Last Thursday, a National weather forecast from USA Today predicted a high of 112 degrees for Oklahoma City, and a high of 110 degrees for Dallas, Texas. Oklahoma City has not seen this type of weather since August 10, 1936. This forecast is just one example of extreme temperature witnessed this summer. As temperatures rise, many question the cause of these extreme temperatures. Is the cause climate change?
Back in 2007, the Intergovernmental Panel on Climate Change (IPCC) predicted that temperatures would increase 1.8 to 5.4 degrees over 1990 levels. Although this increase may sound insignificant, it is cause for concern. To put this temperature change into perspective, NASA explains that the Earth’s current temperature is only five to nine degrees hotter than when the last ice age occurred. NASA summarizes IPCC’s 2007 predictions as including “increased frequency, intensity and duration of heat waves in cities that currently experience them” in North America; “gradual replacement of tropical forest by Savannah in Eastern Amazonia” and “risk of significant biodiversity loss through species extinction in many tropical areas” in Latin America; increased flooding in Europe; reductions of up to 50% in rain-fed agriculture in some regions in Africa; and an increased “death rate from disease associated with floods and droughts” in some regions of Asia. NASA reports that the IPCC now forecasts a temperature change of 2.5 to 10 degrees Fahrenheit over the next century.
A study just released from Berkeley Earth on July 29, 2012 finds the Earth’s land temperature has increased by 1.5 degrees Celsius in the past 250 years, with a 0.9 degree Celsius increase in the past 50 years. Berkeley Earth used earlier data and data from more temperature stations than other studies used. They compared the gradual rise in temperatures to simple math functions, solar activity, and rising populations. Berkeley Earth found that the gradually increasing temperature data fit best with a simple model containing only known volcanic eruptions and carbon dioxide.
The way this happened over the past 250 years was as the Earth’s carbon dioxide, measured from atmospheric samples and air trapped in polar ice, increased, the Earth’s land temperature increased. The sharp drops in temperature matched known volcanic eruptions. These eruptions spewed particles in the air, reflected the sunlight, and cooled the Earth for a few years.
Richard Muller, co-founder of the Berkley Earth Surface Temperature project and previous skeptic of global warming, states that “it appears that essentially all of this increase results from the human emission of greenhouse gasses.” Muller calls himself a “converted skeptic” in his recent New York Times opinion editorial, "The Conversion of a Climate-Change Skeptic." Muller says that the Berkeley Earth study results do not “prove causality and shouldn’t end skepticism, but they raise the bar: to be considered seriously, and alternative explanation must match the data at least as well as carbon dioxide does.” Muller remains skeptical that “polar bears aren’t dying by receding ice and the Himalayan glaciers aren’t going to melt by 2035,” and “the recent warm spell in the United States happens to be more than offset by cooling elsewhere in the world, so its link to ‘global’ warming is weaker than tenuous.” But Muller has become convinced that as carbon dioxide emissions increase, the Earth’s land temperature will continue to rise. This is not a change we can ignore.