All Commentary
Monday, September 17, 2018

Why You Can’t Blame Hurricane Florence on Trump

Not only has Trump not been in office long enough for any of his environmental policies to have a real effect on global climate, hurricanes aren't actually any worse than they have been in the past.

The Washington Post editorial board has accused President Trump of being “complicit” in Hurricane Florence because “he plays down humans’ role in increasing the risks” of “extreme weather,” and “he continues to dismantle efforts to address those risks.” Such weather, they say, is fueled by manmade global warming that creates “unusually warm ocean water” that worsens hurricanes. The board finishes by declaring that Trump and Republicans are guilty of “reality denial” on this issue. However, their editorial is the antithesis of reality.

Trump hasn’t been in office nearly long enough for his policies to alter the earth’s greenhouse gas levels. In fact, his plan to repeal Obama’s “landmark“ climate change regulation has not yet been implemented.

Furthermore, Charles McConnell, a former assistant secretary of energy under Obama and the director of Rice University’s Energy and Environment Initiative, estimated that this regulation would decrease global temperature by only 0.01 degrees Celsius by 2030. Thus, to blame Trump for Hurricane Florence or any other hurricane in the past or future is absurd.

More importantly, the Post’s narrative is at odds with the scientific facts of the matter. These show that from as far back in time as reliable data extends:

  • global hurricane frequency, hurricane intensity, hurricane duration, and general rainfall trends have been level.
  • Atlantic hurricane frequency and intensity trends have been level.
  • U.S. hurricane strikes, major hurricane strikes, and flood trends have been level.

Cyclone and Hurricane Trends

Contrary to the Post and other media outlets, cyclones and hurricanes have not become more common or intense. As the Intergovernmental Panel on Climate Change (IPCC) reported in 2012: “There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities.” This also applies to hurricanes, which are tropical cyclones with winds exceeding 73 miles per hour.

Likewise, the datasets graphed below show that the global number and intensity of cyclones, hurricanes, and major hurricanes have been roughly level for the past four-to-five decades. These data were originally published in the journal Geophysical Research Letters in 2011 and updated this year.

Records of Atlantic hurricanes—which stretch back for more than a century—also show stagnant trends. The National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory recently assessed these data and concluded that “the historical Atlantic hurricane record does not provide compelling evidence for a substantial greenhouse warming-induced long-term increase.”

Similarly, the IPCC reported in 2013: “No robust trends in annual numbers of tropical storms, hurricanes and major hurricanes counts have been identified over the past 100 years in the North Atlantic basin.”

In spite of all those facts, a national scientific poll commissioned by Just Facts in 2017 found that 69 percent of U.S. voters believe that the global “number and intensity of hurricanes and tropical storms have generally increased since the 1980s,” including 90 percent of Democrats and 46 percent of Republicans. This disconnect between perception and reality accords with a mass of global warming-related misinformation spread by the press.

A common thread among much of this misinformation is a focus on local conditions, anecdotes, and short-term trends.

A common thread among much of this misinformation is a focus on local conditions, anecdotes, and short-term trends. Because the earth is vast and its climate varies widely over time and place, it is easy to paint a misleading picture by highlighting certain aspects of it.

For example, the popular narrative that global warming is causing more U.S. hurricane strikes crumbles in the face of long-term data. As detailed by the Geophysical Fluid Dynamics Laboratory, the full record of U.S. landfalling hurricanes actually shows “a slight negative trend beginning from 1900 or from the late 1800s.” Counting only major hurricanes, the trend has been generally flat for 165 years:

Because of the timespan involved, no one could possibly know these facts from life experience, even if they had perfect memories. Yet, a 2008 survey of Virginia residents found that the most common answer people give for believing or disbelieving in global warming is their personal experience of the climate. This makes them easy marks for those who mislead by using half-truths.

Even if this data showed rising numbers of hurricanes, the Geophysical Fluid Dynamics Laboratory emphasizes that one cannot logically assess hurricane trends based only on those that reach land, because they are “much less common” than the full number of hurricanes that form at sea. This highlights the importance of not drawing conclusions from narrow data.

The U.S. contains only 1.9 percent of the world’s surface area. Yet, media outlets and global warming activists often argue that the sky is falling based on local trends and events. This is called “cherry-picking,” which is reporting only information that accords with a certain view while ignoring everything that does not. It is the equivalent of lying by omission.

The Trenberth Study

“I … cannot … continue to contribute to a process … motivated by pre-conceived agendas and being scientifically unsound.”

To support its claim that Hurricane Florence is “feeding off unusually warm ocean water,” the Post cites a 2018 paper in the journal Earth’s Future. Its authors studied the infamous Hurricane Harvey that flooded Houston in 2017 and concluded that “record high ocean heat values not only increased the fuel available to sustain and intensify Harvey but also increased its flooding rains on land.”

The paper was co-authored by Kevin Trenberth, whom the Post quotes to reinforce its argument. A decade ago, Trenberth, a lead author for the IPCC, grossly misrepresented the facts about global warming and hurricanes during a press conference. Consequently, Chris Landsea, a research scientist at the U.S. National Hurricane Center, quit the IPCC and stated, “I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound.”

Trenberth’s new paper follows that pattern and begins by stating that:

  • “human-caused climate change is supercharging” hurricanes.
  • the “Atlantic hurricane season in 2017 broke numerous records,” and its “accumulated cyclone energy was 225% of normal.”
  • “several aspects of the 2017 season were not ‘natural.’ The first was the role of human‐induced climate change….”

This is a classic example of cherry-picking because it singles out one year from one area of the world. In contrast, the comprehensive data provided in the chart above show that global cyclone energy and frequency trends have been about level.

The authors also write that “increases in Atlantic hurricane activity in the 20th century have been attributed mainly to the increases” in sea surface temperatures, which are “primarily driven by human increases in greenhouse gas concentrations….” Once again, the IPCC and Geophysical Fluid Dynamics Laboratory have found no detectable increase in Atlantic hurricane activity over the course of the 20th century.

Trenberth, his coauthors, and the Post’s editorial board ignore such facts while touting anecdotes, model predictions, and leaps of logic.

Moreover, the study that forms the basis of the paper does not prove what its authors claim. It merely finds that Hurricane Harvey traveled over warm ocean waters while absorbing a specific amount of heat, and this heat “likely matches” the amount of heat that it released via rainfall. That’s no surprise given that energy cannot be created or destroyed, and 10 pages into the paper, the authors admit that these findings “unsurprisingly, reflect strong energy exchanges during the hurricane.”

From that mundane result, the authors jump to the assumption that record-high ocean temperatures “likely” increased Harvey’s “size and intensity” and “contributed substantially to the flooding caused by rainfall on land.” This is irrational because there is a significant difference between: (a) finding that a storm absorbed and released a certain amount of heat from the ocean, and (b) concluding that the storm absorbed more heat than it otherwise would have because the ocean was warmer than normal.

The authors don’t empirically justify that leap of logic. Instead, they repeatedly assert that warmer oceans create more cyclone activity. However, at the end of one paragraph, they reveal that this conclusion comes from “global modeling experiments” and “dynamically downscaled experiments.” These are computer models that predict what will happen—not what has actually happened.

Unlike those models, real-world data shows that cyclone activity has been level. The academic serial work Flood Geomorphology stresses the danger of relying on computer models instead of hard data:

True science is concerned with understanding nature no matter what the methodology. In our view, if the wrong equations are programmed because of inadequate understanding of the system, then what the computer will produce, if believed by the analyst, will constitute the opposite of science.

The authors also declare that “a warming ocean will” cause “more rainfall and flooding, which is well supported by the Harvey case.” Concrete, comprehensive data also deflates that assertion:

  • A 2015 paper in the Journal of Hydrology analyzed rainfall measurements “made at nearly 1,000 stations located in 114 countries” and found “no significant global precipitation change from 1850 to present.” The authors noted that previous studies had analyzed shorter timeframes and found rainfall changes that some people had attributed to global warming, but those results were generally not statistically significant and “not entirely surprising given that precipitation varies considerably over time scales of decades.”
  • A 2015 paper in the International Journal of Climatology studied extreme rainfall in England and Wales found that “contrary to previous results based on shorter periods, no significant trends of the most intense categories are found between 1931 and 2014.”
  • A 2012 paper in the Hydrological Sciences Journal examined U.S. flood trends from 200 water gauges with records extending from 85 to 127 years ago. This study found “no strong empirical evidence” for increased flood magnitudes across any of the four major regions of the United States. In the Southwest, the study actually found a decrease in flooding, and in the Northeast, it found results that are “suggestive” of increased flooding but not statistically significant.

Nonetheless, Trenberth, his coauthors, and the Post’s editorial board ignore such facts while touting anecdotes, model predictions, and leaps of logic.

Storm Speeds

The Post cites one other source to support its argument, writing:

Scientists also warn that climate change may be slowing the wind currents that guide hurricanes, making storms more sluggish and, therefore, apt to linger longer over disaster zones. Tropical cyclone movement has slowed all over the planet. Harvey’s stubborn refusal to leave the Houston area was a decisive factor in its destructiveness. Florence may behave similarly.

The hyperlink in the quote above leads to an NPR article, which links to another NPR article, which names the author of a study “published Wednesday in the journal Nature.” None of these publications provide a link to the study or its title, thus ensuring that the vast majority of readers will never lay eyes on it. Except for its abstract, the paper itself is locked behind a paywall, providing another barrier to the primary source.

Three pages in, this paper reveals that it did not determine the causes of the slowdown:

The analyses presented here do not constitute a detection and attribution study because there are likely to be many factors, natural and anthropogenic [manmade], that control tropical-cyclone translation speed.

This study calculates the speeds at which tropical cyclones moved over each of their lives by using data on their positions at different points in time. The data covers the globe from 1949 to 2016, and the calculations show that their overall speed declined by 10 percent during this period “in which global-mean surface temperatures increased by about 0.5 °C.” The paper also says that “the slowdown varies substantially by region and by latitude, but is generally consistent with expected changes” caused by manmade greenhouse gas emissions.

Beyond the fact that the study does not determine causation, the timeframe it covers is short enough to produce illusory trends. For example, the above chart of U.S. hurricane strikes begins in 1851 and shows generally level trends. However, if the data only went back to 1941, it would seem that hurricanes and major hurricanes are trending downward:

Furthermore, the study’s findings are at odds with data on U.S. floods. The study states “there is a substantial and significant slowing trend over land areas affected by North Atlantic tropical cyclones (20 percent reduction over the 68-yr period),” and this has “almost certainly increased local rainfall totals” in this region. However, the above-cited 2012 paper on U.S. flood trends found “no strong empirical evidence” for increased flood magnitudes across any of the four major regions of the United States.

Climate scientist Roy Spencer aptly summarizes the implications of this study for climate change: “But like most claims regarding global warming, the real effect is small, probably temporary, and most likely due to natural weather patterns. Any changes in hurricanes over 70 years, even if real, can easily be part of natural cycles—or incomplete data.”

Potential Harms

In addition to slandering the president of the United States, the Post’s deceptive editorial has the potential to cause serious harm in at least three ways.

First, it may spur voters to support policies that can increase hunger. For instance, a 2018 study in the journal Nature Climate Change found that

by 2050, stringent climate mitigation policy, if implemented evenly across all sectors and regions, would have a greater negative impact on global hunger and food consumption than the direct impacts of climate change. The negative impacts would be most prevalent in vulnerable, low-income regions such as sub-Saharan Africa and South Asia, where food security problems are already acute.

Note that this study, like all studies that project such effects of government policies, should be taken with a grain of salt.

Second, it can sow fear and hopelessness, which can have debilitating effects on people. For example, the World Health Organization found that the areas surrounding the Chernobyl nuclear accident received very low doses of radiation, and local populations show “no evidence of any effect on the number of stillbirths, adverse pregnancy outcomes, delivery complications or overall health of children.” However, these people are suffering because “persistent myths and misperceptions about the threat of radiation have resulted in ‘paralyzing fatalism’ among residents of affected areas.”

Third, it could fuel violence against Republican lawmakers by falsely charging them with deaths caused by hurricanes. This is ironic, given that many news outlets recently declared that Trump was endangering the safety of journalists by calling the “fake news media” the “enemy of the people.”

  • James D. Agresti is the president and cofounder of Just Facts, a think tank dedicated to publishing rigorously documented facts about public policy issues.