Monday, September 2, 2019

Gettting from Temperatures Then to Temperatures Now

Environmental & Science Education 
STEM
Climate Change
Nature of Science
Edward Hessler

Climate science has a great need for historical data. If we are to know how much warmer say the ocean has become we need to know what that temperature was in the past. Fortunately, there are data, millions of data points, but resolving problems inherent in the data involve more than is readily apparent.

Historically, instrumentation to collect water samples (buckets) was different as were methods, protocols and recording the data. Rebecca Hersher of NPR did a great story, Monday August 19, 2019 on how data scientists approach such problems. She includes one potential problem that is not immediately apparent. The reporting is based on a paper published earlier to which you can link. Bucket lists are all the rage these days and this work adds a new wrinkle to buckets.

Hersher includes a video clip--Ocean Weather Ship Record B (Pathe)--showing crew members collecting ocean temperature data as well as launching a balloon to collect meteorological data in 1947. You might want to watch the film first before reading Hersher's essay and think about problems scientists years later, nearly a century out, could face in trying to make sense of them.

In short, Hersher notes that "...different countries used buckets made of different materials, in different sizes, on different lengths of rope — all things that could change a temperature reading."  Recall that in the science of climate change tenths of a degree make a huge difference. 

The scientists engaged in this research were dealing with a database which includes millions of data points "from more than 100 sources," as well as data collected by sailors on ships from different countries.  Hersher quotes one of the scientists involved which is a great way to think about the problem since it is expressed in familiar terms. "This is like if someone left you all their receipts that they had ever spent during their lives, and you were trying to piece together what they had been doing,"  

And furthermore, the research team found that those seemingly small tenths of a degree made another difference, a large one. "When the data was digitized, the U.S. military had dropped everything after the decimal point."  

The abstract from the original paper closes with the following statement. "These findings underscore the fact that historical SST (surface sea temperature) records reflect both physical and social dimensions in data collection, and suggest that further opportunities exist for improving the accuracy of historical SST records."

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