Thursday, June 4, 2015

Hurricane Histories and Carbonate Mysteries

Cross-posted from the State of the Planet Blog

Today, a group of nine PhD students from the Department of Earth & Environmental Sciences at Columbia University (including myself) arrived in Exuma, The Bahamas for a week-long field trip.

The Bahamas might be a vacation destination for most people. But for us, they represent an excellent site to study several different questions about past, present, and future climates.  We will try to answer two main questions on this trip: First, can we reconstruct past hurricane strikes from the geologic record in the Bahamas? Second, islands in the middle of the ocean typically form near areas of strong volcanic activity. Why do the Bahamas—an island chain a thousand miles away from the nearest volcano—even exist?

The Bahamas are constantly under threat from hurricane landfalls. The National Oceanic and Atmospheric Administration (NOAA) has documented over thirty “tropical systems” (storms with wind speeds of 40 miles per hour or greater) coming within 50 miles of Great Exuma Island since the late 19th century. 

Historical tropical storm and hurricane tracks within 50 miles of George Town, Exuma, Bahamas (NOAA)

Many of the storms that traversed this region of the Bahamas continued onward to make landfall in the United States—both Hurricane Irene in 2011 and Hurricane Sandy in 2012 passed over Exuma before their eventual destructive landfalls in the northeastern U.S. We aim to use the geologic record of Exuma to infer past hurricane landfalls that occurred prior to the 19th century. With this information, we can better understand the relationship between hurricane activity and climate, which will help to improve future projections of hurricane activity.
The processes that originally created the Bahamas over 100 million years ago, and continue to operate today, are an area of open scientific debate. By all rights, the Bahamas shouldn’t exist; how and why the islands formed is not yet explained. Maybe surprisingly, the possible explanation for how the islands formed is related to climate. The extensive sediments of the Bahama Banks are comprised nearly exclusively of the mineral calcium carbonate. These calcium carbonate sediments represent a large reservoir of carbon locked away from the atmosphere. Without these sediments, not only would the Bahamas not exist, but concentrations of the greenhouse gas carbon dioxide would be much higher than at present.
Carbonate sedimentation features along Great Bahama Bank as seen during the flight to Exuma (Photo: J. Farmer)
Over the course of this trip, we will investigate the complex, micro- and macro-scale processes that create the calcium carbonate sediments of the Bahamas.
Thanks to funding support from the Extreme Weather and Climate Initiative, Lamont-Doherty Earth Observatory supporter Frank Gumper, and other sources, we’ll spend the next week looking for insights into these two questions. And if we’re lucky, we might even get a few brief moments of downtime in the sun.
Arrival in Exuma! More to follow...

Tuesday, June 24, 2014

Communicating Climate Science: Is Consensus Backfiring?

The “97%” statistic misleads those who (rightly) expect science to be full of disagreements.

I'm supposed to be doing research, but I admit to spending time in the comments sections of news articles about climate change, fact checking and engaging in debates. These debates center on two camps: the “pro-AGW” (anthropogenic global warming) camp, who fully accept the notion that humans are causing climate warming, and the “skeptic” camp, who generally reject either the notions of human influence on climate change or that climate change poses significant future threats.

One of the oft-cited pro-AGW buzzlines is the “97%” statistic. This position refers to a 2013 publication by John Cook and colleagues showing 97% of publishing climate scientists agree that humans are causing global warming. Other independent studies reach starkly similar conclusions on the magnitude of this consensus (Figure 1).

Figure 1. Response to the survey question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" Note the divide between the General Public (darkest blue) and publishing climatologists (lightest blue). From Skeptical Science

While the “97%” statistic is certainly a useful communication tool, I recently encountered a viewpoint suggesting this consensus argument may actually backfire when it comes to communicating the depth of climate science’s knowledge about AGW. A common “skeptic” argument dismisses the climate research field as some form of liberal conspiracy. Though laughable to the average researcher (like myself), the “97%” position may unintentionally impart a sense of truth to these arguments.

The crux of the issue is that the general public likely expects scientific research to be an area of active debate. Consider, for instance, recent disagreements on the existence of black holesor the nature of building blocks for the universeFor those with an expectation of active debate, presentation of an overwhelming consensus on a scientific issue sounds alarm bells, and may lend credence to the notion of collusion or conspiracy.

To be clear, the strong consensus on AGW amongst climate scientists is real. From my reading of the literature, the argument for human-driven warming from carbon dioxide’s effect on temperature is so soundly established across such a broad range of scientific literature that I would have serious reservations about the sanity of a scientist who casually questioned this framework. I emphasize casual- a rigorous disproof of human-driven global warming would be a bombshell, instantly skyrocketing one to fame (and infamy), and likely becoming the highest cited scientific paper in history. However, all attempts to do such over the past several decades have been disproven or found wanting.

Why does this misunderstanding between climate scientists and the general public on the nature of consensus exist? My hypothesis is that the questions of active debate in climate science have moved beyond what is covered in the media and dissected in forums and comments sections. In other words, the presence or absence of AGW, which is still hotly debated in the media, was answered long ago in the climate science community.

With regard to communicating climate science, this hypothesis leads to two outcomes. First, climate scientists feel that the general public poorly understands the basics of climate science. In response, climate scientists feel obliged to show consensus, thereby demonstrating their level of understanding of the climate system and confidence in future projections. As noted previously, however, this consensus approach may dissuade individuals who rightly expect scientific research to involve active debate.

The second outcome is that few climate scientists are willing to roll up their sleeves and engage in a debate about AGW in the public sphere. A primary reason for this may be boredom- since the debate over AGW was already fought out in the scientific literature decades ago, why bother wasting additional time on a largely settled question, particularly when there are many new and interesting question to ponder? Moreover, the desire of climate scientists to engage in such a debate is surely tempered by the experiences of scientists like Michael Mann, who get rewarded for outreach by spending time in the courtroom instead of performing research.

Are there any solutions to this climate communication conundrum? I am not qualified to answer this, but an important consideration, as always, is knowing your audience. The “97%” statistic may work well for those unfamiliar with the basic premise of AGW, convincing otherwise undecided individuals on the understanding and potential severity of future climate change. For those with a more nuanced view and an expectation of debate in science, illustrating that such debates exist in the frontiers of climate research is paramount. Mostly this can be drawn from personal experiences, although I also enjoy this video that perfectly encapsulates my reaction to poor journal reviews (warning: bad language).

Thanks to Disqus member orsonhind and ├╝berskeptic Richard Peacock for inspiring this post.