One hot summer does not mean the globe is warming. Temperatures fluctuate widely, from day to day, season to season, year to year. The summer of 1936 was about as hot as this year. Climate change means a shifting long-term pattern.
The science behind global warming covers three separate ideas. One is concrete and measurable. Temperatures calculated across the globe, in Illinois and in the Arctic, over land and sea and up in the atmosphere, by cheap thermometers and delicate instruments, all show the same thing – the earth has gotten warmer over the last century. Not much, by about one degree since 1980, barely noticeable at any moment. But enough to indicate a new pattern.
The United States is on track for its hottest year ever in 2012, and 6 of the 10 hottest years since record-keeping began have occurred since 1998. The heating up of our climate is not a theory – it is a measurable fact.
The effects of slight changes in temperature are enormous. Since 1990 the border between zones 5 and 6 on the plant hardiness map of the Arbor Day Foundation has shifted more than 150 miles northward. Central Illinois was in zone 5 and now is in zone 6. The amount of sea ice in the Arctic has reached its lowest point ever measured, and is shrinking even faster than scientists predicted a few years ago.
The second element of global warming science cannot be shown by simple measurements: that the cause of warming is the production of greenhouse gases by human activity. Yearly global emissions of carbon dioxide have increased about 50% in the last 20 years. Here scientific experimentation, testing of hypotheses, and synthesis of differing arguments are ways of creating the most plausible explanation. That warming is caused by our behavior in industrialized societies is not a fact, but an idea supported by at least 90% of climate scientists. This theory is as well supported by science and by scientists as the atomic theory that led to the creation of nuclear weapons and nuclear power.
The third element is the least certain and the scariest: that warming increases the number of extreme weather incidents, such as heat waves, storms, and droughts. This is a matter of uncertainty among scientists who agree on the first two ideas. It will take many years of collecting data before anyone can be sure one way or the other.
The debate about climate change is mainly political. Republican politicians generally attribute the evidence about warming to a world-wide conspiracy. Senator James Inhofe of Nebraska has often said that global warming is a “hoax”, based on his religious beliefs. In March he said: “The arrogance of people to think that we, human beings, would be able to change what He is doing in the climate is to me outrageous.” Ron Paul called global warming “the greatest hoax I think that has been around for many, many years.” Rick Perry attributed evidence of warming to “scientists who have manipulated data so that they will have dollars rolling into their projects,” and Paul Ryan agreed that “leading climatologists make clear efforts to use statistical tricks to distort their findings and intentionally mislead the public on the issue of climate change.”
Mitt Romney has shifted his position on global warming. As Governor of Massachusetts, he moved to reduce greenhouse gases until he decided to run for President. In June 2011, he said, “I believe the world is getting warmer, and I believe that humans have contributed to that.” In October, his words shifted: “My view is that we don’t know what’s
causing climate change on this planet.”
The Obama administration has accepted evidence about warming. In 2009, the Environmental Protection Agency moved for the first time to reduce greenhouse gas emissions. Obama’s National Security Strategy of 2010 says that “climate change” is a “severe” national security threat. In April he spoke of his “belief that we’re going to have to take further steps to deal with climate change in a serious way.”
Among voters, according to a poll in 2011, party affiliation also determines scientific belief: 80% of Democrats and 47% of Republicans say that warming has been occurring.
What happens if you take the politics out of the debate? The nation’s insurance companies, through the National Association of Insurance Commissioners, reported in September 2011 their concerns about the effects of warming on the properties they insure. The report’s author, Sharlene Leurig, said, “Climate change will inflict damage across the U.S. . . . Unfortunately, science is telling us that more years in the future are likely to look like 2011.”
Taking Back Our Lives
Posted: Friday, 31 August 2012