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Wetlands 1: Marshes and Mud Flats and Bogs, Oh My!

WetlandsIf you live in the Northeast, Midwest, or along the Pacific coast, don’t be surprised if you see small ponds or lakes appear suddenly in your neighborhood during the spring. These are vernal pools – wet areas that form in low-lying zones where water collects in winter and spring. By summer the water evaporates, leaving the site damp or dry through autumn.

Vernal pools are seasonal wetlands, but many other types occur year-round across North America. Wetlands are areas where the soil is always or usually saturated with water, so they support plants and animals that are adapted to moist conditions. Bogs, marshes, mud flats, swamps, and estuaries are all forms of wetlands.

They don’t always look impressive (that’s one reason why many wetlands have been filled in or paved over), but wetlands play important ecological roles. They serve as nurseries and feeding grounds for many types of fish, mammals, and birds; filter pollutants and sediments out of water; and protect coastlines from the impact of storms.

To put wetlands into context, unit 8 of The Habitable Planet describes Earth’s water resources, how they move through the global water cycle, and threats to fresh water. Section 3 shows how the world’s freshwater resources are distributed between ground and surface waters. Section 8 discusses how pollutants–including biological organisms, chemicals, and sediments–impair water quality.

Wetlands can serve as settings for biology, ecology, or chemistry classes. In  Journey North, learn how wetlands are especially important feeding and nesting zones for whooping cranes. Read about what the birds eat, track their migration stops, and discuss how human actions are affecting the wetlands that these birds use. For a biology or chemistry class, see unit 4, section 7 of Rediscovering Biology, “Microbial Diversity,” for a discussion of how archaea break down carbon in swamps. And the interactive on “Garbage – Solutions for Sewage” offers a case study of Arcata, California’s wastewater management system, which includes artificial (constructed) wetlands that improve water quality through physical and chemical processes.

And if you live in a region where vernal pools form, the Association of State Wetland Managers has news, videos, and links to additional materials about these seasonal spring wetlands and the many species that live in them.

Look for post #2 next Wednesday (April 23) with more ideas for teaching about wetlands during American Wetlands Month in May!

The Smoking Gun of Cosmic Inflation

Physics_cosmic inflationYoung Alvy Singer got it partially right.The main character in the Woody Allen film Annie Hall explained why he gave up doing his homework: “Well, the universe is everything, and if it’s expanding, someday it will break apart and that would be the end of everything!”

The Harvard-Smithsonian Center for Astrophysics recently announced that the BICEP2 collaboration (its research partnership with Caltech/JPL, Stanford/SLAC, and UMinn) had observable evidence to prove how this expansion got started from the point of the Big Bang: through cosmic inflation.  “These results are not only a smoking gun for inflation, they also tell us when inflation took place and how powerful the process was,” said Harvard theorist Avi Loeb. Physics for the 21st Century at Learner.org provides explanatory text, images, and video to help you make sense of the discovery and the theories that led to it.

Start by looking at the text for unit 4 on String Theory to understand how cosmic inflation is responsible for the structure of the universe as it is today.

Short of running backwards the movie of all time, the Cosmic Microwave Background, or CMB, is the best link to the first moments of the development of matter. The CMB is the detection of the relic gas radiating from the Big Bang. Astrophysicists also have been able to find in their data the finger prints of gravitational waves, which are described as ripples in space-time. Dr. Nergis Mavalvala of MIT explains the relation of gravitational waves to today’s astronomy. Watch the segment of the video Gravity, beginning at 14:30 through 16:21, to learn about how these waves are propagated.

The final unit looks in on the work of two astrophysicists, Robert Kirshner and David Spergel, both trying to determine the cause of the acceleration of the expansion of the universe and whether there may be an end to it. Their chief suspect is Dark Energy. Their research may assuage Alvy Singer’s concern about the universe ultimately breaking apart.

Citizen Science II: Making CS more visible

science students clip art(See Part I: From winter into spring here). Citizen science is a fast-growing field, and some practitioners would like to see it become a recognized scientific method. A panel at last month’s American Association for the Advancement of Science (AAAS) annual conference in Chicago considered how to move toward “a science of citizen science.” Panelists agreed that citizen science is producing valuable information on a wide range of issues, and that it is time to start analyzing CS projects and comparing what works across different scientific disciplines.

‘Who makes knowledge? Where and how does it happen? As citizen science matures and becomes more prevalent and professionalized, researchers want to understand these questions,” said Caren Cooper, a research associate at the Cornell Laboratory of Ornithology, which manages multiple citizen science projects.

In Cooper’s view, scientists value and trust data from citizen science projects. CS data is appearing with growing frequency in studies, and authors typically do not qualify it or treat it as inferior to other data sources. By the same token, though, they often do not identify it as coming from citizen science projects. That makes it hard to quantify how many researchers are using citizen science data or what impact it has made.

The Citizen Science Association, founded in 2012, hopes to make CS more visible and professional by launching a journal and spotlighting best practices in citizen science. Those steps should make citizen science more visible and help new projects attract funding.

Several speakers at AAAS discussed the challenges of managing citizen science projects, such as encouraging participants — especially in online projects — and keeping them engaged. Typically, most participants in large-scale CS projects do relatively little work and make small contributions, while much of the input comes from a small group of more engaged players – a pattern that probably is familiar to many teachers.

Like classroom teachers, CS project managers are trying to create learning communities. But their relationships with participants are much more distant and temporary than classroom teachers’ interactions with students. Even so, panelists said, some players in citizen science projects have called their experience transformative and said that participating helped them realize they were good at science. In some cases, participating in a citizen science project had steered people toward studying specific science topics in school. Practitioners would like to know how to make that happen for more participants.

The White House honors a dozen scientists as “Champions of Change” for creating citizen science initiatives in fields ranging from neuroscience to paleontology. As scientists grapple with challenging research problems, teachers can expect that there will be even more opportunities for students to help them.

For ways to get your students involved in citizen science projects, see our previous post Citizen Science I: From winter into spring.

Citizen Science I: From winter into spring

I see youMarch started off with yet another wave of snow, ice and Arctic air across much of North America. But even in regions where winter has been colder than average, like New England and the Midwest, the natural world is transitioning from winter to spring. And that shift offers many science teaching opportunities.

Even if your town is still covered with snow, you can still observe signs of seasonal change, such as lengthening daylight hours or the passage of animals and birds migrating north. Through Annenberg Learner’s Journey North (JN) program, teachers can register their classes and share their findings with other observers across North America. Choose a species that migrates through your region – for example, hummingbirds along the Gulf Coast, or robins across much of the eastern United States. Where and when have they been seen locally in recent years? Is that pattern holding this year? If you see something different, what might be the cause?

Or use the phenology checklist to track changes in sunlight and temperature, and correlate those factors with the emergence of plants and animals locally. Compare your students’ observations with reports from other regions. Why is the timing of spring different across North America? Journey North’s teacher resource page offers other standards-based classroom lessons and advice from teachers who have used JN at different grade levels.

Journey North is also a way to introduce students to the concept of citizen science. Citizen science projects come in many forms, but typically pair volunteers with scientists to collect scientific data. The central idea is that anyone can make observations that will help researchers tackle large-scale questions about the natural world.JNheader102007

When students participate in citizen science projects, they engage in many activities that are central to the scientific process: they observe phenomena, collect data, summarize it, and have opportunities to compare their data with others’ findings and interpret the results. See Annenberg’s course on The Science of Teaching Science for more discussion of how these activities support scientific learning.

Traditional citizen science projects ask participants to collect data in the field for analysis by scientists. One well-known example is the Christmas Bird Count (CBC), administered by the National Audubon Society, which launched in 1900. Thousands of CBC volunteers, often working in teams, count birds in designated zones every year in late December across North America and beyond. Researchers have used the enormous CBC database on bird populations to identify species that are declining or threatened, and develop strategies for protecting them.

Over the past decade another approach to citizen science has evolved, in which scientists ask participants to search through large data sets and sort or process information. Using GalaxyZoo, an astronomy project, view images of galaxies and classify them according to their shapes. More than 150,000 people contributed classifications during the project’s first year.

Games are also becoming a popular way to draw participants into scientific tasks. One of the most popular is Foldit, which has also attracted hundreds of thousands of participants since it debuted in 2008.  Foldit players solve puzzles by folding video images of proteins. To earn high scores, they have to understand basic principles of protein structure, which are explained in introductory challenges. Scientists at the University of Washington developed the program to see whether humans’ puzzle-solving intuitions could help predict the structure of proteins – a key task in biology and medicine. Players can also design new proteins that could prevent or treat diseases.

There is no single directory for citizen science research, but many projects are easy to find online. For a sampling, see the listings at the Cornell Laboratory of Ornithology (birds and bird habitat); Zooniverse (astronomy, climate, and biology); Scientific American magazine’s database (many disciplines); and Scistarter (many disciplines), a website that connects volunteers with citizen science projects. And don’t forget to check out Learner.org’s own Journey North program!

How are you getting your students involved in citizen science projects?

Solving Real-World Problems: National Engineers Week, February 16-22

President Nixon visits the Manned Spaceflight Center to award the Presidential Medal of Freedom to the Apollo 13 Mission Operations Team

President Nixon visits the Manned Spaceflight Center to award the Presidential Medal of Freedom to the Apollo 13 Mission Operations Team

When small children hear the word “engineer,” they may picture someone driving a locomotive. National Engineers Week, which runs from February 16-22, is an opportunity to show them another meaning of the word. Engineers use math and science to solve practical problems and invent new products. And older students should be interested to learn that engineering is a growing field with a diverse array of high-paying jobs.

For a sampling of the many different specialties that make up this field, check out the overviews at DiscoverE of disciplines such as aerospace, electrical, and civil engineering. This survey offers examples that draw on all of the sciences, and can be discussed in combination with course units on Learner.org. For example:

  • Unit 5 of Science in Focus: Energy explains how humans get the energy that they need to survive from food. Agricultural and biological engineers help people produce enough food to meet demand by designing farm equipment and innovative ways to grow food, such as hydroponic systems. They also design farming equipment, help farmers find new ways to plant and harvest, and develop ways to keep food fresh and safe while it is stored and transported to markets.
  • Unit 8, section 4 of The Habitable Planet describes how water moves through the ground and interacts with soil and rock. What happens if chemicals are spilled and seep down into groundwater that communities use for drinking? Environmental engineers know the chemical properties of pollutants and can calculate where they will flow and how quickly they will move. They also monitor and protect water supplies to keep them safe.

Sometimes engineers have to invent completely new solutions to problems that have never been seen before. One famous example was the Apollo 13 flight in 1970, which was dramatized in the movie Apollo 13. During a mission to the moon, an oxygen tank on the spacecraft exploded and ruptured, leaving the crippled flight with limited electricity and oxygen. The crew and flight controllers on the ground had to invent a new plan for getting the astronauts back to Earth.

“All we had to work with was time and experience,” flight director Gene Kranz wrote later. Engineers had to invent many new procedures and improvise a system for filtering carbon dioxide out of the spacecraft’s cabin so that the astronauts could breathe. After the successful return, President Nixon awarded the astronauts and flight operations team the Presidential Medal of Freedom. “We often speak of scientific ‘miracles’ – forgetting that these are not miraculous happenings at all, but rather the product of hard work, long hours and disciplined intelligence,” the award citation stated.

Inspire your students to become engineers with these examples and more of the important work engineers do.

Crystal Clear: Celebrating the International Year of Crystallography

Chemistry_saltcrystalsWhat do diamonds, ice, sand, and table salt have in common? Like most solids, they have crystalline structures: they are made up of atoms or molecules arranged in a regular, repeating order. A century ago, scientists developed a technique called x-ray crystallography that made it possible to analyze the structure of crystalline solids. Since that time crystallography has become a key tool in many scientific fields, including mineralogy, medicine, archaeology, and food science. Twenty-three Nobel Prizes have been awarded for discoveries that relied on crystallography.

The United Nations and the International Union of Crystallography have proclaimed 2014 the International Year of Crystallography to educate people about this versatile technique, which is still relatively unknown to the general public. Since crystallography is widely used in many different scientific fields, this event offers a teaching hook for chemistry, physics, and biology classes.

Annenberg’s new chemistry course, Chemistry: Challenges and Solutions, unit 13, describes the chemical bonds that hold crystalline substances together, and the insight that launched the field of crystallography. British physicist William Henry Bragg and his son William Lawrence Bragg recognized that when a beam of X-rays was aimed at a crystal, planes of atoms within the crystal would diffract (scatter) the rays in patterns that could be used to map the crystal’s internal structure. The Braggs shared a Nobel Prize in 1915 for their work.

Physical Science, session 5, “Density and Pressure,” explains X-ray diffraction and how scientists can use it to reconstruct the size and shape of particles that are too small to be seen with the naked eye. X-rays make this kind of visualization possible because their wavelengths are short enough to interact with individual atoms of molecules.

Crystallography generated key insights in early medical research. Dorothy Crowfoot Hodgkin, a British chemist, used it to map the structures of insulin, penicillin, and vitamin B-12. In 1964 Hodgkin became the third woman to receive the Nobel Prize in chemistry, following Marie Curie and Irène Joliot-Curie. Another key advance occurred when researchers found ways to crystallize biological materials, such as proteins and DNA. In Annenberg’s Rediscovering Biology course, unit 2, “Proteins and Proteomics,” Ned David describes the rapid evolution of techniques for crystallizing proteins. Drug designers use crystallography to visualize the three-dimensional structure of a protein so that they can find the best place for a drug to bind snugly to the protein.

The invention of synchrotrons (large particle accelerators that generate intense light and x-rays) has furthered the growth of crystallography. For examples of crystallography’s diverse applications, see the web page for x-ray scattering research at Lawrence Berkeley Laboratory’s Advanced Light Source. The International Year of Crystallography’s learning page has images, video and audio clips, and links to other online resources about crystallography.   

How will you be teaching about crystallography in 2014?

Ways to teach about climate change (Part II of II)

HP_surface air increase(See Part I: Why should schools teach about climate change? here.) Teaching about climate change can be daunting: the science is complex, multi-disciplinary, and evolving quickly. But many key ideas about how Earth’s climate system works can be used to illustrate basic ideas in biology, chemistry, and physics.

For example, when biology students study how organisms adapt to their environments, teachers can introduce the idea that climate change is shifting many species’ ranges and altering the timing of seasonal events, such as the first flowering of plants in spring. When students study the carbon cycle in chemistry or earth science, teachers can point out that human activities are adding carbon to the atmosphere, and discuss how Earth’s atmosphere and oceans act as “sinks” for carbon.

What should students know about climate science? The National Oceanic and Atmospheric Administration (NOAA), America’s weather and climate agency, suggests that 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.

NOAA’s Climate.gov library breaks climate science literacy down into key principles – how energy flows from the sun to Earth, the interactions among Earth’s systems that regulate climate, factors that make climate variable, and the impacts of human actions. The site also offers visuals, videos, experiments demonstrating key concepts, and interactive tools.

Many climate change concepts can be explored through projects, which give students opportunities to apply ideas – and often, to see the impacts of their personal choices. Clarkson University worked with the New York State Energy Research and Development Authority to develop ten project-based climate modules on topics ranging from the greenhouse effect to the climate impact of a “dream vacation.” Lessons target grades 6-8 but can be adapted for other levels.

School groups can also join ongoing citizen science projects across the United States, many of which focus on climate-related events. Three national examples:

  • Journey North, from Annenberg Learner, is a free program that uses observations from students and citizen scientists to track wildlife migration and seasonal change. Teachers can use Journey North to help students learn which indicators of changing seasons are unaffected by climate change (such as the length of daylight at a given time of year) and which are impacted (such as the first arrival of migratory birds in spring).
  • Project Budburst, sponsored by the National Science Foundation, tracks how plant species are responding to local, regional, and national climate changes. Participants submit ongoing or one-time reports on specific plants. The project offers classroom resources for grades K-12.
  • Project FeederWatch, run by the Cornell Laboratory of Ornithology, is a project that surveys bird populations in back yards, parks, and nature centers across North America from November through April. Researchers use the data to track changes in bird species’ winter abundance and distribution.

The Habitable Planet series from Annenberg Learner also provides tools to teach about climate change. The series, presented in videos and an online textbook, explains fundamental environmental science concepts that support an understanding of climate change. Key units include “Atmosphere,” which describes Earth’s energy balance and the role of greenhouse gases in the atmosphere; “Oceans,” which shows the important role that oceans play in absorbing carbon; and “Energy Challenges,” which explains how fossil fuels were created and describes the pros and cons of these and other energy sources. “Earth’s Changing Climate” ties these issues together to show how greenhouse gas emissions from human activities are altering Earth’s energy balance. (Note: for the most current international assessment of climate change science and impacts, see post here from October 30.)

Why should schools teach about climate change? (Part I of II)

EarthAs new findings about global climate change make news, some science teachers are caught between a rock and a hard place. Hundreds of scientists who contributed to the most recent international assessment of climate change science say they are 95 percent certain that human activities are the cause of global warming in recent decades. That’s the same level of confidence experts have that smoking cigarettes causes cancer.

But over the past five years, more than a dozen bills have been introduced at the state level that would allow teachers to present material challenging that scientific consensus. Recent reports* have spotlighted a textbook review panel in Texas, which includes several members who have questioned evolution and climate change science, and is scheduled to vote this month on an approved list of biology textbooks. (Publishers have not altered texts in response to comments from these reviewers.)

The Next Generation Science Standards offer a counterpoint. The standards recommend introducing students to global climate change in middle school as students learn about weather and climate. High school students are expected to learn about using models to understand Earth’s climate system, and to make evidence-based forecasts of the current rate of global climate change and associated impacts.

The high school standards also link global climate change to human sustainability. Students who understand these concepts should be able to explain how human activities are affecting relationships among Earth systems, such as the atmosphere, hydrosphere, and biosphere, and to think critically about solutions that could reduce human impacts on natural systems.

Twenty-six states helped develop the standards, and eight states have already adopted them: California, Kansas, Kentucky, Maryland, Rhode Island, Vermont, Delaware, and Washington. Kentucky’s Gov. Steve Beshear overruled a legislative subcommittee that voted against adopting the standards, which had already been endorsed by the state Department of Education and Board of Education. “My job . . . is to make sure our children are college and career ready when they leave high school. Part of getting them college and career ready is to make sure they study all the different scientific theories [that] are out there that everybody else in the world will be studying,” Beshear said.

By emphasizing critical thinking and investigation, the Next Generation standards are designed to help students understand how scientists develop and test ideas, and to think across disciplines. Climate change is a topic that is well suited to this approach. It draws on multiple fields of science: for example, we need some basic physics to understand atmospheric circulation, while ocean acidification is a chemical process. And scientific understanding of climate science and climate change impacts is evolving in real time today, as researchers test theories and refine models that help us understand past climate shifts and predict what may happen in coming decades.

*Post update: On November 22, 2013, the New York Times published a new piece on the ongoing controversial textbook process in Texas. See the article here.

(Stay tuned next Wednesday, November 20, for Part II: Ways to teach about climate change.)

World population: more people, more urban (Part II)

(Part II of II updates to The Habitable Planet)

HP_ChinaposterSeven billion and counting

Global population growth is a central issue in environmental studies. More people on Earth means more demand for food, water and other natural resources. Extracting and using those resources creates air and water pollution and generates waste.

Unit 5 of The Habitable Planet, “Human Population Dynamics,” describes patterns of population growth and the relationship between population and environmental impacts. When The Habitable Planet was released in 2007, world population totaled roughly 6.7 billion, and the United Nations projected that it would be just over 9 billion by 2050. Since that time, the world has reached several new milestones.

Late in 2011 world population reached 7 billion, just twelve years after it had topped the 6 billion mark. The U.N.’s latest estimates, released in mid-2013, project that global population will exceed 8 billion by 2025, and that in 2050 it could total up to 9.6 billion. These numbers are higher than earlier estimates, mostly because the U.N. used new methods to estimate current fertility rates in a group of African countries where fertility remains high (Angola, Cameroon, the Democratic Republic of Congo, Ethiopia, Mozambique, Niger, and Nigeria).

As countries modernize, life expectancies improve, and women gain access to contraception and education, fertility rates typically decline in a pattern known as the demographic transition, which is described in section five, unit five of The Habitable Planet. But this shift is not automatic, and U.N. officials warned that “additional substantial efforts” may be needed to help make it happen in countries where fertility is still high.

Bright lights, big cities

Another population trend with major environmental impacts is global urbanization. In 2007 the share of world population living in cities topped 50 percent for the first time in history, and people continue to move from total to urban areas. According to current U.N. estimates, by 2050 more than two-third of the world’s population will live in cities. Most of this movement will take place in the developing world (industrialized countries have already largely urbanized). By 2025 most of the world’s megacities (urban areas with at least 10 million residents) will be in developing countries. Cities on track to join this club include Lagos, Nigeria; Chennai, India, and Shenzen, China.

Students may have trouble understanding why so many people in developing countries move from rural areas to cities, where they often end up living in slums with contaminated air and water and working in unsafe conditions. The collapse of the Rana Plaza building in a suburb of Dhaka, Bangladesh earlier this year, which killed more than 1,100 garment workers, spotlighted the difficulty that millions of the world’s poor face as they try to find a toehold in fast-growing cities.

But in spite of conditions like these, demographers and urban scholars contend that cities offer much better economic opportunities than rural areas. Many students may have seen the 2008 Academy award-winning film Slumdog Millionaire, which follows its fictional hero, Jamal Malik, through his childhood and teenage years in Mumbai, India. Jamal is orphaned, leaves home and faces horrifying exploitation, but finds new opportunities after every escape. Setting aside the only-in-a-movie resolution (Jamal wins wealth and fame on a game show and is reunited with the love of his life), students can discuss why Jamal returns to Mumbai and what his life might have been like if he had tried to make a living as a farmer instead. They also can consider how improvements like affordable housing, clean water supplies, and better public transit would improve conditions for people in megacities like Mumbai and give them more opportunity to create stable, healthy lives.

Questions for discussion:

  • What are the most significant environmental impacts of an average citizen’s lifestyle in one of the African countries where population growth rates remain high? How do they compare with the impacts of an average citizen in the United States? What does this comparison tell you about the relationship between population and the environment?
  • UN-Habitat, a United Nations agency, defines slums as areas that lack at least one of these features:
    • Durable housing
    • Adequate living space (no more than three people sharing a room)
    • Access to clean drinking water
    • Access to improved sanitation (toilets or latrines that separate human waste from contact with water sources)
    • Secure property rights (e.g., rights and legal protection for tenants)

    Which of these resources do you think are most important? What other attributes might also distinguish slums from adequate living places?

Climate change: A new global report finds clear human influence (Part I)

(Part I of II updates to The Habitable Planet)

© Greenpeace/Beltra. Polar bears hunt their prey from Arctic sea ice, so climate change threatens their survival.

© Greenpeace/Beltra.
Polar bears hunt their prey from Arctic sea ice, so climate change threatens their survival.

New warming milestones

Late last month, the Intergovernmental Panel on Climate Change (IPCC) released the first volume of its latest report on the state of Earth’s climate. The IPCC, an international scientific body, was created by the United Nations Environment Programme and the World Meteorological Organization in 1988 to advise national governments about climate science and potential impacts from global warming.

The new report finds that Earth’s climate is unequivocally warming, and that it is extremely likely that human activities have been the “dominant cause” of observed warming since the mid-20th century.[1] The IPCC defines “extremely likely” as equivalent to 95 percent certainty. Its last assessment in 2007 called it 90 percent likely that humans had caused observed climate change in recent decades.

As Unit 12 of The Habitable Planet, “Earth’s Changing Climate,” illustrates, Earth is constantly receiving energy from the sun in the form of visible light and radiating some of that energy back into space as heat. Human activities are increasing the concentrations of greenhouse gases, or GHGs (substances that absorb heat) in Earth’s atmosphere, warming the planet’s surface. Since The Habitable Planet was released in 2007, world GHG concentrations have continued to rise, and climate change impacts have become more severe.

One widely-reported milestone occurred in the spring of 2013, when the average concentration of carbon dioxide (CO2) in Earth’s atmosphere reached 400 parts per million (ppm). [2] Carbon dioxide is the main driver of human-induced climate change, and is generated mainly from burning fossil fuels. In the pre-industrial era, atmospheric CO2 concentrations averaged about 280 ppm. In 2005, when the IPCC published its fourth global climate assessment report, they had reached 379 ppm. According to atmospheric scientists, concentrations of 400 ppm probably last occurred several million years ago, when the planet was far warmer than today.[3]

In its new assessment report, the IPCC estimates that if atmospheric concentrations of CO2 reach double the pre-industrial level (a marker the world is on track to reach by mid-century at current rates), global average temperatures would increase by 2.7 to 8.1 degrees Fahrenheit.[4] For comparison, the world warmed by about 1.4 degrees between 1880 and 2012.[5] Some of the most likely impacts of warming include:

  • More intense and frequent extreme precipitation events (rain and snow) in mid-latitudes and tropical regions;
  • Continued melting and thinning of Arctic sea ice and decreasing spring snow cover in the Northern hemisphere; and
  • Faster sea level rise than the changes that have already been observed in recent decades as ice sheets melt and oceans warm, totaling 21 to 38 inches by 2100 if emissions remain high.

Reaching scientific judgments

IPCC reports represent consensus views of hundreds of scientists who review current findings from many disciplines. Working Group I, which produced this volume, focuses on the state of climate science and draws from fields including meteorology, oceanography and ecology. In total, 209 lead authors, 50 review editors from 39 countries contributed to this volume, which cites some 9,200 scientific publications. Reports from Working Group II (on climate change impacts, adaptation, and vulnerability) and Working Group III (on mitigation, or actions to slow climate change) are scheduled to appear in 2014.

IPCC reports are data-heavy and can be challenging to sift through because they consider what will happen under a range of different emissions scenarios. But students can learn about climate change just from seeing how the IPCC approaches its task. Measuring climate change is a scientific challenge, but governments also need to know how impacts such as rising sea levels will affect their countries, and how much difference actions such as shifting away from fossil fuel will make over a given time period. The IPCC’s summary of areas covered by its working groups shows how many specialties have something to contribute to this effort.

The IPCC’s process also illustrates how scientists come to judgments about large-scale problems. Why does the panel review thousands of individual studies to make estimates for these reports? Why does it use multiple scenarios with high, medium and low GHG emissions to project how climate change may progress? Why do the authors assign values such as “virtually certain” and “very likely” to their estimates, as well as numerical probabilities? A look at the IPCC can show students that finding solutions to complex questions like climate change is a slow, iterative process – but one that the world can’t afford to ignore.

Questions for discussion:

  • Which climate change impacts are likely to have major effects where you live? (The IPCC report describes many projected impacts, including sea level rise, changes in amounts and timing of rain and snowfall, and decreasing snowpack in cold regions.)
  • The United States has experienced a number of extreme weather events in the past several years, including Hurricane Sandy in the fall of 2012, record-scale flooding in Colorado’s Front Range earlier this fall, and a multi-year drought across much of Texas. Does evidence suggest that climate change may have contributed to these events? How could climate change amplify a hurricane, rainstorm or drought?

(Look for Part II, “World population: more people, more urban,” on Wednesday, November 6.)