If I told a neocon he was bleeding and offered a bandaid would they yell at me that I'm a commie or take the bandaid.
-- Evidence for Global Warming
Recent observations of warming support the theory that greenhouse gases are warming the world. Over the last century, the planet has experienced the largest increase in surface temperature in 1,300 years. The average surface temperature of the Earth rose 0.6 to 0.9 degrees Celsius (1.08°F to 1.62°F) between 1906 and 2006, and the rate of temperature increase nearly doubled in the last 50 years. Worldwide measurements of sea level show a rise of about 0.17 meters (0.56 feet) during the twentieth century. The world’s glaciers have steadily receded, and Arctic sea ice extent has steadily shrunk by 2.7 percent per decade since 1978.
2007-10-13
03:29:47
·
8 answers
·
asked by
Spartacus
3
in
Politics & Government
➔ Politics
Even if greenhouse gas concentrations stabilized today, the planet would continue to warm by about 0.6°C over the next century because it takes years for Earth to fully react to increases in greenhouse gases. As Earth has warmed, much of the excess energy has gone into heating the upper layers of the ocean. Scientists suspect that currents have transported some of this excess heat from surface waters down deep, removing it from the surface of our planet. Once the lower layers of the ocean have warmed, the excess heat in the upper layers will no longer be drawn down, and Earth will warm about 0.6°C (1° F).
But how do scientists know global warming is caused by humans and that the observed warming isn’t a natural variation in Earth’s climate? Scientists use three closely connected methods to understand changes in Earth’s climate.
2007-10-13
03:30:14 ·
update #1
They look at records of Earth’s past climates to see how and why climate changed in the past, they build computer models that allow them to see how the climate works, and they closely monitor Earth’s current vital signs with an array of instruments ranging from space-based satellites to deep sea thermometers. Records of past climate change reveal the natural events—such as volcanic eruptions and solar activity—that influenced climate throughout Earth’s history. Today, scientists monitor those same natural events as well as human-released greenhouse gases and use computer models to determine how each influences Earth’s climate.
2007-10-13
03:30:37 ·
update #2