What is Climate change?

Climate change is defined as any significant variation in climate measures—precipitation, temperature, wind—for an extended period, usually decades or longer.

• Global warming is a rise in the average temperature of Earth’s surface.
• In order to estimate temperatures of the past, scientists analyze "proxy" indicators such as tree rings, ice cores, and ocean sediment.
• A French mathematician, Jean Baptiste Joseph Fourier, was the first to recognize a gradual warming of Earth in 1824.
• Fourier developed a theory, later coined the "greenhouse effect" by Nobel laureate Svante Arrhenius, arguing that Earth’s atmosphere traps heat from the sun and reflects it back to Earth. Arrhenius added in the late 1800s that changes in carbon dioxide levels contributed to the effect.
• The average temperature of Earth’s surface has increased by approximately 1.4 degrees Fahrenheit in the past 100 years.
• Scientists predict that the temperature will rise between 2 degrees Fahrenheit and 11 degrees Fahrenheit by 2100.
• The eight warmest years recorded have all been after 1998. The warmest year to date was 2005.
• Climate change could cause a rise in sea levels, extreme weather conditions, and the incidence of tropical diseases such as malaria, experts say.
• Most scientists believe that the proliferation of greenhouse gases caused by human activity is responsible for recent climate change. Others disagree, claiming that natural processes such as increases in the sun’s output or volcanic eruptions are most to blame.
• The IPCC 2001 report said that Antarctica would not start losing ice for 100 years. Since then, Antarctica has not only started losing ice, but is now losing as much as Greenland.
• Greenland’s ice loss has doubled since 2000.
• The rate that sea level is accelerating is 30 times faster than it was for most of the 20th century.
• At the rate that sea level is rising today, it will cross the coastal barrier island disintegration threshold in 3 to 4 years.
• A climate change induced beetle infestation in the Rocky Mountains has killed 52 million acres of trees since about the turn of the 21st century.
• The last record breaking beetle infestation of this sort was 3 million acres in ten years.
• Arctic sea ice is melting 40 to 70 years ahead of schedule.
• The Arctic Ocean has not been ice free in summer in 14 million years.
• The Laptev and northern Siberian seas are now releasing as much methane from melting methane ice, frozen into permafrost during the last ice age when sea level was 250 feet lower, as all of the world’s oceans combined. Methane is a greenhouse gas that was recently discovered to be 34 times more potent than CO2 – we have understood for decades that it was 24 or 25 times more potent.
• The undersides of the great ice sheet discharge rivers emptying the Greenland Ice Sheet are now melting 100 times faster than the surface because of changed, warmer ocean currents.
• The Arctic winter is one month shorter than it was thirty years ago.
• A warmer planet will produce more snow for many decades before it gets warm enough to create less snow. The reason is because warmer air holds more moisture.
• A warmer planet will produce more icebergs because melt water penetrates crevasses to bedrock, lubricating the ice rivers. Warming ocean currents beneath ice shelves and ice rivers destabilize the ice and cause it to disintegrate faster. The massive ice shelves break apart into massive icebergs.
• Because of a warming climate, one quarter of all of the species that Thoreau found at Walden Pond have become locally extinct and one third of the total are at risk of becoming locally extinct.
• Our oceans today are acidifying ten times faster than at any time in the last 65 million years.
• During the interglacial warm period before this one, the closest time in the history of our planet that we can compare to now, sea level rose 6 to 10 feet in 24 years, likely when the West Antarctic Ice Sheet collapsed.
• We have understood for decades that CO2 lasts for 100 to 200 years in our atmosphere and as our planet warms, CO2 will last even longer. Today, given the warming that our planet has undergone already, half of CO2 emissions now stay in our atmosphere for 300 years. Half of what remains stays there for 10,000 years and the remainder stays there forever. In the future, as our planet continues to warm, CO2 will last even longer.

Sources:

• National Academy of Sciences
• Environmental Protection Agency
• National Aeronautics and Space Administration
• Global Warming Archive

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