Some scientists disagree with Global Warming Theory.

They say it is natural.

by

Dr. Nitish Priyadarshi

Rising temperature are already the clearest sign of climate change. So far, according to the IPCC, global average temperatures have risen 0.6⁰ C above the pre-industrial average. Nine of the hottest years on record have occurred since 1988; six of the first eight months of 1998 were the warmest since records began in 1866; and July 1998 was the hottest month ever.

Scientists who assess the planet’s health see indisputable evidence that earth has been getting warmer, in some cases rapidly. Most believe that human activity, in particular the burning of fossil fuels and the resulting buildup of green house gases in the atmosphere, have influenced this warming trend. In the past decades scientists have documented record-high average annual surface temperatures and have been observing other signs of change all over the planet: in the distribution of ice, and in the salinity, levels, and temperatures of the oceans.

Everywhere on earth ice is changing. The famed snows of Kilimanjaro have melted more than 80 percent since 1912. Glaciers in the Garhwal Himalayas in India are retreating so fast that researchers believe that most central and eastern Himalayan could virtually disappear by 2035. Artic sea ice has thinned significantly over the fast half century, and its extent has declined by about 10 percent in the past 30 years.

This is one of the aspect of the global warming which most of scientists believe is man made. There is small minority of atmospheric and other scientists who disagree with this general scientific consensus. According to these scientists we still know too little about natural climate variables that could change the assessment (up or down). In addition, computer models used to predict climate change are improving but still are not reliable.

They also point out that some signs of global warming may not necessarily be caused by human activities. For example, while many glaciers are shrinking, others are growing. Also, glaciers shrink and grow naturally over long periods of time for reasons that are largely unknown.

Finally, they contend that global warming may be a lot less damaging than many people think and can be beneficial for some regions. For example, some countries may be able to increase crop productivity because of more rainfall and longer growing seasons.

They also claim that more carbon dioxide in the atmosphere could increase the rate of photosynthesis in areas with adequate amounts of water and other soil nutrients. This would remove more carbon dioxide from the atmosphere and help slow atmospheric warming.

However recent studies cast doubt on such a generalization for two reasons. First, this effect would slow as the plants reach maturity and take up less carbon dioxide. Second, it is a temporary effect. When the plants die and are decomposed or burned, the carbon they stored is returned to the atmosphere as carbon dioxide.

Are we heading towards major disaster or it is a simply a natural shifting of climate as it happened in the geological past. During the last 2 billion years the Earth's climate has alternated between a "Ice House", like today's world, and a steaming "Hot House", like the world of the dinosaurs. Jurassic climate stayed warm and became more humid. The polar areas were ice-free during this Period.

The history of earth’s climate is characterized by change. Times of glaciations on the earth have been followed by warm intervals and the duration in years of both cold and warm intervals has varied by several orders of magnitude.

What ever may be the truth we have no options but we have to opt wait and watch theory if we don’t stop carbon emission recklessly. But it is also true that the climate of the earth is changing from the time of its birth from hot to cold and cold to hot. Earlier too the earth has passed through global warming due to natural causes, but this time we the humans are culprits for the changes. When man-made factors are added to the natural ones, the ecosystem may be damaged beyond repair.

No Forest No Oxygen.

Can Deforestation bring down oxygen level?

by

Dr. Nitish Priyadarshi

Deforestation, or the removal of forests, is a major problem that has devastating effects all over the world. Europeans began clearing forests more than 500 years ago. The invention of modern machinery made the process even easier. By the end of the 19th century, most of the deciduous forest of North America, Australia and New Zealand had been cleared. In the 21st century, tropical forests are being cut and burned at alarming rates in South America and Southeast Asia. Asia as a whole has already lost about 90 percent of its forests.

With forest resources--"the lungs of the Earth"-- under attack in many regions, some have raised concerns about the planet's oxygen supply.

Oxygen is the most abundant chemical element, by mass, in our biosphere, air, sea and land. Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium, but mainly in combination with something else. The stuff is all around us but we don’t see it. Chemically joined with other elements it accounts for more than a quarter of Earth’s total weight and almost half the mass of the crust. Free or dissolved molecular oxygen, however, represents only 0.01 percent of the total crust, hydrosphere, atmosphere, and biosphere taken together. Only seven of every billion atoms takes the form of molecular oxygen (O2), plus a neglible quantity as atomic or singlet O and ozone (O3). If the atmosphere contained much more oxygen, it would be inflammable. Remove oxygen and only anaerobic bacteria could survive.

How did plants come to alter the atmosphere? The key is the way in which plants create their own food. They employ photosynthesis, in which they use light energy to synthesize food sugars from carbon dioxide and water. The process releases a waste gas, oxygen. Those of us in the animal kingdom rely on oxygen to metabolize our food, and we in turn exhale carbon dioxide as a waste gas. The plant use this carbon dioxide for more photosynthesis, and so on, in a continuing system.

Oxygenic photosynthesis (synthesis by light) is by far the largest and most familiar source of O2. Upon its introduction at precariously trivial and fluctuating levels perhaps 2.8 aeons ago, oxygen began to play a role in the evolution of life and earth’s surface processes. After that, if not earlier, photosynthetic O2 and perhaps plate tectonism joined sunlight, gravity, and water as lead players on the evolutionary stage. Yet, for another 6 to 8 geocenturies it remained at vanishing low levels as a result of reactions with a variety of reduced substances.

Nor was oxygen-evolving photosynthesis the only source of oxygen. Physical splitting of H2O by photolysis was probably the prevailing initial process. Photolysis of CO2, as well as the release of oxygen from the metallic oxides as a result of microbial processes and chemical weathering, are potential but poorly understood sources.
On reaching present levels, perhaps 4 geocenturies ago, oxygen was still consumed by new reduced volcanic gases, erosionally exhumed carbon, and reduced matter in the hydrosphere right up to the present. Levels fluctuate with rates of erosion volcanism, and deforestation. The indefinite continuity of oxygen is not guaranteed.

Forests, a major source of oxygen to our atmosphere, are very important to the world’s climate because they help in rain formation and absorb carbon dioxide (CO2) from the air. As the forests disappear, the weather will change, and some places will dry up.

There are many benefits that we get from our forests. Some of these include cleaner drinking water, a home for plants and animals, economic growth, clean air, recreational opportunities. Another most important benefit we get from trees is called oxygen. If there were no trees to give us oxygen to breath, we would not be able to live. Trees are known as the oxygen supplier to our planet.

As vast forests such as the Amazon are denuded of their beauty and natural resources, our atmosphere is also seriously altered. The forests are stripped faster than they can be replanted, and when severely depleted, photosynthesis is greatly reduced. No photosynthesis, no oxygen. No oxygen, no life. But deforestation continues at a break neck speed in many areas of the world.

Earlier in Jharkhand forest played major role in balancing the temperature difference. But now forest cover is rapidly depleting. Even one of the biggest forest of Asia popularly known as Saranda Forest is also decreasing many fold due to rampant iron ore mining in Jharkhand State. Today the remaining forest areas are unevenly distributed. Bokaro has only 4.4% of area under forest. Similarly Sahebganj has only 2.31%, Dhanbad 12.72%, Deoghar 9.5% and Ranchi only 23.37% of area under vegetation.

At the Survey and Settlement (1902-1910) the area under forests in the Ranchi districts approximated to about 2,281 square miles, i.e. about 32 percent of the total land area of the district. At the Revisional Survey and Settlement (1927-1935) this area shrank to about 1,956 square mils, i.e. 27 percent of the total land area. Thus during a period of 25 years, 325 square miles of forests had disappeared. When the forests were notified under the Bihar Private Forests Act,1946 and demarcation was done only about 1,065 square miles were found under forests in this district. Adding 213 square miles of reserve forests to this, the total area under forest in this district came to 1,278 square miles. Thus in course of a decade over 600 square miles of forests disappeared. Now it has reached up to 23 percent and gradually decreasing further.

The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. The biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth’s atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration and decay remove it from the atmosphere.

Regarding percentage of oxygen present in the atmosphere in the geological past, it was revealed that air bubbles trapped in fossilized amber had been analyzed and found to contain oxygen levels of 38%. Yet today it is well known that the average content of the oxygen in air is only 19% to 21%. If we believe on the report of oxygen level in the fossilized amber, it appears that since the early history of our earth there has been a stunning decrease of 50% in the average oxygen content of the air we breathe. According to other report, analysis of the air in various parts of the world today reveals the frightening fact that the oxygen content continues to decline. In fact in some of the larger and therefore more polluted cities the oxygen levels have been measured at a disturbing level of 12 to 15%. Scientists claim that anything under 7% oxygen content in the air is too low to support human life, even for short periods.

Historical trends, as explained in Atmospheric Oxygen, Giant Paleozoic Insects and the Evolution of Aerial Locomotor Performance by R. Dudley, JExB, show a high of about 35% just before the beginning of the Permian, with a rapid decline to a low of about 13-14% near the beginning of the Triassic, then a small spike at about 17% in mid Triassic, another drop to about 14-15% early in the Jurassic, a sudden climb to about 21% by mid-Jurassic, then a gentle climb to about 26% early in the Tertiary, and a rather constant, steady decline to the present "20.9%."
Our planet’s future is under threat as cutting back tropical forests we put our supply of oxygen gas at risk.
There is difference in opinion about oxygen depletion. Some scientists believe that our atmosphere is endowed with such an enormous reserve of this gas that even if we were to burn all our fossil reserves, all our trees, and all the organic matter stored in soils, we would use up only a few percent of the available oxygen. No matter how foolishly we treat our environment heritage, we simply don’t have the capacity to put more than a small dent in our oxygen supply.

But we can’t take any risk. If forest or plants provide oxygen, cutting or burning trees is definitely going to affect the oxygen balance of our atmosphere.

Sources:

Cloud,P. 1988. Oasis in space, earth history from the beginning. W.W. Norton & Company, New York.
http://www.eia.doe.gov/cneaf/coal/quarterly/co2_article/co2.html
http://en.wikipedia.org/wiki/Oxygen
http://www.sdpo.org.uk/index.php?option=com_content&task=view&id=41&Itemid=61
http://www.columbia.edu/cu/21stC/issue-2.1/broecker.htm

The evolution of the earth’s early atmosphere.

How did Earth's early atmosphere evolved.

by

Dr. Nitish Priyadarshi

The Earth's atmosphere (or air) is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. It has a mass of about five quadrillion metric tons. Dry air contains roughly (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, and trace amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night.

The solid earth accumulated about 4700 m.y. ago from a cloud of cosmic particles and gaseous materials and as they collected gravitationally a hot planetary nucleus formed. This nucleus eventually became the present core as the mantle and crust consolidated. An atmosphere probably existed even in these early stages of the first billion years of earth’s history, though it was apparently transitory. Judging from the atmospheres of the major planets, Jupiter and Saturn, which retain light elements by virtue of their large gravitational attraction, hydrogen and helium would have been abundant in earth’s primordial atmosphere. These elements were derived in part from the original gaseous material of the cosmic cloud, but volcanic outgassing during lithification of the crust probably continued as well. Neon and argon and some of the lighter gases such as xenon probably also existed in the early atmosphere.

The first atmosphere of the earth, then, contained hydrogen, helium, neon, argon and various other lighter and inert gases, none of which is abundant in the present atmosphere. Most of these on liberation to the air now either escape earth’s gravitational pull because of their low densities or are bound up in minerals by chemically reacting with them. It is likely that the primitive atmosphere did not linger long but was dissipated through these processes.

A little reflection tells us that earth’s present atmosphere necessarily evolved from one that was different. We know no primary source for the free molecular oxygen that comprises one –fifth of our present atmosphere. Compared with solar abundances, our atmosphere has only traces of hydrogen and helium but a disproportionate amount of nitrogen.

An important clue to the origin of our ancestral atmosphere is found in the abundances of so-called noble gases – elements that, unlike oxygen, do not (or rarely) combine with others because they have the stable configuration of 8 (or 2 in the case of helium) in their outermost shell of electrons. As they do not ordinarily lose, gain, or share electrons with other elements, variations in their abundance imply different sources. Had earth inherited its atmosphere directly from the solar nebula, the gaseous elements neon, argon, krypton, xenon, and radon should be present in approximately solar abundances, allowing for the addition of radiogenic isotopes. That is not the case. It has been repeatedly noted over the past half-century that all the noble gases are grossly depleted in the earth’s atmosphere compared with solar and cosmic abundances. They are depleted, in fact, by several to many orders of magnitude. This means either that earth accumulated without an atmosphere of nebular proportions or that any initial atmosphere escaped its gravity field in some subsequent episode of heating that accelerated even the heavy noble gases to escape velocities.

The most significant development following sufficient cooling and consolidation of the surface rocks was liberation of abundant water along with CO2 , N2, and H2 S by volcanic outgassing. Water vapor is dissociated in the upper atmosphere by ultraviolet light to yield oxygen and hydrogen. This process constituted the sole source of free oxygen of the early atmosphere, and the build up to significant oxygen concentrations occupied the long interval between at least 3400 and about 2000 m.y. ago. Further, oxygen of the early high atmosphere was photochemically converted to ozone as at present, and with time, ozone concentration led to the development of a screen to ultraviolet light. Lastly, accumulation of water molecules in the atmosphere caused extensive precipitation and hence the initiation of the oceans at some time prior to 3760 m.y. ago, when the oldest known sedimentary rocks were deposited.

Other concept regarding evolution of early oxygen in atmosphere:
If earth’s primitive atmosphere resulted from volcanic outgassing, we have a problem, because volcanoes do not emit free oxygen. Where did the very significant percentage of oxygen in our present atmosphere (20 percent) come from?

The major source of oxygen is green plants. Plants did not just adapt to their environment, they actually influenced it, dramatically altering the composition of the entire planet’s atmosphere by using carbon dioxide and releasing oxygen. This is a good example of how earth operates as a giant system in which living things interact with their environment.

How did plants come to alter the atmosphere? The key is the way in which plants create their own food. They employ photosynthesis, in which they use light energy to synthesize food sugars from carbon dioxide and water. The process releases a waste gas, oxygen. Those of us in the animal kingdom rely on oxygen to metabolize our food, and we in turn exhale carbon dioxide as a waste gas. The plant use this carbon dioxide for more photosynthesis, and so on, in a continuing system.

The first life-forms on earth, probably bacteria, did not need oxygen. Their life processes were geared to the earlier, oxygen less atmosphere. Even today, many anaerobic thrive in environments that lack free oxygen. Later, primitive plants evolved that used photosynthesis and released oxygen. Slowly, the oxygen content of earth’s atmosphere increased. The Precambrian rock record suggests that much of the first free oxygen did not remain free because it combined with (oxidized) other substances dissolved in water, especially iron. Iron has tremendous affinity for oxygen, and the two elements combine to form iron oxides (rust) at any opportunity. To this day, the majority of oxygen produced over time is locked up in the ancient "banded rock" and "red bed" formations.

Then, once the available iron satisfied its need for oxygen, substantial quantities of oxygen accumulated in the atmosphere. By the beginning of the Paleozoic era, about 4 billion years into earth’s existence, the fossil record reveals abundant ocean- dwelling organisms that require oxygen to live.
Once oxygen had been produced, ultraviolet light split the molecules, producing the ozone UV shield as a by-product. Only at this point did life move out of the oceans and respiration evolved.
Hence, the composition of earth’s atmosphere has evolved together with its life-forms, from an oxygen less envelop to today’s oxygen-rich environment.

Sources:
Cloud,P. 1988. Oasis in space, earth history from the beginning. W.W. Norton & Company, New York.
Frakes, L. A. 1979. Climates throughout geologic times. Elsevier, New York.
Tarbuck, E.J. and Lutgens, F.K. 1994. Earth Science. Prentice Hall, New Jersey.
http://knowledgerush.com/kr/encyclopedia/Earth's_atmosphere/
http://en.wikipedia.org/wiki/Earth's_atmosphere

NASA Satellite Detects Red Glow to Map Global Ocean Plant Health

[Fig. Ocean scientists can now remotely measure the amount of fluorescent red light emitted by ocean phytoplankton and assess how efficiently the microscopic plants are turning sunlight and nutrients into food through photosynthesis. (picture source http://www.nasa.gov/)

WASHINGTON -- Researchers have conducted the first global analysis of the health and productivity of ocean plants using a unique signal detected by NASA's Aqua satellite.
Ocean scientists can now remotely measure the amount of fluorescent red light emitted by phytoplankton and assess how efficiently these microscopic plants turn sunlight and nutrients into food through photosynthesis. Researchers also can study how changes in the global environment alter these processes at the center of the ocean food web. Single-celled phytoplankton fuel nearly all ocean ecosystems, serving as the most basic food source for marine animals. Phytoplankton account for half of all photosynthetic activity on Earth and play a key role in the balance of carbon dioxide in the atmosphere. The health of these marine plants affects the amount of carbon dioxide the ocean can absorb from the atmosphere and how the ocean responds to a changing climate. "This is the first direct measurement of the health of the phytoplankton in the ocean," said Michael Behrenfeld, a biologist who specializes in marine plants at Oregon State University. "We have an important new tool for observing changes in phytoplankton every week, all over the planet." All plants absorb energy from the sun, typically more than they can consume through photosynthesis. A small fraction of this extra energy is re-emitted as fluorescent light in red wavelengths. Using the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite, scientists have now observed "red-light fluorescence" over the open ocean. MODIS is the first instrument to observe this signal on a global scale. "The amount of fluorescent light emitted is not constant; it changes with the health of the plant life in the ocean," said Behrenfeld. Scientists previously used satellite sensors to track the amount of plant life in the ocean by measuring the amount and distribution of chlorophyll. "Chlorophyll gives us a picture of how much phytoplankton is present," said co-author Scott Doney, a marine chemist from the Woods Hole Oceanographic Institution in Woods Hole, Mass. "Fluorescence provides insight into how well they are functioning in the ecosystem." With this new measurement, the scientists discovered large areas of the Indian Ocean where phytoplankton were under stress from iron deficiency. They were surprised to see large portions of the ocean "light up" seasonally as phytoplankton responded to a lack of iron in their diet. The amount of fluorescence increases when phytoplankton have too little iron, a nutrient in seawater. Iron reaches the sea surface on winds blowing dust from deserts and other arid areas, and from upwelling currents. The research team detected new regions of the ocean affected by iron deposition and depletion. In the fall and winter and especially the summer, significant southwesterly winds over the Indian Ocean stir up ocean currents and bring more nutrients up from the depths for the phytoplankton to feed on. At the same time, the amount of iron-rich dust delivered by winds is reduced. Climate change could mean stronger winds pick up more dust and blow it to the sea, or less intense winds leave waters dust-free. Some regions will become drier and others wetter, changing the regions where dusty soils accumulate and get swept up into the air. Phytoplankton will reflect and react to these global changes. "On time-scales of weeks to months, we can use this data to track plankton responses to iron inputs from dust storms and the transport of iron-rich water from islands and continents," Doney said. "Over years to decades, we also can detect long-term trends in climate change and other human perturbations to the ocean." These findings appeared in the May edition of the journal Biogeosciences.

Fore more information :

http://www.nasa.gov/topics/earth/features/modis_fluorescence.html