Prediction by Tony Haymet

Tony Haymet, Director of Scripps Institution of Oceanography, Vice Chancellor for Marine Sciences-
Co-chair BioMarine since 2008 shares his views on the future of aquaculture.

Sustainable aquaculture is poised to boom in many parts of the globe. In April 2011, I had the opportunity to visit – for the first time – underutilised catfish farms near the Mississippi River. Many exciting futures were discussed, but I found myself wondering how often the ponds would be flooded. As it happened, a month later, the farms were underwater.

As the physicist Niels Bohr wryly pointed out, “prediction is always difficult, especially when it is about the future”. Statistically reliable predictions are required in many regions for aquaculture in order to estimate and amortise risk.

But aquaculture is far from alone. For many commercial activities, in addition to requiring the best science, our community is increasingly asking demanding questions on the prediction of the natural world. What useful chemicals will be discovered from the ocean and ocean mud? Will the steady trend in movement of California precipitation from snow to rain continue, or accelerate? What is the average recurrence time for earthquakes under or near California’s nuclear reactors? Will the sea level continue to rise at its current rate, or faster, or slower? Is methane gas leaking from fracking operations? From a given library of 10,000 marine compounds, how many useful pharmaceuticals may be expected?

Routinely scientists and engineers are criticised for the style of their estimates, relying as we do on “probability distribution functions” rather than “yes or no” responses. My colleagues in climate sciences are often asked to making predictions about future levels of ocean acidity, global temperature, and –yes – river flow. Of course, no one knows, nor can they know precisely. Despite our very advanced understanding of the spectroscopy of trapping heat in the planetary atmosphere, we really don’t know how much CO2 and other greenhouse gases and particulates our communities will emit over the next 50 to 100 years. Although there is no apparent sign of it today, we just might come to our senses and emit less!

Our geophysicists are frequently asked to tell the world when the “big one” will happen. They are correctly hesitant to do so, or even to frame earthquake analysis in terms of prediction. Still their work has been invaluable as a spur to preparedness. One team, for example, has detected a pattern of regularly spaced quakes in the Southern California segment of the San Andreas Fault but has noted that we are currently several decades “overdue” for the next instalment. With some breathtaking science, they attributed the delay to the diminishing weight load of the Salton Sea, an evaporating lake located 130 miles to the east of my office at Scripps Institution of Oceanography, UC San Diego. Now this same team is getting ready to survey the faultlines adjacent to the San Onofre nuclear power plant located in north San Diego County.

These researchers have done much to characterise the next quake we can expect from this region – temporally and spatially – and have succeeded in managing expectations of their predictive prowess. At least I hope so. Who can forget that Italian scientists were charged with manslaughter in 2011 for (in my own words) not successfully predicting a quake that killed 308 people in 2009. Who knows if this sort of reaction will reach California when the next catastrophic quake hits?

Quite properly, scientists and engineers respond with “if … then” scenarios, along the lines of “if we emit this many gigatons of CO2-equivalent, and this level of black carbon soot, we can expect this range of warming”. It is remarkable how often scientists and engineers are criticised harshly for responding responsibly using the “if …then” format. And yet I confidently predict that this state of things will not change soon.

Institutions such as my own will have to gear up to handle more frequent requests for larger-scale predictions. I believe that we are up to the task of helping society manage its future, but we all have a role in keeping expectations reasonable.

Read more about Tony Haymet here.