Since the Industrial Revolution, carbon dioxide levels in the atmosphere have been increasing, this has been closely followed by an increase in global temperatures.
Global warming is an increase in the Earth’s temperature caused by an increase in the amount of greenhouse gases in the atmosphere.
Greenhouse gases make up the blanket surrounding the planet that keeps it habitable. These gases allow sunlight to pass through the blanket and hit the Earth. Some of this heat from the sun is absorbed by the Earth and is then radiated back to the atmosphere. Greenhouse gases absorb some of this radiated heat, warming the atmosphere to a comfortable temperature for life. Human produced greenhouse gases are accelerating this process, causing the planet to warm more than it should.
Carbon dioxide and other global warming pollutants that we are releasing are collecting like a thickening blanket in the atmosphere and causing the Earth to warm. The more carbon dioxide we release, the warmer the planet will become.
Like the human body, the planet needs to stay within a small temperature range for life to exist comfortably. A small increase in our body temperature can make us feel ill while an increase of just a few degrees can result in our organs failing and even death. Similarly, small changes in the global temperature can result in huge and sometimes devastating consequences for life on Earth.
Rising global temperatures are wreaking havoc on the global climate system — hence the term climate change – causing more intense storms, more severe droughts and shifting rain patterns.
The most common and most important greenhouse gases are carbon dioxide, methane and nitrous oxide. Black carbon is also a potent warmer, although not a greenhouse gas.
Carbon dioxide (CO2)
This greenhouse gas is present in relatively low concentrations in the atmosphere; prior to the Industrial Revolution, it made up about 0.03 percent of the atmosphere. Despite its low levels, CO2makes up about 30 percent of the greenhouse gases naturally found in the atmosphere and it is the major driver of global warming . There are currently approximately 3 trillion metric tons of CO2 in the atmosphere; this is 37 percent higher than the level prior to the Industrial Revolution. In the late 1800s, levels of carbon dioxide were 280 parts per million (ppm). Current concentrations are around 380 ppm. Scientists warn that if the amount of carbon dioxide in the atmosphere goes above 450 ppm, the Earth’s climate could spiral out of control.
Natural sources of carbon dioxide include rotting plant and animal matter, forest fires and volcanoes. The major human sources of CO2 are from the burning of fossil fuels (coal, oil and gas) and from deforestation. Scientists attribute the increased concentration of CO2 in the atmosphere to these human sources.
Methane is a very strong greenhouse gas. Over 100 years, a ton of methane would heat the globe 23 times more than 1 ton of carbon dioxide would. The atmosphere has a methane concentration of 1,774 parts per billion (ppb). This is a 59 percent increase from the methane concentration prior to the Industrial Revolution. There is, however, around 220 times less methane than carbon dioxide in the atmosphere, so overall carbon dioxide has a far greater effect in the atmosphere.
Methane is created by the decay of organic matter. Large amounts come from landfills, cattle and the rest of the livestock sector (chicken and pigs) in general.
Methane hydrates, a frozen combination of methane and water, are found in vast quantities on the sea floor. It is possible that continued climate change could release these frozen stores of methane and cause a sudden, very large addition of methane to the atmosphere. This would massively magnify the greenhouse effect, causing global warming to reach unprecedented levels.
Nitrous Oxide (N2O)
Nitrous oxide has a global warming effect roughly 300 times that of carbon dioxide over 100 years. However, like methane, nitrous oxide exists in much lower concentrations than carbon dioxide in the atmosphere. Nitrous oxide concentrations in the atmosphere are currently 319 ppb, 18 percent higher than what they were prior to the Industrial Revolution.
Nitrous oxide is emitted by bacteria in soil. Agriculture and the use of nitrogen-based fertilizers, along with the handling of animal waste, increase the production of nitrous oxides. Industries, such as the nylon industry, and the burning of fossil fuels in internal combustion engines also release nitrous oxide into the atmosphere.
Black carbon (BC)
Black carbon, or soot, is not an actual greenhouse gas, as it is a solid, and warms the atmosphere differently to a gas. However, it has a significant warming effect on the atmosphere. Black carbon is made up of microscopic particles that result from the incomplete burning of organic matter, especially fossil fuels. Black carbon warms both in the atmosphere and when deposited on lighter surfaces, like snow and ice.
Black carbon may be responsible for as much as 25 percent of observed global warming. The overall contribution of black carbon to global warming may be substantial, perhaps second only to that of carbon dioxide.
Because it can accelerate the melting of snow and ice, black carbon may play a particularly important role in Arctic climate change. Black carbon may be responsible for over 30 percent of Arctic warming. Because the Arctic has warmed at around twice the rate of the rest of the world over the last 100 years, controlling and reducing black carbon emissions is particularly important.
Signs of Climate Change
The signs of a warming planet are all around us and the impacts are already being felt in significant ways. These early signs include increasing ocean acidity, melting glaciers, plant and animal range shifts, increased spread of disease, coral reef bleaching, intensified storms, severe droughts and smoldering heat waves. The following facts are hard to ignore:
– The surface oceans are 30 percent more acidic than they were prior to the Industrial Revolution. This is making it more difficult for corals and other marine calcifiers to build their shells and skeletons. Already, corals across the Great Barrier Reef in Australia and reefs in Thailand and the Caribbean have been found to have severely decreased growth rates, likely caused by increased ocean acidity.
– The number of Category 4 and 5 storms has greatly increased over the last few decades, most likely caused by increasing ocean temperatures.
– In areas of California, sea life is shifting northward, probably in response to warmer ocean and air temperatures.
– The Larsen B ice shelf in Antarctica, which for more than 10,000 years has been a stable mass of mostly solid ice the size of Rhode Island, disintegrated within three months in 2002. Its rapid collapse, which was captured by NASA satellite imagery, astonished climate scientists.
– The current pace of sea-level rise is three times the historical rate and appears to be accelerating.
– The Great Barrier Reef in Australia has experienced an epidemic of coral bleaching due to higher sea surface temperatures. Scientists have found widespread bleaching, with every species of coral suffering. Bleaching occurs when high sea temperatures force corals to expel the colorful algae that provide them with food. If the warm temperatures persist, corals die and reefs crumble.
– Most of the United States has already warmed, in some areas by as much as 2.4 C (4 F). 1998 and 2005 tie for the hottest years globally on record, while 1998 was the second hottest year in the United States. Every single year since 1993 has been in the top 20 warmest years on record.
Impacts of Climate Change
As carbon dioxide levels increase in the atmosphere, the amount the oceans absorb also increases, leading to chemical changes that result in the oceans becoming more acidic. While the oceans are becoming more acidic, they are still on the basic side of the pH scale (basic – neutral – acidic). It is highly unlikely that the oceans will ever become actual acid. However, even small changes in the acidity of the oceans can result in severe ramifications. As they become more acidic, corals and other organisms will find it increasingly difficult to build new skeletons and shells and those that already exist may begin to dissolve.
Sea Level Rise
In 2006, the first inhabited island was lost to rising sea levels. The island of Lohachara, home to some 10,000 people, sank beneath the surface of the Bay of Bengal. This Indian island was situated in an area called the Sundarbans, which has some 70,000 people living on a dozen islands who are all facing the same fate as those of Lohachara. Of the 102 islands in the Indian Sundarbans, only 54 are still habitable. Lohachara’s inhabitants became some of the world’s first global warming refugees, many of whom are still homeless or settled on nearby islands, only to be facing inundation again. Unlike the area’s human inhabitants, its unique wildlife, including 400 endangered Bengal tigers, are unlikely to survive the rising tides.
Rising sea levels are caused by both the warming oceans and melting ice. As water heats above 4 C (39.2 F), it expands through a process known as “thermal expansion”. Global warming is causing the oceans to heat up and expand and therefore rise. The melting of glaciers, ice caps and the Greenland and Antarctic ice sheets — the melting of which is exacerbated by warming ocean — are also contributing to the rising seas.
The 2007 Intergovernmental Panel on Climate Change estimated that sea level could rise between 18 and 59centimeters (7 and 23 inches) by the end of this century. However, these estimates are somewhat conservative and do not include the full effects of a complete melting of the Greenland or West Antarctic ice sheets, which would contribute an additional 12meters (39 feet) combined to sea level rise. While a complete melting of these ice sheets is unlikely by the end of this century, more recent scientific estimates predict a likely 1 meter (3 foot) rise in sea level by 2100.
Scientists have suggested that by 2080, millions of people are likely to be flooded every year and hundreds of millions more may be displaced by rising seas. Whole island nations, such as the Maldives, could disappear off the map altogether and large swaths of low lying areas are likely to be inundated. Sea level rise will flood developed and developing countries alike. Even some of the world’s most important and heavily populated cities, such as New York, London and Bangkok, are at risk of disappearing under the rising waters.
Disrupted Food Webs
Increasing ocean temperatures and the addition of significant amounts of fresh water from melting ice caps and glaciers may cause a disruption in weather patterns and a breakdown in the marine food web.
The movement of water through the oceans is very important because it circulates heat and nutrients around the globe. The mild temperatures of England, which is on the same latitude as Canada, are due to the heat released to the atmosphere by water that is moving from the tropics towards the Arctic. Water is moved around the globe by the great ocean conveyor belt. As warm surface water is moved away from the tropics, it cools and releases its heat to the atmosphere. This heat then warms parts of Europe. The further north this water moves, the cooler and heavier it becomes, eventually sinking to the lower level of the conveyor belt. This cooler water is then carried along the depths of the ocean, picking up nutrients that have gathered there.
As winds move the top layers of the oceans, cold, nutrient rich waters from the depths are brought to the top at “up-welling sites”. These areas are important feeding grounds for phytoplankton — microscopic plants that float in the light filled waters at the top of the ocean. Phytoplankton feed on the nutrients that come from the deep ocean waters and many other species then feed on them. They are the primary producers of the ocean and form the base of many marine food chains.
Fresh water is less dense than sea water. Therefore, the addition of significant amounts of fresh water from melting ice caps and glaciers may result in a slowing of the ocean conveyor belt, leading to cooler winters in Western Europe and a disruption of the circulation of vital nutrients to phytoplankton. Phytoplankton may also be cut off from their food supply as surface temperatures warm, causing the mixing between the warmer top layers and cooler bottom layers to diminish. A decrease in phytoplankton can lead to a collapse of marine food webs, affecting marine mammals (whales, seals and dolphins), sea birds (albatross) and important commercial fish species (cod, salmon and tuna).
Depleted Marine Ecosystems
Scientists predict many ecosystems will be greatly altered or collapse altogether as a response to global warming. The spread of diseases will increase as warmer climates create more hospitable environments for disease carrying agents. Some species may shift to cooler areas in an attempt to avoid rising temperatures; these forced migrations will cause the interlinked elements within ecosystems to become vulnerable or fall apart. Other species that are unable to shift or find themselves without food because their food sources have shifted may become extinct. Experts suggest that one quarter of the world’s species may face extinction by 2050. As species are forced out of their habitats by changing conditions, it is likely that pest and nuisance species will move in and take their place, disrupting ecosystems even further.
The future of many marine ecosystems as we know them is in question. Because of global warming, ecosystems are likely to become less diverse and will be less able to deal with other threats such as over-fishing and bottom trawling, which could result in their destruction.
Increasing sea surface temperatures increase evaporation and the amount of moisture in the atmosphere. This acts as the fuel for thunderstorms. As storms move across the open ocean, they pick up energy from the warm ocean surface and become more powerful. The more heat in the ocean’s surface, the more potential exists for strong winds and heavy rains to be created. It is these winds, rains and storm surges (ocean waters pushed on shore by heavy winds as the storm makes landfall) that can devastate lives and cause billions of dollars of damage.
The Greenhouse Effect
The Earth is habitable because it has a protective blanket of greenhouse gases surrounding it. This blanket traps heat from the sun and allows the Earth to stay at an optimal temperature for life to exist. If this blanket becomes too thick or thin, the Earth’s temperature will respond by becoming too hot or cold for human life. Currently, the blanket is becoming too thick because of the addition of billions of metric tons of global warming pollution, mainly carbon dioxide, that is being released into the atmosphere by human activities.
Roughly 30 percent of the sun’s heat that strikes the Earth is reflected back into space by clouds, particles in the atmosphere and reflective ground surfaces, such as snow, ice and ocean surf.
The remaining 70 percent is absorbed by the land, air and oceans. This absorption warms the Earth’s surface and atmosphere, allowing life to exist.
The heat absorbed by the Earth, ocean and atmosphere is not retained forever, as this would cause the Earth to increase in temperature until it was unbearable. Rocks, air and sea emit some of the heat they absorb, much of which leaves the atmosphere and is lost to space. A small component of the heat, however, is trapped by carbon dioxide and other greenhouse gases in the atmosphere and is returned to the Earth’s surface. This process is called the greenhouse effect. Under normal conditions, the greenhouse effect is positive as it allows the planet to maintain an optimal temperature for life to exist at around 15 C (59 F). Without the greenhouse effect, the earth’s average temperature could be as low as -18 C (0 F).
While the greenhouse effect is vital for life to exist on this planet, we are increasing the greenhouse effect, causing the planet to overheat. As we cut down trees across the globe and burn fossil fuels by driving cars and running power plants, we release billions of metric tons of global warming pollution to the earth’s atmosphere where it can remain for hundreds of years. We release about 30 billion metric tons of carbon dioxide to the atmosphere every year. This massive increase in greenhouse gases is overpowering the earth’s natural ability to regulate temperature, resulting in a warmer planet.
As the global population grows and levels of development and consumption increase, the amount of greenhouse gases being produced will continue to grow unless we act quickly. Many scientists have warned that we are fast approaching the point of no return and that if we don’t cut global greenhouse gas emissions before we pass a tipping point, preventing dangerous global warming may be impossible.
Global Warming Pollution Sources
The largest source of carbon dioxide emissions globally is the combustion of fossil fuels such as coal, oil and gas in power plants, automobiles and industrial facilities. Carbon dioxide is the major driver of global warming. Although carbon dioxide is produced naturally by volcanoes, the decay of dead plant matter and natural forest fires, almost all of these sources of carbon dioxide are balanced by the Earth’s natural systems.
Growing plants and the oceans absorb and store carbon dioxide from the atmosphere so that it can not affect the global climate. It is the addition of billions of metric tons of carbon dioxide to the atmosphere each year, mainly from the burning of fossil fuels, that is overpowering these natural processes. This results in the continued buildup of carbon dioxide in the atmosphere and causes significant global changes to occur.
We are currently pumping over 30 billion metric tons of carbon dioxide into the atmosphere each year. The average person in the world today releases more than 11 kilograms (25 pounds) of carbon dioxide into the atmosphere each day. The average American emits almost five times this amount, producing about 55 kilograms (125 pounds) of carbon dioxide every day. If we do not make significant changes to the way we use and produce energy, global temperatures could increase by another 1.9 C to 3.9 C (3.5 F to 7F) by the middle of this century. This may seem insignificant but this is the largest increase in temperature in the last 1000 years and it is occurring more rapidly than almost any other warming period in history.
This increase in global temperatures is likely to result in a series of catastrophic changes across the globe, including worse droughts, stronger hurricanes, the flooding of low-lying areas by rising sea levels, the extinction of many species and a major disruption in the global production of food.