| Global warming is defined by Wikipedia as "the | | | | (0.22-0.40 F) per decade since 1979. |
| observed increase in the average temperature of | | | | The hypothesis of man-made global warming was |
| the Earth's near-surface air and oceans in recent | | | | first made in the 1880s, but due to the fact that |
| decades and its projected continuation." | | | | 19th century calculations predicted that the mean |
| Most think of global warming as being | | | | global temperature should have risen by more |
| human-made, and while much recent attention to | | | | than 1 C by 1940, and it hadn't, most had |
| global warming is due to the human-made variety, | | | | considered the hypothesis as more of a curiosity. |
| global warming is actually a natural process as the | | | | It wasn't until 1979 when Mrs. Margaret Thatcher |
| Earth has experienced natural global warming and | | | | became the Prime Minister of the United Kingdom |
| cooling many times in the past. The Antarctic | | | | that the hypothesis became a major international |
| EPICA ice core has existed for 800,000 years, | | | | policy issue. |
| and that has included eight glacial cycles with | | | | Global warming has continued to be a major |
| interglacial warming periods that are much hotter | | | | international policy issue since 1979, as the Rio |
| than current temperatures. | | | | Summit in 1992 proposed actions to constrain the |
| Some geologists believe that a rapid build-up of | | | | emissions and the Kyoto Summit in December |
| greenhouse gases caused the Earth to experience | | | | 1997 established binding agreements that would |
| global warming in the early Jurassic period, with | | | | commit nation states to the constraints. |
| average temperatures rising by 5 C (9 F.) This | | | | Europe, Japan, and the United States have agreed |
| caused rock weathering by 400%, which in turn, | | | | in principle to adopt the "Berlin Mandate" that |
| led to CO2 levels dropping back to normal over | | | | requires them to cut their CO2 emissions to 15% |
| the next 150,000 years because rock weathering | | | | below their 1990 levels by 2010. The US is not |
| locks away carbon in calcite and dolomite. | | | | totally convinced this is the right approach, |
| Other past global warming events were believed | | | | however, as the US Department of Energy (DoE) |
| to be caused by sudden releases of methane | | | | has conducted a study that suggests the "Berlin |
| from clathrate compounds, including the | | | | Mandate" will not reduce world-wide emissions of |
| Permian-Triassic extinction event and the | | | | CO2. In fact, the DoE study suggests that the |
| Paleocene-Eocene Thermal Maximum. However, | | | | "Berlin Mandate" could raise CO2 emissions |
| the last glacial period was believed to be caused | | | | because many energy intensive industries would |
| by natural variations in the Earth's orbit, which led | | | | be forced to leave the US, Europe, and Japan |
| to the retreat of the ice sheets because of the | | | | where the constraints are enforced to countries |
| changing amount of solar radiation received at | | | | that have either not adopted the mandate or that |
| high latitude. | | | | don't strictly enforce them, and because those |
| However, the recent attention to the topic of | | | | countries likely would have less energy efficient |
| global warming is due to the fact that human | | | | industries, that would likely raise the level of CO2 |
| actions have caused global warming on a scale | | | | emissions. |
| and with a rapidity unseen before. | | | | The 2000 Democratic Presidential candidate, Al |
| Global average air temperature near the Earth's | | | | Gore, has brought a new focus on global warming |
| surface has increased by 0.56-0.92 C (0.98-1.62 F) | | | | with his 2007 Oscar-winning documentary, "An |
| over the last century. The Intergovernmental | | | | Inconvenient Truth." In this documentary, Mr. |
| Panel on Climate Change (IPCC) concludes that | | | | Gore has offered a passionate and inspirational |
| this observed increase in globally averaged | | | | look at his fervent crusade to expose the myths |
| temperatures since the mid-20th century is very | | | | and misconceptions behind global warming so that |
| likely due to the observed increase in greenhouse | | | | global warming's deadly progress can be stopped |
| gas concentrations due to such activities like | | | | before it's too late. |
| burning coal and fossil fuels, cutting down forests, | | | | As you can see, global warming has been a hotly |
| and overgrazing the land. These activities have | | | | debated global topic for nearly the last 30 years. |
| increased the greenhouse effect, which in turn, | | | | No one is absolutely sure what approach is the |
| has warmed the temperatures near the Earth's | | | | best way to go about reducing the threat of |
| surface and lower atmosphere. | | | | global warming in the future. If it's true that global |
| From the period of 1860-1900, global land and sea | | | | warming could cause epic destruction in the near |
| temperatures had increased by 0.75 C (1.40 F,) | | | | future, more discussion, and more importantly, |
| but from 1979 to the present day, land | | | | action will need to be taken in order to avert that |
| temperatures have increased about twice as fast | | | | destruction. Looking at the history of global |
| as ocean temperatures (about 0.25 C/decade land | | | | warming will likely help in determining a course of |
| temperature versus about 0.13 C/decade ocean | | | | action that will help us avert that possible |
| temperature.) Also, temperatures in the lower | | | | destruction. |
| troposphere have increased between 0.12-0.22 C | | | | |