1. The earth is a natural greenhouse and is kept warm by water vapors, carbon dioxide (CO₂), and other gases in the atmosphere, which absorb the sun’s energy and radiate it back toward the earth. This type of warming is called “natural greenhouse effect.” “Enhanced greenhouse effect,” on the other hand, causes global climate change due to excessive levels of CO₂ in the atmosphere.^a
2. Without the atmosphere to create a greenhouse-type effect, the average temperature on Earth would be just 5° Fahrenheit (F).^g
3. Natural levels of CO₂ in the atmosphere have varied throughout history between 180 and 300 parts per million (ppm). Today’s CO₂ levels hover around 380 ppm, representing a 25% increase over the highest recorded natural levels.^b
4. In the year 1997 alone, the concentration of CO₂ in the atmosphere increased by 2.87 ppm; this increase is more than any other year on record.^a
5. The year 2005 was the warmest on record, and the years 1998 and 2007 are tied for the second warmest. The eight warmest years on record have all occurred since 1998.^a
6. Scientists expect a 3.5° F increase in average global temperatures by the year 2100, resulting in the warmest temperatures in the past million years. During the Pliocene epoch 1.8 million years ago, when the earth’s temperatures were roughly equivalent to today, sea levels were 12-18 feet higher.^a
7. Geologists believe sea levels could rise between seven and 23 inches by the end of the century if current warming trends continue.^f
8. Worldwide, one hundred million people live within three feet of sea level, and much of the world’s population is clustered in coastal areas.^f

Fewer than 25,000 polar bears currently survive in the wild

9. The polar bear, while surviving in drastically reduced numbers, is already effectively extinct in its natural habitat—and no amount of change can save it. Scientists estimate that just 20,000 to 25,000 polar bears still survive in the wild.^g
10. The first forced relocation due to the effects of climate change occurred in 2007 when 100 residents of Tegua Island in the Pacific Ocean were evacuated due to rising sea levels and subsequent flooding.^b
11. For the past million years, cool climate conditions have primarily prevailed throughout the world. It was under these conditions that the human species evolved.^a
12. The earth has always experienced cyclical bouts of climate change. Recorded temperatures throughout history display graphs of peaks and valleys with occasional extreme periods, such as the Little Ice Age of the seventeenth and eighteenth century and the Medieval Warm Period of the eleventh century.^g
13. According to NASA studies, average temperatures around the world have increased 1.4° F since 1880, with most of the change occurring in recent decades.^f
14. During the twentieth century, the earth experienced two warming trends. The first was a burst in temperature from 1900-1930, and the second is a continuing increase in temperature beginning in the 1970s.^g
15. The last two decades of the twentieth century were the hottest decades in more than 400 years and may have been the hottest decades for several thousand years.^f
16. Climate models predict the loss of Arctic sea ice earlier and more rapidly than the loss of Antarctic land ice if warming trends continue.^a
17. Since the 1950s, Arctic sea ice has declined by 15% and the average annual duration of northern lake and river ice has decreased by two weeks.^d
18. As Arctic ice rapidly disappears, scientists believe the Arctic will experience its first ice-free summer as early as the year 2040.^f
19. Average temperatures in the Arctic climates of Alaska, Canada, and Russia have risen at twice the global average in the last century.^f
20. The effects of global warming could destroy the habitats of and threaten extinction for over one million species of plants and animals.^f

Glaciers worldwide have lost 890 cubic miles of ice since 1961

21. Between the years 1961 and 1997, the world’s glaciers lost 890 cubic miles of ice.^b
22. In 1910, Glacier National Park in Montana boasted 150 glaciers—today there are just 27.^f
23. Deserts worldwide are increasing as a result of warmer temperatures. At the end of the year 2007, Australia lost 25% of crop production due to desertification.^d
24. Swedish scientist Svante Arrhenius realized as early as 1896 that human industrial activity was already surpassing the earth’s ability to reabsorb CO₂.^h
25. Fossil fuel burning currently adds nearly six billion tons of CO₂ to the atmosphere every year. Only half of this CO₂ is removed by forests and oceans.^e
26. Rampant deforestation currently causes 20% of the world’s global warming pollution by prohibiting the reabsorption of CO₂.^c
27. Between the first Earth Day in 1970 and the new millennium, human-made emissions of greenhouse gases rose 70%.^g
28. The earth’s atmosphere now contains 40% more CO₂ than before the Industrial Revolution.^g
29. The United States represents less than 5% of the world’s population, yet Americans account for 25% of the world’s commercial energy consumption and 22% of the world’s industrial emissions of CO₂.^e

By 2030, the world will be driven on by more than a billion cars

30. Cars amount to three-quarters of all transportation emissions. At the current rate, the world will be driven on by more than a billion cars in 2030 and a billion more by 2050.^g
31. Roughly 75% of the annual increase in atmospheric CO₂ is due solely to the burning of fossil fuels.^e
32. About 20% of CO₂ emitted into the atmosphere comes from the gasoline burned in motor vehicle engines. The vast majority of emitted CO₂ is a result of fossil fuel burning in power plants for electricity generation.^e
33. While increased concentrations of CO₂ in the atmosphere certainly can increase temperatures, many geologists believe that water vapor accounts for more than 90% of the greenhouse warming effect.^a
34. According to the Internal Energy Agency, the world will invest some $20 trillion in new energy research over the next 25 years in an attempt to slow the effects of global warming.^g
35. Global warming research is primarily conducted by the Intergovernmental Panel on Climate Change (IPCC), a partnership formed in 1998 with the World Meteorological Organization and environmental agencies of the United Nations.^d

-- Posted January 29, 2009

References

^a Archer, David. 2006. Global Warming: Understanding the Forecast. Hoboken, NJ: Wiley-Blackwell.

^b Environmental Defense Fund. “Global Warming Myths and Facts.” Accessed: January 17, 2009.

^c “Global Warming.” Union of Concerned Scientists: Citizens and Scientists for Environmental Solutions. 2008. Accessed: November 27, 2008.

^d IPCC Fourth Assessment Report: Climate Change 2007. Intergovernmental Panel on Climate Change. Accessed: November 21, 2008.

^e Montague, Fred. 2006. Environmental Notebook: Observations, Principles, Trends, and Ideas about Life on Earth. Wanship, UT: Mountain Bear Ink.

^f National Geographic News. “Global Warming Fast Facts.” Accessed: January 14, 2009.

^g Walker, Gabrielle and Sir David King. 2008. The Hot Topic: What We Can Do about Global Warming. Orlando, FL: Harcourt, Inc.