Global Warming

AbstractThis paper discusses the meaning of Global Warming and how it became a common term used

by scientist to describe an increase in global temperature to a problem that will impact not just us human beings, but also all species who we share this planet.

It also describes the different causes of global warming such as greenhouse effect and its impact to society.

This paper also tackles possible solutions to this problem.

IntroductionGlobal warming is a significant increase in the Earth's climatic temperature over a relatively

short period of time as a result of the activities of humans.

In specific terms, an increase of 1 or more degrees Celsius in a period of one hundred to two hundred years would be considered global warming. Over the course of a single century, an increase of even 0.4 degrees Celsius would be significant.1

Global warming is the unequivocal and continuing rise in the average temperature of Earth's climate system. Since 1971, 90% of the warming has occurred in the oceans. Despite the oceans' dominant role in energy storage, the term "global warming" is also used to refer to increases in average temperature of the air and sea at Earth's surface.

Since the early 20th century, the global air and sea surface temperature has increased about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850.2

1 http://science.howstuffworks.com/environmental/green-science/global-warming.htm2 http://en.wikipedia.org/wiki/Global_warming

Causes of Temperature Change

Greenhouse gasesThe greenhouse effect is the

process by which absorption and emission of infrared radiation by gases in a planet's atmosphere warm its lower atmosphere and surface.3

On earth, naturally occurring amounts of greenhouse gases have a mean warming effect of about 33 °C (59 °F). Without the Earth's atmosphere, the temperature across almost the entire surface of the Earth would be below freezing. The major greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect; carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone (O3), which causes 3–7%. Clouds also affect the radiation balance through cloud forcing similar to greenhouse gases.

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.

Human ActivitiesConcern about global warming and climate change grew out of the evidence that human

activities contribute to the release of greenhouse gases that can cause not only changes in temperature, but wind patterns, rainfall and snowfall. People are altering the composition of the atmosphere with emissions from transportation, agriculture, manufacturing and many other activities.4

Particulates and sootGlobal dimming, a gradual reduction in the amount of global direct irradiance at the Earth's

surface, was observed from 1961 until at least 1990.

The main cause of this dimming is particulates produced by volcanoes and human made pollutants, which exerts a cooling effect by increasing the reflection of incoming sunlight. The effects of the products of fossil fuel combustion – CO2 and aerosols – have partially offset one another in recent decades, so that net warming has been due to the increase in non-CO 2 greenhouse gases such as methane.3 http://en.wikipedia.org/wiki/Global_warming4 http://homeguides.sfgate.com/brief-explanation-global-warming-78863.html

Solar activityEvidence against the sun having caused recent climate change comes from looking at how

temperatures at different levels in the Earth's atmosphere have changed.

Models and observations show that greenhouse warming results in warming of the lower atmosphere (called the troposphere) but cooling of the upper atmosphere (called the stratosphere).

Depletion of the ozone layer by chemical refrigerants has also resulted in a strong cooling effect in the stratosphere. If the sun were responsible for observed warming, warming of both the troposphere and stratosphere would be expected.

Effects on the Environment

Natural systemsGlobal warming has been detected in a number of natural systems. Some of these changes are

described in the section on observed temperature changes, e.g., sea level rise and widespread decreases in snow and ice extent.

Global warming also contributed to some of the observed changes, including sea level rise, changes in climate extremes (such as the number of warm and cold days), declines in Arctic sea ice extent, and to glacier retreat.

These above photos taken from the Landsat satellite in 1985, 2002, and 2005 show how a new island has appeared in Greenland following the melting of an arctic glacier. Melting glaciers are one indication that the world is warming up.

Ecological systemsIn 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. Future climate change is expected to particularly affect certain ecosystems, including tundra, mangroves, and coral reefs. It is expected that most ecosystems will be affected by higher atmospheric CO2 levels, combined with higher global temperatures. Overall, it is expected that climate change will result in the extinction of many species and reduced diversity of ecosystems.

Effects on the Social System

Food securityChanges in climate will make it easier to grow

food in some places, but much harder in others. 5 Overall, the world's poorest people are expected to be hit hardest

Under present trends, by 2030, maize production in Southern Africa could decrease by up to 30%, while rice, millet and maize in South Asia could decrease by up to 10%.

By 2080, yields in developing countries could decrease by 10% to 25% on average while India could see a drop of 30% to 40%.

By 2100, while the population of three billion is expected to double, rice and maize yields in the tropics are expected to decrease by 20–40% because of higher temperatures without accounting for the decrease in yields as a result of soil moisture and water supplies stressed by rising temperatures.

Future warming of around 3 °C (by 2100, relative to 1990–2000) could result in increased crop yields in mid- and high-latitude areas, but in low-latitude areas, yields could decline, increasing the risk of malnutrition.

A similar regional pattern of net benefits and costs could occur for economic (market-sector) effects. Warming above 3 °C could result in crop yields falling in temperate regions, leading to a reduction in global food production.

Habitat inundationIn small islands and mega deltas, inundation as a result of sea level rise is expected to threaten

vital infrastructure and human settlements. This could lead to issues of homelessness in countries with low lying areas such as Bangladesh, as well as statelessness for populations in countries such as the Maldives and Tuvalu.

5 http://www.explainthatstuff.com/globalwarmingforkids.html

Responses to Global Warming

MitigationReducing the amount of future climate change is called mitigation of climate change. These are

activities that reduce greenhouse gas (GHG) emissions, or enhance the capacity of carbon sinks to absorb GHGs from the atmosphere.

Studies indicate substantial potential for future reductions in emissions by a combination of emission-reducing activities such as energy conservation, increased energy efficiency, and satisfying more of society's power demands with renewable energy and nuclear energy sources. Climate mitigation also includes acts to enhance natural sinks, such as reforestation.

AdaptationAdaptation to climate change may be planned, either in reaction to or anticipation of climate

change, or spontaneous, i.e., without government intervention. Planned adaptation is already occurring on a limited basis. The barriers, limits, and costs of future adaptation are not fully understood.

Climate engineeringClimate engineering (sometimes called by the more expansive term 'geoengineering'), is the

deliberate modification of the climate. It has been investigated as a possible response to global warming.

Techniques under research fall generally into the categories solar radiation management and carbon dioxide removal, although various other schemes have been suggested.