Download TEAM A - Earth System Science Education Alliance

TEAM A- Kelly Arnold, Kristin Combs, Guy Duncan, and Michael Schoenborn
Spring 2010 ESCI 580- Teaching Middle School Earth System Science
using PBL
Assignment: Cycle B- TEAM Model-Building Assignment Document
Date Due: 02/14/2010
Team Problem Statement
Major causes of global climate change include plate tectonics, solar output, orbital
variations, volcanism, ocean variability and human influences. Changes in sea level are
caused by climatic changes and are apparent in local and eustatic sea level, short term and
periodic changes and long-term changes such as the effects on volume or mass of the
ocean.
Beginning in the nineteenth century, the consumption of fossil fuels (i.e. coal and
petroleum) by the machines of the Industrial Revolution kicked in and began to pick up
steam. Greenhouse gas emissions are an obligatory byproduct of the combustion process
of fossil fuels. While completely unrecognized as a potential driver of global climate
change at the time, this is when mankind’s contribution to greenhouse gases began its
ever rising path to the present. Since the beginning of the Industrial Revolution,
atmospheric carbon dioxide levels have increased 30%, atmospheric methane levels have
increased 15 % and several other greenhouse gases have increased in our atmosphere as
well. Scientists have identified emissions of greenhouse gases into the atmosphere,
mostly as a result of burning fossil fuels, as the major source of anthropogenic climate
change. Currently, global temperatures are projected to increase by 1.0° to 4.5° C during
the next century, primarily because of a projected doubling of greenhouse gas levels.
Global climate change could have both direct and indirect effects on human health.
Severe heat waves could cause an increase in morbidity and mortality. For example, over
500 heat-related deaths occurred over the course of a three day heatwave in Chicago
during the summer of 1995. Additionally, ozone, a photochemical pollutant, is commonly
created under conditions of hot temperatures and stagnant air containing nitrogen oxides.
More than 51 million Americans live in areas where ozone levels exceed the U.S.
Environmental Protection Agency's standard of 0.12 parts per million.
Analyses of epidemiological data by public health researchers has clearly established a
linkage between global climate change and the recent resurgence and re-emergence of
numerous diseases, especially vector-borne diseases, such as West Nile Virus, Malaria
and Dengue Fever. Warmer temperatures and changes in rainfall have created improved
conditions for the propation of both vectors and pathogens. Of particular concern is the
fact that certain disease vectors now survive in areas that were previously inhospitable to
them. If this global climate change-driven trend were to continue, tropical and subtropical
areas that favor malaria-transmitting mosquitoes would expand, leading to an additional
50 to 80 million cases of malaria each year by the end of the next century according to
the World Health Organization.
Global climate change has also adversely impacted agriculture, with a notable example
being the significant drop in monsoonal rains available in areas long dependent upon
them. Computer models based upon current global climate change trends project that
aerosols formed from sulfur compounds, along with greenhouse gases, will combine with
the current greenhouse effect to cause a further 7 to 14% drop in monsoon rainfall over
India and parts of China by the middle of this century. This is obviously considered to be
a significant threat to agriculture, especially given the ever burgeoning demand for food
crops worldwide. As if this news was not dire enough, in addition the loss of arable land
due to sea level rise and shifts in arable zones, largely due to deforestation &/or
desertification, also threaten agricultural productivity. Together these global climate
change-driven phenomena could put an additional 300 million people at severe risk from
hunger and starvation.
Recommended Action

Support legislation to mitigate sources of greenhouse gas emissions in the
environment that negatively affect human health. On an encouraging note,
Scientists at the National Oceanic and Atmospheric Administration have
confirmed that the ban on the production of chlorofluorocarbons and other
halogenated compounds that was phased in beginning in 1977 has resulted in
decreased levels of certain greenhouse gases. For example ozone-depleting
compounds in the lower atmosphere apparently peaked in 1994.

Target research to more accurately predict the effects of pollution sources on
global climate change; specifically, research is needed that could establish the
influence of anthropogenic aerosols on climate. Currently, estimates of cooling
from aerosols involve very large uncertainties, and this cooling may be negating
virtually most of the effects of greenhouse gases. If this is true, global
temperatures could actually be far more sensitive to greenhouse gases than
previously expected, and global temperature could increase dramatically in the
future.

Support research necessary to bring to the forefront the association between
climate change and changes in global health conditions. The research agenda
should include the effects of global warming on heat-related mortality and
morbidity; vector-borne infectious diseases, pathogen replication and distribution
ranges; malnutrition from threatened agriculture, especially in developing
countries; and amplified epidemics of diseases, such as cholera, stemming from
proliferation of algae blooms.

Encourage and facilitate intergovernmental cooperation and multilateral
agreements on important environmental issues related to global climate change.
This includes providing technical assistance to developing industrial nations and
remedial work with heavily industrialized eastern European countries.

Support existing technologies that result in a "cleaner" environment and
sustainable resources. As new technology becomes available, reassess air
emission regulations to integrate the most effective aspects of new developments.
It is recommended that stricter enforcement of current air emissions legislation be
funded and implemented.

Educate key public health and policy institutions by disseminating information on
the relationship between climate change and environmental and public health.

Educate all people the planet over about the importance of acting responsibly at
home by reducing their carbon footprints. This includes promoting the inherent
intelligence of reducing unnecessary consumption, reusing, recycling and
remaining consciously engaged in their communities and respective governments.
Climate Change and its Effects on the Lithosphere
Climate Change models and discussions often center around the effects that take place in
the water, the air and the weather, sometimes including the expected toll to the life forms
on the earth. Ignored, or misunderstood are the possible effects on the lithosphere.
Plate Movement
Philip and Nicolas Parubets have calculated the loss of glaciation and re-glaciation on the
Earth’s crust due to climate change. They found that the unloading and reloading of the
Earth’s plates will unbalance and likely increase tectonic activity. They call it
“isostatical/eustatical readjustments in various parts of the planet's crust”. The United
States, along with other parts of the world, have actively moving plates and large
population centers (i.e. California) built along identified fault lines/plate boundaries. Any
increase in tectonic activity along these zones will have major costs in terms of property,
life and commerce.
Movement of continents, island chains, or mid-ocean ridges could conceivably interfere
with ocean currents thus affecting the ocean, weather and climates on land and then
reinforcing the climate change phenomenon(E>L>H>A>E). These changes in turn affect
the life on the planet(E>L>H>A>E>B).
Reflectivity
Loss of glaciers will mean a loss of the bright surface area of the Earth that reflects some
of the solar radiation that reaches the Earth. This will result in greater amounts of heat
from the sun being absorbed by the Earths crust, oceans and atmosphere (E>L>H>A>E).
Much of the ground that is currently permafrost will also thaw, releasing more methane
and CO2 into the atmosphere (E>L>A>B). Both of these will affect the plants and
animals that depend upon this state (E>L>B).
Weathering
The AAG Center for Global Geography Education states that “with global warming, one
would expect that the rate of weathering of different minerals in the lithosphere would
change”. Increased rainfall and glacier melt will increase the amount of erosion, with
some amount of this reaching rivers, and ultimately the oceans. This sedimentation will
devastate many life forms and life cycles (i.e. coral reefs, salmon etc.). Many minerals
would be broken down with the attendant release of CO2 into the oceans and atmosphere.
In the case of the former acidification increases, with its effects on life in the sea and the
warming of the sea, in turn increasing the release of methane and CO2 , (i.e. dissolving of
calcium carbonate locked up in coral reefs and shells of living and dead organisms)
further adding to the cycle (E>L>H>B>E…ad infinitum).
Climate Change and its Effects on the Biosphere
The effects of climate change on plants and animals are difficult to measure, but
potentially dramatic. Many species inhabit precisely bounded ecological niches, and even
small changes in climate may cause fundamental disruptions in habitat or food
availability. In the past, animals generally had greater latitude to respond to these
pressures by moving from one place to another. Today, however, land development has
constrained and fragmented ancestral ranges and travel routes, making species migration
in response to climate change much more difficult. Moreover, loss of key predator or
prey species may affect the life cycles of other organisms in the food chain (E>B).
Organic processes can also play an important role in regulating the earth’s climate.
Changes in the extent of snow, ice, or vegetation covering the planet’s surface can alter
key climatic processes with unforeseeable effects, such as changing the amount of CO2
consumed by plants or the proportion of the sun’s heat absorbed by the earth.
The body of evidence in support of global climate change continues to mount, and there
are already strong indications that animals, birds and plants are being affected by it in
both their distribution and behavior. Many climate change research scientists have gone
so far as to express their serious concerns about the deleterious effects of global climate
change. Based upon their analyses they project that, unless greenhouse gas emissions are
severely reduced, global climate change could cause a quarter of land animals, birdlife
and plants to become extinct within the next 50 years.
Ecosystems and Biodiversity
The overwhelming majority of studies of regional climate effects on terrestrial species
reveal consistent responses to warming trends, including poleward and elevational range
shifts of flora and fauna. Responses of terrestrial species to warming across the Northern
Hemisphere are well documented by changes in the timing of growth stages (i.e.
phenological changes), especially the earlier onset of spring events, migration, and
lengthening of the growing season (E>A>B).
An ecosystem is an interdependent, functioning system of plants, animals and
microorganisms. An ecosystem can be as large as the Mojave Desert, or as small as a
local pond. Without the support of the other organisms within a given ecosystem, life
forms would not survive—much less thrive. Such support requires that predators and
prey, fire and water, food and shelter, clean air and open space remain in balance with
each other and with the environment around them.
Climate is an integral part of ecosystems and organisms have adapted to their regional
climate over time. Climate change is a factor that has the potential to alter ecosystems
and the many resources and services they provide to each other and to society. Human
societies depend on ecosystems for the natural, cultural, spiritual, recreational and
aesthetic resources they provide.
In various regions across the world, some high-altitude and high-latitude ecosystems have
already been affected by changes in climate. The Intergovernmental Panel on Climate
Change (IPCC) reviewed relevant published studies of biological systems and concluded
that 20 percent to 30 percent of species assessed may be at risk of extinction from climate
change impacts within this century if global mean temperatures exceed 2-3 °C (3.6-5.4
°F) relative to pre-industrial levels.
These changes can cause adverse or beneficial effects on species. For example, climate
change could benefit certain plant or insect species by increasing their ranges. The
resulting impacts on ecosystems and humans, however, could be positive or negative
depending on whether these species were invasive (e.g., weeds or mosquitoes) or if they
were valuable to humans (e.g., food crops or pollinating insects). The risk of extinction
could increase for many species, especially those that are already endangered or at risk
due to isolation by geography or human development, low population numbers, or a
narrow temperature tolerance range.
Observations of ecosystem impacts are difficult to use in future projections because of
the complexities involved in human/nature interactions. For example, changes in land
use, which may occur. Nevertheless, the observed changes are compelling examples of
how rising temperatures can affect the natural world and raise questions of how
vulnerable populations will adapt to direct and indirect effects associated with climate
change.
The IPCC has noted,
“During the course of this century the resilience of many ecosystems (their
ability to adapt naturally) is likely to be exceeded by an unprecedented
combination of change in climate and in other global change drivers
(especially land use change and overexploitation), if greenhouse gas
emissions and other changes continue at or above current rates. By 2100
ecosystems will be exposed to atmospheric CO2 levels substantially higher
than in the past 650,000 years, and global temperatures at least among the
highest as those experienced in the past 740,000 years. This will alter the
structure, reduce biodiversity and perturb functioning of most ecosystems,
and compromise the services they currently provide.”
Mammals
Mammals, with the notable exceptions of whales and dolphins, are primarily terrestrial
animals that inhabit diverse areas of the Earth. Mammalian responses to rising
temperatures and other climate changes are also diverse. Many small mammals are
coming out of hibernation and breeding earlier in the year than they did several decades
ago, while others are expanding their ranges to higher altitudes. Some mammals show
trends toward larger body sizes, probably due to increasing food availability and higher
temperatures (E>A>B). On the other hand, reproductive success in polar bears has
declined due to melting Arctic sea ice (E>A>H>B).
The already endangered Mediterranean Monk Seals need beaches upon which to raise
their pups. Therefore, a rise in eustatic sea level could irretrievably damage shallow
coastal areas used annually by whales and dolphins which need shallow, gentle waters in
order to rear there small calves (E>H>B).
In 2004, the Arctic Climate Impact Assessment (ACIA) summarized some of the
effects of warming temperatures on animals and their habitats in polar-regions, including
parts of Alaska. Polar bears, seals, migratory birds, caribou and reindeer are all
experiencing changes that could have dramatic effects on their species and the
ecosystems they inhabit.
For example, polar bears are dependent on sea ice to hunt seals and to move from one
area to another. Polar bears are unlikely to survive as a species if there is an almost
complete loss of summer sea-ice cover, which is projected to occur before the end of this
century by some climate models. The seals that polar bears hunt are also unlikely to be
able to adapt to an absence of summer sea ice, because they give birth to and nurse their
pups on the ice and use it as a place for resting.
According to the ACIA, caribou and reindeer populations could decline because of their
dependence on tundra for vegetation. As tundra vegetation zones continue to move
northward with the changing climate, the caribou and reindeer could have a more difficult
time finding food and raising their calves (E>A>B).
Birds
Birds are an important part of many functioning ecosystems because of their roles in seed
dispersal, pollination, and as both predator and prey. Scientists have observed that birds
are breeding and laying their eggs earlier and that migratory species have altered their
wintering and/or critical stopover habitats. For example, warmer springs have led to
earlier nesting for 28 migrating bird species on the east coast of the U.S.
The ACIA has stated that the timing of bird arrival in the Arctic may no longer coincide
with the availability of their insect food sources. Important breeding and nesting areas are
projected to decrease sharply as trees shift their range northward, invading tundra areas.
As sea level rises, more tundra area, and thus more habitat for birds and their prey, will
disappear. This could eventually affect the success or failure of the breeding of several
hundred million birds that migrate to the Arctic each summer, which in turn could
determine the population sizes of birds at lower latitudes.
Just as the changing climate could impair the extent to which a bird’s life cycle is
synchronized with its food supply, warming temperatures could affect other ecological
processes that are also vital to ecosystem health. Pollination, seed dispersal, and pest
control by birds are dependent on careful timing of bird arrival, atmospheric temperature
and other climate-related factors, and therefore could be disrupted as the climate changes.
Climate variability and change affects birdlife and animals in a number of ways; birds lay
eggs earlier in the year than usual, plants bloom earlier and mammals are come out of
hibernation sooner. Distribution of animals is also affected; with many species moving
closer to the poles as a response to the rise in global temperatures. Birds are migrating
and arriving at their nesting grounds earlier, and the nesting grounds that they are moving
to are not as far away as they used to be and in some countries the birds don’t even leave
anymore, as the climate is suitable all year round.
Sea level rise can cause loss of wetlands in coastal areas, where some waterfowl spend
the winter months. Sea level is rising along most of the U.S. coast, and around the world,
and is projected to continue rising throughout this century. In locations where the
wetlands cannot move inland due to topography or human development, these important
habitats may be lost and the ecosystems in which they exist forever changed.
Reptiles and Amphibians
The ability of reptiles and amphibians to adapt to changes in climate depends in part on
their ability to move to more suitable habitat. A European study found that most reptile
and amphibian species could expand their ranges in a warmer climate if dispersal were
unlimited, but if they were unable to disperse then the ranges of nearly all species (more
than 97 percent) would become smaller.
In the mountainous cloud forests of Costa Rica, the base of the clouds has been climbing
in altitude as the climate warms. Researchers have found a strong connection between
declines in the frequency of mist days and declines in amphibian populations.
A sea level rise of only 50cm could cause sea turtles to lose their nesting beaches - over
30% of Caribbean beaches are used by turtles during the nesting season and would be
affected.
Impacts of climate change on coral reefs and mangroves may affect sea turtles and
crocodiles. Increases in the severity of tropical storms could also affect sea turtle
populations. Hurricane Emily in 2005 destroyed 1,500 sea turtle nests along the Mexican
coast.
In North America, many amphibians, such as some species of frogs and salamanders, lay
their eggs in temporary pools that form in early spring after snowmelt. If a warmer
climate causes ponds to dry earlier in the season, amphibian populations could suffer.
Fish
Fishing is highly valued in the U.S. as both a commercial enterprise and as a recreational
sport. According to the IPCC, certain fish species are becoming less abundant worldwide.
Fish populations and other aquatic resources are likely to be affected by warmer water
temperatures, changes in seasonal flow regimes, total flows, lake levels, and water
quality. These changes will affect the health of aquatic ecosystems, with impacts on
productivity, species diversity, and species distribution.
Stream habitats are projected to decline across the U.S. by 47 percent for coldwater, 50
percent for cool-water, and 14 percent for warm-water species. In the southern Great
Plains, summer water temperatures already approach the limits for survival of many
native stream fish. An 8°F increase in average annual air temperature is projected to
eliminate more than 50 percent of the habitat of brook trout in the southern Appalachian
Mountains. The Northern pike, which spawn in flooded meadows in early spring and
whose young remain in the meadows for about 20 days after hatching, would be
especially affected by low spring water levels. Higher winter temperatures have been
observed to decrease the survival rate of the eggs of yellow perch (a coldwater species).
On the other hand, one study found that higher winter temperatures (by 2ºC) were
beneficial for rainbow trout. However, the same temperature increase in summer caused
negative effects.
Changes in the geographic distribution of ocean fish stocks have been linked to climateocean system variations such as the El Niño events. Fluctuations in fish abundance
increasingly are regarded as a biological response to climate-ocean variations, and not
just as a result of over-fishing and other human factors. Climate change can compound
the impact of natural variation and fishing activity and make marine life management
more complex. For example, scientists have observed that elevated temperatures have
increased mortality of winter flounder eggs and larvae and lead to later spawning
migrations. As oceans warm, tuna populations are predicted to spread toward currently
temperate regions.
Currently, NOAA is conducting the North Pacific Climate Regimes and Ecosystem
Productivity (NPCREP) project in the eastern Bering Sea and the Gulf of Alaska. This
geographic region was selected for initial climate and ecosystems studies due to its
importance for living marine resources (Alaskan fisheries account for approximately 50
percent of the US commercial fishery landings), model predictions that climate change
will be most severe at high latitudes, and many indications that environmental conditions
are already changing in these regions.
Humans have already destroyed many of the natural migrations of animals. In several
African countries, fences block the Wildebeest’s migratory pathways. Changing rainfall
patterns are causing dams to be erected in some areas of our planet, not taking into
account the migratory fish and mammals that annually migrate up river to breed and
spawn and water birds which rely on wetland sites for migration are at threat from rising
sea levels caused by human effects. In addition the rate of evaporative moisture loss from
the land has accelerated significantly causing severe droughts in many countries, which
are now facing reduced crop production and major drinking water shortages.
Although there is no conclusive evidence that any species have already become extinct
exclusively due to global climate change, many migratory and non-migratory species are
expected to become extinct in the near future.
Invertebrates
Invertebrates represent 97% of all animal species. Though most invertebrates are very
small, their influence on their surroundings can be enormous. Bees, moths, ants and other
insects, for example, perform a critical role in the lifecycles of seed plants by transferring
pollen. Insect pollination is particularly important for production of certain fruits, nuts
and vegetables.
Global climate change could have both positive and negative impacts on invertebrates
and insects. Recent warming in Alaska, for example, has caused spruce budworms to
reproduce further north. Spruce budworms are the most widely found and most
destructive pests to coniferous (evergreen) trees in the western United States. The Kenai
Peninsula in south-central Alaska experienced a massive outbreak of spruce bark beetles
(another serious insect pest) in the 1990s, causing 10-20 percent mortality of trees.
In addition, a range shift toward the poles (northward in the Northern Hemisphere) or to
higher elevations has occurred among many invertebrates that are considered pests or
disease organisms. According to the Western U.S. Bark Beetles and Climate Change
Impact Assessment, the range of Bark Beetles will expand in the Western United States
under climate change.
Butterflies’ habitat ranges in North America have shifted northward and in elevation as
temperatures increased. In some cases, such as the Edith’s Checkerspot Butterfly, local
populations have become extinct in the southern portion of their range.
Marine calcifiers, such as corals and marine snails, play important roles in nearly all
oceanic ecosystems. Ocean acidification makes it more difficult for marine calcifiers to
build shells and skeletons and will likely threaten ecosystem dynamics in areas where
marine calcifiers play dominant roles in the food web. The effects of elevated greenhouse
gas concentrations could cause substantial coral reef loss on tropical and sub-tropical
reefs by 2050.
Corals are anthozoans, the largest class of organisms within the phylum Cnidaria. They
most often exist as colonial organisms composed of thousands of individuals, called
polyps. All species of coral secrete calcium carbonate (CaCO3), and the majority of coral
species form reef structures over time. Coral reefs harbor more than 25 percent of all
known fish and provide our oceans with the highest biodiversity of any marine
ecosystem.
Increasing atmospheric concentrations of greenhouse gases are changing the physical and
chemical properties of the oceans in ways that impact the health of marine calcifiers—
species that makes shells and plates from calcium minerals. Two ongoing changes are
particularly consequential: Increasing sea surface temperatures, due to radiative forcing,
and decreasing carbonate saturation, due to ocean acidification (E>H).
Surface warming and acidification of the oceans adversely affect the health of coral
reefs. Surface warming increases the likelihood of coral bleaching (stress-induced
expulsion of unicellular algae resulting in the loss of coral color) and, if conditions are
warm enough for long enough, can cause reef mortality (IPCC, 2007). Ocean
acidification lowers the saturation states of aragonite and other carbonate minerals,
making these materials less available for construction of the calcified structures reefs
require to survive (Raven et al, 2005).
According to the IPCC:

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Warm-water coral cover has been reduced by 30 percent or higher since the
beginning of the 1980s. Many studies link coral bleaching to warmer sea surface
temperature.
Annual or bi-annual exceedance of water temperature thresholds for bleaching is
projected at the majority of reefs worldwide by 2030 to 2050.
Corals could become rare on tropical and sub-tropical reefs by 2050 due to the
combined effects of increasing dissolved carbon dioxide (CO2) and increasing
frequency of bleaching events.
Since the impacts of increased CO2 are greater at higher latitudes, cold-water corals
are likely to show large reductions in geographical range this century.
Although corals are certainly the best known marine calcifier, many other marine
organisms also rely on calcification, including crustaceans (e.g. shrimp), echinoderms
(e.g. starfish), large calcareous algae, and some phytoplankton (Raven et al, 2005).
Marine calcifiers play important roles in the food chains of nearly all oceanic ecosystems,
help regulate ocean chemistry, and are an important source of biodiversity and
productivity. For example, marine snails, called pteropods, are an important food source
for salmon, mackerel, herring, and cod. Current evidence on climate change and ocean
acidification points toward a continuing trend of impairment in aragonite-dependent
calcifiers by a wide variety of marine organisms that make their shells or skeletons in this
manner, with impacts projected to be particularly acute in the Southern Ocean.
According to a report on ocean acidification by the Royal Society (Raven et al, 2005):

Polar and sub-polar surface waters and the Southern Ocean are projected to be
aragonite under-saturated by 2100, and Arctic waters will be similarly threatened.
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Ocean acidification will likely threaten ecosystem dynamics in the areas where
marine calcifiers play dominant roles in the food web and in carbon cycling.
Lower pH in the oceans may inhibit the ability of echinoderms, such as sea urchins
and mollusks, to form skeletal material.
Ocean acidification could have large consequences for benthic (bottom-dwelling)
organisms, including in particular benthic calcifiers, by changing the pH levels
sediment communities are exposed to and by causing changes in the biological
pump.
Some unicellular species that form the base of marine food chains could experience
reduced growth and fitness as a result of decreased pH levels.
The overall reaction of marine biological carbon cycling and ecosystems to a warm
and high-CO2 world is not yet well understood, but there is a risk that a decrease in
calcifier productivity could lead to cascading effects throughout the food chain.
It should be noted that Marine calcifiers, including corals, are not impacted by the effects
of elevated greenhouse gas concentrations in isolation. Other factors, such as over-fishing
and pollution, affect calcifiers in multiple ways that are both difficult to distinguish from
climate change and likely to reduce resiliency to it.
Figure 1: Existing coral locations and estimated aragonite saturation states of the surface
ocean for the years 1765, 1995, 2040, and 2100 for a ‘business-as-usual’ (i.e. no
mitigation beyond current measures) CO2 emissions scenario. Many calcifiers use
aragonite to make shells and skeletons and are likely to be affected by sub-optimal
saturation levels.(Kleypas et al., 2006)
Plants
The increase in atmospheric carbon dioxide (CO2) levels resulting from fossil fuel
combustion has a fertilizing effect on most plants since CO2 is needed for photosynthesis
(the biochemical mechanism of plant growth). Photosynthesis converts CO2 and water
into the simple sugar glucose and emits oxygen, making it possible for oxygen-breathing
organisms to live on Earth. Sunlight is the energy that powers this reaction. The basic
equation of the process of photosynthesis is (B>A>E):
6H2O + 6CO2 + light -----> C6H12O6 + 6O2
O2 is oxygen CO2 is carbon dioxide C6H12O6 is glucose
Scientific experiments have shown that increasing atmospheric CO2 levels leads to an
increase in plant growth. The photograph shows scientists investigating the effect of
increased CO2 levels on wheat growth.
One might conclude, therefore, that increases in CO2 emissions from fossil fuel
combustion are uniformly beneficial for crop growth. However, in most cases the
negative effects of global climate change, such as increased heat stress and desiccation
are larger than the positive ones.
Prolonged periods of relatively high temperature cause heat stress in plants. Heat stress
significantly reduces plant growth and adversely impacts crop productivity. In more
severe cases, heat-stressed plants do not reproduce at all since excessive heat causes
sterility of the pollen. However, temperature increase may prove beneficial in certain
areas, such as those which are very cold at present. For example, in Siberia or Northern
Europe it may, in the future, be possible to grow crops for longer periods of the year.
There is also widespread concern among the scientific about the inherent capacity of
plant species, especially those that humans depend upon as crop for food. This is because
climate changes are happening at a higher rate now than ever before in the geological
past, so it would appear that plants will have to adapt to new climate conditions more
rapidly than they have ever had to do so previously.
Global Climate Change and Hydrosphere Interactions
The hydrosphere is one of the most affected spheres by global climate change. Global
warming’s effect on the hydrosphere is becoming increasingly researched, but the science
around how fast the hydrosphere is being affected is currently unreliable and often times
inconclusive.
Positive Feedback Loop and Human Power Availability E>H>B>A
The amount of power generated from hydroelectric plants could decrease due to global
warming. Global warming will cause the land to increase in temperature which leads to
an extreme amount of evapotranspiration, therefore drying out the rivers that
hydroelectric plants are placed upon. Less water means less electricity. About seven
percent of the nation’s energy is produced by hydroelectric power. If some of those
hydroelectric plants are rendered useless due to a lack of water from global warming,
then thousands, perhaps millions, will be without power and will have to turn elsewhere
for their energy needs. This in turn could lead to more fossil fuel consumption which
adds more carbon dioxide to the atmosphere resulting in a positive feedback loop.
Negative Feedback Loop E>H>B
Global warming can also lead to a negative feedback loop in some areas. With increased
evaporation in areas with enough water supply, evaporation will increase with the
increased temperatures. Increased evaporation will add more water vapor to the air and
result in more cloud formation which causes increased precipitation. Increased
precipitation will add to the maximum flow of rivers in some locales therefore adding an
increased amount of water available for hydroelectric power. An increase in precipitation
will also lead to a change in water available to plants and animals. This will cause a
change in plant life in areas that receive more rain. For example, sagebrush (Artemisia
tridentata) is a plant that is well adapted to growing throughout much of the American
West. It grows in dry soils and does not tolerate moisture rich soils. Pronghorn
(Antilocapra americana) survive on eating sagebrush and would lose a valuable food
resource if the precipitation in certain areas began to increase therefore making
unfavorable conditions for the sagebrush to grow. However, increased precipitation in
the West would provide more food for animals such as moose, elk, deer, bison and other
mammals large and small that eat moisture loving vegetation such as aspen. This would
in turn provide more food for predators in the area as well.
The above example is something that could happen, but is not likely due to the dryness of
the American West. Global climate change, specifically warming, would increase the
rate of evaporation in already dry places and would result in desertification of many
places that are already in the position of having water as a limiting resource. This could
ultimately lead to an increase in sagebrush type animals and therefore an increase in
pronghorn that feed on the plant.
Melting Ice E>H>B
Global climate change is increasing the rate of melting ice in the Arctic and Greenland
while causing a gain of ice in Antarctica. For the time being, the warming occurring on
the rest of the globe is causing an increase in precipitation that is carried by winds to
Antarctica. An increase in snow over time leads to an increase in ice on the continent of
Antarctica. However, ice in the Arctic and the Greenland ice sheet is melting at an
increasingly quick rate due to dryness and warmer temperatures. Estimates say the Arctic
could be ice free within the next 20-30 years. However, estimates do vary dramatically
and the science surrounding melting rates is still very uncertain and unreliable.
Thickening sea ice in Antarctica means business as usual in terms of the effects on the
biosphere. The organisms that live in Antarctica are adapted to living in cold climates
with a lot of ice and will continue to flourish in the thickening ice conditions. To the
contrary, animals in the Arctic are also adapted to living with snow, ice and cold
temperatures. However, the warming temperatures and melting ice will lead to loss of
biodiversity as the animals and plants in the Arctic lose their habitat. The Greenland ice
sheet is more susceptible to melting than the Antarctic ice sheet because it is closer to the
equator. Scientists can piece together what has happened over previous eras in our
earth’s climate by drilling into glacial ice and looking at levels of carbon dioxide and
other atmospheric gases. Scientists have concluded that during the last period of global
warming, known as an interglacial period, the Greenland ice sheet mostly melted and
consequently caused global ocean levels to rise about 20 feet. The same would occur
today if Greenland’s ice melted therefore causing flooding of coastal cities around the
globe.
Arctic ice is not the only ice that is melting. Many glaciers are retreating as well causing
local changes in habitat for many places. Glaciers help to supply melt water in the spring
to local habitats and provide a water supply to local wildlife, plants and humans. With
the melting of the glaciers, this water supply will initially increase, but in the long term
will decrease as the glacier disappears.
Melting Ice and Erosion E>H>L
The melting of arctic ice will expose many rocks that were previously buried under the
ice. The melting of the ice and newly running water will erode the rocks at a much faster
rate than they currently are undergoing. This in turn will add new soil to the habitat and
could result in a changing of soil type depending on what types of rocks will be eroded.
Rising Sea Levels E>H>B
As glacial and arctic ice melts, sea levels will rise. This has happened before during
periods of warming on the planet that have caused ice to melt. Sea levels will not only
flood coastal cities, but will erode valuable wildlife habitat. All organisms dependent on
coastal habitat will lose that habitat and will either adapt or die as a result.
Carbon Sinks E>H>B
The earth’s oceans are a sink for carbon. This means they absorb carbon from the
atmosphere and store it for long periods of time. Glaciers are a carbon sink and release
carbon dioxide when they melt. This will cause more carbon and greenhouse gases to be
emitted into the atmosphere therefore causing an increase in melting. This is known as a
positive feedback loop as I stated before. Oceans also dissolve and absorb carbon
dioxide. Aquatic plants and animals use the carbon and oxygen for many processes
including feeding and shelter building. When the oceans become oversaturated with
carbon dioxide, it begins to acidify the water. This can cause massive problems for
animals that are adapted to survive in a high pH. Coral reefs are one organism that is
being affected already by warmer ocean temperatures and higher carbon dioxide levels.
Many corals need a certain pH level to survive. When corals are exposed to lower pH
levels, they are unable to make calcium carbonate skeletons. Coral live symbiotically
with algae. The algae produces food for the coral polyp and the algae receives a home in
which to live. When carbon dissolves in the ocean, it becomes carbonic acid. This acid
makes it impossible for the coral to produce their skeletons from calcium carbonate. The
polyps and algae die and all that is left is the white calcium carbonate shells of the former
members of their colonies. Scientists are seeing more and more of these “bleached” coral
reefs as ocean temperatures are warming and carbon levels are increasing in the world’s
oceans.
E>A>H
An increase in carbon sinks can actually abate global warming because it draws the
carbon dioxide out of the air and in turn causes the overall carbon dioxide levels in the
atmosphere to decrease. Carbon dioxide is a greenhouse gas which increases global
climate change because it holds more heat in the atmosphere by reflecting solar radiation
back into the atmosphere rather than into space. In the last few years, scientists have
observed higher carbonic acid levels in the ocean showing evidence that the oceans are
absorbing more carbon dioxide from the atmosphere. Currently the emissions into the
earth’s atmosphere are causing the oceans to become more acidic.
Melting Arctic Ice Causes Further Melting E>H
The diagram below demonstrates how melting arctic ice causes more warm water to
move towards the poles. As the ice melts, the cold ice water drops to the ocean floor and
causes mixing of the ocean temperatures when it meets the warm equatorial waters. This
warm water is carried to the poles and increases the rate of melting of the ice.
http://www.all-creatures.org/hope/gw/hydro-img-033.htm
http://www.all-creatures.org/hope/gw/hydro-img-031.htm
http://www.all-creatures.org/hope/gw/hydro-img-040.htm
Encyclopædia Britannica, Inc
Global Climate Change and the Atmosphere
The protection provided by Earth’s atmosphere is the unique key to allowing the
existence of life by regulating surface temperatures and providing the mixture of gases
necessary to support living organisms. Although Earth’s atmosphere has evolved greatly
over the past, the atmosphere has remained fairly consistent over the past 3 billion years
consisting primarily of two major gases, nitrogen (78%) and oxygen (21%), and a
mixture of “trace” gases (1%). In the past 2000 years, researchers have identified three
periods of variation in atmospheric stability which resulted in changes in global
temperature averages: The Medieval Climate Anomaly ( ~900 to 1300 AD), The Little
Ice Age (~1500 to 1850 AD), and The Industrial Era (~1780 to present). Only the last of
these three periods are considered to be at least influenced if not caused by anthropogenic
events, as opposed to the natural “drivers” (changes in Earth’s orbit, changes in solar
activity, volcanic eruptions) which have been determined to be the major causes of the
two prior periods.
The greenhouse effect is a naturally occurring phenomenon in which solar
radiation which reaches Earth’s surface is radiated outward at different wavelengths
causing the warming of the atmosphere. The insulating blanket provided by “greenhouse
gases” traps some of the sun’s energy to provide a habitable environment on Earth. The
problematic state in which excessive trace gases exist, absorbing and retaining an
increased amount of solar radiation is referred to as an “enhanced greenhouse effect.”
Changes in the concentration of atmospheric trace gases as a result of human
actions (i.e. use of fossil fuels) has become an area of concern due to the heat-trapping
effect certain gases may have on the atmosphere. The Environmental Protection Agency
(EPA) lists four greenhouse gases which enter Earth’s atmosphere through anthropogenic
means: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated
gases (hydrofluoro-carbons, perfluorocarbons, and sulfur hexafluoride). Emissions of
these gases have been measured and tracked globally since 1990. The climate change
effect imposed by changes in concentration of these gases is referred to as “Radiative
Forcing.”
Radiative forcing is a measurement of the change in the energy balance between
the Earth and the atmosphere when contributing factors are altered, such as the
composition of Earth’s atmosphere. When radiative forcing is neutral, no temperature
change is experienced. Positive forcing creates a warmer environment, while negative
forcing results in cooling. The measurements can be calculated for individual greenhouse
gases as well as factors such as constructed dwellings, roads, etc. The following chart
displays changes in the five major greenhouse gases which are thought to directly
account for 96% of the direct positive radiative forcing since 1750.
The impact of these gases is further analyzed as the changes in radiative forcing by the
NOAA Annual Greenhouse Gas Index (AGGI) which seeks to provide a normalized
standard based on actual measurements, not climate model projections with a small
percentage of error. The following chart shows the results of NOAAs calculations for
2008. Yearly updates for the AGGI are posted each spring following analysis of the
previous year’s globally collected air samples.
Figure 4. Radiative forcing, relative to 1750, of all the long-lived greenhouse gases. The NOAA Annual
Greenhouse Gas Index (AGGI), which is indexed to 1 for the year 1990, is shown on the right axis.
According to NOAA calculations, the Radiative Forcing due to anthropogenic causes are
having a greater influence on climate change than the RF caused by natural means
(changes in solar activity and volcanic aerosol eruptions). Of the major greenhouse gases
produced by anthropogenic means, CO2 is thought to have contributed most to climate
change since 1750. Although other gases have a higher potential for trapping heat in the
atmosphere, CO2 is far more abundant and increasing at a more rapid rate. The
following table shows this comparison.
How Does CO2 Compare To Other Climate Drivers?
Although CO2 naturally occurs in Earth’s atmosphere, increasing CO2 concentrations are
directly correlated to antropogenic causes. The balanced carbon cycle taught in most
biology classes no longer exists as the positive CO2 feedback loop continues. Increases
in the concentration of CO2 in Earth’s atmosphere are not balanced by increased photosynthesis. Additionally, warmer temperatures are causing a reduction in the CO2 storage
capacity of Earth’s oceans.
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