Climate Change: Odds Overwhelming That It’s Caused By Humans

Climate change is almost certainly caused by human activity, so say the odds — and so says a new study by an international team of scientists and researchers.

The study was published by the Potsdam Institute for Climate Impact Research and was completed to put the premise that climate change is caused by humans to a defensible test. As the study points out, 13 of the 15 warmest years on record globally have occurred since 2000 – that’s 13 of only 15 years, with nearly each year surpassing the last since the turn of the last century. The odds of this phenomenon happening as the result of natural variations in weather conditions over the years as opposed to human-caused climate change fall between 1 in 5,000 and 1 in 170,000. If data for the year 2015 had been added to the computations, those odds would be even smaller. Records on weather conditions have been kept for approximately 150 years.

Based in Germany, the Potsdam Institute comprises an international group of scientists and sociologists working in the fields of climate change and sustainable development. The research team included lead author Michael Mann, director of the Earth System Science Center at Penn State University. Co-author Stefan Rahmstorf of the Potsdam Institute commented on the findings.

“2015 is again the warmest year on record, and this can hardly be by chance.”

The article, “The Likelihood of Recent Record Warmth,” was published at Nature. Along with noting the statistical odds against a natural warming trend when it comes to climate change, it concludes that it is “quite likely” that the unusual run of record temperature years were, in fact, caused by human activity and, in particular, the burning of fossil fuels.

NASA climate change model
(Image courtesy of NASA)

According to NASA and most climate scientists around the world, climate change is caused by the accumulation of so-called “greenhouse gases” which are produced by burning coal and fossil fuels such as oil. The greenhouse gases blamed for climate change include water vapor, carbon dioxide, methane, and nitrous oxide. These gases form a layer that blankets the earth and both absorbs heat energy that enters earth’s atmosphere from the sun and blocks it from escaping as it otherwise would. Heat energy is then bounced back to the surface of the earth, causing the phenomenon we call climate change.

The Potsdam Institute’s findings on climate change are based on complicated statistical analyses of both actual climate data and the latest computer simulations. The approach allowed researchers to differentiate between natural fluctuations in climatic conditions caused by phenomena such as this year’s El Niño, a warm ocean current that affects temperatures globally or volcanic eruptions, and those caused by human activity. Stefan Rahmstorf concluded.

“Natural climate variations just can’t explain the observed recent global heat records, but man-made global warming can.”

Climate change is on the minds of yet another group of scientists – this time based in Chicago. Climate change is one of the chief reasons that the Doomsday Clock has been set at three minutes to midnight, as announced today by the Bulletin of Atomic Scientists. The organization was founded in 1945 by the scientists who made up the infamous Manhattan Project that created the world’s first atomic bomb. In 1947, they created The Doomsday Clock as a symbol to illustrate how close humanity comes to reaching extinction. The 11:57 p.m. reading is the closest it has come to midnight since 1984 during the height of the Cold War.

It was not quite a year ago that the Republican-controlled U.S. Senate passed a 50-49 vote acknowledging that climate change existed, yet denying that human activity is the chief catalyst. The May 2015 vote came about during the historic debates over the contentious Keystone XL oil pipeline that was eventually vetoed by President Obama last November. In doing so, Obama specifically mentioned climate change as the reason for rejecting the project.

[Image by NASA]