Editor’s note: This question was asked in response to Electronics Cooling’s recent webinar by Roger Stout. To view the webinar, click here.
Question: You mentioned using only the top 100 m of ocean depth when considering how much the temperature could go up in a century? Isn’t that an oversimplification? Besides, average ocean depth is something like several km, isn’t it?
Answer: Yes, that’s an oversimplification. Even a small amount of mixing through the entire depth (which averages 2400 m globally) would “water down” the temperature rise I estimated using just the top 100 m. Similarly, I’ve totally neglected that the land surface of the Earth has an extraordinarily long “characteristic time” (billions of years, in fact), and could thus act as a much larger heatsink than I’ve allowed for, thus mitigating the temperature rise I’ve estimated based on limited diffusion and mixing in the oceans. However, we don’t know how to take advantage of these natural heatsinks with our present technology, and it’s nevertheless true that short-term shifts in average energy balance at the Earth’s surface will show up as short-term temperature shifts. The problem I really didn’t have time to dig into in this presentation is that shifts can occur in any one or all of three ways, and they’re all equivalent in their end effect: (1) changes in albedo (greenhouse gases, for instance, affecting cloud cover and polar ice cap reflectivity); (2) changes in infrared emissivity (again, greenhouse gases, affecting cloud cover, humidity, etc.); (3) raw shifts in energy dumped into the environment. I only focused on #3, but all the other environmental issues that we’ve been struggling with over the last few decades affect #1 and #2. Perhaps the jury is still out on #1 and #2, but for #3, the energy juggernaut is accelerating and it won’t be easily stopped. I haven’t heard anybody talking about #3 – that’s what really scares me. If we’re lucky, I’m off by a hundred years (the long way out); but if we don’t start looking at the right problem right now, our grandchildren will curse us for that 100 years they needn’t have lost. I do not want that to be my legacy.
-Roger Stout
