Re: Top Ten Global Warming Myths
posted at 9/7/2009 2:08 AM EDT
Myth #4: The Earth is getting warmer because the Sun is getting warmer.
Fact: The Sun has warmed the Earth .02 degrees in the last century, whereas in the same period of time, carbon dioxide warmed the Earth .09 degrees.
The question of whether or not the Sun itself is putting out more heat nowadays is a contentious one among climate scientists. Opinions are currently divided, based on difficult-to-measure data, about whether or not the sun is even getting warmer. The scientific uncertainty on this particular issue has been used by politicians (such as Senator James Inhofe, R-OK) to “prove” that human beings have not had an impact on the rising temperatures – they choose to side with the scientists who claim that the sun has warmed. But even the scientists who claim that the sun has warmed point out that the warming they have observed is almost negligible.
Take a look at the graph below from the IPCC Report. It shows that there are indeed a number of factors that affect the global temperature. The most significant of these by far, however, is the effect of human influence through increased output of CO2.
Image source: IPCC
Supplementary materials on this topic can also be found on Realclimate.org.
Sources: Realclimate.org, “How Not to Attribute Climate Change” and “Taking Cosmic Rays for a Spin;” The National Center for Atmospheric Research, "Present Climate: How Do We Know Earth is Warming Now?"
Myth #5: The global mean surface temperature actually decreased between 1940 and 1970, so that means CO2 emissions have nothing to do with global warming.
Fact: The global cooling of 1940-1970 was caused by aerosols in the upper atmosphere blocking the sun’s rays.
Increased industrial production in the years between 1940 and 1970 caused an increase in aerosol emissions, most notably sulfates. These particles are highly reflective and created an albedo effect in the upper atmosphere, blocking solar rays. Pollution control implemented during the 1970s caused the concentration of aerosols in the atmosphere to decrease. In fact, if it had not been for the presence of reflective aerosols, the global temperature would have likely risen, not fallen, during that period of time.
Source: The National Center for Atmospheric Research, “Present Climate: How Do We Know Earth is Warming Now?”
TO BE CONTINUED....