#1 Global warming is caused primarily by carbon dioxide
from burning coal, oil and gas.
Certain gases that trap heat are building up in Earth's atmosphere.
The primary culprit is carbon dioxide, released from burning coal, oil
and natural gas in power plants, cars, factories, etc. (and to a lesser
extent when forests are cleared). The second is methane, released from
rice paddies, both ends of cows, rotting garbage in landfills, mining
operations, and gas pipelines. Third are chlorofluorocarbons (CFCs)
and similar chemicals, which are also implicated in the separate problem
of ozone depletion (see #5 below). Nitrous oxide (from fertilizers and
other chemicals) is fourth.
#2 Earth's average temperature has risen about
1 degree F in the past 100 years and is projected to rise another
3 to 10 degrees F in the next 100 years.
While Earth's climate has changed naturally throughout time, the current
rate of change due to human activity is unprecedented during at least
the last 10,000 years. The projected range of temperature rise is
wide because it includes a variety of possible future conditions,
such as whether or not we control greenhouse gas emissions and different
ways the climate system might respond. Temperatures over the US are
expected to rise more than over the globe as a whole because land
areas closer to the poles are projected to warm faster than those
nearer the equator.
#3 There is scientific consensus that global warming
is real, is caused by human activities, and presents serious challenges.
Scientists working on this issue report that the observed global warming
cannot be explained by natural variations such as changes in the sun's
output or volcanic eruptions. The most authoritative source of information
is the UN Intergovernmental Panel on Climate Change (IPCC)
which draws upon the collective wisdom of many hundreds of scientists
from around the world. The IPCC projects global temperature increases
of 3 to 10 degrees F in the next 100 years and says that human activity
is the cause of most of the observed and projected warming.
#4 There's a difference between weather and climate.
Weather refers to the conditions at one particular time and place,
and can change from hour to hour, day to day, and season to season.
Climate, on the other hand, refers to the long-term average pattern
of weather in a place. For example, we might say that the climate
of South Florida is warm, moist and sunny, although the weather on
a particular day could be quite different than that. Long-term data
are needed to determine changes in climate, and such data indicate
that Earth's climate has been warming at a rapid rate since the start
of intensive use of coal and oil in the late 1800s.
#5 The ozone hole does not cause global warming.
Ozone depletion is a different problem, caused mainly by CFCs (like
Freon) once used in refrigerators and air conditioners. In the past,
CFCs were also used in aerosol spray cans, but that use was banned
in the US in 1978. CFCs deplete the stratospheric ozone layer that
protects life on Earth from excess ultraviolet light that can cause
skin cancer and cataracts in humans and other damage to plants and
animals. An international agreement has phased out most uses of CFCs
but the ozone layer is only just beginning to recover, partly because
these chemicals remain in the atmosphere for a long time. (Although
ozone depletion is not the cause of global warming, there are a number
of connections between the two. For example, many ozone-depleting
compounds are also greenhouse gases. Some of the compounds now replacing
CFCs in order to protect ozone are also greenhouse gases. And ozone
itself is a greenhouse gas. In addition, while greenhouse gas build-up
causes temperatures close to Earth's surface to rise, it cause temperatures
higher up, in the stratosphere, to fall. This stratospheric cooling
speeds ozone depletion, delaying the recovery of the ozone hole.)
#6 Global warming will have significant impacts
on people and nature.
As temperatures continue to rise, precipitation is projected to come
more frequently in the form of heavy downpours. We can probably expect
more extreme wet and dry conditions. In the western US, where snowpack
provides free storage of most of the water supply, reduced snowpack
will make less water available in summer. Coastal areas will become
more vulnerable to storm surges as sea level rises. Plant and animal
species will migrate or disappear in response to changes in climate;
New England may lose its lobsters and maple trees as they move north
into Canada. Natural ecosystems such as coral reefs, mangrove swamps,
arctic tundra, and alpine meadows are especially vulnerable and may
disappear entirely in some areas. While global warming will have impacts
on natural and human systems all around the world, the largest impacts
will be on many natural ecosystems and on people who live in developing
countries and have few resources and little ability to adapt. On the
positive side, warmer winters will reduce cold-related stresses and
growing seasons will lengthen. And there will be tradeoffs in some
areas, such as less skiing but more hiking; and fewer killing frosts
but more bugs.
#7 Sea level has already risen due to warming and
is projected to rise much more.
Many people are under the mistaken impression that only if the polar
ice caps melt will sea level rise. In fact, average sea level around
the world has already risen 4 to 8 inches in the past 100 years due
to global warming and is expected to rise another 4 to 35 inches (with
a best guess of around 19 inches) by 2100. The primary reason for
this rise is that water expands as it warms. The second reason is
that glaciers all over the world are melting, and when land-based
ice melts, the water runs to the sea and increases its level. Thousands
of small islands are threatened by the projected sea-level rise for
the 21st century, as are low-lying coastal areas such as southern
Florida. Of course, if there is any significant melting of the polar
ice sheets, the additional rise in sea level would be enormous (measured
in feet not inches). This is projected to occur on a time scale of
millennia rather than centuries.
#8 Saving energy and developing alternative energy
sources would help.
Each of us can reduce our contribution to global warming by using
less greenhouse-gas-producing energy: driving less, choosing fuel
efficient cars and appliances (like refrigerators and water heaters),
and using solar energy where feasible for water and space heat. We
can encourage our political and business leaders to institute policies
that will save energy and develop alternative energy sources that
do not release carbon dioxide. We can preserve existing forests and
plant new ones. But even if we take aggressive action now, we cannot
completely prevent climate change because once carbon dioxide is in
the atmosphere, it remains there for about a century, and the climate
system takes a long time to respond to changes. But our actions now
and in the coming decades will have enormous implications for future
generations.
#9 An international agreement known as the Kyoto
Protocol has been negotiated to reduce greenhouse gas emissions, but
the US is not participating in it.
Because of its high energy consumption, the US has long emitted more
carbon dioxide than any other country. Because carbon dioxide remains
in the atmosphere for about 120 years, it accumulates, becomes equally
distributed around the world, and has global effects. Thus, while
using large amounts of energy to achieve economic growth, the US and
other wealthy nations have unintentionally burdened the rest of the
world with a long-term problem. And many negative impacts of climate
change are likely to be more severe for poorer countries that lack
the resources to adapt. The US has more technological and financial
resources than other nations. The role of the US in reducing its own
emissions and sharing its technologies with other nations will thus
be critical to the success of international efforts to limit climate
change. Meanwhile, we do not have to wait for the government to take
action. Some companies, governments and individuals have already committed
to reducing their emissions of greenhouse gases without laws or treaties
requiring them to do so.
#10 Protecting the world's climate by stabilizing
atmospheric concentrations of greenhouse gases will require enormous
reductions in current emissions.
Even if ratified, the Kyoto Protocol in its present form is only a
start and would not be nearly enough to stabilize climate. It is estimated
that greenhouse gas emissions would have to be reduced to less than
one third of current levels to stabilize atmospheric concentrations.
This would require a major transformation of the energy sector. A
mix of new and existing energy technologies will be needed to achieve
this, including large increases in energy efficiency and renewable
energy. Researchers are also developing technology to capture and
bury carbon dioxide thousands of feet underground. Major increases
in public and private research and development are needed to make
the necessary technologies available as rapidly and economically as
possible.
Why So Much Controversy?
With such strong scientific consensus
that global warming is real and is largely due to human activities,
why is there so much controversy in the press and among the public?
Why do some people keep insisting it is just an unproven theory?
Some reasons involve communication breakdowns, but even more important
is the deliberate campaign by special interests, including some
in the fossil fuel industry, to undermine or cast doubt on the science.
Climate science can be confusing
and is not easily explained in sound bites or brief newspaper articles.
Many well-intentioned reporters are ill equipped to get the story
right and their mistakes are often perpetuated as other reporters
use previous articles as source material for new ones. Partly as
a result of such problems, many people erroneously believe that
global warming is caused by increased heat entering the atmosphere
due to ozone depletion caused by CFCs.
In addition, most scientists discuss
their research in terms that the public cannot easily understand.
They also use some words that mean different things to a lay audience
than they do to scientists. For example, when scientists speak of
"aerosols," they are referring to tiny atmospheric particles, while
to lay people, an "aerosol" is a spray can.
But the most significant reason
for the controversy is that some special interests have mounted
an active campaign to raise doubts and create confusion about this
issue. For legitimate and other reasons, a very small number of
scientists raise questions about whether warming has or will occur.
When they do, special interests work hard to amplify and distribute
the views of these "contrarians" in order to create confusion among
the press, policymakers and public and give the impression that
there is still a major scientific debate about the reality and causes
of climate change. (Note: not all fossil fuel companies are implicated
in this disinformation campaign. Some, in fact, have acknowledged
the scientific realities and are taking steps to reduce their greenhouse
gas emissions [see a list of such companies at the Pew Center on
Global Climate Change]).
Given all this confusion and controversy,
it is particularly important that teachers and students have access
to reliable information about climate change. It is our hope that
this teachers guide will be of some assistance toward that end.
Background
Materials
You
can get up to speed on climate change issues quickly and efficiently
at this site from the US Environmental Protection Agency. "Frequently
Asked Questions" (FAQ) is a good place to begin. Another good section,
"In the News," offers brief summaries of the latest developments in
climate science and policy and provides links for further details.
"Publications" provides links to authoritative reports from the top
sources. "Outreach" offers a variety of very useful fact sheets (basic
to advanced) to get you and your students started, as well as brochures
that deal with particular aspects of the subject, such as "Climate
Change and Birds" and "Climate Change and Public Lands." One fact
sheet, "Straight Talk on Global Warming," deals with some of the most
common misunderstandings and misrepresentations about the issue.
The "Outreach" section also includes
publications that deal with policies and technological strategies
for reducing human-induced climate change. Links to online tools are
provided for calculating emissions reductions from various strategies.
These tools can easily form the basis of classroom activities such
as calculating carbon dioxide emissions reductions from walking to
school instead of being driven, thus helping students relate personally
to this global scale issue. The glossary is quite extensive and fairly
technical and is a great resource for teachers and more advanced high
school students.
A much simpler and far less comprehensive
glossary for younger students can be found at EPA's Global
Warming Kids Page. Elementary and Middle School students will
find this page an accessible place to begin. It includes simple explanations
of the issues and characterizes scientists as "climate detectives"
searching for clues in ice cores, tree rings and satellite data. It
also provides links and games to appeal to younger students.
UN
CLIMATE INFORMATION KIT
This
is an excellent resource for information on climate change from the
United Nations, World Meteorological Organization, and five other
international agencies. The 63-page guide (downloads in pdf) is clearly
written in plain English, and offers comprehensive information on
the science of global climate change, potential impacts, adaptation
and mitigation strategies, and policies. This policy emphasis - what
the world is doing about climate change - sets this material apart.
Data charts, including greenhouse gas emissions and their sources,
are another useful feature. This thorough guide was updated in the
summer of 2001 with information from the latest reports of the Intergovernmental
Panel on Climate Change (IPCC), the leading authority on the subject.
Note: International units are used in this guide, so take this opportunity
to familiarize your students with converting degrees Celsius to Fahrenheit
and metric measurements to English ones (e.g., meters to feet).
Additional Technical Resources
Teachers
and older students who want more detailed technical information
and a global perspective can go directly to the reports of the Intergovernmental
Panel on Climate Change (IPCC). The IPCC was organized under the
auspices of the United Nations and represents the combined wisdom
of the world's leading climate scientists. "Summaries for Policymakers"
are available on line for the three working groups of the IPCC:
I. the scientific basis of climate change, II. impacts, adaptation
and vulnerability, and III. mitigation, as well as several special
reports.
US
NATIONAL ASSESSMENT OF CLIMATE CHANGE IMPACTS
To
gain a better understanding of what global warming will mean for the
United States, visit the site of the US National Assessment of the
Potential Consequences of Climate Variability and Change. The 150-page
"Overview" report, "Climate Change Impacts on the US," is full of
information and is written in accessible language, while the much
longer "Foundation" document is a more technical report with scientific
references. Both deal with climate change and its projected impacts
on each region of the US and on five key sectors: agriculture, water,
human health, forests, and coastal areas and marine resources.
PEW
CENTER ON GLOBAL CLIMATE CHANGE
The Pew Center on Global Climate Change is an
independent, non-partisan organization dedicated to providing credible
information and innovative solutions to addressing climate change.
Funded by the Pew Charitable Trusts and other sources, the Center
produces reports by leading experts on climate change science, economics,
policies, and solutions. It has also enlisted dozens of major companies
in an effort to use the power of the marketplace to address climate
change. The website offers an excellent set of resources that are
useful for teachers and more advanced students, from the full text
of the Center's reports, to current articles and editorials, to
lists of sites for more information.
The UCS has produced a set of teaching materials designed to
accompany "Global Warming: Early Warning Signs"- a science-based
world map depicting local and regional consequences of global climate
change. The map can be found at www.climatehotmap.org/. While UCS
and the other organizations that produced the map are advocacy groups
that call for policy actions on climate change, the lesson plans
in the UCS Curriculum Guide are scientifically accurate, pedagogically
sound, and do not reflect a bias. Rather, they encourage students
to collect and analyze data and draw their own conclusions.
The 30-page Curriculum Guide is geared towards grades 9-12,
but individual exercises are adaptable to other grade levels. Each
activity is structured to include an initial "Engagement" exercise,
one or more steps of a student "Exploration" project, and ideas
for extended study. The activities align with National Learning
Standards for Science, Geography, Social Studies, Language Arts,
Environmental Education, and Technology, and the specific standards
addressed by each activity are identified.
The web resources suggested for teacher and student use are
authoritative and first rate.
Four activities are presented:
Climate Change in My City: Students use an historical climate index
to analyze climate change at local, regional, and global scales.
Oral History Project: Students interview older residents in the
community about climate changes during their lifetime and compare
the results to a climate change index that is based on historical
temperature measurements.
Climate Change and Disease: Students research the relationship between
hosts, parasites, and vectors for common vector-borne diseases and
evaluate how climate change could affect the spread of disease.
Climate Change and Ecosystems: Students research the interdependencies
among plants and animals in an ecosystem and explore how climate
change might affect those interdependencies and the ecosystem as
a whole.
US
DEPARTMENT OF ENERGY'S ARM EDUCATION SITE AND LESSON PLANS
The Atmospheric Radiation Measurement (ARM) Program is part of
the US Department of Energy's strategy to understand global climate
change. The lesson plans available at this site were designed for
middle school grade levels, but can be modified by the teacher for
both the high school and elementary levels. The lesson plans include
objectives, materials needed, important points to understand, preparation
steps, and procedures. These are fairly traditional science experiments
but are of good quality and scientific accuracy.
The 40 lesson plans cover a variety of basic climate issues
such as the composition and structure of the atmosphere, why the
Earth is hotter at the equator, and the reasons for the seasons.
The lessons also delve into the details of climate change and its
impacts; for example, there are several lessons that illustrate
why sea level rises in a warming climate. Teachers can choose from
among these 40 lessons and develop an excellent series on climate
change. Background information is needed for most lessons and is
provided at the site. It is thorough without being overwhelming,
though teachers may have to help some students in understanding
the more technical information. The site also gives two quizzes
(one basic and one more advanced) to test students understanding.
These are graded instantly on line, with each answer explained.
Another excellent resource on the ARM site is the list of frequently
asked questions sent in by students, along with answers from an
ARM scientist. A tremendous amount of information can be found in
these answers and they respond to very common questions and misconceptions
among students and the public in general. Some answers also identify
additional websites as sources of further information. The section
"Cool Sites" offers a good selection of additional resources on
the web.
What
Can I Do About It?
After learning about climate change, some students may want
to know what they as individuals can do about it. This
site from Environmental
Defense offers 20 simple steps to reduce an individual's contribution
to global warming and gives the approximate carbon dioxide reduction
attained by taking each step. While Environmental Defense is an
advocacy group that supports strong measures to mitigate climate
change, the suggested actions are simply those that are widely recommended
to reduce energy use and its environmental impacts.
Searching the
Web for Other Materials
Climate and weather have long been important science subjects.
Increasing concern about human activities altering Earth's climate
makes these ever more relevant areas of inquiry. Finding high quality
background materials and lesson plans can be a challenge. Sorting
through the plethora of information posted on the Internet, some
of dubious quality, is notoriously difficult.
Internet searches for climate change education materials yield
hundreds of websites, many of which are poor in quality. Some reflect
a bias that global warming is either not occurring or is nothing
to be concerned about. Others reflect an opposite bias: that every
harmful weather event is caused by global warming and that the effects
of climate change will be cataclysmic everywhere. Still others contain
major or minor scientific errors.
It is therefore essential to determine the credibility of any
information you come across. What is the source? For example, weather
reporters of local television stations are not leading authorities
on climate change. And some groups with green sounding names, like
the Global Climate Coalition, are actually lobbying and advocacy
arms of some in the fossil fuel industry. If you come across "The
World Climate Report," for example, you'll see that it bills itself
as "the nation's leading publication covering the breaking news
concerning the science and political science of global climate change."
But in fact, it presents a view that is radically contrary to the
scientific consensus on this issue. It is published by the "Greening
Earth Society," whose mission, funded by some in the fossil fuel
industry, is to discredit the science of climate change and prevent
action on this issue.
In addition, many errors of scientific fact are extremely widespread,
and because they have been repeated so often, they can be easily
mistaken for truth. Examples of widespread errors include confounding
the issues of climate and ozone, and mistakenly citing polar ice
cap melting as the leading cause of current sea level rise due to
warming. The bottom line: use extreme caution when choosing materials
from the web and always carefully consider the source.
Susan Joy Hassol, 2000-2002
