Fact About Global Warming

PARIS (Feb. 2) - A panel of international scientists predicted Friday that global warming will continue for centuries no matter how much people control pollution, in a bleak report that blamed humans for killer heat waves, devastating droughts and stronger storms.

The report said people were "very likely" the cause of global warming - the strongest conclusion to date - and placed the burden on governments to take action.

"It's later than we think," said Susan Solomon, co-chair of Intergovernmental Panel on Climate Change.

Man-made emissions of greenhouse gases are to blame for fewer cold days, hotter nights, heat waves, floods and heavy rains, droughts and stronger storms, particularly in the Atlantic Ocean, the 21-page report said.

It highlighted "increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level."

Authors of the report called it conservative: It used only peer-reviewed published science and was edited by representatives of 113 governments who had to agree to every word. It was a snapshot of where the world is with global warming and where it is heading, but does not tell governments what to do.

Yet if nothing is done, the world is looking at billions of dollars in costs adapting to a warmer world over the next century, co-author Kevin Trenberth said in an interview. He also warned of at least 1 million deaths in droughts, floods and hurricanes.

The study said no matter how much civilization slows or reduces its greenhouse gas emissions, global warming and sea-level rise will continue for centuries.

"This is just not something you can stop. We're just going to have to live with it," said Trenberth, the director of climate analysis at the U.S National Center for Atmospheric Research. "We're creating a different planet. If you were to come back in 100 years' time, we'll have a different climate."

Scientists fear world leaders will take that message in the wrong way and throw up their hands, Trenberth said. Instead, the scientists urged leaders to reduce emissions and adapt to a warmer world with wilder weather.

"The point here is to highlight what will happen if we don't do something and what will happen if we do something," said another author, Jonathan Overpeck of the University of Arizona. "I can tell you if you decide not to do something the impacts will be much larger than if we do something."
The next step is up to public officials, scientists said.

"It is critical that we look at this report ... as a moment where the focus of attention will shift from whether climate change is linked to human activity, whether the science is sufficient, to what on earth are we going to do about it," U.N. Environment Program Executive Director Achim Steiner said.

The strongly worded report put pressure on the Bush administration to reduce the United States' growing share of gases that trap heat in the atmosphere.

The White House issued a statement less than four hours after the report's release defending President Bush's six-year record on climate change.

It said Bush and his budget proposals have devoted $29 billion to climate-related science, technology, international assistance and incentive programs - "more money than any other country."
Bush has called for slowing the growth rate of U.S. greenhouse gas emissions, which averages 1 percent a year, but has rejected government-ordered reductions.

Since 1990, U.S. greenhouse gas emissions have gone up 16 percent. The Bush administration has rejected the Kyoto Protocol, which calls for cuts in emissions of greenhouse gases.

Sharon Hays, White House associate science adviser, called the study "a significant report. It will be valuable to policy makers."

Another report by the panel later this year will address the most effective measures for slowing global warming.

If it looks bad now, the harmful effects during the 21st century "would very likely be larger than those observed during the 20th century," the report said.

The panel predicted temperature rises of 2-11.5 degrees Fahrenheit by the year 2100. It said its best estimate was for temperature rises of 3.2-7.1 degrees.

On sea levels, the report projects rises of 7-23 inches by the end of the century. An additional 3.9-7.8 inches are possible if recent, surprising melting of polar ice sheets continues.
The panel, created by the United Nations in 1988, releases its assessments every five or six years, though scientists have been observing aspects of climate change since as far back as the 1960s. The reports are released in phases - this is the first of four this year.

The projected effects of global warming would vary in different parts of the globe. The closer to the poles, the higher the temperature spikes, the study said.

Dramatic temperature spikes are likely to be seen within 22 years in most of the Northern Hemisphere, the report showed. Northern Africa and other places will see dramatically less rainfall.

The United States could see a 10-degree temperature rise by the end of the century and a more arid south and west, Overpeck said.

And that's just average temperature increases and rainfall amounts, something that doesn't affect people much. The harshest consequences of global warming are the heat waves, droughts, floods, and hurricanes, said study co-author Philip Jones of Britain's University of East Anglia. And those have increased dramatically in the past decade and will get worse in the future, he said.

Global warming could eventually lead to an "ice-free Arctic," warned Gerry Meehl, an official with the U.S National Center for Atmospheric Research.

And when that happened 125,000 years ago, seas rose between 13 and 20 feet. That is looking like a real possibility for the 22nd Century, the report said, though some scientists fear much of it could happen before the end of the century.

Trenberth said the world is paying more attention to scientists now than to previous warnings in 1990, 1995 and 2001. "The tension is more now," he said.

As the IPCC report was being released, environmental activists rappelled off a Paris bridge and draped a banner over a statue used often as a popular gauge of whether the Seine River is running high.

"Alarm bells are ringing. The world must wake up to the threat," said Catherine Pearce of Friends of the Earth.

Associated Press writer Angela Charlton contributed to this report.

Copyright 2007 The Associated Press. The information contained in the AP news report may not be published, broadcast, rewritten or otherwise distributed without the prior written authority of The Associated Press. All active hyperlinks have been inserted by AOL.

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Top 12 Ways To Reduce Global Warming

Save Energy, Money and the Environment

According to the Natural Resources Defense Council, the two biggest offenders in the global warming problem are cars and power plants. In particular, coal-burning power plants are the largest U.S. source of carbon dioxide pollution, producing 2.3 billion tons every year. Cars, the second largest source, are responsible for generating almost 1.1 billion tons of carbon dioxide emissions a year. Carbon dioxide and other air pollution collect in the atmosphere and trap heat from the sun causing the planet to warm up.

The good news is we don't have to wait for technical solutions to reduce the impact of these big offenders. Solutions exist now to allow us to reduce our dependence on power plants and use cleaner transportation options. We just have to start using them. Here are 12 simple ways to do your part to start making a difference now. By saving energy, you’ll also save money.

(Note: According to the EPA, a typical U.S. household generates 45,000 pounds of greenhouse gas emissions each year.)

1. Change Five Lights Replace your five most frequently used lights or the bulbs in them with ones that have earned the Energy Star and you’ll use less energy, which means less pollution from power plants. Your household will also be saving about 700 pounds of carbon dioxide a year and save $90 a year in energy costs (If every household in the country did it -- we would save a trillion pounds of greenhouse gases.) Take the "Change a Light Pledge" and change at least one light in your home.
2. Heat and Cool Smartly
About half the energy we use in our homes goes to heating and cooling. Changing air filters annually, having your system checked annually and useing a programmable thermostat are all easy things you can do. Just by using a programmable thermostat, you can save about 1,800 pounds of carbon dioxide a year and about $100 a year in energy costs. If you want to go the extra mile, see "Bonus Tips" below for how to purchase green power.

3. Put the Freeze on Inefficient Appliances
Get rid of old, energy inefficient appliances and replace with newer energy-efficient models. For example a high-efficiency refrigerator will save you $100 per year and reduce carbon dioxide emissions by 500 pounds a year.

If you replace your current washing machine with a low-energy, low-water-use machine you will be able to reduce your carbon dioxide emissions by 440 pounds per year. For even more savings wash your laundry in warm or cold water, instead of hot. That will bring in a reduction of carbon dioxide emissions of about 500 pounds per year.

4. Reduce and Recycle
Reducing your garbage by 25 percent will reduce carbon dioxide emissions by 1,000 pounds per year. Recycle aluminum cans, glass bottles, plastic, cardboard and newspapers can reduce your home's carbon dioxide emissions by 850 pounds per year.

5. Don't Give Energy Away
If you caulk and weather-strip around doors and windows to plug up leaks you can reduce carbon dioxide emissions by 1,700 pounds per year.

6. Take the Green Way
Leave your car at home two days a week (walk, bike, take public transit or telecommute) and you can reduce your carbon dioxide emissions by 1,590 pounds per year.

7. Buy Products That Have Earned the Energy Star
Over 40 different kind of products now carry the Energy Star -- the government-backed symbol for energy efficiency -- including lighting, home electronics, heating and cooling equipment and appliances. With Energy Star products you can save 30 percent on your energy bills (about $450 a year). For information on high efficiency appliances and other products, visit the Energy Star Web site (www.energystar.gov).

8. Slow the Flow
When purchasing a new vehicle, consider finding a car that gets more miles to the gallon than your current vehicle, and match the vehicle to your needs. The potential carbon dioxide reduction for a car that gets 32 miles per gallon is 5,600 pounds per year. To get more information about finding and buying a fuel-efficient car visit AOL Autos.

9. Make the Right Move
If you spend hours on the road every day to get to work you could save some significant time and money by moving closer to work and reducing your commute. The carbon dioxide emissions you save are icing on the cake.

10. Be a Turnoff
Turn off your TV, video player, stereo and computer when you aren't using them. Turn off your lights when you don't need them and you start saving within a minute or two. Prevent "phantom" energy losses by plugging these devices into a power strip and turning the power strip off when the devices are not in use.

11. Trim Your Load
When you do drive, keep your car tuned up and its tires properly inflated to save on fuel costs as well as reducing carbon dioxide emissions. A tune-up could boost your miles per gallon anywhere from four to 40 percent; a new air filter could get you 10 percent more miles per gallon. Take your roof rack off your car when you aren't using it for more savings.

12. Keep Your Water Heater Cozy
For a water heater more than five years old, wrapping it in an insulating jacket will result in a 1,000 pounds per year reduction of carbon dioxide emissions. Keep your water heater thermostat no higher than 120 degrees F and you can reduce carbon dioxide emissions by 550 pounds per year.


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22 Ways To Help The Earth

Most people want to help the earth, but very few actually go out and do something (If you are one of those few, GREAT JOB!!). To help the earth, you don't have to restore a river or clean up ten miles of highway. You can do those things, but here are some easier ways to help out. For even more ideas, read 50 Simple Things You Can Do To Save The Earth, 50 Simple Things Kids Can Do To Save The Earth, or 50 Simple Things Your Business Can Do To Save The Earth. These are great books all by the EarthWorks Group. Try them!

1. Put a bleach bottle in your toilet. Fill it with water, put on the cap tightly, and put it in the back part of your toilet. A brick inside a plastic bag to contain all the crumbs would also work. Since the average toilet uses 3 to 7 gallons of water per flush, the brick or bottle will displace some water, so your toilet will use ½ - 1 gallon less each time someone uses it!
2. Plant a tree. There are two ways to do this old idea. You could find a tree (like a maple) that produces seeds every spring, collect a few, and plant them. Start them in pots until they're at least a foot tall, then put them in the yard. The other way is, of course, to go out and buy a young tree to plant. The price may vary from $20 to over $200, depending on the size or type of tree. We know that because of the cost, not everyone can plant a tree, but it's a great way to save the earth's oxygen!

   

3. Re-use your plastic sandwich bags. Plastic takes over 100 years to biodegrade, so the less plastic we throw out, the better. After using a plastic bag, wash it out with soapy water and let it dry. Then you can use it over and over again, and it works just as well as a new bag! This will also save you some money when you don't have to buy as many new bags!
4. Make your meals earth-friendly. When packing a lunch, put sandwiches, chips, etc. in reusable plastic containers instead of sandwich bags. Carry your drink in a washable thermos bottle, and your lunch in a reusable lunch container. For meals at home, put leftover food in hard plastic washable and reusable containers. (You could save glass jars and deli containers for this!)
5. Use both sides of paper. If you have to scribble down directions or make a quick math calculation, don't just throw the paper away when you're done! Save it for the next time you need to jot something down quickly. Having a few pages of "scrap" paper around is a good way to keep yourself from wasting new sheets each time.
6. Don't give kids nice packaged computer paper to color on. Little kids seem to love to make one line on a piece of paper and then get a new one. Because of this, don't use packaged printer paper (which can be $6 for 500 sheets) when cheaper notebook or recycled paper will work. If you work in an office, bring home scrap paper that is still blank on one side! Many network printers print out title sheets with every printout, telling who printed it. One-sided "junk" flyers are good too--sometimes they even come in colors. Use these for kids' coloring paper.
7. Make your house energy efficient. One visitor to our site mentioned that after installing compact flourescent light bulbs and other energy-efficient appliances, his electricity bill went down 75%. Compact flourescant bulbs last ten times longer than regular incandescent bulbs, plus they don't produce nearly as much wasted heat.
8. If you don't need a light on, don't use one! If it's 1:00 on a bright sunny day, don't turn on a light that you don't need. If you're going to be in a room for only a minute, try to go without any electric lights at all. Most houses have enough windows that you won't need to use lights for most of the daytime. And if you do have to turn on a light, turn on only as many as you need.
9. If you have a leaky faucet, catch the drips. If your faucet is leaking, of course you should get it fixed. But, what about the time before it's fixed? Put a pan, bowl, or cup underneath to catch the water, and use it for something else like watering a plant, cooking, making Kool-Aid, or drinking! There's nothing wrong with the water; it came out of the tap just like normal. Be careful! A leaking faucet can fill a coffee cup in 10 minutes, so watch the size of your container and how fast it fills up.
10. "Recycle" your clothes. Once your kids grow out of their clothes, or you no longer like or fit into something, DON'T THROW IT AWAY! If you want to make money, try having a garage sale. Too much work? The Salvation Army or other clothing donation stores offer tax refunds for donated clothes. Resale shops will pay you for clothes you give them. Feeling moral? Donate your clothes to the needy or to other clothing drives for the poor.
11. Open windows instead of using air conditioning. When the temperature outside is right around the temperature inside, then save some money, electricity, and the earth by opening some windows. If you do that at night, then your house will cool down without costing you a cent!
12. Donate to an ecological organization. If you don't feel like doing anything for the earth, pay someone else to! If you have extra cash, the groups would greatly benefit from your donation. The more money they have, the more ways they can reach out to help our earth!
13. Buy organically-grown foods. Some grocery stores now have organic sections where you can purchase all kinds of fruits, vegetables, and cereals that have had no chemical fertilizer, pesticides, or herbicides. Show the stores you care by buying these things! They'll be better for you and for the earth because no chemicals are going into the soil or water.
14. Snip your 6-pack holders. Countless animals and birds die from uncut 6-pack holders and other ringed packages each year. They get caught in the holes and are choked to death. Make it a habit to cut all the rings apart when you throw away a 6-pack holder!
15. Buy recycled products! Paper, packaging, plastic containers, cardboard, and other products are being sold that have been recycled. By all means, buy these products, but be carful when reading the labels. Don't confuse "recycled" with "recyclable"! Lots of companies will put the recycling symbol or "100% recyclable" on their products to appeal to ecologists. While that is all fine and good, "made from recycled waste" or "post-consumer waste" is what you really want. If you buy recycled notebook paper for school, no one will really care if your paper is a s hade greyer than the non-recycled kind.

    

16. Use permanent silverware and dishes instead of paper ones. Not only will you save the earth, you'll save money! Why use disposable plastic silverware when you can buy regular ones? The last thing we need is extra garbage in landfills, and this is a great way to cut down on some of it. Use permanent kitchenware unless you absolutely have to use disposable stuff!
17. In general, don't use disposable products at all. Diapers, pens, razors, towels; they're all disposable, so there are many ways to do help the earth this way. Use cloth diapers instead of disposable plastic ones. Don't use paper towels--old t-shirts or towels work fine as messy-use rags. Those multi-use paper towels that claim to be strong enough to use again may be, but it's still cheaper to use an old rag, and the rag will probably work better! What's the use of using disposable razors if you have to buy a new bag every other week? It will save you money just to get a good one to keep using! In other words, don't get sucked into the world of simple disposable items because "it's easy and convenient."
18. Buy in bulk. One 32-ounce bottle will use less packaging than two 16-ounce ones, even though the total size is the same. Plus, the larger bottle will probably cost less per ounce than the other two combined! For an example, let's look at pop. A 2-liter bottle of pop costs $1, or about 1.5¢ per ounce (there's 67 ounces). The packaging comes to about 163 square inches. Opposing this is the 12-pack of cans. The cost is about $3 for 144 ounces, or 2.1¢ per ounce. The total packaging here comes to 600 square inches! The 2-liter is much better! Less cost per ounce, and a lot less garbage in the landfill!
19. Don't buy products with lots of packaging. As you can see from above, the more packaging, the more cost. If you see a small product (for example, a toothbrush) wrapped in five layers of plastic with a flashy cardboardy thing, all in a box made of a foam-like plastic, chances are most of the price is because of the packaging. Find a similar product with less packaging. Wouldn't a plastic wrapper or cardboard box be just as good? Also, stay away from individually wrapped candy and other products. Also, select fresh produce from display bins instead of the pre-packaged variety. The more packaging, the more price, and (more importantly) the more garbage in the landfills.
20. Buy dolphin-safe tuna and other eco-safe products. Every day, dolphins get caught in tuna nets. You can do something about it! Check the label of the tuna you buy to make sure it it dolphin-safe, that is, catching the tuna doesn't harm dolphins. There will be a special logo on the label to tell you if it is dolphin-safe.
21. Spread the word about conservation. Any way you can, get people to think about the earth. There are almost 6,000,000,000 people on this earth, and every one of them needs to take care of it! Always look for environment-safe products and encourage others to do the same. From recycling to buying less packaging to planting trees to saving water to conserving energy, keep the environment in mind. Posters can be a great way to spread the word, so drop by our Poster Page to look at some, print them out, or get your own ideas.
22. Use rechargable batteries. Although they may cost more to buy, rechargable batteries will save you 10 or 20 times the original cost (by not buying new batteries over and over again), and not get thrown in the trash. Prolong the life of any batteries by using a cord (and AC adapter, if necessary) for radios and other appliances when possible.

Earth is Beautiful

Earth is Beautiful

by www.loveearth.com

by dk-loveearth

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Plastic Bag Caused Seriously Polution

Plastic solid waste is one of MANY significant pollutants in ocean world (and freshwater systems as well). In the North Pacific, currents have accumulated floating plastic waste en masse. The flotilla is estimated to be roughly the size of Texas.

This plastic waste has a penchant for finding its way into the mouths of seabirds, turtles, marine mammals and other already-threatened ocean life. Death or some degree of morbidity ensues.

How can this problem be averted or at least mitigated? A top-down approach, directed at waste management, ocean dumping, etc.? Or a bottom-up attack, looking at plastic-use in products, or even eco-friendly polymers? What do you guys think?

Maybe the solution is using paper bag or bring your own shopping bag.

Water Pollution

Water pollution is largely caused by human activity and has had a major impact on our local waterways and their ability to be healthy and function naturally.

Water pollution comes from two sources - point sources or diffuse sources:

• Point source pollution is any pollution that originates from a single location. It is often associated with intensive production activities including farming, manufacturing and service sectors such as sewage treatment plants, on-site sewage management systems, industrial activities and discharges from urban stormwater drains. Point sources are largely regulated through the Protection of the Environment Operations Act, 1997. The Act permits Council and the NSW Department of Environment and Conservation to regulate various polluting issues, including issuing clean up or prevention notices. Nonetheless, point sources can discharge a variety of pollutants to aquatic environments and have the potential to cause severe long-term impacts.

• Diffuse sources are generated mainly by run-off after rain, which collects pollutants from across a wide area. Diffuse sources in urban areas include roads, industrial and commercial premises, parks, gardens and households. Stormwater typically contains litter, nutrients, bacteria, pathogens pesticides, heavy metals, sediment, oils, grease and other pollutants. In rural areas diffuse sources include agricultural activities, such as cropping, irrigation, livestock grazing and intensive livestock industries as well as unsealed roads. Rural run-off can increase the levels of sediment, nutrients, pesticides and chemicals in waterways.

The ability of these pollutant sources to cause a decline in water quality depends on the amount of vegetation cover, intensity of land use and the loss of vegetation along creek banks. All of these factors effect the ability of our waterways to cope with increased nutrients, sediment and changes in flows which causes changes to the health of the waterways through decline in water quality, native plant and animals.

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Air Pollution

Air Pollution is the human introduction into the atmosphere of chemicals, particulates, or biological materials that cause harm or discomfort to humans or other living organisms, or damage the environment.[1] Air pollution causes deaths[2] and respiratory disease.[3] Air pollution is often identified with major stationary sources, but the greatest source of emissions is actually mobile sources, mainly automobiles.[4] Gases such as carbon dioxide, which contribute to global warming, have recently gained recognition as pollutants by climate scientists, while they also recognize that carbon dioxide is essential for plant life through photosynthesis.

The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.

There are many substances in the air which may impair the health of plants and animals (including humans), or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as pollutants.

Pollutants can be classified as either primary or secondary. Primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption or the carbon monoxide gas from a motor vehicle exhaust.

Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog.

Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.

Major primary pollutants produced by human activity include:

• Sulfur oxides (SOx) especially sulfur dioxide are emitted from burning of coal and oil.

• Nitrogen oxides (NOx) especially nitrogen dioxide are emitted from high temperature combustion. Can be seen as the brown haze dome above or plume downwind of cities.

• Carbon monoxide is colourless, odourless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide.

• Carbon dioxide (CO2), a greenhouse gas emitted from combustion.

• Volatile organic compounds (VOC), such as hydrocarbon fuel vapors and solvents.

• Particulate matter (PM), measured as smoke and dust. PM10 is the fraction of suspended particles 10 micrometers in diameter and smaller that will enter the nasal cavity. PM2.5 has a maximum particle size of 2.5 µm and will enter the bronchies and lungs.

• Toxic metals, such as lead, cadmium and copper.

• Chlorofluorocarbons (CFCs), harmful to the ozone layer emitted from products currently banned from use.

• Ammonia (NH3) emitted from agricultural processes.

• Odors, such as from garbage, sewage, and industrial processes

• Radioactive pollutants produced by nuclear explosions and war explosives, and natural processes such as radon.

Secondary pollutants include:

• Particulate matter formed from gaseous primary pollutants and compounds in photochemical smog, such as nitrogen dioxide.

• Ground level ozone (O3) formed from NOx and VOCs.

• Peroxyacetyl nitrate (PAN) similarly formed from NOx and VOCs.

Minor air pollutants include:

• A large number of minor hazardous air pollutants. Some of these are regulated in USA under the Clean Air Act and in Europe under the Air Framework Directive.

• A variety of persistent organic pollutants, which can attach to particulate matter.

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Evolution on Earth

The history of the Earth's atmosphere prior to one billion years ago is poorly understood and an active area of scientific research. The following discussion presents a plausible scenario.

The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from two notably different previous compositions. The original atmosphere was primarily helium and hydrogen. Heat from the still-molten crust, and the sun, plus a probably enhanced solar wind, dissipated this atmosphere.

About 4.4 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes which released steam, carbon dioxide, and ammonia. This led to the early "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. This second atmosphere had approximately 100 times as much gas as the current atmosphere, but as it cooled much of the carbon dioxide was dissolved in the seas and precipitated out as carbonates. The later "second atmosphere" contained largely nitrogen and carbon dioxide. However, simulations run at the University of Waterloo and University of Colorado in 2005 suggest that it may have had up to 40% hydrogen.[7] It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide and methane, kept the Earth from freezing.

One of the earliest types of bacteria was the cyanobacteria. Fossil evidence indicates that bacteria shaped like these existed approximately 3.3 billion years ago and were the first oxygen-producing evolving phototropic organisms. They were responsible for the initial conversion of the earth's atmosphere from an anoxic state to an oxic state (that is, from a state without oxygen to a state with oxygen) during the period 2.7 to 2.2 billion years ago. Being the first to carry out oxygenic photosynthesis, they were able to produce oxygen while sequestering carbon dioxide in organic molecules, playing a major role in oxygenating the atmosphere.

Photosynthesising plants would later evolve and continue releasing oxygen and sequestering carbon dioxide. Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. As oxygen was released, it reacted with ammonia to release nitrogen; in addition, bacteria would also convert ammonia into nitrogen. But most of the nitrogen currently present in the atmosphere results from sunlight-powered photolysis of ammonia released steadily over the aeons from volcanoes.

As more plants appeared, the levels of oxygen increased significantly, while carbon dioxide levels dropped. At first the oxygen combined with various elements (such as iron), but eventually oxygen accumulated in the atmosphere, resulting in mass extinctions and further evolution. With the appearance of an ozone layer (ozone is an allotrope of oxygen) lifeforms were better protected from ultraviolet radiation. This oxygen-nitrogen atmosphere is the "third atmosphere". 200 – 250 million years ago, up to 35% of the atmosphere was oxygen (as found in bubbles of ancient atmosphere were found in an amber).

This modern atmosphere has a composition which is enforced by oceanic blue-green algae as well as geological processes. O2 does not remain naturally free in an atmosphere, but tends to be consumed (by inorganic chemical reactions, and by animals, bacteria, and even land plants at night), and CO2 tends to be produced by respiration and decomposition and oxidation of organic matter. Oxygen would vanish within a few million years due to chemical reactions and CO2 dissolves easily in water and would be gone in millennia if not replaced. Both are maintained by biological productivity and geological forces seemingly working hand-in-hand to maintain reasonably steady levels over millions of years (see Gaia theory).

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Aerosol

An aerosol is a collection of microscopic particles, solid or liquid, suspended in a gas.

In the context of air pollution, an aersol refers to fine particulat matter (Sum of all microscopic solid and liquid particles, of human and natural origin, that remain suspended in a medium such as air for some time. These particles vary greatly in size, composition, and origin, and may be harmful.Particulate matter may be in the form of fly ash, soot, dust, fog, fumes etc.), that is larger than a molecule, but small enough to remain suspended in the atmosphere

for at least several hours.

The term aerosol is also commonly used for a pressurized container (aerosol can) which is designed to release a fine spray of a material such as paint. It has also come to be associated, erroneously, with the gas (propellant) used to expel materials from an aerosol can.

Natural sources of aerosols include salt particles from sea spray, dust and clay particles from the weathering of rocks. Aerosols can also originate as a result of human activities and are often considered pollutants.

Aerosols play an important role in the atmosphere namely in the condensation of water droplets and ice crystals, various chemical cycles, and the absorption of solar radiation.

Source: based on EPA Glossary of Climate Change and GreenFacts

Greenhouse gas

Greenhouse gases are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of infrared radiation emitted by the Earth’s surface, the atmosphere and clouds.

This property causes the greenhouse effect.

Water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH₄), and ozone (O3) are the primary greenhouse gases in the Earth’s atmosphere. Moreover there are a number of entirely human-made greenhouse gases in the atmosphere, such as the halocarbons and other chlorine and bromine containing substances, dealt with under the Montreal Protocol. Beside CO2, N2O and CH₄, the Kyoto Protocol deals with the greenhouse gases sulphur hexafluoride (SF₆), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs).

What makes the climate change?

The Earth’s climate is influenced by many factors, such as the amount of greenhouse gases and aerosols in the atmosphere, the amount of energy coming from the sun or the properties the Earth’s surface. Changes in those factors, through human-related or natural processes, have a warming or a cooling effect on the planet because they alter how much of this solar energy is retained or reflected back to space.

The concentrations in the atmosphere of greenhouse gases such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have all increased markedly since 1750, and now exceed by far their pre-industrial levels.

Carbon dioxide is the most important anthropogenic greenhouse gas. Its concentration in the atmosphere (379 ppm in 2005) is now far higher than the natural range over the last 650 000 years (180 to 300 ppm) and is growing faster than ever since the beginning of its continuous direct measurement in 1960, mainly due to fossil fuel use and to a lesser extent to land use change. For instance, emissions of carbon dioxide from fossil fuel use increased from 6.4 Gt per year in the 90s to 7.2 Gt of carbon per year over the period 2000-2005. Concentrations of methane and nitrous oxide in the atmosphere have also greatly increased since pre-industrial times, and those increases are mostly due to human activities such as agriculture and fossil fuel use.

The effect on climate of each of the different drivers is expressed in terms of “radiative forcing”, with positive forcing causing a warming of the surface and negative forcing a cooling of it. The overall effect of human activities since 1750 is very likely (> 90% certainty) to be one of warming, with an estimated increase of energy, or radiative forcing, of 1.6 Watt per square meter over the whole planet. The relative contribution of various factors can be seen in figure 2. The main warming drivers are the various greenhouse gases and it is likely that the warming that they cause has been increasing during the industrial era at a higher rate than at any time over the last 10 000 years. The main cooling drivers are aerosols and the changes in cloud cover that they cause.