Guest post by David Archibald
This is a little bit amusing. In February, I had a post on the solar – sea level relationship which quantified the sea level fall to come to the end of Solar Cycle 25:
http://wattsupwiththat.com/2012/02/03/quantifying-sea-level-fall/
The site “Skeptical Science” has to date carried two pieces in response to that February post: http://www.skepticalscience.com/Why_David_Archibald_is_wrong_about_solar_sea_level.html
and http://www.skepticalscience.com/Why_David_Archibald_is_wrong_about_solar_sea_level_1B.html
My February post was 624 words and 6 figures. The Skeptical Science responses to date total 3,446 words and 17 figures. The relationship I found between solar activity and sea level is 0.045 mm per unit of annual sunspot number. The threshold between rising and falling seal level is a sunspot amplitude of 40. Below 40, sea level falls. Above that, it rises.
So let’s apply that relationship to the know sunspot record back to the beginning of the Maunder Minimum and see what it tells us. This is the result:
Figure 1: Back-tested Sea Level from 1645
The figure shows sea level falling through the Maunder Minimum due to the lack of sunspots and then fluctuating in a band about 60 mm wide before increasing rapidly from 1934. It then shows sea level peaking in 2003 before declining 40 mm to 2040.
That is pretty much in agreement with the data from the last 150 years, as per this figure combining coastal tide gauge records to 2001 and the satellite record thereafter:
Figure 2: Sea Level Rise 1850 with a Projection 2040
The glaciers started retreating in 1859, with sea level responding with a rise of 1 mm per annum up to 1930. There was an inflection point in 1930 with the rate of sea level rise almost doubling to 1.9 mm per annum. Sea level also stopped rising from 2003. So the back-tested model and the sea level record are in agreement for at least the last 150 years.
Jevrejeva et al (http://www.psmsl.org/products/reconstructions/2008GL033611.pdf) reconstructed sea level back to 1700:
Figure 3: Global Mean Sea Level Reconstruction since 1700
This longer term reconstruction shows the rise of sea level once the glaciers started retreating. It also shows the acceleration of sea level rise from the early 1930s. As Solanki noted in 2004, the Sun was more active in the second half of the 20th Century than at any time in the previous 8,000 years: http://earthobservatory.nasa.gov/Newsroom/view.php?id=25538 A sea level response to that would be expected.
In summary, the sea level trend fluctuations driven by the internal variability of the ocean-atmosphere coupled system were overprinted by higher solar activity from 1933 to 2003. The period of best fit within that, from 1948 to 1987, has allowed the solar component of sea level rise to be elucidated.
As Solanki noted in 2004, the Sun was more active in the second half of the 20th Century than at any time in the previous 8,000 years
That was very likely not the case at all: http://www.leif.org/research/The%20long-term%20variation%20of%20solar%20activity.pdf
Not certain about sea levels, but the North Atlantic currents variability appear to have solar connection:
http://www.vukcevic.talktalk.net/CET-NAP-SSN.htm
I skimmed one of the two responses. Valid arguments appear to be raised. A response to the response would be responsible. haha
“Can we please stop looking at actual data
and only pay attention to Gore’s movie of Florida drowning?
We all know that sea level will start galloping up any day now,
and it will be too late when it does, so we have to act now, now, now.!”
As sea level continues to decline, those Warmista screams will get even shriller.
They were hoping to decarbonize us before that so they could take credit for the drop.
It’s worse than we thought. Those poor seals.
Can someone please expalin how in an La Nina year the global heat energy of the oceans is rising. Is this another example of data adjustments?
Dr. Archibald, I think your approach in the ‘balance point’ in solar activity as indicated by sunspots has merit to be investigated further. E.M.Smith left this link on a previous post… http://www.geomag.bgs.ac.uk/images/image022.jpg which may correlate even better than merely the sunspot count. Three years ago I did a limited amount of investigation on such a balance point in the sunspot count in relation to global temperatures, not sea level, and came up with a figure of about 47 as the zero point. It’s hard to ignore this relationship for I also found it never seems to fail as far as data is available.
Will keep following your work on this subject.
There are at least four components which impacted sea level in the last 150 years: glacial melt, thermal expansion (ocean heat accumulation), reservoir volume increase, and ground water pumping. Reservoir increases and groundwater pumping appear to have mostly canceled each other out.
Ocean water expansion does not take place due to sunspots, it takes place warming… which is propagated downward from the surface by ‘eddy mixing’. Glaciers melt because of warming, sometimes combined with less winter snowfall.
So it sounds like you are suggesting that a change in the number of sunspots explains all of the observed warming since the little ice age, and with it the observed rise in sea level. It is reasonable that changes in solar activity make some contribution (heck, measured solar intensity and spectrum both change with solar activity!). But I would caution that correlation is not causation. The measured ocean heat content has continued to rise (not stopped!), albeit at a slower rate than pre-2003, but the measured heat content continues to increase, especially for 0-2000 meters depth (http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/). The measured mass of Greenland ice and Antarctic peninsula ice continue to decline. The measured rate of sea level rise has slowed since 2004, but it is still increasing (http://sealevel.colorado.edu/).
.
Let me make a simple prediction: Sea level in 10 years time will for certain be higher than today; almost certainly somewhere between 20 and 35 mm higher.
Sorry mate, but I’m very skeptical about your claims here. Correlation doth not causation imply. The skeptical science articles make some good points.
Suggestion. A post by Leif on the basics of Sun Measurement. i.e. what indicators and metrics are used and the basic meaning behind them. I for one, get so many different opinions on whether or not the sun has been active or not. I’m sure it would come down to which measurements are being used, start point, etc. etc. If it’s already been done, I would truly appreciate being pointed to it.
Cheers
[REPLY: for the thoughts of Dr. Svalgaard, try here. -REP]
Leif Svalgaard says:
April 22, 2012 at 7:22 am
Leif, this is very interesting. The last bout of sea level rise began in 1850. I know that because I just watched a video on it.
http://www.youtube.com/watch?v=lks2hh6LGsE
The presenter could not say why it began in 1850 rather than 1950 or so when man-GHGs were ramping up. I think you just supplied the answer!
David,
How does one derive the annual sun spot number? What is the time resolution of the dataset?
P
@Ian Correlation does not mean causation unless a good operating model of the why it works can be figured out. Then it doesn’t prove anything until all possible results are tested and if the model fails even one test, it is wrong. I’d say a “the sun turned up the boiler so the system responded” model makes more sense as the dominant factor in climate than “a trace back recruited a bunch of friends and burned up the planet” model. Not to say the trace gas might have some SMALL role, just that it isn’t likely dominant.
RobW,
Ocean heat content normally increases a bit due to La Nina and decreases a bit due to el Nino. Changes in globally averaged temperatures due to ENSO are more due to a redistribution of heat than a large net change in heat. During la Nina easterly winds in the tropical pacific are stronger and push warm surface water toward the west (deepening the West Pacific warm pool). This exposes colder water in the Eastern Pacific, which does not lose heat to space as rapidly (because it is cooler), and less heat is transported to higher latitudes, which means it becomes a bit cooler on average. Less loss of heat to space means heat is on net accumulating. In the el Nino phase, the easterly winds drop, and some of the accumulated (deep) warm water in the West Pacific warm pool dissipates, leading to a warmer average surface temperature for the tropical Pacific, especially in the Eastern Pacific, and more heat loss to space…. as well as more transport of warmth from the tropics to higher latitudes. So el Nino leads to slightly higher globally averaged surface temperatures, and a little higher loss of heat to space. The migration of this heat over time can be seen clearly in the following graphic from RSS, where each strong el Nino shows up as a ‘(‘ shaped pattern in temperature anomaly:
http://www.ssmi.com/data/msu/graphics/tlt/plots/MSU_AMSU_Channel_TLT_Time_Lat_v03_3.png
The el Nino warmth starts close to the equator, but slowly (months) migrates to higher latitudes.
Ian H says:
April 22, 2012 at 8:40 am
“Correlation doth not causation imply”
True, but without correlation nothing else matters.
Your argument would carry more weight if you plotted all simulated and observed records on the same chart. By eyeball, your back-testing shows an increase from 1975 to the present of 160mm. The Jevrejeva reord shows an increase over the same period of about 300 mm. Your second graph shows an increase from 1870 to 1930 of 50mm. The Jevrejeva figures show an increase of closer to 100mm.
stevefitzpatrick
You are extrapolating but you may be right.
Presumably we have to get back to the temperatures of 1858 before the glaciers stop melting. Does anyone think it will have cooled that much in the next ten years? Not as far as I can tell. So, how about a counter bet: The glaciers will have stopped melting fifty years from now.
Would be interesting to read the Skeptical Science posts, but I am not allowed there so hard to know if any critique by them is valid.
Paul Westhaver says:
April 22, 2012 at 9:26 am
How does one derive the annual sun spot number?
http://www.leif.org/research/SSN/Clette1.pdf
What is the time resolution of the dataset?
one number per day. the annual sunspot number is the average of all days of the year.
One if the great mistakes in modern science is the quest to explain “why”. History shows that “why” is at best temporary in science. “Why” is better left to religion and philosophy.
Why does a dog chase a rabbit? Why does the rabbit run? Does the rabbit run because the dog is chasing it, or does the dog chase the rabbit because the rabbit is running?
In the end the “why” is really not very important. What is important is this: Will the dog catch the rabbit? The ability to predict that answer is the basis of science. It is what gives science value.
Now, we might try and predict the outcome by studying the dog and rabbit in great detail, and to simulate their motion in computers, and get a completely useless result.
On the other hand, we might count the number of cloudy days in the previous year and find that it provides a very accurate prediction. Why? Well, maybe the number of cloudy days determines vegetation and fat rabbits run slower than lean ones. Or maybe the number of parasites increases in cloudy weather which slows the rabbits in the next season. Or maybe we will never find the reason, or we will think we have found the reason, but we will be wrong.
Why does it matter? If the count of the number of clouds provides an accurate prediction of how likely the dog is to catch the rabbit, that is the value to science.
Interstellar Bill says:
April 22, 2012 at 7:55 am
As sea level continues to decline, those Warmista screams will get even shriller.
They were hoping to decarbonize us before that so they could take credit for the drop.
Too late. The Won took credit for that in 2007.
ferd berple says:
April 22, 2012 at 10:18 am
One if the great mistakes in modern science is the quest to explain “why”.
The ‘why’ is important for understanding.
Why does a dog chase a rabbit?
The dog is hungry and needs to eat
Why does the rabbit run?
It does not like to be eaten
As Solanki noted in 2004, the Sun was more active in the second half of the 20th Century than at any time in the previous 8,000 years
That was very likely not the case at all: http://www.leif.org/research/The%20long-term%20variation%20of%20solar%20activity.pdf
Your case for some fraction of the SSN increase being the result of alterations in the methods of counting is fairly compelling, although I would still worry about the error bars on your proposed corrections (and some of the inconsistencies that you acknowledge). However, all of these corrections apply at most to the sunspot record, and really only to a relatively short century timescale of the sunspot record — over a longer timescale the sunspot records span multiple humans, methods, tools and are difficult to compare to contemporary records on a quantitative basis, are they not?
I’m curious, though, how you extend the conclusion that the 20th century was exceptional in solar activity back over the entire Holocene. Isn’t most of that conclusion derived from completely independent proxies, in particular radioactive proxies? Again, there is a lot of literature and having started to read my way through a lot of the older literature (and observing your name repeatedly as a cited reference:-) I’m certain that you are far more familiar with this literature than I, but the review by Ushokin (2008) has some radioactive proxy derived figures that — if they are reliable, which I am not equipped to judge — fairly unambiguously suggest that the 20th century was indeed exceptional over the Holocene. See e.g. Figure 14 or Figure 17. Is this junk science? If so, how do we know — what is wrong with the reconstructions?
In any event, it is not clear what relevance a correction to the smoothed sunspot number in the 20th century has to the radioactive proxy record on a millennial scale. Of course the 20th century itself is a serious problem in many ways. As noted in the article, a variety of factors from extensive nuclear testing in the late 50s through early 70s (much of it atmospheric) to the release of C_14 depleted carbon into the atmospheric cycle from the burning of aged-out fossil fuels (Suess effect) which is itself confounded by the further release of aged out CO_2 from oceanic stores by global warming. The Be record in that sense seems to be somewhat less easily confounded, but even there we don’t necessarily know what is going on.
Looking at Ushokin and your talk, I remain unconvinced that the level of solar activity in the late 20th century was not unusual over a millennial time scale, although you have certainly cast some doubt on the issue. If nothing else, we live in “interesting times” (possibly in the sense of the Chinese curse). Whether or not the late 20th century was a millennial-scale peak in solar activity in terms of any or all measures of solar activity (where SSN is just one, and as I think you note, not really the best one to use as a proxy in part because it is subject to a fair bit of quantitative or subjective interpretation and hence variation), solar activity is now far down from whatever kind of peak that it was, and promises to go down further still. We are thus at a critical point in theories that attempt to connect solar activity to global climate in contrast to CO_2. If global temperatures hold or decrease in the teeth of inexorably increasing CO_2, it will at the very least be yet another compelling coincidence between secular climate changes and secular changes in solar activity by any or all measures.
We need not be too concerned that such coincidences fail, in and of themselves, to be strongly predictive in either forecast or hindcast, because anybody who thinks that global climate can be explained by simple/logistic one-parameter models is so obviously mistaken that they shouldn’t at this point be taken seriously in the debate. Climate variation is clearly multivariate in its functional form, with non-Markovian effects from a broad range of time scales. So it is entirely plausible that climate is driven directly and indirectly by solar state but that the effect is only strong when other modulators are in the right state or phase (e.g. the decadal oscillations, oceanic state, whatever).
Climate is a hard problem. I was reading the Google Books copy of Solar Variability, Weather and Climate (1982) and was struck by the fact that — 30 years after this review was written — almost nothing has changed. Well, one thing has changed — the book as far as I can tell mentions “CO_2” no more than two times in all of its pages as a possibly significant driver of global climate. But in particular, all of the open questions it cites are still open questions. There are compelling coincidences between solar state and climate, but few of them stand up over very long time scales and all of them are difficult to explain because the problem is multivariate with many negative feedbacks!
There was a lovely paragraph in one of the articles where it was pointed out that in many winters, a heavy snowfall can blanket a geologically signficant fraction of e.g. North America, greatly increasing its albedo. Yet, instead of reflecting enough heat to trigger a return to ice age conditions, negative feedbacks almost instantly kick in, the snow melts, and things return to “normal”. For better or worse, physics addresses the time scale of right now — the sun kicks out a CME and it affects things now (where “now” is on a timescale of hours, days). Snow falls. Hurricanes loom. Magnetic fields shift. Solar constant varies. Albedo bounces up and down as clouds form an ice forms or melts. All of the feedbacks tend to minimize these influences — they change things for a day, a week, but after a month or more the climate system has “forgotten” them due to damping.
Or has it? Somehow there is long time scale modulation that influences climate, where tiny changes in some driver(s) in the multivariate system shifts the climate trajectory around. Simple descriptions fail because the changes are nonlinear and coupled; it isn’t “this”, it is “this, and this, and that, and the other thing too”, and not just now but ten years ago, twenty years ago, fifty or five hundred years ago that contribute.
I continue to be baffled by the really long time scale variability in the Earth’s climate. Is the current ice age (the one that started 3 million years ago) caused by real solar variability, the helium burning cycle that can drop solar output “suddenly” (by geological time standards) and then only slowly build it up again? What causes the bistability between regression to warm phase behavior from the newly dominant cold phase? (Not what MODULATES this bistability, what is its CAUSE.)
Many questions, few answers, and even modern physics aided with satellites and advanced instrumentation cannot overcome the curse of short baselines of truly accurate observations, decades to predict centuries and millennia and million year variations.
rgb
Having recently been on holiday down in Portugal (I was flying … 🙂 ) and enjoyed the most of their surroundings.
Thought I could get away climate nonsense, even got to realize something that AGW-proponents may be difficult to explain.
I was on the south coast of the Algarve area and was entranced by the beach area I was staying at. I took several hour-long walks on the beach, as I lived close by. The first thing I pondered, most of which are unrelated to AGW but not completely, was that the sand by the water contains a very large amount of shell fragments. The idea that came up: “If a handful of sand is made up almost half of shell fragments, how much there is for the entire shoreline?” (About 6 km / 9.6 miles long …) I felt suddenly very small …
Further into the land, I marveled at what a lot of fine pebbles lying on the ground. (The occasional shell fragments were here too …) This is, however, typically after the coastlines, the problem was that this was not at sea level … Ran to my hotel room to pick up my GPS and found that I discovered these little round stones about 48 m / 157 ft above sea level. Then measured by the water and got there -2 m / -6.5 ft at low tide and later 4 m / 13.1 ft at the river. So we have a difference of about 50 m / 164 ft ( +/- tolerance of 12 satellites). Now I felt even smaller than preceding discovery, when I looked out over the Atlantic and realized the amount of water required … Now, this area was not affected by the last ice age, so any significant land elevation can’t be the question. Nor because of continental drift, as the distance between America and Europe increases.
Is 2-8 m /6.5-26 ft sea level rise, because of (fictional) melting of ice, a real problem?
Isn’t there a tax that we could all pay, which would regulate the number of sunspots?