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Human-caused atmospheric changes

How has human civilization changed Earth’s atmosphere?

First we’ll look at the layers and composition of Earth’s atmosphere, then we’ll look at the changes we’ve made.

What is our atmosphere composed of?

 

Is our atmosphere the same everywhere, and just abruptly ending where outer space begins? Nope, the atmosphere gets less dense as we increase in altitude.

The acidity of natural rain

Rain picks up chemicals that naturally are in the air; this causes rain to usually be slightly acidic.  About 5.6 on the pH scale.

lower numbers are more acidic.

pH of 7 is the middle. Neutral. No acid or base (alkaline)

higher numbers are more basic (alkaline)

pH scale natural rain

from www3.epa.gov, acid rain, student site.

Acid rain

“Acid rain” is any precipitation with higher than normal acid. This can include acidic rain, snow, fog, or hail.

Some small amount of acid rain is fine. For a short period of time, it is not harmful to humans or to the environment in general.  But since the Industrial Revolution, humans have burned more and more fossil fuels per year, releasing tons of chemicals into the atmosphere. This has vastly increased the amount of acid precipitation, for years – then decades – and now centuries. This does have a bad effect on the Earth’s environment.

Where does it come from?

Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents.

The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids.

These then mix with water and other materials before falling to the ground.

While a small portion of the SO2 and NOX that cause acid rain is from natural sources such as volcanoes, most of it comes from the burning of fossil fuels.

The major sources of SO2 and NOX in the atmosphere are:

  • Burning of fossil fuels to generate electricity.  Two thirds of SO2 and one fourth of NOX in the atmosphere come from electric power generators.

  • Vehicles and heavy equipment.

  • Manufacturing, oil refineries and other industries.

Winds can blow SO2 and NOX over long distances and across borders.

This makes it a problem for everyone and not just those who live close to these sources.

Acid Rain graphic

( Excerpted from Acid Rain, http://www.epa.gov/acidrain/what-acid-rain )

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The below is from Regentsprep.org – Ecology Human Biosphere Influence

What problems does it cause? 

* Destruction of limestone and marble monuments.

* Acidification of aquatic ecosystems, destroying life in them.

* Damage forests and other plants.

acid rain

 

SO2 and NOx

SO2 sulfur dioxide – primarily produced for sulfuric acid manufacture, preservative for dry fruits, used in wine-making to prevent spoiling.

Huge amounts of SO2 get into the atmosphere from power plants burning sulfur-containing coal or oil.

NOx – NOx  refers to NO and NO2.   You find large amounts of this gas in areas of high motor vehicle traffic, such as in large cities.

NOx gases are formed whenever combustion occurs in the presence of nitrogen – as in an air-breathing engine; they also are produced naturally by lightning. In the air it reacts with water vapor to form nitric acid, part of acid rain.

NOx is also directly bad for people – nitric acid in the air worsens respiratory diseases, such as emphysema or bronchitis, or may also aggravate existing heart disease.

NOx also destroys ozone in the stratosphere, which is bad because that lets too much of the Sun’s UV light through.

{ loosely adapted from NOx, Wkipedia }
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Smog

Smog is air pollution that reduces visibility. The term was first used in the early 1900s to describe a mix of smoke and fog. The smoke usually came from burning coal. Smog was common in industrial areas, and remains a familiar sight in cities today.

Smog before and after the EPA

Today, most of the smog we see is photochemical smog. Photochemical smog is produced when sunlight reacts with nitrogen oxides and at least one volatile organic compound (VOC) in the atmosphere.

Nitrogen oxides come from car exhaust, coal power plants, and factory emissions.

VOCs are released from gasoline, paints, and many cleaning solvents.

When sunlight hits these chemicals, they form airborne particles and ground-level ozone—or smog.

Ozone can be helpful or harmful. The ozone layer high up in the atmosphere protects us from the sun’s dangerous ultraviolet radiation. But when ozone is close to the ground, it is bad for human health. Ozone can damage lung tissue, and it is especially dangerous to people with respiratory illnesses like asthma. Ozone can also cause itchy, burning eyes.

Smog is unhealthy to humans and animals, and it can kill plants. Smog is also ugly. It makes the sky brown or gray. Smog is common in big cities with a lot of industry and traffic.

Cities located in basins surrounded by mountains may have smog problems because the smog is trapped in the valley and cannot be carried away by wind. Los Angeles, California, and Mexico City, Mexico, both have high smog levels partly because of this kind oflandscape.

{ from http://education.nationalgeographic.com/education/encyclopedia/smog/?ar_a=1 }

Beijing, China: The air on a day after rain (left) and a smoggy day (right)
{ http://en.wikipedia.org/wiki/Smog }

Beijing_smog_comparison_August_2005

{ image below is from http://www.ozoneexpertsblog.com/blog/2011/11/why-should-i-use-ozone.html }

Smog

Global warming and greenhouse gases

Greenhouse gases and the greenhouse effect

Global warming has not stopped

Was there a pause in the rate of air temperature rise?

The ozone layer, UV light, and CFCs

https://kaiserscience.wordpress.com/earth-science/weather/ozone-layer-and-cfcs/

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Environmental Protection

The following is from Regentsprep.org Environmental Protection

USA EPA

In 1970, then President Richard Nixon and Congress worked together to establish the Environmental Protection Agency – EPA – responding to growing public demand for cleaner water, air and land.

Prior to the creation of the EPA the government had no concerted way to regulate and oversee the environmental impact of industrial pollution/emissions.

The EPA has been charged with setting national standards for: emissions and pollutants, issuing permits, overseeing cleanup efforts for past pollution damage.

The EPA works with industry to curb pollution through voluntary pollution control efforts and energy conservation efforts.

Learning Standards

Massachusetts Curriculum FrameworksMassachusetts Curriculum Frameworks

Grades 6–8: Overview of Science and Engineering Practices

Examine and interpret data to describe the role human activities have played in the rise of global temperatures over time; construct, analyze, and/or interpret graphical displays of data and/or large data sets to identify linear and nonlinear relationships; distinguish between causal and correlational relationships in data; consider limitations of data analysis.

8.MS-ESS3-5. Examine and interpret data to describe the role that human activities have played in causing the rise in global temperatures over the past century.

High School. HS-ESS3-5. Analyze results from global climate models to describe how forecasts are made of the current rate of global or regional climate change and associated future impacts to Earth systems.
Clarification: Climate model outputs include both climate changes (such as precipitation and temperature) and associated impacts (such as on sea level, glacial ice volumes, and atmosphere and ocean composition).

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas

Disciplinary Core Ideas

LS2.C: Ecosystem Dynamics, Functioning, and Resilience
A complex set of interactions within an ecosystem can keep its numbers and types of organisms relatively constant over long periods of time under stable conditions. If a modest biological or physical disturbance to an ecosystem occurs, it may return to its more or less original status (i.e., the ecosystem is resilient), as opposed to becoming a very different ecosystem. Extreme fluctuations in conditions or the size of any population, however, can challenge the functioning of ecosystems in terms of resources and habitat availability. (HS-LS2-2),(HS-LS2-6)

Moreover, anthropogenic changes (induced by human activity) in the environment—including habitat destruction, pollution, introduction of invasive species, overexploitation, and climate change—can disrupt an ecosystem and threaten the survival of some species. (HS-LS2-7)

Cross Cutting Concepts

Cause and Effect:  Empirical evidence is required to differentiate between cause and correlation and make claims about specific causes and effects. (HS-LS2-8),(HS-LS4-6)

Scale, Proportion, and Quantity: The significance of a phenomenon is dependent on the scale, proportion, and quantity at which it occurs. (HS-LS2-1)

Using the concept of orders of magnitude allows one to understand how a model at one scale relates to a model at another scale. (HS-LS2-2)

Stability and Change: Much of science deals with constructing explanations of how things change and how they remain stable. (HS-LS2-6),(HS-LS2-7)

Next Generation Science Standards

HS-ESS3-4. Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.

HS-ESS3-5. Analyze geoscience data and the results from global climate models to make an evidence-based forecast of the current rate of global or regional climate change and associated future impacts to Earth’s systems.
[Clarification: Examples of evidence, for both data and climate model outputs, are for climate changes (such as precipitation and temperature) and their associated impacts (such as on sea level, glacial ice volumes, or atmosphere and ocean composition).]

[Assessment Boundary: Assessment is limited to one example of a climate change and its associated impacts.]

HS-ESS3-6. Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.

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