The Sahelian-drought, that began in 1968 and took place in sub-Saharan Africa, was responsible for the deaths of between 100,000 to 250,000 people, the displacement of millions more and the collapse of the agricultural base for several African nations. In North America during the 1930’s, parts of the Canadian Prairies and the “Great Planes” in the US turned to dust as a result of drought and poor farming practices. This “Dust Bowl” forced countless farmers to abandon their farms and way of life and made a fragile economic situation even worse. In both cases, a combination of factors led to the process known as Desertification. This is defined as the persistent degradation of dryland ecosystems due to natural and man-made factors, and it is a complex process.
Desertification can be caused by climactic variances, but the chief cause is human activity. It is principally caused by overgrazing, overdrafting of groundwater and diversion of water from rivers for human consumption and industrial use. Add to that overcultivation of land which exhausts the soil and deforestation which removes trees that anchor the soil to the land, and you have a very serious problem! Today, desertification is devouring more than 20,000 square miles of land worldwide every year. In North America, 74% of the land in North America is affected by desertification while in the Mediterranean, water shortages and poor harvests during the droughts of the early 1990s exposed the acute vulnerability of the Mediterranean region to climatic extremes.
In Africa, this presents a serious problem where more than 2.4 million acres of land, which constitutes 73% of its drylands, are affected by desertification. Increased population and livestock pressure on marginal lands have accelerated this problem. In some areas, where nomads still roam, forced migration causes these people to move to new areas and place stress on new lands which are less arid and hence more vulnerable to overgrazing and drought. Given the existing problems of overpopulation, starvation, and the fact that imports are not a readily available option, this phenomenon is likely to lead to greater waves of starvation and displacement in the near future.
Against this backdrop, the prospect of a major climate change brought about by human activities is a source of growing concern. Increased global mean temperatures will mean more droughts, higher rates of erosion, and a diminished supply land water; which will seriously undermine efforts to combat drought and keep the world’s deserts from spreading further. The effects will be felt all over the world but will hit the equatorial regions of the world especially hard, regions like Sub-Saharan Africa, the Mediterranean, Central and South America, where food shortages are already a problem and are having serious social, economic and political consequences.
We have written many articles about desertification for Universe Today. Here’s an article about the largest desert on Earth, and here’s an article about the Atacama Desert.
Earth as viewed from the cabin of the Apollo 11 spacecraft. Credit: NASA
Have you ever wondered why the Earth is tilted instead of just perpendicular with its plane of orbit? Scientists have taken a crack at answering that question. The main consensus is that it has to do with Earth’s formation along with the rest of the planets in the Solar system. This time in cosmic history is still a mystery to us but we do have some ideas about what went on. We know that the birth of the Sun created a new source of gravity in the young Solar System. The tidal forces between the young sun and the rest of the nebula the Sun was born from created further instability in the gases and dust left in the nebula. This allowed for the steady formation of the planets.
After millions of years passed enough matter collided to gain mass and its own gravity and become small versions of planets called planetessimals and protoplanets. These pre-planets collided to create even larger planets. This set the stage for how the Earth approached its final form. It looks like it probably collided with a another proto-planet and in the process it was tilted.
All the same the Earth’s tilt is very important. It is perfectly positioned so that it gives us the seasons and on top of that the seasons are near perfectly calibrated for life. When compared with other planets Earth’s tilt allows for season that are not too extreme in temperature but are pretty well balanced. At the same if it had stay in the “perfect” position one side of the Earth would be too hot at time and then too cold.
We have written many articles about the Earth’s tilt for Universe Today. Here’s an article about why Earth has seasons, and here’s an article about the Earth’s axis.
It interesting that we have explored further into space than we have explored the depths of the Earth. The main reason for that is the pressure and the heat. We know through seismography that temperatures in the inner parts of the Earth actually exceed the surface temperature of the Sun! That is pretty hot. So why is the center of the Earth Hot. The answer comes from a lot different sources. The first is heat left over from the formation of the Earth. The next source is gravitational pressure put on core by tidal forces and the rotation of the Earth. The last known source of heat is the radioactive decay of elements in the inner part of the Earth.
The Earth is pretty old at 4 billion years old and there are still things we don’t completely understand about its formation. We do know that gravity played a role pulling in more matter and compressing it to form the Earth. When you have matter colliding at high velocities like it did in the early stages of the Solar System’s development all that kinetic energy has to go somewhere. In the case of Earth that energy was turned into heat. This heat is the initial source for the temperatures in the Earth’s interior.
The next source of heat is gravitational pressure. The Earth is under immense pressure due to the tidal forces exerted by the Sun, the Moon, and the other planets in the Solar System. When you include the fact that it is also rotating the Earth’s core is under immense pressure. This pressure basically keeps the core hot in the same way as a pressure cooker. It also helps to minimize the heat it loses.
The last and most important source of heat is nuclear fission of heavly elements in the Earth’s interior. In short the Earth has a nuclear engine inside it. It is thank to the continous nuclear fission of elements in the Earth’s interior that replaces the heat the Earth loses keeping it nice and hot. This fission process occurs in the form of radioactive decay. It also creates the convection currents in the mantle that drive plate tectonics.
The Ozone Layer is the portion of the atmosphere that contains high levels of the oxygen molecule ozone. This molecule plays an important role acting as a natural UV shield for the Earth. You may wonder where is the ozone layer located to play such a vital role so effectively. The Ozone layer is actually located in the stratosphere in a region that is 10 to 50 km above the Earth.
So why is the Ozone layer so important? As mention before the secret lies in oxygen molecules. Normal oxygen in its natural molecular state is made up of only two atoms. However this changes when oxygen in the thermosphere is exposed the Sun’s ultraviolet rays. The rays separate oxygen molecules the free oxygen joins with the remaining two atom oxygen molecules to create ozone. This process might seem simple but it helps to screen out 99.5 percent of the ultraviolet radiation that the Sun sends towards earth. The times that the ozone layer didn’t screen out this type of radiation at such levels life was almost wiped out according to the geologic record.
You might think that this is an exaggeration until you observe the biological damage UV rays can do. We have already seen the harm caused when people don’t take the proper precautions when going to the beach. The least harm comes in the form of sun burn. People overexposed to the UV rays that do make it to earth have their skin damaged by the UV energy that penetrates their skin. However it gets more serious the longer a person is exposed to UV rays. The reason is because the damage gets to the cellular level causing cancers and genetic damage. Essentially it’s like being exposed to a nuclear reactor in melt down. The high energy radiation over time would accumulate harm in living tissue until it killed the organism exposed to it.
Despite its importance industry produced and released chemicals into the air that interfered with the ozone cycle. The main problem chemical CFC’s prevented oxygen molecules from complete the bonding process that is important for the completion of the ozone cycle this caused a major depletion of ozone in key areas of the Earth’s atmosphere. This is huge when the natural concentration of ozone was already quite low. This just goes to show the delicate balance that was upset. Fortunately nations upon hearing the harm caused started bans on CFC’s while industry tried to find alternatives to use in products. The result started to show with ozone depletion actually slowing down and reversing with scientist predicting recovery within the next century.
We have written many articles about the ozone layer for Universe Today. Here’s an article about the depletion of the ozone layer, and here’s an article about the ozone layer.
High concentrations of carbon dioxide (in red) tend to congregate in the northern hemisphere during colder months, when plants can't absorb as much from the atmosphere. This picture is based on a NASA Goddard computer model from ground-based observations and depicts concentrations on March 30, 2006. Credit: NASA's Goddard Space Flight Center/B. Putman/YouTube (screenshot)
What if it were possible to just suck all the harmful pollutants out of the air so that they wouldn’t be such a nuisance? What if it were also possible to convert these atmospheric pollutants back into fossil fuels, or possibly ecologically-friendly bio fuels? Why, then we would be able to worry far less about smog, respiratory illnesses, and the effects that high concentrations of these gases have on the planet.
This is the basis of Carbon Capture, a relatively new concept where carbon dioxide is captured at point sources – such as factories, natural-gas plants, fuel plants, major cities, or any other place where large concentrations of CO² are known to be found. This CO² can then be stored for future use, converted into biofuels, or simply put back into the Earth so that it doesn’t enter the atmosphere.
Description:
Like many other recent developments, carbon capture is part of a new set of procedures that are collectively known as geoengineering. The purpose of these procedures are to alter the climate to counteract the effects of global warming, generally by targeting one of the chief greenhouse gases. The technology has existed for some time, but it has only been in recent years that it has been proposed as a means of combating climate change as well.
Schematic showing both terrestrial and geological sequestration of carbon dioxide emissions from a coal-fired plant. Credit: web.ornl.gov
Currently, carbon capture is most often employed in plants that rely on fossil fuel burning to generate electricity. This process is performed in one of three basic ways – post-combustion, pre-combustion and oxy-fuel combustion. Post-combustion involves removing CO2 after the fossil fuel is burned and is converted into a flue gas, which consists of CO2, water vapor, sulfur dioxides and nitrogen oxide.
When the gases travel through a smokestack or chimney, CO² is captured by a “filter” which actually consists of solvents that are used to absorb CO2 and water vapor. This technique is effective in that such filters can be retrofitted to older plants, avoiding the need for a costly power plant overhaul.
Benefits and Challenges:
The results of these processes have so far been encouraging – which boast the possibility of up to 90 % of CO² being removed from emissions (depending on the type of plant and the method used). However, there are concerns that some of these processes add to the overall cost and energy consumption of power plants.
According to 2005 report by the Intergovernmental Panel on Climate Change (IPCC), the additional costs range from 24 to 40% for coal power plants, 11 to 22% for natural gas plants, and 14 to 25% for coal-based gasification combined cycle systems. The additional power consumption also creates more in the way of emissions.
Vehicle emissions are one of the main sources of carbon dioxide today. Credit: ucsusa.org
In addition, while CC operations are capable of drastically reducing CO², they can add other pollutants to the air. The amounts of kind of pollutants depend on the technology, and range from ammonia and nitrogen oxides (NO and NO²) to sulfur oxides and disulfur oxides (SO, SO², SO³, S²O, S²O³. etc.). However, researchers are developing new techniques which they hope will reduce both costs and consumption and not generate additional pollutants.
Examples:
A good example of the Carbon Capture process is the Petro Nova project, a coal-fired power plant in Texas. This plant began being upgraded by the US Dept. of Energy (DOE) in 2014 to accommodate the largest post-combustion carbon-capture operation in the world.
Consisting of filters that would capture the emissions, and infrastructure that would place it back in the Earth, the DOE estimates that this operation will be capable of capturing 1.4 million tons of CO2 that previously would have been released into the air.
In the case of pre-combustion, CO² is trapped before the fossil fuel is even burned. Here, coal, oil or natural gas is heated in pure oxygen, resulting in a mix of carbon monoxide and hydrogen. This mix is then treated in a catalytic converter with steam, which then produces more hydrogen and carbon dioxide.
When complete, the US Department of Energy’s (DoE) Petro Nova will be the largest post-combustion carbon capture operation in the world. Credit: DOE
These gases are then fed into flasks where they are treated with amine (which binds with the CO² but not hydrogen); the mixture is then heated, causing the CO² to rise where it can be collected. In the final process (oxy-fuel combustion), fossil fuel is burned in oxygen, resulting in a gas mixture of steam and CO². The steam and carbon dioxide are separated by cooling and compressing the gas stream, and once separated, the CO² is removed.
Other efforts at carbon capture include building urban structures with special facilities to extract CO² from the air. Examples of this include the Torre de Especialidades in Mexico City – a hospital that is surrounded by a 2500 m² facade composed of Prosolve370e. Designed by Berlin-based firm Elegant Embellishments, this specially-shaped facade is able to channel air through its lattices and relies on chemical processes to filter out smog.
China’s Phoenix Towers – a planned-project for a series of towers in Wuhan, China (which will also be the world’s tallest) – is also expected to be equipped with a carbon capture operation. As part of the designers vision of creating a building that is both impressively tall and sustainable, these include special coatings on the outside of the structures that will draw CO² out of the local city air.
Then there’s the idea for “artificial trees“, which was put forward by Professor Klaus Lackner of the Department of Earth and Environmental Engineering at Columbia University. Consisting of plastic fronds that are coated with a resin that contains sodium carbonation – which when combined with carbon dioxide creates sodium bicarbonate (aka. baking soda) – these “trees” consume CO² in much the same way real trees do.
A cost-effective version of the same technology used to scrub CO² from air in submarines and space shuttles, the fronds are then cleaned using water which, when combined with the sodium bicarbonate, yields a solution that can easily be converted into biofuel.
In all cases, the process of Carbon Capture comes down to finding ways to remove harmful pollutants from the air to reduce humanity’s footprint. Storage and reuse also enter into the equation in the hopes of giving researchers more time to develop alternative energy sources.
Helium is the second lightest element in the known universe. It is also the second most abundant. According to some estimates helium accounts for as much as 24 percent of the Universe’s mass. This element is also plentiful since it is a prime product of fusion nuclear reactions involving hydrogen. So if it is so plentiful where is Helium found?
The problem is that just because an element is common in the universe at large does not mean that it is common on Earth. Helium is an element that fits this scenario. Helium only accounts for 0.00052% of the Earth’s atmosphere and the majority of the helium harvested comes from beneath the ground being extracted from minerals or tapped gas deposits. This makes it one of the rarest elements of any form on the planet.
Like mentioned before Helium is rare on Earth but there are places where it is readily found. If you look at space the majority of helium is in stars and the interstellar medium. This is due to the fusion reaction that powers most stars fusing single hydrogen atoms to create helium atoms. This process balanced with a star’s gravity is what helps it to stay stable for billions of years. On Earth the majority of helium found comes from radioactive decay. This is the opposite nuclear reaction called fission that splits atoms. For this reason radioactive minerals in the lithosphere like uranium are prime sources for helium.
On Earth there are key locations where concentrated helium can be harvested. The United States produces the majority of the world’s helium supply at 78%. The rest of the world’s helium is harvested in North Africa, The Middle East, and Russia. The interesting thing is that thanks to these deposits the world’s demand for helium is being met regularly. Also unlike petroleum which can decades to form from organic material, 3000 metric tons of Hydrogen is produced yearly. Until helium demand reaches at least the same level of demand as petroleum there it little chance of that demand outpacing supply.
Helium is looking to be a major player in the near future. Governments are looking into using the gas as source of hydrogen for fuel cells and other transportation technologies. At the moment the promise is still tentative but at least with better surveying and knowledge of gas deposits there will be a supply waiting if becomes the next major element to power human civilization. In the meanwhile ours is still a planet beholden to carbon.
You may not have heard much about geothermal energy but it is one of the hottest alternative energy commodities around. It is a renewable and clean energy source that will be around for a long time. However where does geothermal energy come from? The answer is the earth itself. The world geothermal comes from the Greek words geo which means earth and therme which means heat. Basically geothermal energy is heat energy harvested from the Earth itself.
Geothermal heat is produced by the core of the Earth itself. You may not think that energy to be much when compared to the sun but you would be wrong in some aspects. The Earth’s core alone is 11,000 degrees. That is hotter than the surface of the sun. The Earth’s geothermal energy is created by the decay of radioactie materials in the core and in the surrounding layers of rock.
However this still doesnt tell us how this energy becomes accessible. The deepest mankind can even go with the best technology is around 11 km. The answer is plate tectonics. bounadaries and faults are cracks in the Earth’s crust where magma rises near or to the surface. Geothermal plants take advantage of this fact using water heated by this volcanic activity to produce electric power.
The main place where geothermal energy can be used have not only volcanic activity but also enough ground water to be used to power the turbines that generate power. Prime areas are near volcanoes, hot springs, and geysers. Large volcanic islands like Greenland have vast resources in terms of geothermal energy. In the end the most common location for geothermal reservoirs will be where ever there are major plate boundaries with a lot of seismic and volcanic activity.
The benefits of geothermal energy is already being discussed in nations like Iceland as way to reduce reliance on foreign oil. Geothermal is abundant where it can be accessed and can easily produce energy on par with the output of other types of energy production such as nuclear reactors. The best part is that it is clean energy. There is no way it can produce pollution that can harm the environment. The only risk is that drilling in active volcanic area can make them vulnerable to earthquakes.
In the end Geothermal still one of the best possible sources of clean energy on the planet. As the technology improves for accessing it more homes around the world will have the opportunity to be powered by this renewable energy resource.
We have written many articles about geothermal energy for Universe Today. Here’s an article about Geothermal Energy, and here’s an article about how geothermal energy works.
What is a hurricane? Well, a hurricane is a tropical cyclone that occurs in the North Atlantic Ocean or the Northeast Pacific Ocean and remains east of the International Dateline. Tropical cyclones are characterized by a large low pressure center and numerous thunderstorms. These produce strong winds and heavy rain. These cyclones feed on heat released when moist air rises causing condensation of the water vapor that is contained in the moist air. These storms are fueled by a different heat mechanism than other cyclonic windstorms(nor’easters, polar lows, and European windstorms). They are classified as a warm core storm system.
All tropical cyclones are areas of low atmospheric pressure. As a matter of fact, the pressures recorded at the center of tropical cyclones are among the lowest that occur at sea level. A hurricane is characterized and driven by the release of large amounts of latent heat of condensation(water vapor condenses as it moves upward). This heat is distributed vertically around the center of the storm, so, except at the surface of water, it is warmer inside the cyclone than it is outside. At the center of the hurricane is an area of sinking air. If this area is strong enough, it can develop into a large eye. Weather in the eye is normally calm and free of clouds, but the surface of the sea may be tossing violently. The eye is normally circular in shape, and may range in size from 3 km to 370 km in diameter.
While a tropical cyclone’s primary energy source is the release of the heat of condensation, solar heating is the initial source of that evaporation. An initial warm core system(an organized thunderstorm complex) is necessary for the formation of a tropical cyclone, but a large flux of energy is needed to lower atmospheric pressure. The influx of warmth and moisture from the underlying ocean surface is critical for tropical cyclone strengthening and most of it comes from the lower 1 km of the atmosphere. Condensation leads to higher wind speeds. These faster winds and the lower pressure associated with them cause an increase in surface evaporation and more condensation. This positive feedback system continues and feeds the hurricane until the conditions for hurricane formation are gone. The rotation of Earth causes the system to spin,(the Coriolis effect) which gives it a cyclonic appearance and affects its trajectory.
Tropical cyclones are distinguished by the deep convection that fuels them. Since convection is strongest in the tropics it defines the initial domain of the tropical cyclone. To continue to feed itself a tropical cyclone must remain over warm water. When a tropical cyclone passes over land, it is cut off from its heat source and its strength diminishes rapidly. The passage of a tropical cyclone over the ocean can cause the upper layers of the ocean to cool substantially, which can influence subsequent cyclone development. Scientists at the National Center for Atmospheric Research in the US estimate that a tropical cyclone releases heat energy equal to 70 times the world energy consumption, 200 times the worldwide electrical generating capacity, or the same as exploding a 10 megaton nuclear bomb every 20 minutes.
Well, there you have the answer to what is a hurricane. It is a tropical nightmare, but if humans could somehow harness that energy we would never need fossil fuels again.
A new NASA image of Earth, by Robert Simmon and Marit Jentoft-Nilsen, based on MODIS data.
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Despite recent news of potential habitable exoplanets and amazing images of Mars and the Saturn system returned from visiting spacecraft, the ol’ home planet is still about the most gorgeous-looking planetary body out there. We first saw it as a whole “blue marble” when the Apollo astronauts sent back pictures while circling the Moon, and it has been said that the original “Blue Marble” image taken by the Apollo 17 crew has been one of the most viewed and most influential images ever. But truth be told, that “Blue Marble” really wasn’t all that blue (see the original below). However, this new look at the home world shows how prevalent water really is. This composite image is based largely on observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.
It sure is pretty.
According to the NASA Earth Observatory website, Earth’s water content is about 1.39 billion cubic kilometers (331 million cubic miles), with the bulk of it, about 96.5%, being in the global oceans. As for the rest, approximately 1.7% is stored in the polar icecaps, glaciers, and permanent snow, and another 1.7% is stored in groundwater, lakes, rivers, streams, and soil. Only a thousandth of 1% of the water on Earth exists as water vapor in the atmosphere.
Here’s the original “Blue Marble,” the view of the Earth as seen by the Apollo 17 crew traveling toward the moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is the first time the Apollo trajectory made it possible to photograph the south polar ice cap. Almost the entire coastline of Africa is clearly visible. The Arabian Peninsula can be seen at the northeastern edge of Africa. The large island off the coast of Africa is Madagascar. The Asian mainland is on the horizon toward the northeast.
The original 'Blue Marble' taken by Apollo 17. Credit: NASA
Princeton University has developed software that can produce realistic “movies” of earthquakes based on complex computer simulations, and these visualizations will be available on the internet within hours of a disastrous upheaval. For example, this video of a 5.7 scale Earthquake off the coast of Peru occurred yesterday, September 22, 2010. “In our view, this could truly change seismic science,” said Princeton’s Jeroen Tromp, a professor of geosciences and applied and computational mathematics, who led the effort. “The better we understand what happens during earthquakes, the better prepared we can be. In addition, advances in understanding seismic waves can aid basic science efforts, helping us understand the underlying physics at work in the Earth’s interior. These visualizations, we believe, will add greatly to the research effort.”
