At his son Roger Jr.’s Substack, veteran climate scientist Roger Pielke Sr. has published an intriguing post explaining pretty much everything you ever wanted to know about the warming of the world’s oceans and why the data matter so much. He begins by pointing out that whereas the warming of the air is an unstable way of measuring the effect of greenhouse gases and the overall energy imbalance at the top of the atmosphere they create, the warming of the oceans (including the deep ocean) is better, for two reasons. First because there are no delayed reactions: once the heat energy stops the oceans stop warming. Second the heat gets mixed and dissipated by worldwide currents so taking a global average doesn’t depend as much on finding just the right locations. With some basic number crunching Pielke Sr. shows that the total effect on the global climate system as reflected in ocean warming is much smaller (about 50%) than that proposed by NASA scientist James Hansen using satellite data.
Pielke Sr. makes use of the Argo data, a remarkable collection of temperature readings collected continuously by a fleet of about 4,000 robotic floats that cruise the world’s oceans continuously diving and surfacing and beaming their records to a central archive. Its main limitation is that the Argo series only began in 2003 so there is only 20 years of reliable data available for the deep ocean. It shows that the seas have warmed up a bit, and Pielke Sr. crunches through the numbers to estimate how much energy has been added to the climate system in terms of top-of-the-atmosphere radiative imbalance. He figures it to be about 0.66 Watts per square meter, give or take 0.5.
This number is similar to estimates from several other publications based on ocean temperature changes. But it is only half as much as a recent estimate by James Hansen based on energy measurements at the top of the atmosphere from weather satellites. Hansen argues that the energy imbalance up there has doubled over the past 20 years. Pielke Sr. comments that the satellite method requires measuring a small difference between two huge numbers, a process in which very small error bars spell the difference between statistical significance and no discernible signal. The ocean method by contrast yields the change directly based on more stable data series.
Is 0.6 Watts per square meter a large number? For comparison, Pielke Sr. shows a chart of the annual global energy imbalance through the seasons, which has a natural cycle spanning about 25 Watts per square meter. And according to Wikipedia the annual energy flows in and out are about 340 Watts per square meter. So we’re talking about less than 0.2 percent of the total. A frail reed upon which to base the notions of the climate.