Distance does not fall into this category. Still, if you want to use d to represent distance, how could I stop you?

All right then, how about x? Distance is a simple concept and x is a simple variable. Why not pair them up? Many textbooks do this, but this one will not. The variable x should be reserved for one-dimensional motion along a defined x-axis or the x-component of a more complex motion. Still, if you want to use x to represent distance, how could I stop you?

As I said a moment ago, English is currently the dominant language of science, but this has not always been the case nor is there any reason to believe that it will stay this way forever. Latin was preeminent for a long time, but it is little used today. Still, there are thousands of technical and not so technical words in the English language that have Latin roots. The Latin word for distance is spatium. It's also the source of the English word space. In this book, and many others, the letter s will be used for distance and displacement.

Scalar quantities are italicized. Vector quantities bolded. For these reasons, we will use the italicized symbols s0 (ess nought) for the initial position on a path, s for the position on the path any time after that, and ∆s (delta ess) for the space traversed going from the one position to another — the . Similarly, we will use the bolded symbols s0 (ess nought) for the initial position vector, s for the position vector any time after that, and ∆s (delta ess) for the change in position — the .

Imagine some object traveling along an arbitrary path on top of an infinite two-dimensional grid. Place an observer anywhere in space — on or off the path, it doesn't matter. Make the observer's position the origin of the grid. Draw an arrow from the origin to the moving object at any moment. This is our position vector. It's a vector because it has a magnitude (a size) and a direction. It starts when the object is at s0 . It ends when its at s. Its change, ∆s , is the displacement.

Keep imagining our imaginary object traveling along an arbitrary path, but this time ignore the coordinate system. Think about the path the same way you think about traveling on a highway. There is no x or y coordinate on a highway (and certainly no z). No up, down, left, or right. No north, south, east, or west. There is only forward. Coordinates are for sailors or pilots. Distances are for drivers. Locations on highways are indicated with mileposts or milestones. How far down the road have you gone. How much distance have you covered? It starts when the object is at s0 . It ends when its at s. Its change, ∆s , is the distance.

If you think Latin deserves its reputation as a "dead tongue" then I can't force you to use these symbols, but I should warn you that their use is quite common. Old habits die hard. The use of spatium goes back to the first book on kinematics as we know it — Dialogues Concerning Two New Sciences (1638) by Galileo Galilei .

In uno stesso moto equabile, lo spazio percorso in un tempo più lungo è maggiore dello spazio percorso in un tempo più breve. In the case of one and the same uniform motion, the distance traversed during a longer interval of time is greater than the distance traversed during a shorter interval of time.
Galileo Galilei, 1638 Galileo Galilei, 1638

OK, that was actually Italian. Galileo wrote to the people of the Mediterranean boot in his regional dialect, but the rest of Europe would most likely have read a Latin translation.

Spatium transactum tempore longiori in eodem motu aequabili maius esse spatio transacto tempore breviori. In the case of one and the same uniform motion, the distance traversed during a longer interval of time is greater than the distance traversed during a shorter interval of time.
Galilaeus Galilaei, 1638 Galileo Galilei, 1638


The SI unit of distance and displacement is the [m]. A meter is a bit longer than the distance between the tip of the nose to the end of the farthest finger on the outstretched hand of a typical adult male. Originally defined as one ten millionth of the distance from the equator to the north pole as measured through Paris (so that the Earth's circumference would be 40 million meters) then the length of a precisely cut metal bar kept in a vault outside of Paris then a certain number of wavelengths of a particular type of light. The meter is now defined in terms of the speed of light. One meter is the distance light (or any other electromagnetic radiation of any wavelength) travels through a vacuum after 1 299,792,458 of a second.

Multiples (like km for road distances) and divisions (like cm for paper sizes) are also commonly used in science.

There are also several natural units that are used in astronomy and space science.

  • A is now 1852 m (6080 feet), but was originally defined as one minute of arc of a great circle, or 1 60 of 1 360 of the Earth's circumference. Every sixty nautical miles is then about one degree of latitude anywhere on Earth or one degree of longitude on the equator. This was considered a reasonable unit for use in navigation, which is why this mile is called the nautical mile. The ordinary mile is more precisely known as the that is, the mile as defined by statute or law. Use of the nautical mile persists today in shipping, aviation, and at NASA (for some unknown reason).
  • Distances in near outer space are sometimes compared to the : 6.4 × 10 6 m. Some examples: the planet Mars has about ½ the radius of the Earth, the size of a geosynchronous orbit is about 6½ Earth radii, and the Earth-moon separation is about 60 Earth radii.
  • The mean distance from the Earth to the Sun is called an : approximately 1.5 × 10 11 m. The distance from the Sun to Mars is 1.5 au from the Sun to Jupiter, 5.2 au and from the Sun to Pluto, 40 au. The star nearest the Sun, Proxima Centauri, is about 270,000 au away.
  • For really large distances, the is the unit of choice. A light year is the distance light would travel in a vacuum after one year. It is equal to 9.5 × 10 15 m (about ten trillion kilometers or six trillion miles). This unit is described in more detail in the next section.


Let's change how we observe the world and see how it affects distance and displacement. A symmetric operation is a change that results in no change. Quantities that are not affected by a change are said to show a symmetry. The opposite of symmetry is asymmetry and the opposite of symmetric is asymmetric.

First, the location of the observer does not matter. Place the origin wherever it's convenient (or wherever it's inconvenient). It won't matter. Distance and displacement are not affected by a of the origin. There is no special place when it comes to measuring distance and displacement. All locations in the universe are equivalent for centering your coordinate system. Space is .

Second, the orientation of the axes is irrelevant. Point them in any direction you want (or don't want). Just keep the x-axis perpendicular to the y-axis. (This you must not change.) Distance and displacement are not affected by a of the axes. There is no special direction when it comes to orienting your coordinate system. All directions are equivalent. Space is .

Third, and most difficult to state in words, the chirality or handedness of the coordinate system is also irrelevant. Frequently, the x-axis points to the right and the y-axis points up (that is, toward the top of a page, blackboard, whiteboard, computer display, etc.). If we add a third z-axis, in what direction should it point: in or out (that is, into or out of the page, blackboard, etc.)? If you chose out, then you've made a right-handed coordinate system. If you chose in, then it's a left-handed coordinate system.

The two possible coordinate systems are like hands because they are mirror images of one another. No amount of rotation will ever allow you to line up all the parts of your left hand onto all the parts of your right hand. Align the fingers and thumbs of both hands and your palms will face in opposite directions. Align your palms and fingers and your thumbs will point in opposite directions. The Greek word for hand is χερι (kheri), so this property of hands and coordinate systems (and organic molecules and magnetic interactions) is called . It is equivalent to a reflection in a mirror. A right-handed coordinate system is right-handed when viewed directly but left-handed when viewed in a mirror — when viewed through the looking glass, to use a literary reference.

Distance and displacement are not affected by a of the coordinate system. This is not true for all physical quantities, however. The ones that don't work the same when viewed in a mirror are called . Some examples of pseudovectors are torque, angular momentum or spin, and magnetic field. The direction of a pseudovector is always related to a hand rule of some sort (like the one used in vector multiplication). But as we have just discussed and as everyone knows, right hands become left hands and left hands become right hands when viewed in a mirror. Wrong hand means wrong direction. Space appears to know the difference between left and right for some quantities.

This line of latitude is a quarter of the way from the equator to the South Pole. During the winter solstice, the sun is directly overhead.

The equator divides the earth into two halves, or hemispheres. The Northern Hemisphere is the half of the earth between the North Pole and the equator. The Southern Hemisphere is the half of the earth between the South Pole and the equator.

The earth can also be broken up another way: into the Eastern Hemisphere and the Western Hemisphere. The Western Hemisphere includes North and South America, their islands, and the surrounding waters. The Eastern Hemisphere includes Asia, Africa, Australia, and Europe.

Arctic soil study turns up surprising results

Across the globe, the diversity of plant and animal species generally increases from the North and South Poles towards the Equator but surprisingly that rule isn't true for soil bacteria, according to a new study by Queen's University biology professor Paul Grogan.

"It appears that the rules determining the patterns for plant and animal diversity are different than the rules for bacteria," says Professor Grogan.

The finding is important because one of the goals in ecology is to explain patterns in the distribution of species and understand the biological and environmental factors that determine why species occur where they do.

Researchers examined the composition and genetic difference of soil bacterial communities from 29 remote arctic locations scattered across Canada, Alaska, Iceland, Greenland and Sweden.

The report also had a second surprising finding. The researchers expected that soil samples taken 20 metres apart would be more similar in terms of bacterial diversity than soil samples taken 5,500 kilometres apart because, in theory, plant or animal communities from nearby locations are likely to be more genetically similar than those from distant locations.

Generally, they found that each soil sample contained thousands of bacterial types, about 50 per cent of which were unique to each sample.

"It turns out that there is no similarity pattern in relation to distance at all, even in comparing side-by-side samples with samples taken from either side of a continent -- this really amazed me," says Professor Grogan.

The research team included researchers from Queen's and the University of Colorado.

The findings have been accepted for publication in the journal Environmental Microbiology.

Story Source:

Materials provided by Queen's University. Note: Content may be edited for style and length.

Melanin and melanogenesis as a protective mechanism against sun exposure

The chemical contents, transfer and accumulation of melanosomes in keratinocytes determines hair and skin color, but establishing the biological function of melanin pigmentation can be enigmatic and dependent on environmental cues. While the number of melanocytes between different skin tones is relatively constant, dark skinned individuals have a higher density of large, singly dispersed melanosomes. These remain intact as they move upwards in the epidermis to form caps over the nuclei of keratinocytes, protecting against UVR DNA damage. Melanosomes in light-skinned Europeans are smaller and less dense, and aggregate into membrane-bound complexes and degrade rapidly [102]. It is assumed that the benefits of darker skin are to do with protection against UV light. Apart from protecting against the damaging effects of solar UVR, melanin has several other roles in the body, including scavenging reactive oxygen species, protecting nutrients from photodamage and possibly modulating the inflammatory response. Melanin can also provide camouflage, transport energy and bind drugs, and is involved in hearing, sight and regulation of body heat [103].

In addition, some of the precursors and intermediates of melanogenesis (Figure 2) also appear to be diffusible molecules involved in the photoprotective pathway as signaling or hormone-like regulators of melanocyte or keratinocyte functions [104]. In particular, the action of the DCT pigmentation gene and the DHICA metabolite it produces provides a new insight into the function of the melanogenic pathway that is distinct from the production of the final melanin polymer. A cell culture model treating human melanocytes with MC1R agonists has shown strong induction of the DCT protein in wild-type cells, but not in melanocytes homozygous for MC1R alleles associated with red hair color. This suggests that the ability to produce DHICA is compromised in Europeans carrying these variant alleles, along with an alteration in the type of melanin being synthesized [105]. Moreover, overexpression of DCT in WM35 amelanotic melanoma cells reduced their sensitivity to oxidative stress and their protection against DNA damage [106]. When Dct knockout mice were exposed to UVR, they had decreased levels of eumelanin and increased levels of reactive oxygen species (ROS), sunburn cells and apoptotic cells. DHICA-derived melanin showed a strong hydroxyl radical scavenging ability [107] and inhibited lipid peroxidation [108].

Protection pathways in the skin against ultraviolet radiation (UVR). UVR induces DNA damage, which leads to activation of p53 and the formation of POMC and MC1R activation factors. MC1R action can be blocked by ASIP. Upon receptor activation of cAMP, dopachrome tautomerase (DCT) activity is upregulated and this leads to the generation of 5,6-dihydroxyindole-2-carboxylic acid (DHICA). MC1R also activates melanosome maturation and transfer to the keratinocyte. DHICA removes reactive oxygen species (ROS), and activates catalase (CAT) and peroxisome proliferator activated receptor (PPAR) in keratinocytes. Finally, DCT provides antagonistic feedback to p53 in melanocytes [112].

As DHICA is a diffusible molecule, it may enter keratinocytes directly to induce increased UVR resistance [109]. When primary keratinocyte cultures were treated with DHICA a range of cellular changes were seen, including expression and activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase. This led to decreased cell damage and apoptosis after UVA exposure. The regulation of this DHICA-mediated differentiation of the keratinocytes was found to involve peroxisome proliferator activated receptors (PPARs) [109]. In summary, these experiments indicate that DCT, and the subsequent action of its product DHICA, are intrinsically linked to protection of skin cells against cell death and ROS after UVR exposure, as well as their role in the generation of protective eumelanin pigment.

Lakes and Ponds

Lakes and ponds can range in area from a few square meters to thousands of square kilometers. Temperature is an important abiotic factor affecting living things found in lakes and ponds. In the summer, thermal stratification of lakes and ponds occurs when the upper layer of water is warmed by the sun and does not mix with deeper, cooler water. Light can penetrate within the photic zone of the lake or pond. Phytoplankton (algae and cyanobacteria) are found here and carry out photosynthesis, providing the base of the food web of lakes and ponds. Zooplankton, such as rotifers and small crustaceans, consume these phytoplankton. At the bottom of lakes and ponds, bacteria in the aphotic zone break down dead organisms that sink to the bottom.

Nitrogen and phosphorus are important limiting nutrients in lakes and ponds. Because of this, they are determining factors in the amount of phytoplankton growth in lakes and ponds. When there is a large input of nitrogen and phosphorus (from sewage and runoff from fertilized lawns and farms, for example), the growth of algae skyrockets, resulting in a large accumulation of algae called an algal bloom . Algal blooms ([link]) can become so extensive that they reduce light penetration in water. As a result, the lake or pond becomes aphotic and photosynthetic plants cannot survive. When the algae die and decompose, severe oxygen depletion of the water occurs. Fishes and other organisms that require oxygen are then more likely to die, and resulting dead zones are found across the globe. Lake Erie and the Gulf of Mexico represent freshwater and marine habitats where phosphorus control and storm water runoff pose significant environmental challenges.

Accommodations for Diversity

If students struggle with writing (dysgraphia), they can have the teacher write their words for them as they dictate.

There are a variety of visual and auditory cues meant to build learning in this lesson.

If a student cannot see the board or the foam model of the earth, invite them to move closer.

If a student has auditory discrimination problems, invite him or her to sit closer to the front, or have this student work with a partner who can repeat something the student may have missed the first time.

For a printable version of this lesson plan (including the worksheet) click here.

44.5 | Climate and the Effects of Global Climate Change

By the end of this section, you will be able to:

  • Define global climate change
  • Summarize the effects of the Industrial Revolution on global atmospheric carbon dioxide concentration
  • Describe three natural factors affecting long-term global climate
  • List two or more greenhouse gases and describe their role in the greenhouse effect

All biomes are universally affected by global conditions, such as climate, that ultimately shape each biome’s environment. Scientists who study climate have noted a series of marked changes that have gradually become increasingly evident during the last sixty years. Global climate change is the term used to describe altered global weather patterns, including a worldwide increase in temperature, due largely to rising levels of atmospheric carbon dioxide.

Climate and Weather

A common misconception about global climate change is that a specific weather event occurring in a particular region (for example, a very cool week in June in central Indiana) is evidence of global climate change. However, a cold week in June is a weather-related event and not a climate-related one. These misconceptions often arise because of confusion over the terms climate and weather.

Climate refers to the long-term, predictable atmospheric conditions of a specific area. The climate of a biome is characterized by having consistent temperature and annual rainfall ranges. Climate does not address the amount of rain that fell on one particular day in a biome or the colder-than-average temperatures that occurred on one day. In contrast, weather refers to the conditions of the atmosphere during a short period of time. Weather forecasts are usually made for 48-hour cycles. Long-range weather forecasts are available but can be unreliable.

To better understand the difference between climate and weather, imagine that you are planning an outdoor event in northern Wisconsin. You would be thinking about climate when you plan the event in the summer rather than the winter because you have long-term knowledge that any given Saturday in the months of May to August would be a better choice for an outdoor event in Wisconsin than any given Saturday in January. However, you cannot determine the specific day that the event should be held on because it is difficult to accurately predict the weather on a specific day. Climate can be considered “average” weather.

Global Climate Change

Climate change can be understood by approaching three areas of study:

  • current and past global climate change
  • causes of past and present-day global climate change
  • ancient and current results of climate change

It is helpful to keep these three different aspects of climate change clearly separated when consuming media reports about global climate change. It is common for reports and discussions about global climate change to confuse the data showing that Earth’s climate is changing with the factors that drive this climate change.

Evidence for Global Climate Change

Since scientists cannot go back in time to directly measure climatic variables, such as average temperature and precipitation, they must instead indirectly measure temperature. To do this, scientists rely on historical evidence of Earth’s past climate.

Antarctic ice cores are a key example of such evidence. These ice cores are samples of polar ice obtained by means of drills that reach thousands of meters into ice sheets or high mountain glaciers. Viewing the ice cores is like traveling backwards through time the deeper the sample, the earlier the time period. Trapped within the ice are bubbles of air and other biological evidence that can reveal temperature and carbon dioxide data. Antarctic ice cores have been collected and analyzed to indirectly estimate the temperature of the Earth over the past 400,000 years (Figure 44.26a). The 0 °C on this graph refers to the long-term average. Temperatures that are greater than 0 °C exceed Earth’s long-term average temperature. Conversely, temperatures that are less than 0 °C are less than Earth’s average temperature. This figure shows that there have been periodic cycles of increasing and decreasing temperature.

Before the late 1800s, the Earth has been as much as 9 °C cooler and about 3 °C warmer. Note that the graph in Figure 44.26b shows that the atmospheric concentration of carbon dioxide has also risen and fallen in periodic cycles note the relationship between carbon dioxide concentration and temperature. Figure 44.26b shows that carbon dioxide levels in the atmosphere have historically cycled between 180 and 300 parts per million (ppm) by volume.

Figure 44.26 Ice at the Russian Vostok station in East Antarctica was laid down over the course 420,000 years and reached a depth of over 3,000 m. By measuring the amount of CO2 trapped in the ice, scientists have determined past atmospheric CO2 concentrations. Temperatures relative to modern day were determined from the amount of deuterium (an isotope of hydrogen) present.

Figure 44.26a does not show the last 2,000 years with enough detail to compare the changes of Earth’s temperature during the last 400,000 years with the temperature change that has occurred in the more recent past. Two significant temperature anomalies, or irregularities, have occurred in the last 2000 years. These are the Medieval Climate Anomaly (or the Medieval Warm Period) and the Little Ice Age. A third temperature anomaly aligns with the Industrial Era. The Medieval Climate Anomaly occurred between 900 and 1300 AD. During this time period, many climate scientists think that slightly warmer weather conditions prevailed in many parts of the world the higher-than-average temperature changes varied between 0.10 °C and 0.20 °C above the norm. Although 0.10 °C does not seem large enough to produce any noticeable change, it did free seas of ice. Because of this warming, the Vikings were able to colonize Greenland.

The Little Ice Age was a cold period that occurred between 1550 AD and 1850 AD. During this time, a slight cooling of a little less than 1 °C was observed in North America, Europe, and possibly other areas of the Earth. This 1 °C change in global temperature is a seemingly small deviation in temperature (as was observed during the Medieval Climate Anomaly) however, it also resulted in noticeable changes. Historical accounts reveal a time of exceptionally harsh winters with much snow and frost.

The Industrial Revolution, which began around 1750, was characterized by changes in much of human society. Advances in agriculture increased the food supply, which improved the standard of living for people in Europe and the United States. New technologies were invented and provided jobs and cheaper goods. These new technologies were powered using fossil fuels, especially coal. The Industrial Revolution starting in the early nineteenth century ushered in the beginning of the Industrial Era. When a fossil fuel is burned, carbon dioxide is released. With the beginning of the Industrial Era, atmospheric carbon dioxide began to rise (Figure 44.27).

Figure 44.27 The atmospheric concentration of CO2 has risen steadily since the beginning of industrialization.

Current and Past Drivers of Global Climate Change

Since it is not possible to go back in time to directly observe and measure climate, scientists use indirect evidence to determine the drivers, or factors, that may be responsible for climate change. The indirect evidence includes data collected using ice cores, boreholes (a narrow shaft bored into the ground), tree rings, glacier lengths, pollen remains, and ocean sediments. The data shows a correlation between the timing of temperature changes and drivers of climate change: before the Industrial Era (pre-1780), there were three drivers of climate change that were not related to human activity or atmospheric gases. The first of these is the Milankovitch cycles. The Milankovitch cycles describe the effects of slight changes in the Earth’s orbit on Earth’s climate. The length of the Milankovitch cycles ranges between 19,000 and 100,000 years. In other words, one could expect to see some predictable changes in the Earth’s climate associated with changes in the Earth’s orbit at a minimum of every 19,000 years.

The variation in the sun’s intensity is the second natural factor responsible for climate change. Solar intensity is the amount of solar power or energy the sun emits in a given amount of time. There is a direct relationship between solar intensity and temperature. As solar intensity increases (or decreases), the Earth’s temperature correspondingly increases (or decreases). Changes in solar intensity have been proposed as one of several possible explanations for the Little Ice Age.

Finally, volcanic eruptions are a third natural driver of climate change. Volcanic eruptions can last a few days, but the solids and gases released during an eruption can influence the climate over a period of a few years, causing short-term climate changes. The gases and solids released by volcanic eruptions can include carbon dioxide, water vapor, sulfur dioxide, hydrogen sulfide, hydrogen, and carbon monoxide. Generally, volcanic eruptions cool the climate. This occurred in 1783 when volcanos in Iceland erupted and caused the release of large volumes of sulfuric oxide. This led to haze-effect cooling, a global phenomenon that occurs when dust, ash, or other suspended particles block out sunlight and trigger lower global temperatures as a result haze-effect cooling usually extends for one or more years. In Europe and North America, haze-effect cooling produced some of the lowest average winter temperatures on record in 1783 and 1784.

Greenhouse gases are probably the most significant drivers of the climate. When heat energy from the sun strikes the Earth, gases known as greenhouse gases trap the heat in the atmosphere, as do the glass panes of a greenhouse keep heat from escaping. The greenhouse gases that affect Earth include carbon dioxide, methane, water vapor, nitrous oxide, and ozone. Approximately half of the radiation from the sun passes through these gases in the atmosphere and strikes the Earth. This radiation is converted into thermal radiation on the Earth’s surface, and then a portion of that energy is re-radiated back into the atmosphere. Greenhouse gases, however, reflect much of the thermal energy back to the Earth’s surface. The more greenhouse gases there are in the atmosphere, the more thermal energy is reflected back to the Earth’s surface. Greenhouse gases absorb and emit radiation and are an important factor in the greenhouse effect: the warming of Earth due to carbon dioxide and other greenhouse gases in the atmosphere.

Evidence supports the relationship between atmospheric concentrations of carbon dioxide and temperature: as carbon dioxide rises, global temperature rises. Since 1950, the concentration of atmospheric carbon dioxide has increased from about 280 ppm to 382 ppm in 2006. In 2011, the atmospheric carbon dioxide concentration was 392 ppm. However, the planet would not be inhabitable by current life forms if water vapor did not produce its drastic greenhouse warming effect.

Scientists look at patterns in data and try to explain differences or deviations from these patterns. The atmospheric carbon dioxide data reveal a historical pattern of carbon dioxide increasing and decreasing, cycling between a low of 180 ppm and a high of 300 ppm. Scientists have concluded that it took around 50,000 years for the atmospheric carbon dioxide level to increase from its low minimum concentration to its higher maximum concentration. However, starting recently, atmospheric carbon dioxide concentrations have increased beyond the historical maximum of 300 ppm. The current increases in atmospheric carbon dioxide have happened very quickly—in a matter of hundreds of years rather than thousands of years. What is the reason for this difference in the rate of change and the amount of increase in carbon dioxide? A key factor that must be recognized when comparing the historical data and the current data is the presence of modern human society no other driver of climate change has yielded changes in atmospheric carbon dioxide levels at this rate or to this magnitude.

Human activity releases carbon dioxide and methane, two of the most important greenhouse gases, into the atmosphere in several ways. The primary mechanism that releases carbon dioxide is the burning of fossil fuels, such as gasoline, coal, and natural gas (Figure 44.28). Deforestation, cement manufacture, animal agriculture, the clearing of land, and the burning of forests are other human activities that release carbon dioxide. Methane (CH4) is produced when bacteria break down organic matter under anaerobic conditions. Anaerobic conditions can happen when organic matter is trapped underwater (such as in rice paddies) or in the intestines of herbivores. Methane can also be released from natural gas fields and the decomposition that occurs in landfills. Another source of methane is the melting of clathrates. Clathrates are frozen chunks of ice and methane found at the bottom of the ocean. When water warms, these chunks of ice melt and methane is released. As the ocean’s water temperature increases, the rate at which clathrates melt is increasing, releasing even more methane. This leads to increased levels of methane in the atmosphere, which further accelerates the rate of global warming. This is an example of the positive feedback loop that is leading to the rapid rate of increase of global temperatures.

Figure 44.28 The burning of fossil fuels in industry and by vehicles releases carbon dioxide and other greenhouse gases into the atmosphere. (credit: “Pöllö”/Wikimedia Commons)

Documented Results of Climate Change: Past and Present

Scientists have geological evidence of the consequences of long-ago climate change. Modern-day phenomena such as retreating glaciers and melting polar ice cause a continual rise in sea level. Meanwhile, changes in climate can negatively affect organisms.

Geological Climate Change

Global warming has been associated with at least one planet-wide extinction event during the geological past. The Permian extinction event occurred about 251 million years ago toward the end of the roughly 50-million-year-long geological time span known as the Permian period. This geologic time period was one of the three warmest periods in Earth’s geologic history. Scientists estimate that approximately 70 percent of the terrestrial plant and animal species and 84 percent of marine species became extinct, vanishing forever near the end of the Permian period. Organisms that had adapted to wet and warm climatic conditions, such as annual rainfall of 300–400 cm (118–157 in) and 20 °C–30 °C (68 °F–86 °F) in the tropical wet forest, may not have been able to survive the Permian climate change.

Watch this NASA video ( to discover the mixed effects of global warming on plant growth. While scientists found that warmer temperatures in the 1980s and 1990s caused an increase in plant productivity, this advantage has since been counteracted by more frequent droughts.

Present Climate Change

A number of global events have occurred that may be attributed to climate change during our lifetimes. Glacier National Park in Montana is undergoing the retreat of many of its glaciers, a phenomenon known as glacier recession. In 1850, the area contained approximately 150 glaciers. By 2010, however, the park contained only about 24 glaciers greater than 25 acres in size. One of these glaciers is the Grinnell Glacier (Figure 44.29) at Mount Gould. Between 1966 and 2005, the size of Grinnell Glacier shrank by 40 percent. Similarly, the mass of the ice sheets in Greenland and the Antarctic is decreasing: Greenland lost 150–250 km3 of ice per year between 2002 and 2006. In addition, the size and thickness of the Arctic sea ice is decreasing.

Figure 44.29 The effect of global warming can be seen in the continuing retreat of Grinnel Glacier. The mean annual temperature in the park has increased 1.33 °C since 1900. The loss of a glacier results in the loss of summer meltwaters, sharply reducing seasonal water supplies and severely affecting local ecosystems. (credit: modification of work by USGS)

This loss of ice is leading to increases in the global sea level. On average, the sea is rising at a rate of 1.8 mm per year. However, between 1993 and 2010 the rate of sea level increase ranged between 2.9 and 3.4 mm per year. A variety of factors affect the volume of water in the ocean, including the temperature of the water (the density of water is related to its temperature) and the amount of water found in rivers, lakes, glaciers, polar ice caps, and sea ice. As glaciers and polar ice caps melt, there is a significant contribution of liquid water that was previously frozen.

In addition to some abiotic conditions changing in response to climate change, many organisms are also being affected by the changes in temperature. Temperature and precipitation play key roles in determining the geographic distribution and phenology of plants and animals. (Phenology is the study of the effects of climatic conditions on the timing of periodic lifecycle events, such as flowering in plants or migration in birds.) Researchers have shown that 385 plant species in Great Britain are flowering 4.5 days sooner than was recorded earlier during the previous 40 years. In addition, insect-pollinated species were more likely to flower earlier than wind-pollinated species. The impact of changes in flowering date would be mitigated if the insect pollinators emerged earlier. This mismatched timing of plants and pollinators could result in injurious ecosystem effects because, for continued survival, insect-pollinated plants must flower when their pollinators are present.

The Great Pyramid of Giza, a monument like no other

The numeric value of 144,000: A key role in the Building process of the Pyramid

It’s fascinating to read about the numerous details and studies on the Great Pyramid of Giza, but there are many ‘unknown’ details about the Pyramid that are not mentioned in history books and schools, these points are indicative of a far more advanced civilization which participated in the planning and construction of the great Pyramid, evidence of that are the numerous complex mathematical formulas incorporated and used in the construction. Interestingly, the outer mantle was composed of 144,000 casing stones, all of them highly polished and flat to an accuracy of 1/100th of an inch, about 100 inches thick and weighing approx. 15 tons each. It is believed that the numeric value of 144,000 plays a key role in the harmonic connection that eventually determined the exact size of the structure. (source) (source)

The Great Pyramid shined like a star. It was covered with casing stones of highly polished limestone

The Great Pyramid of Giza was originally covered with casing stones (made of highly polished limestone). These casing stones reflected the sun’s light and made the pyramid shine like a jewel. They are no longer present being used by Arabs to build mosques after an earthquake in the 14th century loosened many of them. It has been calculated that the original pyramid with its casing stones would act like gigantic mirrors and reflect light so powerful that it would be visible from the moon as a shining star on earth. Appropriately, the ancient Egyptians called the Great Pyramid “Ikhet”, meaning the “Glorious Light”. How these blocks were transported and assembled into the pyramid is still a mystery. (source)

The Great Pyramid is the only Pyramid in Egypt with both descending and ascending inner passages

The fact that the Great Pyramid of Giza is the only one in Egypt with descending and ascending inner passages is a fact that cannot be overlooked when comparing it to other similar structures in Egypt. While the reason behind it still remains a mystery, it is evident that the Great Pyramid was the most unique structure built in ancient Egypt.

Aligned true North

The Great Pyramid of Giza is the most accurately aligned structure in existence and faces true north with only 3/60th of a degree of error. The position of the North Pole moves over time and the pyramid was exactly aligned at one time. Furthermore, the Great Pyramid is located at the center of the land mass of the earth. The east/west parallel that crosses the most land and the north/south meridian that crosses the most land intersect in two places on the earth, one in the ocean and the other at the Great Pyramid.

The only 8-sided Pyramid in Egypt

This is a fact unknown to many people. The Great Pyramid of Giza is the only Pyramid discovered to date which in fact has eight sides. The four faces of the pyramid are slightly concave, the only pyramid to have been built this way.

The centers of the four sides are indented with an extraordinary degree of precision forming the only 8 sided pyramid, this effect is not visible from the ground or from a distance but only from the air, and then only under the proper lighting conditions. This phenomenon is only detectable from the air at dawn and sunset on the spring and autumn equinoxes, when the sun casts shadows on the pyramid. (Check out the above image)

The Value of Pi represented in the Great Pyramid

The relationship between Pi (p) and Phi (F) is expressed in the fundamental proportions of the Great Pyramid. Even though textbooks and mainstream scholars suggest that the ancient Greeks were those who discovered the relationship of Pi, it seems that the builder of the Great Pyramid predated the ancient Greeks by quite some time. Pi is the relationship between the radius of a circle and its circumference. The mathematical formula is:

Circumference = 2 * pi * radius (C = 2 * pi * r)

According to reports, the vertical height of the pyramid holds the same relationship to the perimeter of its base (distance around the pyramid) as the radius of a circle bears to its circumference. If we equate the height of the pyramid to the radius of a circle than the distance around the pyramid is equal to the circumference of that circle.

The celestial connection

While many believe there is a direct correlation between the constellation of Orion and the Pyramids at the Giza plateau, many people are unaware of the fact that the Descending Passage of the Great Pyramid pointed to the pole star Alpha Draconis, circa 2170-2144 BCE. This was the North Star at that point in time. No other star has aligned with the passage since then.

Orion and The Great Pyramid

The southern shaft in the King’s Chamber pointed to the star Al Nitak (Zeta Orionis) in the constellation Orion, circa 2450 BCE. The Orion constellation was associated with the Egyptian god Osiris. No other star aligned with this shaft during that time in history.

The Sun, math and the Great Pyramid

Twice the perimeter of the bottom of the granite coffer times 10^8 is the sun’s mean radius. [270.45378502 Pyramid Inches* 10^8 = 427,316 miles]. The height of the pyramid times 10**9 = Avg. distance to the sun. <5813.2355653 * 10**9 * (1 mi / 63291.58 PI) = 91,848,500 mi>Mean Distance to the Sun: Half of the length of the diagonal of the base times 10**6 = average distance to the sun Mean Distance to Sun: The height of the pyramid times 10**9 represents the mean radius of the earth’s orbit around the sun or Astronomical Unit. < 5813.235565376 pyramid inches x 10**9 = 91,848,816.9 miles>Mean Distance to Moon: ] The length of the Jubilee passage times 7 times 10**7 is the mean distance to the moon. <215.973053 PI * 7 * 10**7 =1.5118e10 PI = 238,865 miles >(source)

The Great Pyramid and planet Earth

The weight of the pyramid is estimated at 5,955,000 tons. Multiplied by 10^8 gives a reasonable estimate of the earth’s mass. With the mantle in place, the Great Pyramid could be seen from the mountains in Israel and probably the moon as well (citation needed). The sacred cubit times 10**7 = polar radius of the earth (distance from North Pole to Earth’s center) <25 PI * 10**7 * (1.001081 in / 1 PI) * (1 ft / 12 in) * (1 mi/ 5280 ft) = 3950 miles >

The curvature designed into the faces of the pyramid exactly matches the radius of the earth. (source) (source)

Not for mummies

The Great Pyramid of Giza was erected, according to mainstream scholars, to serve as the eternal resting place for a Pharaoh. Contrary to the mainstream theories, no mummy has ever been discovered in the Great Pyramid of Giza. This important fact provides much needed space to theorize about the possible use of the Great Pyramid of Giza which, as we can see, was not meant to serve as a tomb.

When it was first entered by the Arabs in 820 AD, the only thing found in the pyramid was an empty granite box in the King’s chamber called the “coffer”. (source)

Built in harmony with the galaxy

According to reports, on midnight of the autumnal equinox in the year when the builder of the Great Pyramid finished its construction process, a line extending from the apex pointed to the star Alcyone.

Alcyone is the brightest star in the Pleiades open cluster, which is a young cluster, aged at less than 50 million years. It is located approximately 400 light years from Earth. (source)

It is believed that our solar system revolves around this star accompanied with other solar systems much like the planets in our solar system revolve around the sun. How the ancient builders of the Pyramid have such advanced astronomical knowledge still remains a mystery.

The Ark of the Covenant and the Great Pyramid of Giza

A detail that was unknown to me until not long ago is that the volume or cubic capacity of the Coffer in the King’s chamber is exactly the same volume to the Ark of the Covenant as described in the Bible. Interestingly, The granite coffer in the “King’s Chamber” is too big to fit through the passages and so it must have been put in place during construction.

The mysterious coffin in the Great Pyramid

If the great coffin wasn’t meant to house the remains of a Pharaoh, then what was its real purpose? The coffer was made out of a block of solid granite. This would have required bronze saws 8-9 ft. long set with teeth of sapphires. Hollowing out of the interior would require tubular drills of the same material applied with a tremendous vertical force. Microscopic analysis of the coffer reveals that it was made with a fixed point drill that used hard jewel bits and a drilling force of 2 tons.

Watch the video: The science of symmetry - Colm Kelleher (October 2022).