Future temperatures

By starting another such thread I contribute to the misunderstanding that Earth-system science is only about surface temperatures.

As so often, stimulated by a new publication:

Knutson, T.R., Zhang, R. & Horowitz, LW (2016). Prospects for a prolonged slowdown in global warming in the early 21st century. Nature Communications 7: 13676 DOI: 10.1038/ncomms13676

First see their Fig. 1. The matter considered is whether 21st century temperatures may be more like rates (and models) from early 1970s (0.2 oC per decade). Or more like 1998-2015 (0.1 oC per decade). They conclude 16% chance of this rate continuing through 2020, 11% chance of this rate continuing through 2025, etc.



Over the entire century, these would result in +1 or +2 oC. To my understanding this is what could be expected from direct effects of CO2 and (the more minor) CH4, N2O, etc. To attain +3 or +4 oC, additional positive feedbacks are invoked.

Those include cloud or aerosol forcing (both still poorly constrained), CO2 loss from biological reservoirs (see recent Crowther et al.), and increased atmospheric water vapor.

Effects of additional CO2 releases, whether biological or fossil burning, would have logarithmic effects. Less than linear, this is Beer-Lambert law, and pretty darn solid. Effects of increased atmospheric water vapor seem constrained by two things. Global water vapor increases have been so small as to present detection difficulties during 40 years of +T. And they might remain small, because a juicy atmosphere just rains more.

Under all that we have the global ocean doing its (poorly understood) thing, which looks like holding down +T about every 60 years. This is what Knutsen et al. are on about, referring to it as internal variability. Those ‘ocean cycles’ were strong, then weak, and the current one has only slowed the increase. Oceanography literature on this is a tough slog (cause they write for themselves), but this is the general idea, and I present it in an (over) simplified way.

For me the +3 or +4 oC models are not compelling. Ocean cycles do not arise mechanistically; they need to be ‘dialed in’. Water vapor is ‘habeus corpus’. Cloud forcing remains a muddle. Those personal misgivings do not exclude a hot century.

Knutsen et al. do not predict a +1 oC century, but they are on the ‘low end’ of climate modelers. Incidentally they use (are) the GFDL model; recently invoked by mojo about Arctic ice.

Being not a modeler, and with caveats as above, I am inclined towards a +2 oC century. From plain old extrapolation. While at the same time recognizing that WE DON’T KNOW how that would affect the human enterprise. And obviously I have scant basis to exclude slower or faster.

Climate cooling, especially as a direct solar effect, is much easier to exclude, even though endorsed by some loud voices. One would notice that most active sun (1955-1965) happened during a –T ‘phase’, and current low-activity sun happens during +T. It is a lot (perhaps too much) to hope that sun will counteract infrared absorption by +CO2 this century.

Finally to what I consider obvious. Human enterprise needs much more energy production this century. As much as can be done without burning fossils; great. The rest needs to be filled in by +CO2. So we will get to 500 or maybe even 700 ppm CO2. For direct effects, bear in mind that log(10) of 400, 500 and 700 are 2.60, 2.70, 2.85. Not kablooey. We can manage this. Not by ignoring, not by hoping, but by understanding and doing.

 

Yes the 'temperature lower troposphere' proxy, separately developed and compiled by UAH and RSS is familiar to us here. Including it being more sensitive than direct surface measurements to ENSO. Very familiar. In the former one can see that 5-year averages are not always higher than the previous ones

I quickly made that from Roy Spencer's data including 2016 November to illustrate. I know this is less sparkly than Daily Mail, but it gets us a bit closer to the idea of climate.

Surface measurements are calmer in the face of ENSO. There, 5-year, 10-year (etc.) averages have steadily increased for 45 years. We are very familiar with that as well.

But media, without sparkles, would be somewhat dull.

 

If any saw my response as, um, 'too measured', you can read Phil Plait instead

Follow-up: House Science Committee global warming tweet debunked again.

He put the hammer down.

 

The most recent dot is 2011 Dec through 2016 Nov, averaged. UAH global TLT anomaly oC. And so forth backwards. Data from RoySpencer.com.

Seven dots means 35 years. Usually I do 'furnish' graphs but the point here seems just as clear without. In contrast, the daily mail graph is decorated lavishly. Contrast as an editorial statement. And you who claims to prefer pigs w/o lipstick

Yes, first vs last (better a regression utilizing all data) is the UAH slope. Surface T (direct instrumental) slopes are steeper. Go higher in the atmosphere (by microwave emission) see a smaller positive slope. Stratosphere has a negative slope.

 

Yes. So we can agree that there are things to be learned by studying thermal patterns at all levels, through time. You won't find me dissing UAH or RSS. Only the misunderstanding and misrepresentation of their carefully developed products.

 

Concerning the original Daily Mail (and its Breitbart echo) the Weather Channel took them out back for some schoolin' also

Weather Channel Destroys Breitbart Over BS Climate Change Story | The Huffington Post

Video is not available everywhere, but this should be:

 

T squiggles in graph@1. Have tried to make them more sensible with 10-yr non-overlapping averages. For me, this is what can be abstracted from the surface instrumental climate record. BEST goes back further (to the little ice age), but with less signal and more noise.



There are ups and downs. The most recent up, +0.17 oC/decade, can be compared with UAH RSS TLT +0.12 oC/decade. Future decades would have to increase substantially faster to attain +3 or +4 this century. Conversely, would have to decrease (by a lot) to began an ice age. As I have stated many times, neither extreme is supported by clearly established mechanisms.

Shorter-term variations are interesting to talk about, but they do not inform climate.

 

Huck. Oh Bob! can you not appreciate that Daily Mail Breitbart etc. throwing a hail Mary is fun?

Plait and Weather Channel get all excited. In my typical schoolish way, I ask "what can we learn from this?"

Everybody benefits. Please join me in doubting that anyone 'on the fence' saw a few months of -T, sparkly lights, and concluded "Well all that warming stuff is over".

Because if somebody remains on the fence now, it pretty much means they are vaccinated against sparkly.

 

Ah Priuschat. Seems like 10 years ago somebody posted here about a final nail being pounded into the coffin of global-warming hoax. Time having passed, instead of a nail we have another upward dot.

Ten years. we still have folks doing the happy dance (Bless them). Everybody else is still not doing their required reading. Viscosity on both sides is a matter of unending amazement for me.

 

Anyway, Felt, you are most welcome to join in. Earth gets about 1300 watts/m2 from sun at our distance, which is obviously a nice amount. The hot core (which is hard to imagine both in size and hotness) diffuses about 0.1 watt/m2 out through the crust on average. Much more in surface-hot places. Hot core does much additional ‘work’ in terms of plate tectonics, and I don’t know of a place where that has been expressed in similar units.

If Earth lacked an atmosphere, its climate would be as on Moon, which is to say, really bad. Mostly it is water vapor in atmosphere, then CO2, then methane and a few other minor gases, that provide Earth with a climate of 12 oC plus or minus and an acceptable amount. CO2 was more a long time ago, and things were hotter here. But biology did not wink out and I think that is important. Now CO2 is getting a little bit higher again, at so are temperatures. We chat endlessly about how much hotter and how soon.

Climate models suggest +3 or 4 oC this century, but I consider that very reliant on water vapor increasing. It has not (much) yet, and for it to do so would require that rainfall not also increase to match. A warmer atmosphere will certainly have more CAPE which makes water vapor ascend to a freezing level and there’s your rain.

+T may be less (or at least, slower). If people can get their heads around that, we can attend to having enough energy and food and water for a growing population. That would be a very good idea.

We are simply not clever (or motivated) enough to increase energy production without also increasing CO2. Therefore, current 400 ppm CO2 will very likely increase to 600. My opinion is that 800 would push infrared absorption just a bit too far. But it is an experiment underway and by mid-to-late century, effects will be much more obvious.

Or it could possibly become colder. A persistently weak sun (apparently with volcanic help) did this in the little Ice age when CO2 was 280 ppm. More recently, with higher CO2, solar effects have been much smaller.

Grapsing at every brief –T as heralding a new ice age is popular, apparently, but it does not make much use of science.

That is my summary, disagreeing both with PC’s mojo AND Gavin Schmidt etc. I inhabit the underpopulated middle ground.

 

My expectation is that notable sea-level increases from West Antarctic ice sheet losses is going to focus people's thinking on this issue before +T does. OK people are already focused, but my contention is that is about the edges and not the middle.

Increasing entropy law should be accompanied by 'in closed systems'. It is not always easy to be certain about that.

Lug nuts. Look how long we went before knowing that. If folks respected their tools and used them appropriately, we might never have learned. If I think of a way to tie that back to 'environmental' I'll let you know