Science Data Exploration

Earth as a system,
from Investigating Earth Systems

Learning about the Earth as a system provides a wide range of opportunities for students to explore various sets of data to better understand the individual components — the atmosphere, the hydrosphere, the geosphere, the biosphere — and how they are interconnected. Throughout our study of Earth science, I give students multiple occasions to interpret, analyze, and evaluate various Earth system data. Over the years, I've built up a collection of simple, useful datasets for students to manipulate using graphing software such as Microsoft Excel, Create A Graph, or Google Spreadsheet. Here is a sampling of some of these data.

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The Atmosphere

Each year, we begin our study of the Earth system within the atmosphere—the gaseous envelope surrounding our planet which has evolved from and interacts with the other "spheres" of the Earth system. Investigating the composition of Earth's atmosphere is thus a logical first step in our data exploration.

Composition of Earth's Atmosphere

Data source: Wallace, J.M. and Hobbs, P.V., 1977, Atmospheric Science—An Introductory Survey

Compound	Percent
Nitrogen	78.08
Oxygen	20.95
Argon	0.93
Trace Gases	0.04

It is useful to refer back to this set of data often during our climate studies, reminding students that the tiny fraction of trace gases are responsible for the greenhouse effect and instrumental in maintaining the balance in Earth's energy budget.

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The Hydrosphere 

As we move from the atmosphere to the hydrosphere, students explore how water is distributed across our planet as well as examine the composition of ocean water. When examining global water distribution, it is useful to have students consider how much of this water is readily available for daily human use. Additionally, this set of data provides an opportunity for students to learn how to create "pie-of-pie" graphs to best show data that has a large range of values.

Global Water Distribution

Data source: Gleick, P. H., 1996, Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp. 817-823

Water Source	Percent
Oceans, Seas, and Bays	96.5
Ice Caps, Glaciers, and Permanent Snow	1.74
Groundwater (fresh)	0.76
Groundwater (saline)	0.94
Soil Moisture	0.001
Ground Ice and Permafrost	0.022
Lakes (fresh)	0.007
Lakes (saline)	0.006
Atmosphere	0.001
Swamp Water	0.0008
Rivers	0.0002
Biological Water	0.0001

"Have you ever had a mouthful of ocean water?" is a great question to ask students when introducing the next set of data. It elicits an immediate "Ewww!" response and primes students to think about the compounds contained in that mouthful of water and how they got there.

Composition of Ocean Water

Data source: National Science Teachers Association, 1992, Project Earth Science, Physical Oceanography

Element	Percent
Oxygen	85.7
Hydrogen	10.8
Chlorine	1.9
Sodium	1.05
Magnesium	0.135
Sulfur	0.0885
Calcium	0.04
Potassium	0.038
Bromine	0.0065
Carbon	0.0028
Other	0.001

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The Geosphere 

When we transition to our studies of the geosphere, students take a look at data comprising the Earth's crust. The composition of Earth's crust shows many commonalities with the composition of ocean water data above. It is useful to have students compare and contrast the two sets of data. It is quite a challenging discussion when students are asked to explain how the Earth's crust can be nearly 50% oxygen; it helps reinforce the meaning of "compound."

Composition of Earth's Crust

Data source: Glencoe Earth Science, 1999

Element	Percent
Oxygen	46.6
Silicon	27.7
Aluminum	8.1
Iron	5.0
Calcium	3.6
Sodium	2.8
Potassium	2.6
Magnesium	2.1
Other	1.5

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The Solar System 

Finally, as we move from the safety of our home planet and journey into the rest of the solar system, it is interesting to ponder the composition of the solar system itself. Once again, it is useful to compare and contrast the similarities and differences among the various sets of data ("What's up with all that hydrogen?"). It is also interesting to ponder how knowledge of Earth's composition can help scientists understand and make sense of the compositions of other objects in our solar system.

Composition of the Solar System

Data source: Mineral Information Institute, Golden CO, 2002, http://www.mii.org

Element	Percent
Hydrogen	91.04
Helium	8.81
Oxygen	0.08
Carbon	0.03
Neon	0.01
Nitrogen	0.01
Magnesium	0.004
Silicon	0.003
Iron	0.003

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With an endless variety of Earth system data available, students have many opportunities to deeply engage in scientific analysis and interpretation as well as develop an appreciation for the Earth as an interconnected system. If you use other interesting datasets, please feel free to share them in the comments...

My Thanks

For enriching my life as a scientist and educator, I am eternally grateful…

• NASA, NOAA, and USGS — for providing invaluable science resources
• NSTA — for championing scientific literacy
• Free and open internet — for democratizing information access
• My science heroes — for inspiring me with your words
• My teaching colleagues — for being courageous allies and supportive friends
• My students — for nurturing the planet and seeking to understand the universe

Happy Thanksgiving to all!

Global Climate Change Article Analysis

Image credit: IAN Symbol Libraries

To finish our annual study of global climate change, I ask students to survey a variety of scientific literature outlining the impacts of climate change around the world and to interpret their findings. Students need the opportunity to engage with the scientific literature around global climate change in order to develop their own sense of climate science literacy. The US Global Change Research Program sums up the importance of climate literacy in the following guide, Climate Literacy—The Essential Principles of Climate Sciences:

"Climate Science Literacy is an understanding of your influence on climate and climate’s influence on you and society. A climate-literate person:

• understands the essential principles of Earth’s climate system,
• knows how to assess scientifically credible information about climate,
• communicates about climate and climate change in a meaningful way, and
• is able to make informed and responsible decisions with regard to actions that may affect climate."

I provide students with a wide sampling of scientific articles that document climate change and climate change impacts from around the world. Each student selects, reads, and summarizes the main scientific ideas from several of these articles, then chooses one article to interpret in more detail. In the final analysis, students create a labeled diagram that illustrates the main scientific ideas from their chosen article and explains the connection between the science and the climate change impacts.

For most students, this is the first time they have engaged in a formal literature review of scientific material, thus time and support is provided to help students dissect these articles efficiently. At our school we use a Mark-It-Up reading strategy, which helps students break down complex texts into the comprehensible essentials. Students write their "mark-it-up" notes on stickies and place these stickies around the room next to their article's placard. All students visit and review the stickies created by other students before drafting their final analysis.

For the articles themselves, I keep my eyes open for timely and relevant stories from reputable and fairly unbiased science sources such as BBC Science, National Geographic, NPR, NOAA, NASA, etc. The articles are usually no more than two pages in length, span a range of teenage reading levels, are scientifically-based with data and evidence, and encompass a wide range of climate impacts around the planet. A few of these articles are provided in the links at the end of this post.

As mentioned in my previous post, my greatest hope is that my students develop an appreciation for science so that they can make logical and informed decisions based on data and evidence, not hype and hot air.

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A Sampling of Climate Change Articles:

• BBC, Alien Invaders: The Next Generation
• Boston Globe, Scientists Say Climate Change Could Make Coffee and Chocolate Endangered Foods
• NOAA, Life of an Air Flask
• NOAA News, NOAA Greenhouse Gas Index Continues Climbing
• NPR, Climate Change Presents a Burr for Coffee Growers
• NYTimes, Carbon Detectives Are Tracking Gases in Colorado

Global Climate Change 101

One of the most troubling aspects of the global climate change "debate" is how poorly those who deny climate change understand the basic physics and chemistry of Earth's atmosphere. As we study global climate and climate change in the classroom each year, I strive to help students understand the basic scientific principles of Earth's atmosphere first, then present students with the opportunity to work with some of the global climate data. My students are afforded the privilege to develop their own conclusions about global climate change based on the data and evidence that scientists have collected.

The Greenhouse Gases

Our study of climate change begins with a look at the greenhouse gases and the greenhouse effect. When first asked, students unsurprisingly respond that the greenhouse effect is a "bad thing," exhibiting their imperfectly developed understanding of this natural phenomenon. I must often confront this and other types of misconceptions in my science classroom, thanks mainly to the disinformation that students have been exposed to through television media.

The greenhouse effect refers to the ability of Earth's atmosphere to retain additional heat energy because of the presence of various greenhouse gases, such as water vapor and carbon dioxide. The greenhouse effect is a wholly natural phenomenon; without it, Earth's average temperature would be 33°C lower than it is now, and the planet would be completely frozen. No greenhouse effect means no liquid water, which means no plants, which means no life.

So, this natural greenhouse effect is truly a good thing for our planet. But what happens when the greenhouse effect is altered, by adding additional greenhouse gases to Earth's atmosphere? Any change in the composition of Earth's atmosphere will alter its chemistry and add imbalance to Earth's energy budget. (Earth's energy budget is a balance of energy: solar energy from the Sun flows into Earth's atmosphere, is converted to infrared heat energy by the atmosphere, clouds, and surface of the Earth, which eventually flows back into space.) The Earth system will respond to changes in atmospheric chemistry through a variety of feedback mechanisms, but ultimately the physics dictates that increased greenhouse gases create a warmer planet.

There are four major, naturally-occurring greenhouse gases in Earth's atmosphere: water vapor, carbon dioxide, methane, and nitrous oxide. As mentioned above, these gases help create a favorable temperature on our planet. However, since the beginning of the Industrial Revolution back in the 1700's, humans have been adding more of these gases plus a host of new, synthetic gases to the atmospheric mix. The concentrations of almost all of these gases have been rising steadily for the past 200+ years.

Why are these invisible, colorless, odorless gases called "greenhouse gases?" What do they actually do in the atmosphere? This is an abstract concept for students to grasp, but it is imperative that they understand how these greenhouse gases behave to appreciate their role in maintaining an atmospheric heat balance. One excellent tool is the Greenhouse Effect simulation, part of the PhET collection developed by the University of Colorado. In this interactive simulation, students can see what happens when both solar energy from the Sun and infrared heat energy from the Earth interact with various gaseous molecules present in Earth's atmosphere. Molecules such as nitrogen and oxygen—the two most abundant molecules in Earth's atmosphere—allow both solar and infrared energy to pass through the atmosphere uninterrupted. In contrast, greenhouse gas molecules such as carbon dioxide and methane allow the solar energy to pass into the Earth's atmosphere freely, but disrupt the return flow of infrared energy back into space. Because of the greenhouse gases, the heat energy leaving planet Earth takes longer to return to space, thus warming the planet.

What data do we have to support and validate the phenomenon of the greenhouse effect? For the past 50 years, NOAA scientists have been collecting air samples all around the globe and measuring the concentrations of different greenhouse gases in our atmosphere. The concentrations are steadily increasing as humans add more of these gases into the atmosphere through the burning of fossil fuels and the release of gases through various industrial and agricultural processes. NOAA developed a simplified measure of the combined effects of these gases, the Annual Greenhouse Gas Index (AGGI). The AGGI provides mathematical values for each of the greenhouse gases that indicate their individual contribution to the greenhouse effect and the warming of our planet. My students graph the AGGI data each year and draw conclusions about the patterns and trends in the data. SPOILER ALERT: The data support greenhouse theory.

The approach to which I introduce students to global climate change is entirely evidence based. For any scientist to make claims or propose hypotheses about the natural universe (including planet Earth) requires that she or he follow the evidence trail. An overwhelming body of evidence, including laboratory testing, supports scientists' explanations about the greenhouse effect, the changes to the greenhouse balance, and its impacts on global climate. To ignore both the evidence and the rigorous science behind it presents a moral and ethical dilemma that I believe is irresponsible to the inhabitants of this planet—our only home in the universe. My greatest hope is that my students develop an appreciation for science so that they can make logical and informed decisions based on data and evidence, not hype and hot air.

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Classroom resources for global climate change studies:

• Greenhouse Gases 
• UCAR/NOAA Our Changing Climate
• NASA Earth's Energy Budget
• PhET Greenhouse Effect simulation
• NPR All About Carbon movies
• NOAA POET The Carbon Cycle
• NOAA Annual Greenhouse Gas Index (AGGI)
• NOAA Life of an Air Flask
• AGGI lab