There is no doubt that there is climate change is ongoing at the present time, and we are experiencing a warmer climate lately. There have always been natural changes in the climate. It all depends on energy flow. Energy flows through communities. Main Source of Energy for our planet is Sun.
The evidence for climate change is “unequivocal” – says the latest report of IPCC. It says there is a 90 per cent chance that present climate change is caused by human activity and may bring “abrupt and irreversible” effects and warns that deep cuts in greenhouse gas emissions are needed quickly to avert more heat waves, melting glaciers and rising sea levels
Over the last 100 years, the average temperature of the air near the Earth´s surface has risen a little less than 1° C. This is responsible for the conspicuous increase in storms, floods and raging forest fires we have seen in the last ten years.
The Earth’s outer atmosphere is irradiated by huge amounts of energy from the Sun. The atmosphere reflects and absorbs some of this energy, but most reaches the Earth’s surface. Energy enters food chains only when sunlight is used in photosynthesis. Plants can benefit from the warming of soil because it makes them grow faster. About half of the light energy is used evaporating water from moist soil; this is what dries the ground out after rain.
Only a portion of the sugar made in photosynthesis contributes to the increase in biomass. Some of it is used in respiration as a source of energy to drive the synthesis of other substances the plant needs in its growth. The energy transformations involved are not 100% efficient so energy is also lost to the environment as heat. Only the molecules used in tissues, for example sugars used to make cellulose for new cell walls, proteins for cytoplasm and lipids for waterproofing the leaves, contribute to the biomass of plants. This biomass amounts to 1–5% of the light energy received per square metre and is the source of energy for primary consumers.
A food chain does not consist of a set amount of organic matter and energy being passed along like a baton from one organism to another. In reality, the baton gets smaller and smaller with each transfer. When an herbivore eats a plant, it does not get all the energy the plant received from the sun. This decrease is because the herbivore may not eat all parts of the plant, and it may not be able to digest what it does eat. These undigested plant parts are excreted as waste. The same holds true for other organisms along the food chain (i.e., when one organism eats a second, the consumer does not receive all the energy obtained by and contained within the second organism).
Another reason energy obtained by one organism isn’t passed on in the food chain is because it is no longer available (Second Law of Thermodynamics). Some energy has already been used by the first organism. A plant uses some of the energy it receives to grow and function. An herbivore uses its energy to grow, but also to look for food and run away from predators. A predator uses large amounts of energy to chase after its food in addition to its regular life processes (e.g., breathing, digesting food, moving). The energy these organisms use eventually leaves their bodies in the form of heat.
The amount of energy that is transferred from one organism to the next varies in different food chains. Generally, about ten percent of the energy from one level of a food chain makes it to the next. Click on thumbnail below to see an example of heat loss in food chains.
Because energy is “lost” with each successive link, there must be enough energy in the organisms to allow for this loss and still have enough energy remaining for the consumers in the next level. In other words, the total biomass (organic matter) of the producers must be greater than the total biomass of the herbivores they support, and the total biomass of the herbivores must be greater than that of the carnivores. Because of this energy loss there are usually more producers than herbivores, and more herbivores than carnivores in an ecosystem.
Food webs are very complex. Ecologists often consider energy transfer between trophic levels rather than energy passing down a food chain. They measure the energy per square metre fixed by primary producers, how much energy passes to the primary consumers grazing on that area of vegetation, how much then passes on to secondary consumers, and so on. It is very difficult to accurately measure and portray energy transfer because animals’ feeding habits can be complex.
Food Chains and the Carbon Cycle
When we talk about the flow of energy in food chains, the transfer of energy between organisms also includes the transfer of matter, specifically carbon-based materials. Unlike energy, however, carbon and other elements of matter cycle within ecosystems, being used again and again as they travel through food chains, the atmosphere, soil, and water. Energy enables carbon to move through these different components of an ecosystem, however, it is important to note that carbon cycles within a system and energy flows through an ecosystem. Carbon dioxide is the most important greenhouse gas in the atmosphere.Since the beginning of the industrial revolution, the average amount of carbon dioxide in the atmosphere has increased by nearly 40%. Changes in land use pattern, deforestation, land clearing, agriculture, and other activities have all led to a rise in the emission of carbon dioxide.
Carbon transfers and Human Societies
It is possible to make food (energy) chains out of other fuel usages besides food. For example, how we power our homes and run our cars are types of food chains. The fuel sources are mainly fossil fuels and these are burned to provide our society with energy. Like food chains, using energy to power our homes or run our cars involves the flow of energy and the cycling of carbon (see above graphic). And, as with food chains energy is “wasted” or “lost” with each transfer.
Ozone is a triatomic form of oxygen (O3) found in Earth’s situated in the stratosphere about 15 to 30 km above the earth’s surface. In 1985, using satellites, balloons, and surface stations, a team of researchers comprising Joe Farman, Brian Gardiner, and Jonathan Shanklin discovered a balding patch of ozone in the upper stratosphere, the size of the United States, over Antarctica.This balding patch is also called ozone hole.Hole Formation is based on Two different mechanisms.In Meteorological mechanism movement of air from one place to another in the upper stratosphere plays the key role. Cold temperature in the upper atmosphere causes nitric acid to freeze into crystals forming wispy pink clouds which in turn forms a vortex of tightly twisted winds thus forming a hole in the upper atmosphere.
In chemical mechanism different chemicals are responsible for the destruction of the ozone layer .Topping the list are chlorofluorocarbons (CFC’s). Others are carbon tetrachloride, methyl chloroform, halons, methyl bromide etc .
Ozone depletion and climate change are linked in many ways, through their effects on physical and chemical processes in the atmosphere, as well as interaction between the atmosphere and the rest of the global ecosystem. Changes in temperature and other natural and human-induced climatic factors such as cloud cover, winds and precipitation impact directly and indirectly on the scale of the chemical reactions that fuel destruction of the ozone in the stratosphere. Recent research indicates that climate change by 2030 may surpass CFCs as the main cause of overall ozone loss.
On the other hand the fact that ozone absorbs solar radiation means it counts as a greenhouse gas (GHG), much as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and halogen source gases. Stratospheric ozone depletion and increases in global ozone near the Earth’s surface (tropospheric ozone) in recent decades contribute to climate change. The 2006 report by the Environmental Effects Assessment Panel takes this into account, focusing its assessment on interaction with climate change.
Many of the man-made ozone depleting chemicals (e.g. CFCs and HCFCs) and their replacements (e.g. HFCs) are potent greenhouse gases.
The build-up of GHGs, including ozone destructing substances and their replacements, is known to enhance warming of the lower atmosphere, called the troposphere (where weather systems occur).
The troposphere and stratosphere are not independent of one another. Changes in the circulation and chemistry of one can affect the other. Changes in the troposphere associated with climate change may affect functions in the stratosphere. Similarly changes in the stratosphere due to ozone depletion can affect functions in the troposphere in intricate ways that make it difficult to predict the cumulative effects.
In addition to destroying the ozone layer, most ozone destructing substances are potent greenhouse gases. The global warming potential of CFCs, halons and HCFCs are thousands of times more than the most commonly-know greenhouse gas, carbon dioxide. These chemicals directly contribute to climate change if they are emitted to the atmosphere. They also contribute indirectly to climate change through the use of electricity to power appliances that use ozone destructing substances.
Small changes in the energy output of the sun can have a major impact on global weather patterns, such as the intensity of the Indian monsoon, that could be predicted years in advance, a team of scientists said.
Energy Flow, Global Warming and Climate Change
The interior of a car heats up when the car is sitting in the Sun with the windows closed. This heating occurs because sunlight comes in through the windows and is absorbed by the seats and other interior objects. In being thus absorbed, the light energy is converted into heat energy, which is given off in the form of infrared radiation. Unlike sunlight, infrared radiation is blocked by glass and so cannot leave the car. The trapped heat energy causes the interior air temperature to rise. This is the same phenomenon that keeps a green hose warmer than the surrounding environment.
On a global scale, CO2, water vapour and other gases in the atmosphere play a role analogous to the glass in the greenhouse. So they are, called greenhouse gases. These Greenhouse gases are like a heat blanket insulating Earth and delaying the loss of infrared energy (heat) to space. Without this insulation, average surface temperature on earth would be 21 degree cooler, and life as we know would be impossible. Therefore, our global climate is dependent on Earth’s concentration of greenhouse gases.
Besides warming, earth’s atmosphere is also subject to cooling process. Clouds play a role in this cooling. High clouds have a greenhouse effect, absorbing some of the infrared radiation and emitting some infrared themselves. Overall, the net impact of clouds is judged to be a slightly cooling effect.
Volcanic activity can also lead to planetary cooling. When Mount Pinatubo erupted in 1991, some 20 million tons of particles and aerosols entered the earth’s atmosphere and contributed to a significant drop in global temperature as radiation was reflected and scattered away.
Climatologists have found that anthropogenic sulphate aerosols (from ground level pollution) play a significant role in cancelling out some of the warming from greenhouse gases.
Global atmospheric temperatures are a balance of the effects of factors leading to cooling and factors leading to warning. The net result varies, depending on one’s location. This balance contributes much uncertainty to our predictions of what will happen in the future as greenhouse gases continue to increase.
Earth is a planet, covered more than two-thirds by oceans.Being . on land, it is hard for us to imagine that the ocean plays a dominant role in determining our climate. The oceans are the major source of water for the hydrologic cycle and the main source of heat energy entering the atmosphere. The evaporation of water vapour from ocean supplies the atmosphere with latent heat of condensation. The oceans play a vital role in climate because of their innate heat capacity. The entire heat capacity of the atmosphere is equal to that of just the top 3 m of ocean water. Through the movement of ocean currents, the oceans are highly important as conveyors of heat. Enormous quantities of heat are laterally moved through water, from hot equatorial regions to higher latitudes. A notable example is Gulf Stream, which keeps Western Europe warm. A crucial concept in this regard is thermohaline circulation.
The thermohaline circulation also known as Ocean Conveyor Belt plays an important role in energy flow to the Polar Regions, and thus in regulating the amount of sea ice in these regions. Changes in the thermohaline circulation are thought to have significant impacts on the earth’s radiation budget. Insofar as the thermohaline circulation governs the rate at which deep waters are exposed to the surface, it may also play an important role in determining the concentration of carbon dioxide in the atmosphere. While it is often stated that the thermohaline circulation is the primary reason that Western Europe is so temperate, it has been suggested that this is largely incorrect, and that Europe is warm mostly because it lies downwind of an ocean basin, and because of the effect of atmospheric waves bringing warm air north from the subtropics. However, the underlying assumptions of this particular analysis have been challenged.
The ocean conveyor belt plays a crucial role in helping to shape the Earth’s climate. However, global climate changes could alter, or even halt, the current as we know it today. As the Earth heats up, there could be an increase in precipitation and a melting of freshwater ice in the Arctic Ocean (when salt water freezes it leaves the salt behind), which would flow into the Atlantic Ocean. This additional freshwater could dilute the Atlantic Gulf Stream to the point where it would not continue to sink into the depths of the ocean.
This conveyor system acts as a giant, complex conveyor belt, moving water masses from the surface to deep oceans and back again, according to the density of mass. A key area is the high-latitude North-Atlantic, where salty water from the Gulf Stream moves northward on the surface and is cooled by Arctic air currents. Cooling increases the density of water ,which then sinks to the depths of 4000 m- the North Atlantic Deep Water(NADW).This deep water spreads southward through the Atlantic to the southern tip of Africa, where it is joined by cold Antarctic waters ,to spread northward into the Indian and pacific oceans as deep currents. The currents gradually slow down and warm, becoming less dense and welling up to the surface, where they are further warmed and begins a movement of surface waters back again toward the North Atlantic. This movement transfers enormous quantities of heat toward Europe, providing a climate that is much warmer than the high latitudes there would suggest. This circulation operates about over a period of 1000 years for one cycle and is vital to the maintenance of current climatic conditions.
The sun, in addition to emitting radiation, emits a stream of ionized particles called the solar wind that affects the Earth and other planets in the solar system. The solar wind, which carries the particles from the sun’s magnetic field, known as the interplanetary magnetic field, takes about three or four days to reach the Earth. When the charged electrical particles approach the Earth, they carve out a highly magnetized region — the magnetosphere — which surrounds and protects the Earth.
Charged particles carry currents, which cause significant modifications in the Earth’s magnetosphere. This region is where communications spacecraft operate and where the energy releases in space known as substorms wreak havoc on satellites, power grids and communications systems.
The rate at which the solar wind transfers energy to the magnetosphere can vary widely, but what determines the rate of energy transfer is unclear.
- Food Chain and Food Web Vocabulary Words – Literacy Station for Science (teacherlingo.com)
- Heat for Deep Ocean Ecosystem Comes From Interior of Earth : Study (rashidfaridi.wordpress.com)
- Polar melt shakes up food chain (stoptheaclu.com)
- Chapter 1 (ecocriticalreading.wordpress.com)
- Thes Bacteria Eat Electricity And Make Fuel (fastcoexist.com)
- How sustainable is biomass as a renewable energy source? (bioenergyconsult.wordpress.com)