Judith Curry has a new post called the relentless increase of ocean heat content. It mentions two – very good in my opinion – alarming blog posts, one by Stefan Rahmstorf and the other by Joe Romm. These two posts discuss the relevance and significance of the continued rise of ocean heat content. I think they’re both very clear and make a compelling case as to the significance of this continued rise in ocean heat content. Judith, however, finishes her post with the comment
So, can anyone figure out why 0.06C is a big deal for the climate? Or how all that heat that is apparently well mixed in the ocean could somehow get into the atmosphere and influence weather/temperatures/rainfall on the land? Or is sequestering heat in the ocean a fortuitous ‘solution’ to the global (surface) warming problem?
Maybe I should really not be surprised by anything that is said by some with regards to global warming/climate change, but I was somewhat taken aback by Judith’s questions. A comment by someone called lolwot, maybe was similar to my first thought
I can. But really I shouldn’t be having to explain this to a climate scientist.
So, I thought I would try to explain why the continued rise of ocean heat content is significant and why we can’t expect it to be a fortuitous solution.
- The ocean is part of our climate system. Increasing its heat content will presumably have an impact on our climate. It’s also a reasonably sensitive ecosystem and so the ecology of the ocean will likely be influenced by rising ocean temperatures. This is in addition to issues related to ocean acidification.
- The continued rise of ocean heat content tells us that overall warming continues despite the slowdown in surface warming. This indicates that our basic understanding of the influence CO2 and other greenhouses gases is robust. Hence, the likely claim by the IPCC that scientists are 95% certain that the warming is anthropogenic. There is no other (natural) known way to explain the slow rise in surface temperatures, the continued rise in ocean heat content, and the rapid decline in Arctic sea ice.
- We can’t expect the ocean to continue sequestering this heat. There are probably two basic reasons for this.
- One is that we would expect there to be ENSO events in which energy from the ocean is released to heat the land and atmosphere. That overall warming continues tells us that such an event would cause a step increase in surface temperatures that would remain, rather than decay back to the previous level. Hence we might expect to see surface warming as a series of step changes that ratchet up the surface temperatures, rather than as a smooth rise in surface temperature.
- The other reason is that even though most of the heat is going into the oceans at the moment, surface temperatures continue to rise at about 0.05oC per decade. If this slowdown continues then the top-of-the-atmosphere energy imbalance will rise. The only way that surface temperatures could continue rising slowly is if an ever increasing fraction of this excess goes into the oceans. This may be possible, but seems highly unlikely. So even if we don’t see another ENSO event (which is also unlikely) the rate of surface warming should increase anyway as the energy imbalance increases (i.e., basic physics tells us that we can’t expect the slowdown in surface warming to continue).
- As I mentioned in point 2, the continued rise in ocean heat content tells us that our basic understanding of global warming is robust. That an energy imbalance exists, tells us that surface temperatures have to eventually rise so that the outgoing energy will match that coming in. Given that our understanding of the basics is robust probably indicates that our understanding of the equilibrium climate sensitivity is robust (within the uncertainties). We can’t avoid an eventual rise in surface temperatures unless our understanding of the basics is wrong and there is no evidence to suggest that this is the case.
So, that’s my attempt to explain to Judith why the continued rise in ocean heat content is significant. I’ll finish with another comment from lolwot (I don’t know who this person is, but they seem to make some very good comments on Judith’s blog. I hope she appreciates having such a knowledgeable commenter). This first part of this comment is a quote from someone else. The rest is lolwot’s response.
“The point is that the warmists keep pointing to the 10**23 joules that have gone into the ocean as evidence of global warming.”
Well it is! jesus christ!