The document discusses global warming and its potential effects. It defines global warming as an increase in average surface temperatures due to rising levels of greenhouse gases from human activities. The document then examines global warming using systems and game theory perspectives to analyze potential feedback cycles and scenarios. It discusses both positive and negative feedback cycles and how crossing thresholds could trigger irreversible changes to the climate system.

1. Franklin Kan Go
BSBA4
Global Warming
The U.S. Environmental Protection Agency definition of global warming:
“Global warming is an average increase in the temperature of the atmosphere near the Earth’s
surface and in the troposphere, which can contribute to changes in global climate patterns.
Global warming can occur from a variety of causes, both natural and human induced. In common
usage, “global warming” often refers to the warming that can occur as a result of increased
emissions of greenhouse gases from human activities.”
Case study: Global Warming
This case study on the potential damage from global warming consists of the following parts:
1. This page, which is a summary of the scenarios for the effects of global warming and a short
discussion on how we should try to choose between the scenarios.
2. We will examine global warming and the alternate scenarios using two different views; the
systems view and the games view. You have already used these two views previously. In the
systems view, we will focus on comparing positive and negative feedback controls and in the
games view we evaluate different scenarios in a game against nature.
3. A link to a website that describes the problem and costs
EPA Global Warming
4. A like to a website that describes abrupt climate change
http://www.ncdc.noaa.gov/paleo/abrupt/index.html
Feedback Cycles in Global Warming
One of the causes of global warming, or more generally, global climate change is increased
atmospheric CO2 that comes from anthropogenic sources. Human activity is increasing the
release of CO2 into the atmosphere by burning fossil fuels, burning forests, deforestation and
destruction of the soil, along with other activities. This pulse of CO2 into the atmosphere is a
perturbation and the earth system will respond with some changes. Our focus is to attempt to
identify important responses and determine whether these responses will counter the increase in
CO2 or temperature, or whether the response will exacerbate the change.
In a systems view of this system, we are looking for feedback cycles that are either positive or
negative (Figure 1). A negative feedback cycle will resist change with compensatory flows in
other parts of the system. Conversely, a positive feedback will accelerate the rate of change.

2. Figure 1: Several possible feedback cycles for global warming.
The details are discussed in the text below.
• There is a negative feedback cycle involving CO2, temperature and algae.
o increased CO2 causes surface temperature to rise
o which leads to increased algae growth rates in the ocean,
o which depletes atmospheric CO2
o thus countering the rise in atmospheric CO2.
• There is a positive feedback cycle involving air temperature, CO2 and soil organisms.
o increased CO2 causes surface temperature to rise
o increased temperature causes soil organisms to respire faster
o faster respiration converts more soil organics to CO2
o thus accelerating the cycle of CO2 input.
• There is another positive feedback involving surface albedo of glaciers and temperature.
o increased temperature causes glaciers to melt
o the loss of reflective surface of the glacier leads to more absorption of sunlight
o more absorption leads to higher temperatures
o thus accelerating the melting and temperature rise
It is crucial that we understand these cycles and the potential interaction between these cycles.
The negative feedback cycles will lead to controlling or minimizing temperature gain, whereas
positive feedback processes will contribute to acceleration of the problem. If we are very lucky,
there may be very strong negative feedback controls that will buffer human impact. If we are less
lucky, a slight anthropogenic change may trigger a set or processes that will cause a shift in the
processes that control surface temperature. In terms of resilience; if the overall global system is
very resilient, human perturbation may be quickly fixed, on the other hand, once we cross a
threshold (exceed the resilience) there may be a dramatic and essentially irreversible shift in the
fundamental processes of the system.
Systems View Simulations of the Possible Scenarios
One aspect of the systems view that is very useful is the construction of simulation models that
will predict what will happen if the current processes continue at the same rate. A simple
simulation is the projection of when oil or natural gas reserves will be depleted if they are
consumed at the same rate as they are now compared to if there is the same rate of growth of the
consumption. This is a very enlightening comparison that shows that a resource that might last

3. 200 years at the current rate of consumption (barrels of oil per year for example) might only last
50 years if we project that the rate of growth of consumption continues at 5% per year.
We have seen other examples of this type of modeling when we studied population growth
models. Pure exponential growth occurs if we assume that the growth rate remains unchanged,
whereas the "logistic" equation is on example of the pattern of growth that factors in reduced
growth rate as resources are depleted. Variations on the "logistic" model include boom and bust
cycles or irruptive growth.
Similar, but more involved, simulations can be constructed for human population growth, energy
resource depletion, pollution, and quality of life indicators. Donella Meadows and colleagues
(Meadows et al. 1992) have created very large models that project future scenarios based on
current consumption and growth rates and slight variations in those assumptions. They have used
these to explore possible future scenarios and examine characteristics of systems that lead to
global collapse compared to the characteristics of systems that lead to sustainable societies.
Figure 2 presents a cartoon of one of their comparison.
Figure 2a: In this scenario the initial resources are lower which leads to a moderate rise in
population. As resources are depleted, industrial output only creates a low level of pollution
which is eventually reduced. The population goes through a minor correction as expected from
the industrial transition.

4. Figure 2b: In this simulation, higher initial resources lead to more rapid population growth and
the level of pollution reaches as level that is high enough to degrade natural resources, including
food production. The drop in resources and pollution lead to a major correction, i.e. bust, in the
population.
Both of these scenarios are equally probably but one is much more desirable. The simulation
shows illustrates the importance of containing a potentially positive feedback between increased
population leading to increased pollution which destroys food production capacity and leads to
an overshoot in population and a crash. Although we may see a population crash as a "natural"
correction in human population, the causes and circumstances (environmental degradation and
starvation) would probably be considered very undesirable future for most people.
Choosing Between Scenarios
Each scenario represents a set of initial conditions and response parameters that are theoretically
under human social control. The choice of strategy can be portrayed as a "game against nature",
where each strategy that you choose has different outcomes depending on uncertain natural
events. Figure 3 was presented earlier in the "games view" as a game against nature.
No tornado Tornado comes right
down your street
You - spend You "wasted" your You suffered only
money to money minor damage and
prepare for a lived through the storm
bad tornado
You - spend You didn't waste your Your house is wrecked
the money on a money and you have and it isn't the same
new TV a cool TV in front of watching your TV
your lounger from a folding chair
Figure 3: A simple game against nature.

5. In the present case study, you choices are more sophisticated strategies for managing natural
resources and reducing pollution impact, and the natural uncertainty has to do with the global
biogeochemical cycle response to resources, pollution and human population. For the purposes
of this case study, the pollution is the general CO2 increase in the atmosphere caused by
increased energy use and poor land use management. The choices might be represented by the
game against nature shown in Figure 4.
CO2 pollution is CO2 pollution causes a
countered by healthy downward spiral in natural
oceans critical natural resources
You - spend You "wasted" your You suffered only minor
money to reduce money damage and lived through the
CO2 output worst of global degradation
You - spend the You didn't waste your Your population crashes, your
money increasing money and you have a economy is wrecked,
industrial growth bigger economy with Hollywood is underwater and
more TVs to sell. there's nothing good on TV.
Figure 4: The "game against nature" modified to show how dealing with CO2 pollution might be
the best strategy. Many people would rationally choose the strategy that results in the least bad
outcome, the "maximin" solution.
References
Meadows et al. 1992
John Rueter
July 22, 2003
What are the household appliances that contribute to global warming?
A good rule of thumb is that household appliances consume electricity and therefore contribute
to global warming in proportion to the amount of heat they produce, because the production of
heat is what usually requires the most energy. If you put your hand over the back of a television
set, you will feel the heat rising from it as a byproduct of what the appliance does.
So, electric heaters and oil or gas heaters contribute most considerably to global warming, as do
hot water systems. Air conditioners are also culprits, but surprisingly reverse cycle air
conditioning is somewhat better than electric heaters because it uses the heat pump effect, rather
than simply generating heat. So, minimize your use of heaters and wear a jumper with the heater
at a low setting. Better still, use a reverse cycle air conditioner if you have one. Close internal
doors so that you do not have to heat or cool unoccupied rooms. Consider installing a roof-top
solar hot water system.
Refrigerators are another culprit because they operate twenty four hours a day. When buying a
new refrigerator, look for its energy rating and try to choose a refrigerator with a higher

6. efficiency rating. Turn second refrigerators off when they are not really needed.
Use cold water in washing machines and try to wash clothes only when you have a full load.
Dish washers are a wonderful convenience, but they use a lot of electricity, and they use the
same amount of electricity every time you use them, whether full or not. So, try to use them only
once a day.
A hidden source of electricity wastage is in appliances left in standby mode. I would not turn my
microwave oven off at the wall when not in use, partly because I rely on the clock and partly
because much of the convenience would be lost, but consider turning other appliances off at the
wall.
Incandescent light globes work by heating a wire filament until it glows white hot, so they are
obviously very heavy users of electricity. These should be replaced by modern high-efficiency
lights that use a fraction of the electricity and therefore contribute only a fraction of the carbon
emissions that lead to global warming.
How do electrical appliances have an affect on global warming?
Manufacturing them generally involves plastics made from fossil fuels, which will eventually
lead to increased atmospheric CO2.
The manufacturing process generally involves the use of fossil fuels (to mine metals, transport
raw materials, and run machines/equipment used to manufacture the final product)
Fossil fuels (usually gasoline/diesel) are most likely used to transport the appliances to the point
of sale.
If your electricity comes from coal or other fossil fuel sources, using the appliance involves
increasing the power company's use of fossil fuels.
Burning or otherwise using fossil fuels increases atmospheric CO2, which causes global
warming.
Preventive Measures for Global Warming
As global temperatures rise, global warming is an increasing concern. The current level of
carbon dioxide in the atmosphere is higher than it has been at any point in history, according to
NASA, and the rise in global temperatures is moving at a faster rate than any point in the past
1,300 years. (See References 1) Scientific organizations, including NASA and the National
Oceanic and Atmospheric Administration (NOAA) agree that human behaviors and activities are
a primary cause of the warming trend. (See References 2) To mitigate the existing damage and
prevent global warming from accelerating, you can take steps to reduce emissions associated
with your behaviors and lifestyle.
Reduce Energy Use
The energy you use at home and work contributes to increased levels of carbon dioxide; usually,
fossil fuels are burned to produce and transport the energy, releasing greenhouse gases into the

7. atmosphere. By reducing your energy use, you can reduce your personal carbon footprint. The
first thing the U.S. Environmental Protection Agency recommends is changing out standard light
bulbs for compact fluorescent or LED lights, which use up to 75 percent less energy and last
longer. You can also upgrade heating and cooling systems and insulate your home properly to
make sure your home is not wasting energy. To reduce dependence on fossil fuels, buy green
power, which is produced from renewable sources like solar or wind. (See References 5)
Update Buying Habits
The way you shop and the products you buy can contribute to global warming: the materials'
sourcing, manufacturing, transportation and disposal all have the potential to cause emissions
and pollutants to be released into the air. The EPA recommends buying Energy Star-certified
products, which are designed to be efficient and last longer. When you can, buy used products
and items with recycled content and minimal packaging. (See References 7) When it comes time
to throw away items, try to recycle them or donate them to another source so that they don't end
up in a landfill. Be mindful of food waste and try to compost leftover food scraps. Although food
waste decomposes quickly, when this takes place unattended in a landfill the process releases
methane, a greenhouse gas. Incineration of biodegradable materials also releases pollutants.
Change Transportation Habits
Transportation --- in particular, car travel --- is responsible for about 25 percent of energy use in
the U.S., according to the EPA, and also puts chemicals and pollutants into the air. To reduce
your emissions, change your driving habits. The easiest way to cut carbon emissions is to drive
less: carpool to work, take public transportation, walk or ride a bike. Consider telecommuting to
work; the EPA says that working at home even one day per week can significantly reduce your
carbon footprint if you are a car commuter. Keep your car maintained so that it runs efficiently.
Turn off your car instead of idling, and don't drive aggressively, as abrupt acceleration and
driving at high speeds burns up fuel. (See References 6)
Stop Deforestation
Deforestation is a major contributor to global warming. When large expanses of forest are cut or
burned, carbon dioxide, a greenhouse gas, is released into the atmosphere. Because trees also
take carbon dioxide from the air, cutting down large numbers of trees causes carbon dioxide
levels to rise even further. (See References 3) Although much of the major deforestation is taking
place in tropical areas, you can take action to help prevent further loss. Support politicians who
champion reforestation projects, donate to organizations that promote foreign forest management
and look for wood products that have the FSC-US Forest Management Standard certification to
ensure that your buying behaviors are not contributing to deforestation. (See References 4)

8. Climate change: How do we know?
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct
measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution.
(Source: NOAA)
Resources
The following are the key
sources of data and
information contained on
this page:
• IPCC Fourth
Assessment Report,
Summary for
Policymakers
• IPCC Fourth
Assessment Report,
Technical Summary
• NOAA
Paleoclimatology
The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven
cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking
the beginning of the modern climate era — and of human civilization. Most of these climate changes are
attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

9. The current warming trend is of particular significance because most of it is
"Scientific evidence for very likely human-induced and proceeding at a rate that is unprecedented in
warming of the climate the past 1,300 years.1
system is unequivocal."
- Intergovernmental Panel
on Climate Change
Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture,
collecting many different types of information about our planet and its climate on a global scale. Studying
these climate data collected over many years reveal the signals of a changing climate.
Certain facts about Earth's climate are not in dispute:
• The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th
century.2 Their ability to affect the transfer of infrared energy through the atmosphere is the scientific
basis of many JPL-designed instruments, such as AIRS. Increased levels of greenhouse gases must
cause the Earth to warm in response.
• Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s
climate responds to changes in solar output, in the Earth’s orbit, and in greenhouse gas levels. They
also show that in the past, large changes in climate have happened very quickly, geologically-
speaking: in tens of years, not in millions or even thousands.3
The evidence for rapid climate change is compelling:
Sea level rise
Global sea level rose about 17 centimeters (6.7 inches) in the
last century. The rate in the last decade, however, is nearly
double that of the last century.4
Republic of Maldives: Vulnerable to sea
level rise
Global temperature rise
All three major global surface temperature reconstructions
show that Earth has warmed since 1880. 5 Most of this warming
has occurred since the 1970s, with the 20 warmest years having
occurred since 1981 and with all 10 of the warmest years
occurring in the past 12 years. 6 Even though the 2000s
witnessed a solar output decline resulting in an unusually deep
solar minimum in 2007-2009, surface temperatures continue to
increase. 7

10. Warming oceans
The oceans have absorbed much of this increased heat, with the
top 700 meters (about 2,300 feet) of ocean showing warming of
0.302 degrees Fahrenheit since 1969.8
Shrinking ice sheets
The Greenland and Antarctic ice sheets have decreased in mass.
Data from NASA's Gravity Recovery and Climate Experiment
show Greenland lost 150 to 250 cubic kilometers (36 to 60
cubic miles) of ice per year between 2002 and 2006, while
Antarctica lost about 152 cubic kilometers (36 cubic miles) of
ice between 2002 and 2005.
Flowing meltwater from the Greenland ice
sheet
Declining Arctic sea ice
Both the extent and thickness of Arctic sea ice has declined
rapidly over the last several decades. 9
Visualization of the 2007 Arctic sea ice
minimum

11. Glacial retreat
Glaciers are retreating almost everywhere around the world —
including in the Alps, Himalayas, Andes, Rockies, Alaska and
Africa.10
The disappearing snowcap of Mount
Kilimanjaro, from space.
Extreme events
The number of record high temperature events in the United
States has been increasing, while the number of record low
temperature events has been decreasing, since 1950. The U.S.
has also witnessed increasing numbers of intense rainfall
events.11
Ocean acidification
Since the beginning of the Industrial Revolution, the acidity of
surface ocean waters has increased by about 30 percent.12,13
This increase is the result of humans emitting more carbon
dioxide into the atmosphere and hence more being absorbed
into the oceans. The amount of carbon dioxide absorbed by the
upper layer of the oceans is increasing by about 2 billion tons
per year.14,15
Global Climate Change Indicators
National Oceanic and Atmospheric Administration
National Climatic Data Center
Many lines of scientific evidence show the Earth's climate is changing. This page presents the
latest information from several independent measures of observed climate change that illustrate
an overwhelmingly compelling story of a planet that is undergoing global warming. It is worth
noting that increasing global temperature is only one element of observed global climate change.
Precipitation patterns are also changing; storms and other extremes are changing as well.
How do we know the Earth's climate is warming?

12. Thousands of land and ocean temperature measurements are recorded each day around the globe.
This includes measurements from climate reference stations, weather stations, ships, buoys and
autonomous gliders in the oceans. These surface measurements are also supplemented with
satellite measurements. These measurements are processed, examined for random and systematic
errors, and then finally combined to produce a time series of global average temperature change.
A number of agencies around the world have produced datasets of global-scale changes in
surface temperature using different techniques to process the data and remove measurement
errors that could lead to false interpretations of temperature trends. The warming trend that is
apparent in all of the independent methods of calculating global temperature change is also
confirmed by other independent observations, such as the melting of mountain glaciers on every
continent, reductions in the extent of snow cover, earlier blooming of plants in spring, a shorter
ice season on lakes and rivers, ocean heat content, reduced arctic sea ice, and rising sea levels.
The Global Surface Temperature is Rising
Global annual average temperature measured over land and oceans. Red bars indicate
temperatures above and blue bars indicate temperatures below the 1901-2000 average
temperature. The black line shows atmospheric carbon dioxide concentration in parts per million.
Global average temperature is one of the most-cited indicators of global climate change, and
shows an increase of approximately 1.4°F since the early 20th Century. The global surface
temperature is based on air temperature data over land and sea-surface temperatures observed
from ships, buoys and satellites. There is a clear long-term global warming trend, while each
individual year does not always show a temperature increase relative to the previous year, and
some years show greater changes than others. These year-to-year fluctuations in temperature are
due to natural processes, such as the effects of El Ninos, La Ninas, and the eruption of large
volcanoes. Notably, the 20 warmest years have all occurred since 1981, and the 10 warmest have
all occurred in the past 12 years.
U.S. Surface Temperature is also Rising

13. Annual surface temperatures for the contiguous U.S. compared to the 20th Century (1901-2000)
average. Calculated from the U.S. Historical Climatology Network (USHCN version 2). More
information: U.S. Surface Temperature Data, USHCN v2.
Surface temperatures averaged across the U.S. have also risen. While the U.S. temperature
makes up only part of the global temperature, the rise over a large area is not inconsistent with
expectations in a warming planet. Because the U.S. is just a fraction of the planet, it is subject to
more year-to-year variability than the planet as a whole. This is evident in the U.S. temperature
trace.
Sea Level is Rising
Annual averages of global sea level. Red: sea-level since 1870; Blue: tide gauge data; Black:
based on satellite observations. The inset shows global mean sea level rise since 1993 - a period
over which sea level rise has accelerated. More information: Coastal Sensitivity to Sea Level
Rise (USGCRP) and Climate Change 2007: The Physical Science Basis.
Global mean sea level has been rising at an average rate of approximately 1.7 mm/year over the
past 100 years (measured from tide gauge observations), which is significantly larger than the
rate averaged over the last several thousand years. Since 1993, global sea level has risen at an
accelerating rate of around 3.5 mm/year. Much of the sea level rise to date is a result of
increasing heat of the ocean causing it to expand. It is expected that melting land ice (e.g. from
Greenland and mountain glaciers) will play a more significant role in contributing to future sea
level rise.
Global Upper Ocean Heat Content is Rising

14. Time series of seasonal (red dots) and annual average (black line) of global upper ocean heat
content for the 0-700m layer since 1955. More information: BAMS State of the Climate in 2009.
While ocean heat content varies significantly from place to place and from year-to-year (as a
result of changing ocean currents and natural variability), there is a strong trend during the period
of reliable measurements. Increasing heat content in the ocean is also consistent with sea level
rise, which is occurring mostly as a result of thermal expansion of the ocean water as it warms.
Northern Hemisphere Snow Cover is Retreating
Average of monthly snow cover extent anomalies over Northern Hemisphere lands (including
Greenland) since Nov 1966. Right: Seasonal snow cover extent over Northern Hemisphere lands
since winter 1966-67. Calculated from NOAA snow maps. From BAMS State of the Climate in
2009 report.
Northern Hemisphere average annual snow cover has declined in recent decades. This pattern is
consistent with warmer global temperatures. Some of the largest declines have been observed in
the spring and summer months.
Glacier Volume is Shrinking

15. Cumulative decline (in cubic miles) in glacier ice worldwide. More information: Global Climate
Change Impacts in the U.S.
Warming temperatures lead to the melting of glaciers and ice sheets. The total volume of glaciers
on Earth is declining sharply. Glaciers have been retreating worldwide for at least the last
century; the rate of retreat has increased in the past decade. Only a few glaciers are actually
advancing (in locations that were well below freezing, and where increased precipitation has
outpaced melting). The progressive disappearance of glaciers has implications not only for a
rising global sea level, but also for water supplies in certain regions of Asia and South America.
U.S. Climate Extremes are Increasing
Enlarge above graph. Annual Climate Extremes Index (CEI) value for the contiguous United
States. Larger numbers indicate more acive climate extremes for a year. More information: CEI.
One way climate changes can be assessed is by measuring the frequency of events considered
"extreme" (among the most rare of temperature, precipitation and storm intensity values). The
Climate Extremes Index (CEI) value for the contiguous United States is an objective way to
determine whether extreme events are on the rise. The figure to the left shows the the number of
extreme climate events (those which place among the most unusual of the historical record) has
been rising over the last four decades.
How do we know humans are the primary cause of the warming?
A large body of evidence supports the conclusion that human activity is the primary driver of
recent warming. This evidence has accumulated over several decades, and from hundreds of
studies. The first line of evidence is our basic physical understanding of how greenhouse gases
trap heat, how the climate system responds to increases in greenhouse gases, and how other
human and natural factors influence climate. The second line of evidence is from indirect
estimates of climate changes over the last 1,000 to 2,000 years. These estimates are often
obtained from living things and their remains (like tree rings and corals) which provide a natural
archive of climate variations. These indicators show that the recent temperature rise is clearly
unusual in at least the last 1,000 years. The third line of evidence is based on comparisons of
actual climate with computer models of how we expect climate to behave under certain human
influences. For example, when climate models are run with historical increases in greenhouse
gases, they show gradual warming of the Earth and ocean surface, increases in ocean heat
content, a rise in global sea level, and general retreat of sea ice and snow cover. These and other
aspects of modeled climate change are in agreement with observations.
Climate Model Indications and the Observed Climate

16. Simulated global temperature in experiments that include human influences (pink line), and
model experiments that included only natural factors (blue line). The black line is observed
temperature change.
Global climate models clearly show the effect of human-induced changes on global
temperatures. The blue band shows how global temperatures would have changed due to natural
forces only (without human influence). The pink band shows model projections of the effects of
human and natural forces combined. The black line shows actual observed global average
temperatures. The close match between the black line and the pink band indicates that observed
warming over the last half-century cannot be explained by natural factors alone, and is instead
caused primarily by human factors.
800,000 Year Record of Carbon Dioxide (CO2) Concentrations
Carbon dioxide concentration (parts per million) for the last 800,000 years, measured from
trapped bubbles of air in an Antarctic ice core. The 2008 observed value is from the Mauna Loa
Observatory in Hawaii and projections are based upon future emission scenarios. More
information on the data can be found in the Climate Change Impacts on the U.S. report.
Over the last 800,000 years, natural factors have caused the atmospheric carbon dioxide (CO2)
concentration to vary within a range of about 170 to 300 parts per million (ppm). The
concentration of CO2 in the atmosphere has increased by roughly 35 percent since the start of the
industrial revolution. Globally, over the past several decades, about 80 percent of human-induced
CO2 emissions came from the burning of fossil fuels, while about 20 percent resulted from
deforestation and associated agricultural practices. In the absence of strong control measures,
emissions projected for this century would result in the CO2 concentration increasing to a level
that is roughly 2 to 3 times the highest level occurring over the glacial-interglacial era that spans
the last 800,000 or more years.

17. Energy from the Sun Has Not Increased
Global surface temperature (top, blue) and the Sun's energy received at the top of Earth's
atmosphere (red, bottom). Solar energy has been measured by satellites since 1978.
Climate Change Basics
Climate change is happening
Our Earth is warming. Earth's average temperature has risen by 1.4°F over the past century,
and is projected to rise another 2 to 11.5°F over the next hundred years. Small changes in the
average temperature of the planet can translate to large and potentially dangerous shifts in
climate and weather.
The evidence is clear. Rising global temperatures have been accompanied by changes in
weather and climate. Many places have seen changes in rainfall, resulting in more floods,
droughts, or intense rain, as well as more frequent and severe heat waves. The planet's oceans
and glaciers have also experienced some big changes - oceans are warming and becoming more
acidic, ice caps are melting, and sea levels are rising. As these and other changes become more
pronounced in the coming decades, they will likely present challenges to our society and our
environment.
Top of Page

18. Humans are largely responsible for recent climate change
Over the past century, human activities have released large amounts of carbon dioxide and other
greenhouse gases into the atmosphere. The majority of greenhouse gases come from burning
fossil fuels to produce energy, although deforestation, industrial processes, and some agricultural
practices also emit gases into the atmosphere.
Greenhouse gases act like a blanket around Earth, trapping energy in the atmosphere and causing
it to warm. This phenomenon is called the greenhouse effect and is natural and necessary to
support life on Earth. However, the buildup of greenhouse gases can change Earth's climate and
result in dangerous effects to human health and welfare and to ecosystems.
The choices we make today will affect the amount of greenhouse gases we put in the atmosphere
in the near future and for years to come.
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Climate change affects everyone
Learn More
• The Signs of Climate Change in the United States
• Climate Change Facts: Answers to Common Questions
• Multimedia Gallery
Our lives are connected to the climate. Human societies have adapted to the relatively stable
climate we have enjoyed since the last ice age which ended several thousand years ago. A
warming climate will bring changes that can affect our water supplies, agriculture, power and
transportation systems, the natural environment, and even our own health and safety.
Some changes to the climate are unavoidable. Carbon dioxide can stay in the atmosphere for
nearly a century, so Earth will continue to warm in the coming decades. The warmer it gets, the
greater the risk for more severe changes to the climate and Earth's system. Although it's difficult
to predict the exact impacts of climate change, what's clear is that the climate we are accustomed
to is no longer a reliable guide for what to expect in the future.
We can reduce the risks we will face from climate change. By making choices that reduce
greenhouse gas pollution, and preparing for the changes that are already underway, we can
reduce risks from climate change. Our decisions today will shape the world our children and
grandchildren will live in.
Top of Page
We can make a difference

19. You can take action. You can take steps at home, on the road, and in your office to reduce
greenhouse gas emissions and the risks associated with climate change. Many of these steps can
save you money; some, such as walking or biking to work can even improve your health! You
can also get involved on a local or state level to support energy efficiency, clean energy
programs, or other climate programs.
Calculate your carbon footprint and find ways to reduce your emissions through simple everyday
actions.
Personal Greenhouse Gas Emissions Calculator
EPA and other federal agencies are taking action. EPA is working to protect the health and
welfare of Americans through common sense measures to reduce greenhouse gas pollution and
to help communities prepare for climate change.
Climate Change
At Home
What You Can Do At Home
Related Links
• ENERGY STAR
• EPA's Reduce, Reuse, and Recycle
• EPA's WaterSense program
• EPA's GreenScapes program
• EPA's Household Emissions Calculator
Printable Version: What You Can Do at Home (PDF) (1 pg., 216 KB, About PDF)
Did You Know?
Flex Fuel Vehicles are specially-designed to run on either traditional gasoline or a blend of 85%
ethanol and 15% gasoline known as "E-85." E-85 reduces GHG emissions by 20%. FFVs are
available to consumers in a range of models at no extra cost.
Making a few small changes in your home and yard can reduce greenhouse gases and save you
money. Explore our list of 10 simple steps you can take to reduce greenhouse gas emissions:

20. 1. Change five lights
Replace your five most frequently used light fixtures or the lightbulbs in them with ENERGY
STAR® qualified products and you will help the environment while saving $70 a year on energy
bills. ENERGY STAR lighting provides bright, warm light; generates 75% less heat; uses about
75% less energy than standard lighting; and lasts from 10 to 50 times longer.
2. Look for ENERGY STAR
When buying new products for your home, look for EPA's ENERGY STAR label to help you
make the most energy-efficient decision. You can find the ENERGY STAR label on more than
60 kinds of products, including appliances, lighting, heating and cooling equipment, electronics,
and office equipment. Over their lifetime, products in your home that have earned the ENERGY
STAR label can reduce greenhouse gas emissions by about 130,000 pounds and save you
$11,000 on energy bills.
3. Heat and cool smartly
Heating and cooling accounts for almost half your energy bill--about $1,000 a year! There is a
lot you can do to drive down this cost. Simple steps like changing air filters regularly, properly
using a programmable thermostat, and having your heating and cooling equipment maintained
annually by a licensed contractor can save energy and increase comfort, while helping to protect
the environment. Depending on where you live, you can cut your annual energy bill by more
than $200 by replacing your old heating and cooling equipment with ENERGY STAR-qualified
equipment.
4. Seal and insulate your home
Reduce air leaks and stop drafts by using caulk, weather stripping, and insulation to seal your
home's envelope and add more insulation to your attic to block out heat and cold. A
knowledgeable homeowner or skilled contractor can save up to 20% on heating and cooling costs
and significantly enhance home comfort with comprehensive sealing and insulating measures.
5. Reduce, reuse, recycle
Reducing, reusing, and recycling in your home helps conserve energy and reduces pollution and
greenhouse gas emissions from resource extraction, manufacturing, and disposal. If there is a
recycling program in your community, recycle your newspapers, beverage containers, paper, and
other goods. Also, composting your food and yard waste reduces the amount of garbage that you
send to landfills and reduces greenhouse gas emissions. Visit EPA's Individual WAste Reduction
Model (iWARM) to learn about the energy benefits of recycling, rather than landfilling, common
waste products.
6. Use water efficiently
It takes lots of energy to pump, treat, and heat water, so saving water reduces greenhouse gas
emissions. Saving water around the home is simple. Three percent of the nation's energy is used
to pump and treat water so conserving water conserves energy that reduces greenhouse gas
pollution. Reduce the amount of waste you generate and the water you consume whenever
possible. Pursue simple water-saving actions such as not letting the water run while shaving or
brushing teeth and save money while conserving water by using products with the WaterSense
label. Did you know a leaky toilet can waste 200 gallons of water per day? Repair all toilet and
faucet leaks right away. Running your dishwasher only with a full load can save 100 pounds of
carbon dioxide and $40 per year. Be smart when irrigating your lawn or landscape. Only water
when needed, and do it during the coolest part of the day; early morning is best. See EPA's
WaterSense site for more water saving tips.

21. 7. Be green in your yard
Composting your food and yard waste reduces the amount of garbage that you send to landfills
and reduces greenhouse gas emissions. EPA's GreenScapes program provides tips on how to
improve your lawn or garden while also helping the environment.
8. Purchase green power
Power your home by purchasing green power. Green power is environmentally friendly
electricity that is generated from renewable energy sources such as wind and the sun. There are
two ways to use green power: You can buy green power, or you can modify your house to
generate your own green power. Buying green power is easy. It offers a number of
environmental and economic benefits over conventional electricity, including lower greenhouse
gas emissions, and it helps increase clean energy supply. There are a number of steps you can
take to create a greener home , including installing solar panels and
researching incentives for renewable energy in your state .
9. Calculate your household's carbon footprint
Use EPA's Household Greenhouse Gas Emissions Calculator to estimate your household
greenhouse gas emissions resulting from energy use, transportation, and waste disposal. This tool
helps you understand where your emissions come from and identify ways to reduce them.
10. Spread the word
Tell family and friends that energy efficiency is good for their homes and good for the
environment because it lowers greenhouse gas emissions and air pollution. Tell five people and
together we can help our homes help us all.
Is global warming going to destroy earth?
Best Answer
It won't destroy the earth, but it could certainly end civilization as we know it, that is if we don't
seriously decrease the CO2 being released into the atmosphere and stop deforestation.
A:
yes because there are going to be alot of problems with the earth.
A:
NO! The Earth is currently very cold. We have polar ice caps which is quite unusual for the
Earth. For most of geologic time the Earth has not had ice caps. (The Earth is currently very cold
because of weathering of the mountains - the planet is about as mountainous as it has ever been.)
A:
Technically speaking, the Earth is in an ice age, and it has been for 30 million years or so.
Currently we are in an interglacial. The ice ebbs and flows to and from the poles according to an
instability in the orbit of the Earth around the Sun. The ice retreated about 12,000 years ago and
will start advancing in the near future (2000 - 4000 years time). The glacial periods last for

22. 120,000 years or so.
Excess carbon dioxide is blamed for the global warming crisis we may experience in the near
future. However, the concentration of carbon dioxide in the atmosphere is about as low as it has
ever been (over the whole of geologic time). If we enhance the carbon dioxide concentration we
will just return the planet's atmosphere to a state it was in over 100 million years ago. As we
know, the planet was not dead then.
Excess carbon dioxide is not stable in the Earth's atmosphere. It dissolves in water vapor, falls as
acidic rain, and ends up in the oceans. There it is used by some plankton species to make shells.
Ultimately it ends up as chalk and limestone. It will take some 25000 for all the excess carbon
dioxide to rain out. Then it will be like global warming had never happened.
A:
The problem about global warming is not about harming the planet, but rather about destroying
human civilization. We are a species which evolved in a cold world. We cannot survive easily in
a hot world. For example, wheat will only grow well in temperate climates and most big cities
are on the coast. This means in a hot world, food will be become scarcer and there will be
significant human migration.
When will Global Warming destroy earth?
and will it be quick or slow and painful?
Best Answer - Chosen by Asker
2050 looks like the point where even the blindest anti-environmentalist will notice some kind of
change going on.....as for the rest of us it will be very obvious within the next decade....by 2100
it won't be a fun planet to live on.....
it is always going to be gradual with huge Katrina like disasters along the way.....it has started
already and will continue for a long time despite even the most drastic cuts of emissions....it
seems like the tipping point will be passed by 2100 if not 2050 or earlier.....
Other Answers (10)
• sse
Never!!! No such thing!!! Dont be brainwashed by CNN!
o 5 years ago
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• The Voice of Reason
Never
o 5 years ago
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• thor
When the sun goes nova in a couple billion years. Until then there will be both difficult
and easy times for life to survive on this planet.

23. o 5 years ago
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• grizzie
The earth will still be here--it'll just be a much less hospitable place for a large number of
its current species (including humans) to live. A lot of them won't make it.
o 5 years ago
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• James
It wont. Global warming is a natural cycle, and the earth will cool again
Source(s):
http://www.junkscience.com/news/robinson…
http://newsbusters.org/node/10604
http://sermons.trbc.org/20070225_11AM.ht…
http://www.foxnews.com/story/0,2933,1925…
http://www.globalwarminghoax.com/e107_pl…
http://www.prisonplanet.com/archives/glo…
http://www.sciencedaily.com/releases/200…
http://www.theage.com.au/articles/2004/1…
http://www.movermike.com/posts/118339711…
http://www.globalwarminghoax.com/news.ph…
http://allthingsconservative.typepad.com…
http://www.canada.com/nationalpost/story…
http://www.earthtimes.org/articles/show/…
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• gerafalo...
Global warming will not destroy the Earth. At worst the oceans will rise 2 feet.
Source(s):
The IPCC report
o 5 years ago
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• Just wonderin'
The earth even by global warming experts accounts has only warmed approx. 1 degree
over the last 100 years. With the change of technology over that period it is entirely
possible that the 1 degree of change can be attributed to accuracy of measurement rather
than a real change. Also by global warming experts accounts, the world has already
survived at least one ice age and the earth was not destroyed, so I suppose it is more a
matter of what you mean by destroyed. All global warming doomsday scenarios are
based on computer models. Computer models are based on human input. Therefore I
suppose the destruction of the earth will occur whenever the inventor of the internet (Al
Gore) tells it to.

24. Source(s):
Just wishing common sense was more common.
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• fyzer
Well, as the sun heats up about 10% every billion years and will end as a red giant before
dissipating as a nova in about 4-5 billion years, it's an issue I wouldn't be too concerned
about.
As for the current hysteria,don't worry about it, it's just that, hysteria.
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• Ingela
It will never "destroy earth" but it can destroy a whole lot of life on it if we don't act
powerful enough to stop it.
I continue to be optimistic about the future. It's never too late to do something about it,
but for every month that the world don't take more steps in the right direction, moving
away from deforestation and the burning of fossil fuel the future looks more and more
grim for many. Not later than by mid-century I would guess that everyone on earth will
be rather personally affected from the consequences of it, no matter where you live.
So, in a human life perspective the changes is rather slow and gradual, but in the
perspective of our planet, they are explosive!
Resolved Question
Show me another »
How long will it take for global warming to destroy the earth?
• 2 years ago
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asgspifs
Best Answer - Chosen by Voters
It's not the destruction of Earth via GW that is a concern, it is the degradation of the environment
in which we live, to the point that it will be difficult for us to continue to survive, that is a
concern.
Not to sound selfish, but I don't care that much about the Earth - it will be just fine for another 5

25. billion years or so - it's the environment that I live in and that my grand children will live in that I
care more about.
Other Answers (6)
• SpartanC...
Well, in 500 million to 900 million years, we could see a boil-off due to increasing solar
output accelerating the CO2 cycle, resulting in the extinction of animal life. In another
billion years after that, all surface water will have likely disappeared.
Note that this is natural warming due to the Sun's life cycle. Anthropogenic global
warming in the modern timescale stands to be more of an inconvenience (for us, perhaps
a major one), rather than an end to the world.
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• TheRockM...
The earth will not be destroyed, the atmosphere will change causing widespread
extinction to living species which have adapted to the present chemical composition of
the atmosphere. therefore climate change will only affect the CLIMATE not the whole
planet. The destruction of the earth is as unknown as is its formation.
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• jonal
What do you mean by 'destroy the Earth?'
Our planet was once a big ball of hot rock, much hotter than it is now.
It had vast amounts of CO2, sulphur, noxious gases of many kinds, and a lot of water

26. eventually.
Out of that came an Earth we think of as 'normal' because it's the one we live on now and
we relate various measurements of bits of it to that supposed 'normal' condition of the
Earth.
Actually, what it is now is just how it's turned out so far after four thousand five hundred
million years just as Mars is what it is now, or Mercury or any planet.
During that time it got hit by a massive object which threw up enough material to make
the Moon plus what fell back onto the Earth ( and for a while the Earth had rings like
Saturn) and by another millions of years later which still leaves a mark now in the
Yucatan peninsular and wiped out half of all life on Earth including most of the dinosaurs
as a result not only of the impact but of the dark days following it of thick clouds of water
and dust and incessant rain which may have lasted for months or years.without stopping
and would have led to massive flooding over most of the Earth's land areas.
It had ice ages and lots of them. It had warm periods and lots of them.It had an Antarctic
continent with no ice at all.
That was 'normal' then, each in it's own time.
Venus isn't destroyed either. It's about the same size as the Earth and the same age and
has a surface temperature high enough to melt lead because it's thick atmosphere of
carbon dioxide and sulphuric acid produces a massive greenhouse effect and the planet is
closer to the Sun than we are so it gets more heat from the Sun than we get
The thick atmosphere also reflects light brilliantly like big white cumulus clouds on a
sunny day on Earth which is one reason Venus appears so bright to us in the sky.
All we see is the brilliant light reflected from it's atmosphere which is even thicker and
denser than clouds over the Earth.
The other reason is it's relative closeness to us. At it's closest to us it's our nearest
neighbour apart from the Moon.
Being a hot volcanic planet with a dense acidic atmosphere hasn't destroyed it. It's just
going along nicely being Venus and not some other planet.
Now put 'global warming' into it all. Not much is it but plenty enough to make millions
out of in grants and research money.
The 'goodie' scientists ...the honest ones...were never fooled in the first place.
The big worry is not destroying the Earth but destroying so much of it's valuable
resources by digging up rainforest and overfishing the sea and the various other bits of
environmental disasters.
Get those sorted and the Earth and it's inhabitants including tens of thousands of species
of animals and plants will be fine.
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• Jason Colter

27. Never...Destroy us? Who knows? lol but man won't "destroy the earth" it's easy to kill
each other off, harder to destroy a planet...unless we build a death ray hahaha Human
beings haven't been here too long in the earth's history. We're a blink of the earth's eye. If
we're gone tommorrow, the earth will live on and she won't miss us.
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• lare
global warming is the necessary pre-cursor to ice ages, it does not escalate indefinitely. in
the past, ice age cycles have not destroyed people.
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• Al
never, but the climate will progressively bring stronger storms, higher sea levels. The
earth would survive even without an atmosphere, we would not of course.
o 2 years ago
Sources:
http://www.definitionofglobalwarming.com/
http://web.pdx.edu/~rueterj/courses/casestudies/globalwarming/index.html
http://wiki.answers.com/Q/What_are_the_household_appliances_that_contribute_to_global_war
ming
http://answers.yahoo.com/question/index?qid=20110412114924AAN29WM
http://greenliving.nationalgeographic.com/preventive-measures-global-warming-2209.html
http://climate.nasa.gov/evidence/
http://www.ncdc.noaa.gov/indicators/
http://www.epa.gov/climatechange/basics/

28. http://www.epa.gov/climatechange/wycd/home.html
http://wiki.answers.com/Q/Is_global_warming_going_to_destroy_earth
http://answers.yahoo.com/question/index?qid=20070925222506AArvbfK