Physics Tip Sheet #71, July 26, 2007
American Physical Society
Highlights in this Issue: stronger evidence for the human origin of global warming, and a better way to choose the champs.
Stronger evidence for human origin of global warming
Pablo F. Verdes
Physicist Pablo F. Verdes of the Heidelberg Academy of Sciences in Germany has found a way to avoid the subjective flaws of climate models by applying sophisticated analysis techniques to data from the past hundred and fifty years. The approach mathematically stitches together known facts about the global climate into a more objective and coherent picture.
Verdes, now at Novartis Pharma, examined data on temperature anomalies, the strength of the radiation emitted from the Sun, and volcanic activity. The relatively recent increases in solar radiation, combined with reduced volcanic activity, contribute to the increase in world temperatures. However, Verdes' analysis demonstrates that these natural causes do not completely explain the observed warming.
Verdes calculated the amount of non-natural influence required to match the increases in temperature observed in the last 150 years. He plotted the influence over time. Then, he compared it to the evolution of greenhouse gasses, taking into account the cooling due to aerosols. With allowances for error, he found that influences attributable to greenhouse gasses mirror the graph of non-natural influence needed to explain the observed temperature increase of recent decades.
His research shows that, if you look at global warming as a puzzle, and you put together the natural factors such as increased solar radiation and reduced volcanic activity, a hole remains. The human factors of greenhouse gas and aerosol emission complete the picture. - KM
Choosing the champs
E. Ben-Naim and N. W. Hengartner
According to the physicists' analysis and simulations of league play, there¿s always at least some chance that a lesser team can prevail in any given game. The randomness of outcomes means that it takes a large number of games to guarantee that the best team accumulates the most wins. Specifically, it requires that the total number of games played in a season should be roughly the cube of the number of teams involved. For the 16 team National League, that means 4096 regular season games altogether and 2744 games for the 14 team American League.
Some fans might prefer things the way they are, with underdogs like the 2003 Florida Marlins having a shot at winning the Word Series. For those who would rather the title only go to the very best team in any given year, a modified schedule could get the job done with many fewer games, according to the physicists.
By adding a preliminary round to the season, and eliminating the weakest teams before regular league play begins, the physicists showed that the best team in the National League would be virtually guaranteed to be among the top two or three teams with the best records, even with a significantly reduced number of games. Although the very best team may not always end up in the lead, a preliminary round or two would at least ensure that the top teams aren't eliminated from the playoffs through simple bad luck.
Although the baseball schedule is far from perfect, according to the new research, author Ben-Naim points out that the relatively large number of games that the teams play each year results in better sorting than occurs in professional football, hockey, and basketball. The National Football League, for example has comparable numbers of teams to Major League Baseball, but plays far fewer games each year, which makes the pro football season outcome much more random. - JR
Katherine McAlpine and James Riordon contributed to this Tip Sheet.
The American Physical Society (www.aps.org) is a non-profit membership organization working to advance and diffuse the knowledge of physics through its outstanding research journals, scientific meetings, and education, outreach, advocacy and international activities. APS represents over 50,000 members, including physicists in academia, national laboratories and industry in the United States and throughout the world. Society offices are located in College Park, MD (Headquarters), Ridge, NY, and Washington, DC.