The Obama Administration's just-released National Climate Assessment report leaves the impression that if we don't quickly launch into action to reduce our emissions of greenhouse gases (primarily by shifting away from using fossil fuels), we will be inundated by an endless flow of misfortune unleashed by the ensuing climate change. The flood has already begun.
Nothing could be further from the truth.
First, the assessment report frequently confuses climate with climate change. The natural climate of the United States is constantly overflowing with extreme weather hazards of all sorts — hurricanes, tornadoes, droughts, floods, blizzards, heat waves, hard freezes and on and on. It's the norm. The assessment would have you think that every time one of these types of events happens, now or in the future, it is because we are emitting carbon dioxide into the atmosphere. Such a conclusion is a stretch and has never been proven. A thorough review of climate science would demonstrate that the impact of human-caused climate change on the behavior of most types of extreme weather is poorly understood. Instead, the vagaries of climate dominate our experiences.
Second, greenhouse gas emissions from the United States have a truly minimal and diminishing effect on the future course of the Earth's climate. Rather, that course is being set by developing nations such as China and, soon, India. Research has shown that eliminating all greenhouse gas emissions from the United States now and forever only mitigates less than two-tenths of a one degree of warming by the end of the century — but the cost to do so would hurt our economy dearly. Few folks are willing to pay such a price for no measureable return.
Third, a growing body of scientific evidence — which is based in observations rather than climate models — strongly suggests that future climate change is going to be smaller than we are commonly told in reports such as this National Climate Assessment or those from the United Nations Intergovernmental Panel on Climate Change. This means that reducing carbon-dioxide emissions from the United States will have even less of an impact than the tiny number mentioned above.
Finally, suggesting that we will be overwhelmed by negative impacts from climate change ignores our demonstrated human ability to respond to environmental challenges. A changing climate is only filled with negatives if we sit unresponsive and let it sweep over us. However, such an outcome is completely at odds with human civilization. The National Climate Assessment seems to sparingly recognize this fact, but then is quick to dismiss it as a way forward.
A glaring example concerns the death toll from heat waves. The assessment tells us that incidents of extreme heat have become more common and longer-lasting, and that we should expect the trend to continue into the future (until presumably that we stop emitting greenhouse gases). The report recognizes that "[s]ome of the risks of heat-related sickness and death have diminished in recent decades, possibly due to better forecasting, heat-health early warning systems, and/or increased access to air conditioning for the U.S. population." It ignores those findings, though, to conclude "increasingly frequent and intense heat events lead to more heat-related illnesses and deaths." This is not only a non sequitur but it is also completely wrong.
Scientific literature is chock full of studies that demonstrate that the population's sensitivity to extreme heat is decreasing, resulting in lower rates of people dying during heat waves. This is true across the United States and in major cities around the world. A new paper by researchers from the Harvard School of Public Health examined trends in heat-related mortality across the United States and concluded "[t]his study provides strong evidence that acute (e.g., same-day) heat-related mortality risk has declined over time in the U.S., even in more recent years." Another recent look into heat-related mortality published in the prominent science journal Nature Climate Change concluded that "climate change itself leads to adaptation" a finding that "highlights one of the many often overlooked intricacies of the human response to climate change." Such an observation applies directly to the National Climate Assessment.
Let's get one thing clear: The National Climate Assessment is a political call to action document meant for the president's left-leaning constituency. What pretense of scientific support that decorates it quickly falls away under a close and critical inspection.
Perhaps most telling is the letter to the members of Congress that introduces the just-released report, co-signed by White House Science Adviser John Holdren and National Oceanic and Atmospheric Administration head Kathryn Sullivan. The letter concludes, "When President Obama launched his Climate Action Plan last year, he made clear that the essential information contained in this report would be used by the Executive Branch to underpin future policies and decisions to better understand and manage the risks of climate change."
When the president launched his Climate Action Plan last year, the National Climate Assessment was still being revised and reviewed. Yet somehow, the president already knew that it would help his environmental agenda and imminent executive actions on the issue. It seems the message was preordained — the mark of politics trumping science.
Paul C. Knappenberger is assistant director of the Center for the Study of Science at the Cato Institute.