The global warming controversy is a dispute regarding the nature and consequences of global warming. The disputed issues include the causes of increased global average air temperature , especially since the mid-20th century, whether this warming trend is unprecedented or within normal climatic variations, and whether the increase is wholly or partially an artifact of poor measurements. Additional disputes concern estimates of climate sensitivity, predictions of additional warming, what the consequences are, and what action should be taken (if any). Individuals, corporations, and political organizations are involved, so the debate is vigorous in the popular media and on a policy level.

The earth has warmed up by about 0.6ºC in the last 100 years. During this period, human emissions of greenhouse gases have increased, largely as a result of the burning of fossil fuels and deforestation. …An increase in the average temperature of the earth’s atmosphere, especially a sustained increase sufficient to cause climatic change. Most scientists believe that a rise in carbon dioxide levels (caused by automobile, power plant, and other emissions) will lead to further global warming.The greenhouse effect acts to warm the plant and increase average global temperatures. This is seen as a major environmental hazard as average temperatures rise, leading to a possible change in weather patterns and agricultural output… All greenhouse gases contribute to the ‘trapping’ of infrared radiation, hence heat, in the lower atmosphere. Due to the relative sizes of the GHG molecules, some trap more than other. Methane for instance has ten times the Global Warming potential (GWP) of carbon dioxide. …

UN DEVELOPMENT GOAL CAMPAIGN  Jeffrey Sachs and Angelina Jolie Defined Climate Change and will to change in order to achieve goals.

Attribution of recent climate change is the effort to scientifically ascertain mechanisms responsible for relatively recent changes observed in the Earth’s climate. The effort has focused on changes observed during the period of instrumental temperature record, when records are most reliable; particularly on the last 50 years, when human activity has grown fastest and observations of the upper atmosphere have become available. The dominant mechanisms to which recent climate change has been attributed all result from human activity. They are:

• increasing atmospheric concentrations of greenhouse gases
• global changes to land surface, such as deforestation
• increasing atmospheric concentrations of aerosols.