Unusually High Frequency of Heatwaves Indicates Human Influence on Global Warming


The unusually high frequency of heatwaves suggests a human influence.

There has been a definite, palpable impact on the Earth’s climate by global warming. The unusually high frequency of heatwaves indicates that there has to be a human influence. As much of the USA sizzles through another scorching summer and the Midwest endures a historic drought, NASA’s climatologist James Hansen states that the future he predicted in 1988 has finally arrived.


Hansen and his colleagues have published a paper entitled Perceptions of Climate Change in the journal PNAS. They used seasonal temperature records from 1951-80, which was a relatively stable period, as a baseline. Then, they analyzed the frequency and scale of subsequent temperature anomalies. They conclude that on average, the Earth’s temperature has warmed by 0.5-0.6 °C (0.9-1.1 °F). Since then, the shift has impacted many parts of the world. Extremely hot summers, with a 3.5°C (6.3°F) warmer temperature, have affected 10% of the world since 2006, which is an order of magnitude higher than the period of 1951-80.

The likelihood that these events would have occurred without global warming is minuscule, states Hansen. The study is purely statistical and doesn’t try to explain how climate changes have affected extremely hot summers. It should help people understand global warming and the profound effect humans have on the climate system, states Kevin Trenberth, a climatologist at the US National Center for Atmospheric Research in Boulder, Colorado.

Reference: “Perception of climate change” by James Hansen, Makiko Sato and Reto Ruedy, 6 August 2012, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.1205276109

1 Comment on "Unusually High Frequency of Heatwaves Indicates Human Influence on Global Warming"

  1. This article shows definite evidence that climate has indeed been warming over recent years however I do not see how it was determined that Humanity is the cause of global warming. If Human Beings are the main cause of global warming then we have hope; Humanity can make changes and innovations that can reverse global warming. On the other hand, if global warming were a natural condition caused by, say the sun burning hotter or volcanic activity releasing the lion’s share of carbon dioxide and other greenhouse gases causing atmospheric temperature increase then life would be a hopeless “On The Beach” situation for all of Mankind. I prefer to believe we are responsible for global warming and we should do something to reverse it or at least slow its’ progress…

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