* Weather: day to day changes in the atmosphere (shifts in temperature, rain, wind, clouds, etc.)
* Climate: average pattern of weather over decades or centuries (long periods of time). Influenced by slow changes in the ocean, the land, the Earth’s orbit around the sun, Sun’s energy output, etc.
* The ice ages have alternated withice-free interglacial periods. Pattern: 80,000-year period of ice and glaciers building up 10,000-year period of ice at its maximum level 10,00-year period during which ice melts and glaciers retreat.
* Within the last two years, Earth’s temperature has risen sharply
* Solar energy from incoming sunlight is not distributed evenly since the Earth is constantly rotating the tropicsreceive more incoming solar energy that the poles. (Milankovitch effect)
* Paleoclimatologists – research from past climate.
* Proxy data consists of evidence drawn from natural environmental sources as ice from ice caps and glaciers, sediment from shorelines and ocean bottoms, tree rings, and holes dug deep into the soil.
* Climatologists – observe the present climate and changes
*400,000 years ago, the Antarctic ice cap was an open ocean warm enough to support warm-water creatures.
* 400,000 years ago the sea level was 18 meters higher than it is today
* 10,000 years ago, as glaciers moved northward, a sudden shift to warmer temperatures melted the ice. The sudden flood of water brought a flood of fine, grained sand with it, which buried the trees and prevented thefrom rotting
* If you drill a hole anywhere on Earth’s surface, you could observe a temperature profile and be able to reconstruct what had happen to that specific location
* Data shows that 80% of the sites are hotter today than they were 5 centuries ago
* The twentieth century has been the warmest century from the last five and the 1990´s were the warmest decade of the whole millennium* Many climate scientists agree that the global warming is human-made.
* Doubling the concentration of carbon dioxide would boost temperatures significantly
* Humanity was engaged to the geophysical experiment the world’s oceans could no longer hold the carbon dioxide being released in the air, as a result we were changing the planet’s atmosphere and forcing nature tochange its behavior
* Analysis of global temperatures showed that Earth was definitely warning and that the cause way excess of carbon dioxide in the atmosphere cause by human activities (green house effect)
* President Clinton: “If we fail to reduce the emission of greenhouse gases, deadly heat waves and drought will become more frequent, coastal areas will flood, and economies will bedisrupted.”
* Facts on global warming temperature:
* Temperature of the planet has risen about 0.9 F since the 1880´s
* Until the 1990´s, 1988 was the warmest year
* 1998 has been the warmest year so far and 1999 the second warmest
* Facts on carbon dioxide emissions:
* We add 4.4 billion tons of carbon dioxide to the atmosphere per year
* Humanactivities have contributed a 20% to 30% increase in carbon dioxide
* Primary activities contributing to the release of gases are: burning fossil fuels and cutting down forests
* Believers: global warming is linked to increase carbon dioxide emissions due to human activities
* John Houghton: “we have good reasons for believing the effect is real.”
* James McCarthy:“there is no debate in the scientific community about the fact that global warming is caused by human activities
* Michael McCracken: “human activities are dramatically modifying atmospheric composition and this is going to change the climate.”
* Tom Karl: “If you look out the window fifty years from now, we’re going to be responsible for more of it.”
* Dissenters: Have doubts...