A pastor recently wrote to the Cornwall Alliance,

I am currently responding to an online debate over a new report over rising ocean temperatures. The report says that once the raw data is passed through new methods of calibration and bias it shows a dramatic increase in ocean temperatures.

I seem to remember that somewhere around the mid 1990’s that the people recording ocean temperatures changed their methods because the traditional recordings were not showing any increase in ocean temperatures.  Can you help me remember when that happened and why?

It so happens that Dr. Roy Spencer, one of our Senior Fellows, addressed the issue of ocean warming in a recent post that we reproduced on our blog. See “Chuck Todd Devotes an Hour to Attacking a Strawman.” Here’s the key text relevant to this question:

Between 2005 and 2017, the global network of thousands of Argo floats have measured an average temperature increase of the upper half of the ocean of 0.04 deg. C. That’s less than 0.004 C/year, an inconceivably small number.

Significantly, it represents an imbalance in energy flows in and out of the climate system of only 1 part in 260. That’s less than 0.5%, and climate science does not know any of the NATURAL flows of energy to that level of accuracy. The tiny energy imbalance causing the warming is simply ASSUMED to be the fault of humans and not part of some natural cycle in the climate system. Climate models are adjusted in a rather ad hoc manner until their natural energy flows balance, then increasing CO2 from fossil fuels is used as the forcing (imposed energy imbalance) causing warming.

I’ve not been able to find anything about the allegation that ocean temperature measurement methods were changed specifically because past methods hadn’t yielded expected warming. I suppose that’s possible, but it wouldn’t invalidate the new methods. It is clear, further, that, prior to Argo, ocean temperature measurements were much farther than now from statistically representative either horizontally or vertically. Argo is a significant improvement, though even its roughly 4,000 floats still can only measure a vanishly small percentage of the oceans’ temperatures. With 360 million square kilometers of ocean, that’s one bouy for every 90,000 square kilometers (~34,750 square miles), leaving the vast majority of ocean area unmeasured. And with average ocean depth of 3,688 meters (12,100 feet), the bouys measure at the surface, at 1,000 meters (3,281 feet), and at 2,000 meters (6,562 feet)—leaving the vast majority of the vertical span unmeasured. Nonetheless, this system gives us the best available data, so we’re stuck working with it as best we can. You can read more about Argo at https://en.wikipedia.org/wiki/Argo_(oceanography).