Tag: heavy precipitation

Heavy Rains Increasing, but Not Disproportionately So

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

A new paper has been published in the journal Geophysical Research Letters that examines trends in heavy rainfall amounts across the U.S. The paper is authored by Newcastle University’s Renaud Barbero and colleagues, and, to summarize, finds that the heaviest rainfall events of the year have been increasing in magnitude since 1951 when averaged across nearly 500 stations distributed across the U.S. (note: results from individual stations may differ from the general finding).

Someone with a critical eye might ask the real question, which is “how much?” That such a number does not jump out of this paper—a cynic would say—probably means it is very small. Read on and you will find the answer.

That rainfall on the rainiest day of the year is increasing is, of itself, hardly surprising considering that the total annual rainfall amount averaged across the U.S. has also been increasing during this same period (again, results from individual locations/regions may (and do) depart from this generality).

Changes in heavy rainfall like this are often luridly described as a “disproportionate increase” in extreme events, or that extreme precipitation increases are “worse than expected.”

Going to Extremes: Federal Climatologist Slams Alarmist Federal Climate Report

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

Second only to incidences of high temperature, supporters of government action to restrict energy choice like to say “extreme” precipitation events–be they in the form of rain, sleet, snow, or hail falling from tropical cyclones, mid-latitude extratropical storms, or summer thunderstorm complexes–are evidence that greenhouse gas emissions from human activities make our climate and daily weather worse.

The federal government encourages and promotes such associations. Take, for example, the opening stanzas of its 2014 National Climate Assessment: Climate Change Impacts in the United States, a document regularly cited by President Obama in support of his climatic perseverations:

This National Climate Assessment concludes that the evidence of human-induced climate change continues to strengthen and that impacts are increasing across the country.

Americans are noticing changes all around them. Summers are longer and hotter, and extended periods of unusual heat last longer than any living American has ever experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours.

President Obama often calls out the extreme rain meme when he is running through his list of climate change evils. His Executive Order “Preparing for the Impacts of Climate Change,” includes:

The impacts of climate change – including…more heavy downpours… – are already affecting communities, natural resources, ecosystems, economies, and public health across the Nation.

So, certainly the science must be settled demonstrating a strong greenhouse-gas altered climate signal in the observed patterns of extreme precipitation trends and variability across the United States in recent decades, right?

Wrong.