Core-Environment

= Atmosphere and Change = = Describe the functioning of the atmospheric system in terms of the energy balance between solar and long wave radiation. = = Explain the changes in this balance due to external forces (changes in solar radiation, changes in the albedo of the atmosphere and changes in the long wave radiation returned to space). =

Earth’s Energy Budget - Effect of the Atmosphere on Solar Radiation Based on diagram on the left diagram without an atmosphere, solar radiation is reflected by surface scattering back to space, and the surface emits longwave radiation to space. Based on the diagram on the right, the atmosphere absorbs much upwelling longwave energy and emits some back to the surface as counter-radiation. The atmosphere also scatters some shortwave radiation back to space.

Absorption Absorption of incoming radiation is mainly by atmosphere (ozone, clouds, water vapour, carbon dioxide, ice particles and dust) and ground surface. Only about 20% of the incoming radiation is absorbed. The temperature of the absorbing surface is raised in the process, The importance of absorption in the atmosphere involves the outgoing long wave radiation, other wise known as the Green House Effect.

Reflection A portion of arriving energy bounces directly back into space without being absorbed or performing any work. This returned energy is called reflection.

The Earth's Albedo Define as the ratio of the reflected radiation to the total intercepted radiation. Expressed as a fraction or percentage. Earth has an Albedo of 0.30; meaning 30% of the radiation is reflected back into space. Moon has an Albedo of 0.07, meaning only 7% is reflected back, and 93 % is absorbed.

Type of Surfaces Albedo values

1 Fresh snow 0.75 - 0.90 2 Cloud tops 0.60 - 0.90 3 Old snow 0.50 - 0.70 4 Sand 0.15 - 0.35 5 Seas 0.05 - 0.10 6 Forest 0.03 - 0.10

Spatial and seasonal variations in Albedo easonal changes like the arrival of snow and changes in vegetation covers will affect surface Albedo. Human activities like deforestation and urbanisation will change albedo Changes in albedo affect cloud formation and thus precipitation. (Are you able to explain this?) If the atmosphere does not exist, then all radiation not absorbed by the ground will be radiated to space, then the planet’s surface will not be warm enough for life! (Think of the moon)

Scattering - the colour of the sky Insolation encounters an increasing density of atmospheric gases, fine dust and smoke as it travels toward the surface. The gas molecules redirect / deflect radiation, changing the direction of light’s movement without altering its wavelengths.

The Greenhouse Effect The energy from latent heat and sensible heat together with LW radiation ground emission is absorbed by the atmosphere and ‘re-radiates’ back to the earth to complete the system. The atmosphere absorbs about 20% of incoming SW radiation and 95% of outgoing LW radiation. Absorption is carried out by Greenhouse gases include water vapour, carbon dioxide, ice dust and ice particles and ozone. The atmosphere transforms the radiation into energy which allows it to radiate back to the earth to complete the system, thus keeping the atmosphere warm. – This is the Greenhouse Effect. Thus the surface of the Earth is warmer than it would be in the absence of an atmosphere because it receives energy from two sources: the Sun and the atmosphere. It is not a bad phenomenon (as commonly misused in the mass media, it is critical for life!). With out the GHE, the earth surface will be so cold, no life can exist! A real greenhouse prevents air from escaping out by reflecting the energy back, while the atmosphere absorbs the energy and "re-radiates" to the earth.

Earth’s Radiation Balance – Horizontal Balance There is a general decrease of insolation (and thus temperature) from the Equator to the Polar Regions. The poles are colder (less energy), thus a net loss in energy and the equator is very warm (more energy), thus a net gain. The positive heat gain in the tropics will lead to overheating, while the negative heat balance in the poles will lead to frozen surfaces, both inhibiting sustenance of life. Instead, excess energy in the tropics is distributed vertically and transported pole-wards to obtain global balance. Net radiation surplus from the equator is transferred by ocean currents and winds to the poles where a net-loss exist. Annual surface net radiation from pole to pole. Where net radiation is positive, incoming solar radiation exceeds outgoing longwave radiation. There is an energy surplus, and so energy moves poleward as latent heat and sensible heat. The Pole-ward transfer of energy lead to the development of a global circulation of wind and ocean currents.

= Discuss the causes and environmental consequences of global climate change. =

Natural Causes of Climate Change – A selection only -summary (a) Sun spot Activities: Variations in solar energy Radiation from the Sun is not constant, but varies at least by ~0.1 to 0.2%. There is a 22 year cycle of sunspots that causes a similar 22 year cycle of solar radiation. This cycle is thought by many scientists to play a minor role in climate change (though this is still subject to heated debate).

(b) Milankovitch Cycles: Astronomical relationship between the sun and the Earth There are three types of orbital change of relevance to our discussion. These were first described by the Yugoslavian astronomer Milutin Milankovitch who first proposed the idea of a climate connection in the 1930's. The basic premise of the theory is that, as the Earth travels through space, three separate cyclic movements combine to produce variations in the amount of solar energy falling on the Earth.

(c) Changes in Oceanic Circulation Ocean currents have been known to change direction or slow down. Much of the heat that escapes from the oceans is in the form of water vapour, the most abundant greenhouse gas on Earth. Yet, water vapour also contributes to the formation of clouds, which shade the surface and have a net cooling effect.

(d) Meteorites An impact from a comet/meteorite would have released huge quantities of vaporised material into the atmosphere, blocking out the Sun and causing an initial "impact winter". Debris containing the iridium would gradually return to Earth forming the clay deposit. After this there would have been an increase in temperatures caused by the large amounts of carbon dioxide released by a spread of global fires. In addition, chemical reactions taking place in the atmosphere between pollutants would result in the formation of globally distributed acid rains.

Human activities and long term climatic change – the accelerated Green House effect. The amount of heat energy added to the atmosphere by the greenhouse effect is controlled by the concentration of greenhouse gases in the Earth's atmosphere. All of the major greenhouse gases have increased in concentration since the beginning of the Industrial Revolution (about 1700 AD). As a result of these higher concentrations, scientists predict that the greenhouse effect will be enhanced and the Earth's climate will become warmer.

(a) Carbon dioxide (CO2) Most of the increase in carbon dioxide comes from burning of fossil fuels such as oil, coal and natural gas, and from deforestation. Globally, human activities are adding about 26 gigatonnes (26,000 million tonnes) of carbon dioxide into the atmosphere each year. Prior to 1700, levels of carbon dioxide were about 280 parts per million. This increase in carbon dioxide in the atmosphere is primarily due to the activities of humans. Beginning in 1700, societal changes brought about by the Industrial Revolution increased the amount of carbon dioxide entering the atmosphere. Emissions from fossil fuel combustion account for about 65 % of the extra carbon dioxide now found in our atmosphere. The remaining 35 % is derived from deforestation and the conversion of prairie, woodland, and forested ecosystems primarily into agricultural systems.

(b) Chlorofluorocarbons Artificially created chlorofluorocarbons are the strongest greenhouse gas per molecule. Low concentrations in the atmosphere reduce their overall importance in the enhancement of the greenhouse effect. Current measurements in the atmosphere indicate that the concentration of these chemicals may soon begin declining because of reduced emissions. Reports of the development of ozone holes over the North and South Poles and a general decline in global stratospheric ozone levels over the last two decades have caused many nations to cutback on their production and use of these chemicals.

(c) Methane The growth rate of methane has slowed during the past 20 years. In 1992, methane concentrations briefly stabilised but have since been growing at about 8 ppbv per year. Anaerobic conditions associated with rice paddy flooding results in the formation of methane gas. However, an accurate estimate of how much methane is being produced from rice paddies has been difficult to obtain. Scientists believe that the contribution of rice paddies is large because this form of crop production has more than doubled since 1950. Grazing animals release methane to the environment as a result of herbaceous digestion. Some researchers believe the addition of methane from this source has more than quadrupled over the last century. Land-use change in the tropics, due to deforestation, ranching, and farming, may be causing termite numbers to expand. If this assumption is correct, the contribution from these insects may be important. Methane is also released from landfills, coal mines, and gas and oil drilling. Landfills produce methane as organic wastes decompose over time. Coal, oil, and natural gas deposits release methane to the atmosphere when these deposits are excavated or drilled.

(d) Nitrous Oxide Most of the nitrous oxide added to the atmosphere each year comes from deforestation and the conversion of forest, savanna and grassland ecosystems into agricultural fields and rangeland. The use of nitrate and ammonium fertilizers to enhance plant growth is another source of nitrous oxide. Accurate measurements of how much nitrous oxide is being released from fertilization have been difficult to obtain. Estimates suggest that the contribution from this source may represent from 50 % to 0.2 % of nitrous oxide added to the atmosphere annually.

3. The Effects of the Greenhouse Effects Without the greenhouse effect life on this planet would probably not exist as the average temperature of the Earth would be a chilly -18 degrees Celsius, rather than the present 15 degrees Celsius. If the earth's atmosphere warms, the upper layers of the oceans will also warm.

(a) Like most substances, water expands when heated. Expansion will raise sea level. Land-based ice in the temperate regions of the world (such as South and North America and Greenland) will melt more rapidly.

(b) Glaciers may retreat. Melting will also contribute to increased sea level. (Floating sea ice does not change the sea level when it melts.) On the other hand, increased precipitation over Antarctica and Greenland would lock water away in the ice caps.

(c) Scientists estimate that by the end of the 21st century, global warming will raise average sea level by between 13 and 110 cm above the 1990 level. Regional variations of up to 50 per cent are possible.

(d) Records show that global sea level has risen by between 10 and 25 cm during the past century. However, it is not possible to attribute this increase to the enhanced greenhouse effect.

A selection of effects from http://www.americanprogress.org [ indicates source of report] Greenland’s Melting Greenland is melting at a rate of 52 cubic miles per year—much faster than once predicted. If Greenland’s entire 2.5 million cubic kilometers of ice were to melt, it would lead to a global sea level rise of 7.2 meters, or more than 23 feet. [LA Times]

Less Ice in the Arctic The amount of ice in the Arctic at the end of the 2005 summer “was the smallest seen in 27 years of satellite imaging, and probably the smallest in 100 years.” Experts said it’s the strongest evidence of global warming in the Arctic thus far. [Washington Post]

The Northwest Passage Becomes a Reality Remember the “Northwest Passage”? For centuries, explorers were obsessed with the almost-mythical idea of northern sea route connecting the Atlantic and Pacific. Well...it’s here. So much of the ice cover in the Arctic disappeared this summer that ships were able to take recreational trips through the Arctic Sea, and scientists say so much of the ice cover will disappear in upcoming years that the passage could be open to commercial shipping by 2020. [CNN]

Ice Shelf in Antarctica Bites the Dust In 2002, a chunk of ice in Antarctica larger than the state of Rhode Island collapsed into the sea. British and Belgian scientists said the chunk was weakened by warm winds blowing over the shelf ... and that the winds were caused by global warming. [ENS]

Ice Shelf in Canada Bites the Dust In 2005, a giant chunk of ice the size of Manhattan broke off of a Canadian ice shelf and began free floating westward, putting oil drilling operations in peril. [Reuters]

Say Farewell to Glaciers “In Glacier National Park, the number of glaciers in the park has dropped from 150 to 26 since 1850. Some project that none will be left within 25 to 30 years.” [AP]

The Green, Green Grass of Antarctica Grass has started to grow in Antarctica in areas formerly covered by ice sheets and glaciers. While Antarctic hair grass has grown before in isolated tufts, warmer temperatures allow it to take over larger and larger areas and, for the first time, survive through the winter. [UK Times]

The Swiss Foothills Late last summer, a rock the size of two Empire State Buildings in the Swiss Alps collapsed onto the canyon floor nearly 700 feet below. The reason? Melting glaciers. [MSNBC]

Giant “Sand Seas” in Africa Global warming may unleash giant “sand seas” in Africa—giant fields of sand dunes with no vegetation—as a shortage of rainfall and increasing winds may “reactivate” the now-stable Kalahari dune fields. That means farewell to local vegetation, animals, and any tourism in the areas. [National Geographic]

Florida’s National Marine Sanctuary in Trouble Global warming is “bleaching” the coral in the Florida Keys National Marine Sanctuary, killing the coral, tourism, and local fish that live among the coral for protection. [Washington Post]

The Oceans are Turning to Acid It sounds like a really bad sci-fi movie, but it’s true: The oceans are turning to acid! Oceans absorb CO2 which, when mixed with seawater, turns to a weak carbonic acid. Calcium from eroded rocks creates a “natural buffer” against the acid, and most marine life is “finely tuned” to the current balance. As we produce more and more CO2, we throw the whole balance out of whack and the oceans turn to acid. [CS Monitor]

Say Goodbye to the Great Barrier Reef According to the U.N., the Great Barrier Reef will disappear within decades as “warmer, more acidic seas could severely bleach coral in the world-famous reef as early as 2030.” [CBC News]

Mediterranean Sea? Try the Dead Sea. Italian experts say thanks to faster evaporation and rising temperatures, the Mediterranean Sea is quickly turning into “a salty and stagnant sea.” The hot, salty water “could doom many of the sea's plant and animal species and ravage the fishing industry.” [AP]

A Sacred River Dries Up The sacred Ganges River in India is beginning to run dry. The Ganges is fed by the Gangotri glacier, which is today “shrinking at a rate of 40 yards a year, nearly twice as fast as two decades ago.” Scientists warn the glacier could be gone as soon as 2030. [Washington Post]

Disappearing African Rivers Geologists recently projected a 10 percent to 20 percent drop in rainfall in northwestern and southern Africa by 2070. That would leave Botswana with just 23 percent of the river it has now; Cape Town would be left with just 42 percent of its river water. [National Geographic]

Suddenly Vanishing Lakes What happened to the five-acre glacial lake in Southern Chile? In March, it was there. In May, it was ... gone. Scientists blame global warming. [BBC News]

Goodbye to the Mangrove Trees Next on the global warming hit list: Rising sea levels linked to climate change mean we could lose half of the mangrove trees of the Pacific Isles by the end of the century. [UNEP]

Volcanoes Blow Their Tops British scientists warn of another possible side effect of climate change: A surge of dangerous volcanic eruptions. [ABC News Australia]

More Hurricanes Over the past century, the number of hurricanes that strike each year has more than doubled. Scientists blame global warming and the rising temperature of the surface of the seas. [USA Today]

More Floods During the summer of 2007, Britain suffered its worst flood in 60 years. Scientists point the finger directly at global warming, which changed precipitation patterns and is now causing more “intense rainstorms across parts of the northern hemisphere.” [Independent]

More Wildfires Global warming has also allowed non-native grasses to thrive in the Mojave Desert, where they act as fast-burning fuel for wildfires. [AP]

Thunderstorms Get Dangerous Hurricanes aside, NASA scientists now say as the world gets hotter, even smaller thunderstorms will pose more severe risks with “deadly lightning, damaging hail and the potential for tornadoes.” [AP]

Burning Poo As “shifting rainfall patterns” brought on by global warming “have made northern Senegal drier and hotter,” entire species of trees (like the Dimb Tree) are dying out, making it harder for natives to find firewood. As a result, more people are having to burn cow dung for cooking fires.[MSNBC]

A New Dust Bowl Calling Mr. Steinbeck. Scientists this year reported the Southwest United States is "expected to dry up notably in this century and could become as arid as the North American dust bowl of the 1930s," a process which has already started. [ABC News]

Soil and Change Explain the causes of soil degradation. Discuss the environmental and socio-economic consequences of this process, together with management strategies.

Water and Change Identify the ways in which water is utilized at the regional scale. Examine the environmental and human factors affecting patterns and trends in physical water scarcity and economic water scarcity. Examine the factors affecting access to safe drinking water.

Biodiversity and change Explain the concept and importance of biodiversity in tropical rainforests. Examine the causes and consequences of reduced biodiversity in this biome.

Sustainability and the environment Define the concept of environmental sustainability. Evaluate a management strategy at a local or national scale designed to achieve environmental sustainability.