Introduction to the Earth

Basic Terminology and Concepts

Fall 2012 , Lecture 1

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Ecosphere

• That part of the earth consisting of five spheres: Atmosphere Biosphere Cryosphere Hydrosphere Lithosphere

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Atmosphere

• The gaseous layer which surrounds the earth, and which is held by gravitational attraction. It consists of layers, the bottom ones of which are: Thermosphere > 80 km Mesopause Mesosphere 45 - 80 km Stratopause Stratosphere 12 - 45 km Tropopause Troposphere 0 -12 km

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Hydrosphere

• Earth's water, in any physical state – Gaseous Liquid Solid

Cryosphere• Some places on Earth are

so cold that water is a solid—ice or snow. Scientists call these frozen places of our planet the "cryosphere." The word "cryosphere" comes from the Greek word for cold, "kryos."

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•The cryosphere includes Antarctica, the Arctic, and places far away from the cold poles, at high elevations. Frozen soil can be found high in the mountains of the United States, the northern reaches of Canada, China, and Russia• The cryosphere expands during the cold winter months. Seasonal areas of the cryosphere include places where snow falls, and where soil, rivers, and lakes freeze.

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Lithosphere

• The outermost part of the solid earth, consisting of the entire crust and the upper mantle, from the surface to a depth of about 70 kilometers (km)

• It is stronger and mechanically more rigid than the asthenosphere (70 - 250 km), which lies under it

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Interior of the Earth

• Crust – Continental (0-40 km, to a maximum of 100km) Oceanic (0-10 km)

• Mantle – Upper (bottom of crust to 700 km, and includes the

transition zone (350 to 700 km) Lower (700 - 2900 km)

• Core – Outer (2900 - 4980 km - liquid iron-nickel) Inner (4980 - 6370 km - solid)

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Biosphere

• Interface layer between earth's crust, atmosphere, cryosphere, and hydrosphere where life is found

• Includes the total ecosystem of the earth

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Ecosystem

• Community of interacting organisms, of all species – includes Plants Animals Microbes

• Includes interactions of organisms within this community, and of organism with the chemical and physical systems of earth

Biome

• A large community of plants and animals that occupies a distinct region

• Biomes are usually divided into terrestrial and aquatic

• Often said to be a group of ecosystems that have a similar climate and are therefore inhabited by particular plant and animal species

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Terrestrial Biomes

• Terrestrial biomes, typically defined by their climate and dominant vegetation, include: Grassland Tundra Desert Tropical rainforest Deciduous and coniferous forests

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Aquatic Biomes

• Freshwater Lakes and ponds Rivers

• Marine Pelagic Benthic Intertidal zones

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Pelagic Biomes

• Pelagic is derived from the Greek work pélagos, meaning Open Ocean

• It is the name for oceanic water not in direct contact with a shore or the bottom

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Benthic Biomes• The benthic zone is the ecological region at the lowest level

of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers

• Organisms living in this zone are called benthos They generally live in close relationship with the substrate bottom

and many are permanently attached to the bottom

• The superficial layer of the soil lining the given body of water, the benthic boundary layer, is an integral part of the benthic zone, as it greatly influences the biological activity which takes place there

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Anthropogenic

• Refers to the impact of human activities on the natural world, causing changes in the ecosystem Includes impacts on biophysical environments,

and biodiversity Impacts vary in magnitude and temporal scale,

and affect the rate at which change occurs

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Environmental Issues

• Changes in the ecosphere caused by: Natural processes Human activities

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Changes By Other Species

• Humans are not the only species to cause environmental change

• Cyanobacteria, the first organisms capable of photosynthesis, gradually changed the atmosphere of earth from one without oxygen to one with the present 21% oxygen content

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So What Makes Humans Different?

• Humans are the first species to be aware of their influence

• Humans assume, to some extent, responsibility for wise management of the planet

• Humans affect change at rates unprecedented in the geological record

Anthropocene

• Term introduced by Nobel Prize-winning atmospheric chemist Paul Crutzen in the 1970’s

• The term was meant to emphasize the central role of man in geology and ecology

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Prelude to the Anthropocene

• Significant human alteration of the biosphere began more than 15,000 years ago as Paleolithic tribes evolved social learning, advanced hunting and foraging technologies, and the use of fire, and used them to open up forested landscapes and kill off megafauna

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Rise of Agriculture

• Agriculture impacted earth beginning more than 8000 years ago. Domestication of plant and animal species Engineering ecosystems to support them Humans introduced a wide range of

unambiguously anthropogenic processes into the biosphere

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8000 Years Before Present (YBP)

• 8000 years ago, with a population of just 10 million or so, humans had already altered as much as a fifth of Earth's ice-free land, primarily by using fire to clear forest

• Small populations had such extensive impacts because early agriculture emphasized labor efficiency No plowing Cultivation had to be constantly shifted to the most fertile areas Most of the landscape was in some stage of recovery, giving rise

to "semi-natural" woodlands

Among the first anthropogenic biomes, or "anthromes".

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Human Transformation of Earth

• Human populations increased and expanded for millennia Vast tracts of pristine forest were converted to semi-natural

woodlands and less productive land into rangeland

• Population growth created ever more intensively transformed anthromes by tillage, irrigation, manuring and cropping.

• By 1750, more than half of the terrestrial biosphere had been converted into anthromes, Permanent record left in soils, sediments and the atmosphere

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Industrial Transformation

• Rise of industrial systems in the past century has transformed the majority of the terrestrial biosphere into intensively used anthromes dominated by novel ecological processes

• At 7 billion+ and growing, transformation of the last wild biomes into anthromes continues Process will end soon as we reach the limits of the usable

biosphere Already, more than 12 per cent of Earth's ice-free land is used

continuously for crops and 16 per cent for livestock

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Start of the Anthropocene• Together with Eugene Stoermer, Paul Crutzen

proposed a start for the anthropocene as follows: “To assign a more specific date to the onset of the "anthropocene"

seems somewhat arbitrary, but we propose the latter part of the 18th century, although we are aware that alternative proposals can be made (some may even want to include the entire Holocene). However, we choose this date because, during the past two centuries, the global effects of human activities have become clearly noticeable. This is the period when data retrieved from glacial ice cores show the beginning of a growth in the atmospheric concentrations of several "greenhouse gases", in particular CO2 and CH4. Such a starting date also coincides with James Watt's invention of the steam engine in 1784” (International Geosphere-Biosphere Programme Newsletter 41, 2000)

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Anthropocene: Pro and Anti

• The term has raised protests from stratigraphers

• Part of the controversy involves a definite marker for the beginning of the anthropocene

• For those wishing to know more about the controversy about the use of “Anthropocene” as a geologic epoch:• Pro: The Anthropocene: a new epoch of geological time?

• Anti: Is the Anthropocene an issue of stratigraphy or pop culture?

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Technology Improvements

• During the last fifty years

• Have greatly contributed to our awareness of environmental change Especially contributing to our knowledge of

global scale processes

• Greatly enhanced out knowledge of the temporal scale of global change

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Examples of Technological Change

• Satellite observations

• Computational power

• Rapid communication (Internet)

Blue Marble Images• Beginning with the Apollo 8 mission, NASA has published

increasing detailed images of Planet Earth

• NASA's Earth Observing System (EOS) has provided striking new insights into many aspects of Earth, including its clouds, oceans, vegetation, ice, and atmosphere, for the last decade

• EOS satellites are being replaced by the next generation Suomi National Polar-orbiting Partnership

• Suomi NPP orbits the Earth about 14 times each day and observes nearly the entire surface

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“Blue Marble” Western

Hemisphere

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• Image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP• The NPP satellite was renamed 'Suomi NPP' on January 24, 2012 to honor the late Verner E. Suomi of the University of Wisconsin.

Composite image uses a number of swaths of the Earth's surface taken on January 4, 2012

“Blue Marble” Eastern

Hemisphere

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• Image is a composite of six separate orbits taken on January 23, 2012 by the Suomi National Polar-orbiting Partnership satellite• Four vertical lines of 'haze' visible in this image shows the reflection of sunlight off the ocean, or 'glint,'

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Changes to the Ecosphere

• Many examples of modification of ecospheric components have been described

• Representative examples of these modifications are shown on the following slides

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Atmospheric Modifications

• Depletion of ozone (O3) in the ozone layer (stratosphere) which affects UV light absorption Ozone “hole” Leads to increased rates of skin cancer

• Acid deposition – introduction of pollutant gasses into the atmosphere leads to the formation of “acid rain”

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Atmospheric Modifications cont.

• Modification of the climate system by the introduction of “greenhouse” gases Major gases are carbon dioxide, freons, methane,

nitrous oxide Are leading to a warmer earth, and will increase

number and severity of major storms May affect short and medium term climate, and

may modify the areas in which food can be grown

May create climate refugees

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Hydrological Modifications

• Diagram shows a local example of the hydrological cycle

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Hydrological Cycle Modifications

• Withdrawal of water• Pollution of water• Impoundment of water (dams) • Modifications in erosion and depositional rates

Silting of rivers and estuaries Increased erosion below dams

Changes in form of precipitation – rain rather than snow

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Biosphere Modifications

• Mobilization and redistribution of chemical elements

• Most important carbon (C), nitrogen (N), and oxygen (O)

Results in enrichment and depletion of various parts of the system, leading to problems like red tide, depletion of soil productivty, etc.

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Biosphere Modifications cont.

• Human activities change natural environment Often results in changes in species distribution,

especially in loss of biological diversity (biodiversity) Rapid expansion of urban and suburban areas decreases

available habitat Deforestation Expansion of farming into marginal environments Land use that is insensitive to long term changes

• Salinization

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Results of Environmental Change

• Species reduction Mass mortality - a large number of individuals die,

which may lead to a new equilibrium distribution, with a smaller number of individuals of the species in question, or the original equilibrium may be approximately restored, to precatastrophe levels

Extinction - A complete elimination of a species. Extinction can and does occur naturally - Man's activities have increased the rate of extinction, with one recent estimate of 70 species/day

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Natural Events

• Natural events often lead to mass mortality in many species - extinction may occur in severely geographically restricted species

• Examples: Earthquakes Volcanoes Tsunamis Hurricanes Small meteorite impacts

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Large Scale Extinction

• Large meteorite impacts can result in mass extinctions Example: Cretaceous-Tertiary event that wiped dinosaurs, and

many other species, from the face of the earth

Immense lava flows Example: Permian-Triassic event, 251 million years ago, that

eliminated 90+% of the species on earth – this is the largest extinction event on earth – From eruption of Siberian Traps and associated methane release

• Large scale nuclear war would probably have the same effect

• Anthropogenic change?????

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Environmental Action

• Awareness of environmental change does not always translate to actions favorable to the stabilization of the ecosystem

• Why?

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Political Problems

• Politicians make most policy decisions, yet relatively few politicians have any training in science or technology Some overcome this by relying on

science/technology advisors

• Political considerations may cause them to rely more heavily on political or economic advisors, whose perspective is usually focused on a much smaller time scale

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Economic Gain

• Short term economic gain is a powerful motive• Example: Drilling for oil in the Arctic Wildlife

Preserve will provide profit, and will very temporarily stave off the decline in oil production This may make the final decrease in petroleum even

more difficult for humans, since we will have built more automobiles, power plants, etc.

It will also create immense difficulties for many Arctic species

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Sources of Pollution

• Pollution may occur from a variety of sources• Generally we can divide pollution sources

into two types: Point sources – pollution emanating from a single

source, such as a power plant smokestack Non-point sources – pollution derived from a

variety of sources, such as smog from automobile exhaust

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Scope of Environmental Problems

• Environmental problems are generally split into one of three groups, with the possibility of overlap between groups Local – effluent introduced into a stream from

an industrial plant Regional – acid rain in the northeastern U.S.,

extending into Canada Global – Greenhouse gas warming of the planet

Welcome to the Anthropocene

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