Global warming

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For scientific and political disputes, see Global warming controversy, Scientific opinion on
climate change and Public opinion on climate change.
For past climate change see Paleoclimatology and Geologic temperature record. For the Sonny
Rollins album see Global Warming (album).

1880-2009 global mean surface temperature change relative to the 1961–1990 average. Source:
NASA GISS

Comparison of ground based (blue) and satellite based (red: UAH; green: RSS) records of
temperature variations since 1979. Trends plotted since January 1982.

Mean surface temperature change for the period 2000 to 2009 relative to the average
temperatures from 1951 to 1980.[1]

Global warming is the increase in the average temperature of Earth's near-surface air and oceans
since the mid-20th century and its projected continuation. According to the 2007 Fourth
Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface
temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century.[2][A] Most of the
observed temperature increase since the middle of the 20th century has been caused by
increasing concentrations of greenhouse gases, which result from human activity such as the
burning of fossil fuel and deforestation.[3] Global dimming, a result of increasing concentrations
of atmospheric aerosols that block sunlight from reaching the surface, has partially countered the
effects of warming induced by greenhouse gases.

Climate model projections summarized in the latest IPCC report indicate that the global surface
temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.[2] The
uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse
gas concentrations and the use of differing estimates of future greenhouse gas emissions. An
increase in global temperature will cause sea levels to rise and will change the amount and
pattern of precipitation, probably including expansion of subtropical deserts.[4] Warming is
expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers,
permafrost and sea ice. Other likely effects include changes in the frequency and intensity of
extreme weather events, species extinctions, and changes in agricultural yields. Warming and
related changes will vary from region to region around the globe, though the nature of these
regional variations is uncertain.[5] As a result of contemporary increases in atmospheric carbon
dioxide, the oceans have become more acidic, a result that is predicted to continue.[6][7]

The scientific consensus is that anthropogenic global warming is occurring.[8][9][10][B] Nevertheless,

political and public debate continues. The Kyoto Protocol is aimed at stabilizing greenhouse gas
concentration to prevent a "dangerous anthropogenic interference".[11] As of November 2009, 187
states had signed and ratified the protocol.[12]

Proposed responses to climate change include mitigation to reduce emissions, adaptation to the
effects of global warming, and geoengineering to remove greenhouse gases from the atmosphere
or block incoming sunlight.

Temperature changes
Main article: Temperature record

Two millennia of mean surface temperatures according to different reconstructions, each

smoothed on a decadal scale, with the actual recorded temperatures overlaid in black.
Evidence for warming of the climate system includes observed increases in global average air
and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.
[13][14][15][16][17]
The most common measure of global warming is the trend in globally averaged
temperature near the Earth's surface. Expressed as a linear trend, this temperature rose by
0.74 ± 0.18 °C over the period 1906–2005. The rate of warming over the last half of that period
was almost double that for the period as a whole (0.13 ± 0.03 °C per decade, versus 0.07 °C ±
0.02 °C per decade). The urban heat island effect is estimated to account for about 0.002 °C of
warming per decade since 1900.[18] Temperatures in the lower troposphere have increased
between 0.13 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite
temperature measurements. Temperature is believed to have been relatively stable over the one
or two thousand years before 1850, with regionally varying fluctuations such as the Medieval
Warm Period and the Little Ice Age.[19]

Estimates by NASA's Goddard Institute for Space Studies (GISS) and the National Climatic Data
Center show that 2005 was the warmest year since reliable, widespread instrumental
measurements became available in the late 19th century, exceeding the previous record set in
1998 by a few hundredths of a degree.[20][21] Estimates prepared by the World Meteorological
Organization and the Climatic Research Unit show 2005 as the second warmest year, behind
1998.[22][23] Temperatures in 1998 were unusually warm because the strongest El Niño in the past
century occurred during that year.[24] Global temperature is subject to short-term fluctuations that
overlay long term trends and can temporarily mask them. The relative stability in temperature
from 2002 to 2009 is consistent with such an episode.[25][26]

Temperature changes vary over the globe. Since 1979, land temperatures have increased about
twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade).[27] Ocean
temperatures increase more slowly than land temperatures because of the larger effective heat
capacity of the oceans and because the ocean loses more heat by evaporation.[28] The Northern
Hemisphere warms faster than the Southern Hemisphere because it has more land and because it
has extensive areas of seasonal snow and sea-ice cover subject to ice-albedo feedback. Although
more greenhouse gases are emitted in the Northern than Southern Hemisphere this does not
contribute to the difference in warming because the major greenhouse gases persist long enough
to mix between hemispheres.[29]

The thermal inertia of the oceans and slow responses of other indirect effects mean that climate
can take centuries or longer to adjust to changes in forcing. Climate commitment studies indicate
that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C
(0.9 °F) would still occur.[30]

External forcings
External forcing refers to processes external to the climate system (though not necessarily
external to Earth) that influence climate. Climate responds to several types of external forcing,
such as radiative forcing due to changes in atmospheric composition (mainly greenhouse gas
concentrations), changes in solar luminosity, volcanic eruptions, and variations in Earth's orbit
around the Sun.[31] Attribution of recent climate change focuses on the first three types of forcing.
Orbital cycles vary slowly over tens of thousands of years and thus are too gradual to have
caused the temperature changes observed in the past century.

Greenhouse gases

Main articles: Greenhouse effect, Radiative forcing, and Carbon dioxide in Earth's atmosphere

Greenhouse effect schematic showing energy flows between space, the atmosphere, and earth's
surface. Energy exchanges are expressed in watts per square meter (W/m2).

Recent atmospheric carbon dioxide (CO2) increases. Monthly CO2 measurements display
seasonal oscillations in overall yearly uptrend; each year's maximum occurs during the Northern
Hemisphere's late spring, and declines during its growing season as plants remove some
atmospheric CO2.

The greenhouse effect is the process by which absorption and emission of infrared radiation by
gases in the atmosphere warm a planet's lower atmosphere and surface. It was proposed by
Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896.[32]

Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F).[33][C]
The major greenhouse gases are water vapor, which causes about 36–70 percent of the
greenhouse effect; carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which
causes 4–9 percent; and ozone (O3), which causes 3–7 percent.[34][35][36] Clouds also affect the
radiation balance, but they are composed of liquid water or ice and so have different effects on
radiation from water vapor.

Human activity since the Industrial Revolution has increased the amount of greenhouse gases in
the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone,
CFCs and nitrous oxide. The concentrations of CO2 and methane have increased by 36% and
148% respectively since 1750.[37] These levels are much higher than at any time during the last
650,000 years, the period for which reliable data has been extracted from ice cores.[38][39][40] Less
direct geological evidence indicates that CO2 values higher than this were last seen about 20
million years ago.[41] Fossil fuel burning has produced about three-quarters of the increase in CO2
from human activity over the past 20 years. Most of the rest is due to land-use change,
particularly deforestation.[42]

Over the last three decades of the 20th century, GDP per capita and population growth were the
main drivers of increases in greenhouse gas emissions.[43] CO2 emissions are continuing to rise
due to the burning of fossil fuels and land-use change.[44][45]:71 Emissions scenarios, estimates of
changes in future emission levels of greenhouse gases, have been projected that depend upon
uncertain economic, sociological, technological, and natural developments.[46] In most scenarios,
emissions continue to rise over the century, while in a few, emissions are reduced.[47][48] These
emission scenarios, combined with carbon cycle modelling, have been used to produce estimates
of how atmospheric concentrations of greenhouse gases will change in the future. Using the six
IPCC SRES "marker" scenarios, models suggest that by the year 2100, the atmospheric
concentration of CO2 could range between 541 and 970 ppm.[49] This is an increase of 90-250%
above the concentration in the year 1750. Fossil fuel reserves are sufficient to reach these levels
and continue emissions past 2100 if coal, oil sands or methane clathrates are extensively
exploited.[50]

The destruction of stratospheric ozone by chlorofluorocarbons is sometimes mentioned in

relation to global warming. Although there are a few areas of linkage, the relationship between
the two is not strong. Reduction of stratospheric ozone has a cooling influence.[51] Substantial
ozone depletion did not occur until the late 1970s.[52] Ozone in the troposphere (the lowest part of
the Earth's atmosphere) does contribute to surface warming.[53]

Aerosols and soot

Ship tracks over the Atlantic Ocean on the east coast of the United States. The climatic impacts
from aerosol forcing could have a large effect on climate through the indirect effect.

Global dimming, a gradual reduction in the amount of global direct irradiance at the Earth's
surface, has partially counteracted global warming from 1960 to the present.[54] The main cause
of this dimming is aerosols produced by volcanoes and pollutants. These aerosols exert a cooling
effect by increasing the reflection of incoming sunlight. The effects of the products of fossil fuel
combustion—CO2 and aerosols—have largely offset one another in recent decades, so that net
warming has been due to the increase in non-CO2 greenhouse gases such as methane.[55]
Radiative forcing due to aerosols is temporally limited due to wet deposition which causes
aerosols to have an atmospheric lifetime of one week. Carbon dioxide has a lifetime of a century
or more, and as such, changes in aerosol concentrations will only delay climate changes due to
carbon dioxide.[56]

In addition to their direct effect by scattering and absorbing solar radiation, aerosols have
indirect effects on the radiation budget.[57] Sulfate aerosols act as cloud condensation nuclei and
thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar
radiation more efficiently than clouds with fewer and larger droplets.[58] This effect also causes
droplets to be of more uniform size, which reduces growth of raindrops and makes the cloud
more reflective to incoming sunlight.[59] Indirect effects are most noticeable in marine stratiform
clouds, and have very little radiative effect on convective clouds. Aerosols, particularly their
indirect effects, represent the largest uncertainty in radiative forcing.[60]

Soot may cool or warm the surface, depending on whether it is airborne or deposited.
Atmospheric soot aerosols directly absorb solar radiation, which heats the atmosphere and cools
the surface. In isolated areas with high soot production, such as rural India, as much as 50% of
surface warming due to greenhouse gases may be masked by atmospheric brown clouds.[61]
Atmospheric soot always contributes additional warming to the climate system. When deposited,
especially on glaciers or on ice in arctic regions, the lower surface albedo can also directly heat
the surface.[62] The influences of aerosols, including black carbon, are most pronounced in the
tropics and sub-tropics, particularly in Asia, while the effects of greenhouse gases are dominant
in the extratropics and southern hemisphere.[63]

Solar variation

Main article: Solar variation

Solar variation over thirty years.

Variations in solar output have been the cause of past climate changes.[64] The effect of changes
in solar forcing in recent decades is uncertain, but small, with some studies showing a slight
cooling effect,[65] while others studies suggest a slight warming effect.[31][66][67][68]

Greenhouse gases and solar forcing affect temperatures in different ways. While both increased
solar activity and increased greenhouse gases are expected to warm the troposphere, an increase
in solar activity should warm the stratosphere while an increase in greenhouse gases should cool
the stratosphere.[31] Observations show that temperatures in the stratosphere have been cooling
since 1979, when satellite measurements became available. Radiosonde (weather balloon) data
from the pre-satellite era show cooling since 1958, though there is greater uncertainty in the early
radiosonde record.[69]

A related hypothesis, proposed by Henrik Svensmark, is that magnetic activity of the sun deflects
cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect
the climate.[70] Other research has found no relation between warming in recent decades and
cosmic rays.[71][72] The influence of cosmic rays on cloud cover is about a factor of 100 lower than
needed to explain the observed changes in clouds or to be a significant contributor to present-day
climate change.[73]

Feedback
Main article: Climate change feedback

Feedback is a process in which changing one quantity changes a second quantity, and the change
in the second quantity in turn changes the first. Positive feedback amplifies the change in the first
quantity while negative feedback reduces it. Feedback is important in the study of global
warming because it may amplify or diminish the effect of a particular process. The main positive
feedback in global warming is the tendency of warming to increase the amount of water vapor in
the atmosphere, a significant greenhouse gas. The main negative feedback is radiative cooling,
which increases as the fourth power of temperature; the amount of heat radiated from the Earth
into space increases with the temperature of Earth's surface and atmosphere. Imperfect
understanding of feedbacks is a major cause of uncertainty and concern about global warming. A
wide range of potential feedback process exist, such as Arctic methane release and ice-albedo
feedback. Consequentially, potential tipping points may exist, which may have the potential to
cause abrupt climate change.[74]

Climate models
Main article: Global climate model

Calculations of global warming prepared in or before 2001 from a range of climate models under
the SRES A2 emissions scenario, which assumes no action is taken to reduce emissions and
regionally divided economic development.
The geographic distribution of surface warming during the 21st century calculated by the
HadCM3 climate model if a business as usual scenario is assumed for economic growth and
greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C
(5.4 °F).

The main tools for projecting future climate changes are mathematical models based on physical
principles including fluid dynamics, thermodynamics and radiative transfer. Although they
attempt to include as many processes as possible, simplifications of the actual climate system are
inevitable because of the constraints of available computer power and limitations in knowledge
of the climate system. All modern climate models are in fact combinations of models for
different parts of the Earth. These include an atmospheric model for air movement, temperature,
clouds, and other atmospheric properties; an ocean model that predicts temperature, salt content,
and circulation of ocean waters; models for ice cover on land and sea; and a model of heat and
moisture transfer from soil and vegetation to the atmosphere. Some models also include
treatments of chemical and biological processes.[75] Warming due to increasing levels of
greenhouse gases is not an assumption of the models; rather, it is an end result from the
interaction of greenhouse gases with radiative transfer and other physical processes.[76] Although
much of the variation in model outcomes depends on the greenhouse gas emissions used as
inputs, the temperature effect of a specific greenhouse gas concentration (climate sensitivity)
varies depending on the model used. The representation of clouds is one of the main sources of
uncertainty in present-generation models.[77]

Global climate model projections of future climate most often have used estimates of greenhouse
gas emissions from the IPCC Special Report on Emissions Scenarios (SRES). In addition to
human-caused emissions, some models also include a simulation of the carbon cycle; this
generally shows a positive feedback, though this response is uncertain. Some observational
studies also show a positive feedback.[78][79][80] Including uncertainties in future greenhouse gas
concentrations and climate sensitivity, the IPCC anticipates a warming of 1.1 °C to 6.4 °C
(2.0 °F to 11.5 °F) by the end of the 21st century, relative to 1980–1999.[2]

Models are also used to help investigate the causes of recent climate change by comparing the
observed changes to those that the models project from various natural and human-derived
causes. Although these models do not unambiguously attribute the warming that occurred from
approximately 1910 to 1945 to either natural variation or human effects, they do indicate that the
warming since 1970 is dominated by man-made greenhouse gas emissions.[31]

The physical realism of models is tested by examining their ability to simulate current or past
climates.[81] Current climate models produce a good match to observations of global temperature
changes over the last century, but do not simulate all aspects of climate.[42] Not all effects of
global warming are accurately predicted by the climate models used by the IPCC. Observed
Arctic shrinkage has been faster than that predicted.[82] Precipitation increased proportional to
atmospheric humidity, and hence significantly faster than current global climate models predict.
[83][84]

Attributed and expected effects

Main articles: Effects of global warming and Regional effects of global warming

Global warming may be detected in natural, ecological or social systems as a change having
statistical significance.[85] Attribution of these changes e.g., to natural or human activities, is the
next step following detection.[86]

Natural systems

Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s
measurements began that allow the monitoring of glacial mass balance, reported to the WGMS
and the NSIDC.

Global warming has been detected in a number of systems. Some of these changes, e.g., based on
the instrumental temperature record, have been described in the section on temperature changes.
Rising sea levels and observed decreases in snow and ice extent are consistent with warming.[17]
Most of the increase in global average temperature since the mid-20th century is, with high
probability,[D] attributable to human-induced changes in greenhouse gas concentrations.[87]

Even with current policies to reduce emissions, global emissions are still expected to continue to
grow over the coming decades.[88] Over the course of the 21st century, increases in emissions at
or above their current rate would very likely induce changes in the climate system larger than
those observed in the 20th century.

In the IPCC Fourth Assessment Report, across a range of future emission scenarios, model-based
estimates of sea level rise for the end of the 21st century (the year 2090-2099, relative to 1980-
1999) range from 0.18 to 0.59 m. These estimates, however, were not given a likelihood due to a
lack of scientific understanding, nor was an upper bound given for sea level rise. Over the course
of centuries to millennia, the melting of ice sheets could result in sea level rise of 4–6 m or more.
[89]

Changes in regional climate are expected to include greater warming over land, with most
warming at high northern latitudes, and least warming over the Southern Ocean and parts of the
North Atlantic Ocean.[88] Snow cover area and sea ice extent are expected to decrease. The
frequency of hot extremes, heat waves, and heavy precipitation will very likely increase.

Ecological systems

In terrestrial ecosystems, the earlier timing of spring events, and poleward and upward shifts in
plant and animal ranges, have been linked with high confidence to recent warming.[17] Future
climate change is expected to particularly affect certain ecosystems, including tundra,
mangroves, and coral reefs.[88] It is expected that most ecosystems will be affected by higher
atmospheric CO2 levels, combined with higher global temperatures.[90] Overall, it is expected that
climate change will result in the extinction of many species and reduced diversity of ecosystems.
[91]

Social systems

There is some evidence of regional climate change affecting systems related to human activities,
including agricultural and forestry management activities at higher latitudes in the Northern
Hemisphere.[17] Future climate change is expected to particularly affect some sectors and systems
related to human activities.[88] Low-lying coastal systems are vulnerable to sea level rise and
storm surge. Human health will be at increased risk in populations with limited capacity to adapt
to climate change. It is expected that some regions will be particularly affected by climate
change, including the Arctic, Africa, small islands, and Asian and African megadeltas. In some
areas the effects on agriculture, industry and health could be mixed, or even beneficial in certain
respects, but overall it is expected that these benefits will be outweighed by negative effects.[92]

Responses to global warming

Mitigation

Main article: Climate change mitigation

See also: Fee and dividend

Reducing the amount of future climate change is called mitigation of climate change. The IPCC
defines mitigation as activities that reduce greenhouse gas (GHG) emissions, or enhance the
capacity of carbon sinks to absorb GHGs from the atmosphere.[93] Many countries, both
developing and developed, are aiming to use cleaner, less polluting, technologies.[45]:192 Use of
these technologies aids mitigation and could result in substantial reductions in CO2 emissions.
Policies include targets for emissions reductions, increased use of renewable energy, and
increased energy efficiency. Studies indicate substantial potential for future reductions in
emissions.[94] Since even in the most optimistic scenario, fossil fuels are going to be used for
years to come, mitigation may also involve carbon capture and storage, a process that traps CO2
produced by factories and gas or coal power stations and then stores it, usually underground.[95]

Adaptation

Main article: Adaptation to global warming

Other policy responses include adaptation to climate change. Adaptation to climate change may
be planned, e.g., by local or national government, or spontaneous, i.e., done privately without
government intervention.[96] The ability to adapt is closely linked to social and economic
development.[94] Even societies with high capacities to adapt are still vulnerable to climate
change. Planned adaptation is already occurring on a limited basis. The barriers, limits, and costs
of future adaptation are not fully understood.

Geoengineering

Another policy response is engineering of the climate (geoengineering). This policy response is
sometimes grouped together with mitigation.[97] Geoengineering is largely unproven, and reliable
cost estimates for it have not yet been published.[98] Geoengineering encompasses a range of
techniques to remove CO2 from the atmosphere or to block incoming sunlight.

UNFCCC

Most countries are Parties to the United Nations Framework Convention on Climate Change
(UNFCCC).[99] The ultimate objective of the Convention is to prevent "dangerous" human
interference of the climate system.[100] As is stated in the Convention, this requires that GHGs are
stabilized in the atmosphere at a level where ecosystems can adapt naturally to climate change,
food production is not threatened, and economic development can proceed in a sustainable
fashion.

The UNFCCC recognizes differences among countries in their responsibility to act on climate
change.[101] In the Kyoto Protocol to the UNFCCC, most developed countries (listed in Annex I
of the treaty) took on legally binding commitments to reduce their emissions.[102] Policy measures
taken in response to these commitments have reduced emissions.[103] For many developing (non-
Annex I) countries, reducing poverty is their overriding aim.[104]

At the 15th UNFCCC Conference of the Parties, held in 2009 at Copenhagen, several UNFCCC
Parties produced the Copenhagen Accord.[105] Parties agreeing with the Accord aim to limit the
future increase in global mean temperature to below 2 °C.[106] The 16th Conference of the Parties
(COP16) was held at Cancún in 2010. It produced an agreement, not a binding treaty, that the
Parties should take urgent action to reduce greenhouse gas emissions to meet the 2 °C goal. It
also recognized the need to consider strengthening the goal to a global average rise of 1.5 °C.[107]

Views on global warming

Main articles: Global warming controversy and Politics of global warming
See also: Scientific opinion on climate change and Public opinion on climate change

Per capita greenhouse gas emissions in 2000, including land-use change.

Total greenhouse gas emissions in 2000, including land-use change.

There are different views over what the appropriate policy response to climate change should be.
[108][109]
These competing views weigh the benefits of limiting emissions of greenhouse gases
against the costs. In general, it seems likely that climate change will impose greater damages and
risks in poorer regions.[110]

Politics

Developed and developing countries have made different arguments over who should bear the
burden of economic costs for cutting emissions. Developing countries often concentrate on per
capita emissions, that is, the total emissions of a country divided by its population.[111] Per capita
emissions in the industrialized countries are typically as much as ten times the average in
developing countries.[112] This is used to make the argument that the real problem of climate
change is due to the profligate and unsustainable lifestyles of those living in rich countries.[111]

On the other hand, commentators from developed countries point out that total carbon
emissions,[111] carrying capacity, efficient energy use and civil and political rights are very
important issues. World population is the number of humans per unit area. However the land is
not the same everywhere. Not only the quantity of fossil fuel use but also the quality of energy
use is a key debate point. For example, efficient energy use supporting technological change
might help reduce excess carbon dioxide in Earth's atmosphere. The use of fossil fuels for
conspicuous consumption and excessive entertainment are issues that can conflict with civil and
political rights. People in developed countries argue that history has proven the difficulty of
implementing fair rationing programs in different countries because there is no global system of
checks and balances or civil liberties.

The Kyoto Protocol, which came into force in 2005, sets legally binding emission limitations for
most developed countries.[102] Developing countries are not subject to limitations. This exemption
led the U.S. and Australia to decide not to ratify the treaty,[113] [114][115] although Australia did
finally ratify the treaty in December 2007.[116] Debate continued at the Copenhagen climate
summit and the Cancún climate summit.

Public opinion

In 2007–2008 Gallup Polls surveyed 127 countries. Over a third of the world's population was
unaware of global warming, with people in developing countries less aware than those in
developed, and those in Africa the least aware. Of those aware, Latin America leads in belief that
temperature changes are a result of human activities while Africa, parts of Asia and the Middle
East, and a few countries from the Former Soviet Union lead in the opposite belief.[117] In the
Western world, opinions over the concept and the appropriate responses are divided. Nick
Pidgeon of Cardiff University said that "results show the different stages of engagement about
global warming on each side of the Atlantic", adding, "The debate in Europe is about what action
needs to be taken, while many in the U.S. still debate whether climate change is happening."[118]
[119]

Other views

Most scientists accept that humans are contributing to observed climate change.[44][120] National
science academies have called on world leaders for policies to cut global emissions.[121] However,
some scientists and non-scientists question aspects of climate-change science.[122][123]

Organizations such as the libertarian Competitive Enterprise Institute, conservative

commentators, and some companies such as ExxonMobil have challenged IPCC climate change
scenarios, funded scientists who disagree with the scientific consensus, and provided their own
projections of the economic cost of stricter controls.[124][125][126][127] In the finance industry,
Deutsche Bank has set up an institutional climate change investment division (DBCCA),[128]
which has commissioned and published research[129] on the issues and debate surrounding global
warming.[130] Environmental organizations and public figures have emphasized changes in the
current climate and the risks they entail, while promoting adaptation to changes in infrastructural
needs and emissions reductions.[131] Some fossil fuel companies have scaled back their efforts in
recent years,[132] or called for policies to reduce global warming.[133]

Etymology
The term global warming was probably first used in its modern sense on 8 August 1975 in a
science paper by Wally Broecker in the journal Science called "Are we on the brink of a
pronounced global warming?".[134][135][136] Broecker's choice of words was new and represented a
significant recognition that the climate was warming; previously the phrasing used by scientists
was "inadvertent climate modification," because while it was recognized humans could change
the climate, no one was sure which direction it was going.[137] The National Academy of Sciences
first used global warming in a 1979 paper called the Charney Report, it said: "if carbon dioxide
continues to increase, [we find] no reason to doubt that climate changes will result and no reason
to believe that these changes will be negligible."[138] The report made a distinction between
referring to surface temperature changes as global warming, while referring to other changes
caused by increased CO2 as climate change.[137] This distinction is still often used in science
reports, with global warming meaning surface temperatures, and climate change meaning other
changes (increased storms, etc..)[137]

Global warming became more widely popular after 1988 when NASA scientist James Hansen
used the term in a testimony to Congress.[137] He said: "global warming has reached a level such
that we can ascribe with a high degree of confidence a cause and effect relationship between the
greenhouse effect and the observed warming."[139] His testimony was widely reported and
afterward global warming was commonly used by the press and in public discourse.[137]

What is global warming? 

Global warming is when the earth heats up (the temperature rises).  It happens when greenhouse gases
(carbon dioxide, water vapor, nitrous oxide, and methane) trap heat and light from the sun in the earth’s
atmosphere, which increases the temperature.  This hurts many people, animals, and plants.  Many cannot
take the change, so they die.

What is the greenhouse effect?

The greenhouse effect is when the temperature rises because the sun’s heat and light is trapped in the
earth’s atmosphere.  This is like when heat is trapped in a car. On a very hot day, the car gets hotter when
it is out in the parking lot.  This is because the heat and light from the sun can get into the car, by going
through the windows, but it can’t get back out.  This is what the greenhouse effect does to the earth.  The
heat and light can get through the atmosphere, but it can’t get out.  As a result, the temperature rises.

The squiggle lines coming from the sun are visible light and The sun’s heat can get into the car through
the lines and arrows inside the car are infrared light.  the windows but is then trapped.  This
makes what ever the place might be, a
greenhouse, a car, a building, or the earth’s
atmosphere, hotter.  This diagram shows the heat coming into a car as visible light (light you can see) and
infrared light (heat).  Once the light is inside the car, it is trapped and the heat builds up, just like it does
in the earth’s atmosphere.

Sometimes the temperature can change in a way that helps us.  The greenhouse effect makes the earth
appropriate for people to live on.  Without it, the earth would be freezing, or on the other hand it would be
burning hot.  It would be freezing at night because the sun would be down.  We would not get the sun’s
heat and light to make the night somewhat warm.  During the day, especially during the summer, it would
be burning because the sun would be up with no atmosphere to filter it, so people, plants, and animals
would be exposed to all the light and heat.

Although the greenhouse effect makes the earth able to have people living on it, if there gets to be too
many gases, the earth can get unusually warmer, and many plants, animals, and people will die.  They
would die because there would be less food (plants like corn, wheat, and other vegetables and fruits). 
This would happen because the plants would not be able to take the heat.  This would cause us to have
less food to eat, but it would also limit the food that animals have.  With less food, like grass, for the
animals that we need to survive (like cows) we would even have less food.  Gradually, people, plants, and
animals would all die of hunger.  

What are greenhouse gasses?

Greenhouse gasses are gasses are in the earth’s atmosphere that collect heat and light from the sun.  With
too many greenhouse gasses in the air, the earth’s atmosphere will trap too much heat and the earth will
get too hot.  As a result people, animals, and plants would die because the heat would be too strong. 

What is global warming doing to the environment?

Global warming is affecting many parts of the world.  Global warming makes the sea rise, and when the
sea rises, the water covers many low land islands.  This is a big problem
for many of the plants, animals, and people on islands.  The water covers
the plants and causes some of them to die.  When they die, the animals
lose a source of food, along with their habitat.  Although animals have a
better ability to adapt to what happens than plants do, they may die also. 
When the plants and animals die, people lose two sources of food, plant
food and animal food.  They may also lose their homes.  As a result, they
would also have to leave the area or die.  This would be called a break in
the food chain, or a chain reaction, one thing happening that leads to another and so on.  

The oceans are affected by global warming in other ways, as well.  Many things that are happening to the
ocean are linked to global warming.  One thing that is happening is warm water, caused from global
warming, is harming and killing algae in the ocean.

Algae is a producer that you can

see floating on the top of the
water.  (A producer is something
that makes food for other
animals through photosynthesis,
like grass.)  This floating green
algae is food to many consumers
in the ocean.  (A consumer is
something that eats the producers.)  One kind of a consumer is small fish.  There are many others like
crabs, some whales, and many other animals.  Fewer algae is a problem because there is less food for us
and many animals in the sea. 

Global warming is doing many things to people as well as animals and plants.  It is killing algae, but it is
also destroying many huge forests.  The pollution that causes global warming is linked to acid rain.  Acid
rain gradually destroys almost everything it touches.  Global warming is also causing many more fires
that wipe out whole forests.  This happens because global warming can make the earth very hot.  In
forests, some plants and trees leaves can be so dry that they catch on fire. 

What causes global warming?  

Many things cause global warming.  One thing that causes global warming is electrical pollution. 
Electricity causes pollution in many ways, some worse than others.  In most cases, fossil fuels are burned
to create electricity.  Fossil fuels are made of dead plants and animals.  Some examples of fossil fuels are
oil and petroleum.  Many pollutants (chemicals that pollute the air, water, and land) are sent into the air
when fossil fuels are burned.  Some of these chemicals are called greenhouse gasses.

We use these sources of energy much more than the sources that give off less pollution.  Petroleum, one
of the sources of energy, is used a lot.  It is used for transportation, making electricity, and making many
other things.  Although this source of energy gives off a lot of pollution, it is used for 38% of the United
States’ energy.

Some other examples of using energy and polluting the air are:

Turning on a light
Watching T.V.
Listening to a stereo
Washing or drying clothes
Using a hair dryer
Riding in a car
Heating a meal in the microwave
Using an air conditioner
Playing a video game
Using a dish washer

When you do these things, you are causing more greenhouse gasses to be sent into the air.  Greenhouse
gasses are sent into the air because creating the electricity you use to do these things causes pollution.  If
you think of how many times a day you do these things, it’s a lot.  You even have to add in how many
other people do these things!  That turns out to be a lot of pollutants going into the air a day because of
people like us using electricity. The least amount of electricity you use, the better.

When we throw our garbage away, the garbage goes to landfills.  Landfills are those
big hills that you go by on an expressway that stink.  They are full of garbage.  The
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garbage is then sometimes burned.  This sends an enormous amount of greenhouse gasses into the air
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and makes global warming worse. t
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Another thing that makes global warming worse is when people cut down trees.  Trees and other plants
collect carbon dioxide (CO2), which is a greenhouse gas. y
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Carbon dioxide is the air that our body lets out when we breathe. With fewer trees, it is harder for l
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people to breathe because there is more CO2 in the air, and we don’t breathe CO2, we breathe oxygen.  o
Plants collect the CO2 that we breathe out, and they give back oxygen that we breathe in.  With less w
trees and other plants, such as algae, there is less air for us, and more greenhouse gases are sent into the
air. This means that it is very important to protect our trees to stop the greenhouse effect, and also so we c
can breathe and live.  o
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This gas, CO2, collects light and heat (radiant energy), produced by the sun, and this makes the earth r
warmer.  The heat and light from the sun is produced in the center of the sun.  (The sun has layers just
like the earth.)  o
n
 
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u
This layer is called the core.  Just like a core of an apple, it is in the middle.  Here there is a very high
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temperature, about 27,000,000F.  This heat escapes out of this layer to the next layer, the radiative s
zone. This layer is cooler, about 4,500,000F.   Gradually, the heat and light will pass through the i
convection zone at a temperature of around 2,000,000F.   When it gets to the surface, the temperature d
is about 10,000F.  Finally, the heat and light is sent into space.  This is called radiant energy (heat e
and light).  The radiant energy reaches the earth’s atmosphere.  As a result of this process we get light
i
and heat.  When you pollute, you send chemicals into the air that destroy our atmosphere, so more heat s
and light cannot escape from the earth’s atmosphere.
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What are people doing to stop global warming?   h
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People are doing many things to try to stop global warming.  One thing people are doing is carpooling. 
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Carpooling is driving with someone to a place that you are both going to.  This minimizes the amount
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of greenhouse gases put into the air by a car. r
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Another thing that people are doing is being more careful about leaving things turned on like the a
television, computer, and the lights.   A lot of people are taking time away from the television, and c
instead, they are spending more time outdoors.  This helps our planet out a lot.  Now, more people are e
.
even riding busses, walking to school, and riding their bikes to lower the amount of greenhouse gases in  
the air.  Planting trees and recycling also helps.  If you recycle, less trash goes to the dump, and less
trash gets burned.  As a result, there are fewer greenhouse gasses in our atmosphere.  T
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Watch what you buy.  Many things, such as hairspray and deodorant, now are made to have less of an
impact on the atmosphere.  Less greenhouse gasses will rise into the air, and global warming will slow
down.

What is the government doing to stop global warming?

The government is doing many things to help stop global warming. The government made a law called
The Clean Air Act so there is less air pollution.  Global warming is making people get very bad illnesses
that could make them disabled, very sick, and sometimes even die.  The Clean Air Act is making many
companies change their products to decrease these problems.  Part of the law says that you may not put a
certain amount of pollutants in the air.  Hairspray and some other products, like foam cups, had this
problem.  Making and using these products let out too much volatile organic compounds (VOC’s), ozone-
destroying chemicals (chlorofluorocarbons (CFC’s), and related chemicals (such as CO2) into the air. 
Now, almost all of these products have a label on them telling people what this product can do to the
environment and many people.  By 2015 all products listed on the Clean Air Act will have this label on
them:

WARNING: contains or manufactured with (the chemical would

go here.  For example chlorofluorocarbons (CFC’s), a substance
which harms public health and the environment by destroying
ozone in the upper atmosphere.  

Almost all of the other chemicals that could be harmful will have this label on them hopefully by this time
(2015) as well.

The Clean Air Act has also made car companies change some of the things inside of the cars.  Cars
pollute a lot.  While cars make more than half of the world’s smog (visible pollution in the air), many
things that cars need to move and heat up make even more pollution.  Some things that are inside of cars,
buses, trucks, and motorcycles, like gasoline, pollute the air when the fuel is burned.  It comes out as a
chemical and when mixed in the air, forms smog.  Smog is a kind of pollution that you see in the form of
a cloud.  If you have ever been to California you can see a lot of smog in some places.  Sometimes the
smog gets so bad that you cannot see at all!  Smog forms when car exhaust, pollution from homes, and
pollution from factories mixes in the air and has a chemical reaction.  The sun’s heat and light add to the
reaction.

Cars, buses, and trucks are also responsible for over 50% of dangerous chemicals let into the air.  Some of
these chemicals can cause cancer, birth defects, trouble breathing, brain and nerve damage, lung injures,
and burning eyes.  Some of the pollutants are so harmful that they can even cause death.
What are some of the other dangerous chemicals?

Some other chemicals that cause air pollution and are bad for the environment and people are:

Ozone- Ozone is produced when other pollution chemicals combine.  It is the basic element of smog. 
It causes many different kinds of health issues dealing with the lungs.  It can damage plants and
limit sight.  It can also cause a lot of property damage.
VOC’s (volatile organic compounds, smog formers)- VOC’s are let into the air when fuel is burned.
This chemical can cause cancer.  It can also harm plants.
NOx (nitrogen dioxide)- This chemical forms smog.  It is also formed by burning sources of energy,
like gas, coal, and oil, and by cars.  This chemical causes problems in the respiratory system
(including the lungs).  It causes acid rain, and it can damage trees.  This chemical can eat away
buildings and statues.
CO (carbon monoxide)- The source of this chemical is burning sources of energy.  It causes blood
vessel problems and respiratory failures.
PM-10 (particulate matter)- The source of this chemical is plowing and burning down fields.  It can
cause death and lung damage.  It can make it hard for people to breathe.  The smoke, soot, ash, and
dust formed by this chemical can make many cities dirty.
Sulfur Dioxide- This chemical is produced by making paper and metals.  This chemical can cause
permanent lung damage.  It can cause acid rain which kills trees and damages building and statues.
Lead- This chemical is in paint, leaded gasoline, smelters, and in lead storage batteries.  It can cause
many brain and nerve damages and digestive problems.

Kid can help stop global warming, too!!

Although adults do many things to help stop global warming, kids can do just as much.  Kids can’t do
hard things like making a law, but we can do easier things like not watching as much TV.  You can listen
to your parents when they say, turn off your lights or go play outside.  Listening to them and actually
trying to help can help you, your environment, and the world.

Global Warming Solutions

Obviously there is no one magic solution to the problem of global warming. There are instead
hundreds of questions that need to be asked and addressed so as to create an overall Earth plan
that will develop our planet wisely. The changes we can make, both large and small when
combined will curtail global warming for the better. In this section we discuss the latest green
designs, products and ideas as yet undeveloped that will reduce environmental damage overall.
 We plan to offer honest value comparisons of
products such as hybrid cars. If the carbon footprint made from producing a hybrid is ten times
larger than that it erases it is news that should be shared. Compact florescent lights are great
energy savers but are all of these exactly what they claim to be? And furthermore will light
emitting diodes render CFLs obsolete before they are universally adapted.

As always the future holds a newer and possibly better design. We will be bringing you articles
examining what will come and those products that are already available but await widespread
acceptance. Developments in mass renewable energy production in such areas as solar and wind
power are of interest to all. We will also be looking back at past successful use of these energy
choices. Zenith sold tiny windmills in the late 1930s that would charge a car battery that in turn
would run a radio for days. Has the technological upgrade been utilized?
We will find solutions to the problem of global warming by asking countless questions about the
processes we rely upon to live. We answer these questions on a personal level by changing the
habits, which build each of our carbon footprints and on a global level by insisting that social and
governmental structure acknowledge the need for environmental protection.
Global Warming Solutions
What Can We Do?
Main Content

Photograph by Paul Nicklen

The evidence that humans are causing global warming is strong, but the question of what to do
about it remains controversial. Economics, sociology, and politics are all important factors in
planning for the future.

Even if we stopped emitting greenhouse gases (GHGs) today, the Earth would still warm by
another degree Fahrenheit or so. But what we do from today forward makes a big difference. 
Depending on our choices, scientists predict that the Earth could eventually warm by as little as
2.5 degrees or as much as 10 degrees Fahrenheit.

A commonly cited goal is to stabilize GHG concentrations around 450-550 parts per million
(ppm), or about twice pre-industrial levels. This is the point at which many believe the most
damaging impacts of climate change can be avoided.  Current concentrations are about 380 ppm,
which means there isn't much time to lose.  According to the IPCC, we'd have to reduce GHG
emissions by 50% to 80% of what they're on track to be in the next century to reach this level.

Is this possible?

Many people and governments are already working hard to cut greenhouse gases, and everyone
can help.

Researchers Stephen Pacala and Robert Socolow at Princeton University have suggested one
approach that they call "stabilization wedges." This means reducing GHG emissions from a
variety of sources with technologies available in the next few decades, rather than relying on an
enormous change in a single area.  They suggest 7 wedges that could each reduce emissions, and
all of them together could hold emissions at approximately current levels for the next 50 years,
putting us on a potential path to stabilize around 500 ppm.

There are many possible wedges, including improvements to energy efficiency and vehicle fuel
economy (so less energy has to be produced), and increases in wind and solar power, hydrogen
produced from renewable sources, biofuels (produced from crops), natural gas, and nuclear
power.  There is also the potential to capture the carbon dioxide emitted from fossil fuels and
store it underground—a process called "carbon sequestration."

In addition to reducing the gases we emit to the atmosphere, we can also increase the amount of
gases we take out of the atmosphere.  Plants and trees absorb CO2 as they grow, "sequestering"
carbon naturally.  Increasing forestlands and making changes to the way we farm could increase
the amount of carbon we're storing.

Some of these technologies have drawbacks, and different communities will make different
decisions about how to power their lives, but the good news is that there are a variety of options
to put us on a path toward a stable climate.