From the University of Southampton:
The tides they are a changin’
Scientists from the University of Southampton have found that ocean tides have changed significantly over the last century at many coastal locations around the world.
Increases in high tide levels and the tidal range were found to have been similar to increases in average sea level at several locations.
The findings of the study are published online in the journal Earth’s Future.
It is well documented that global average sea levels are rising; but tide levels, have generally been considered to have undergone little change on decadal time scales. It is also often presumed that tides will not change much over the next century. As such, long-term changes in tides are not accounted for in many practical applications and scenarios affected by rising sea levels.
The team used a dataset of 220 sea level records from around the world, which ranged in length from 30 to 150 years. By extracting the tide data from the other components of sea level, they were able to isolate changes in 15 tidal levels by looking at different records of high and low waters from the tidal signal.
Lead author Robert Mawdsley, postgraduate research student in Ocean and Earth Science, says: “We find that at many sites around the world significant changes in tidal levels have already occurred, and at some sites the magnitude of the changes are comparable with the increase in global mean sea level through the 20th century.
“For example, increases in average high water of over one millimetre per year have occurred around the world, including Calais in France, Manilla in the Philippines, Wilmington in the USA and Broome in Australia. Increases in mean high water of approximately half a millimetre per year occur at UK sites, such as Heysham, Millport and Port Patrick, all of which are around the Irish Sea. Decreases in mean high water and tidal range occur at many sites around the UK, including Milford Haven, Lowestoft and Ilfracombe. This has potential impacts on energy extraction, such as the tidal lagoon in Swansea Bay.”
“The magnitude and global distribution of changes in tides have been hinted at before,” said co-author Dr Ivan Haigh, Lecturer in Coastal Oceanography. “However, here we have been able to assess changes in different tidal levels, which are used for many practical applications. Tides exert a major influence on the coast, affecting coastal flooding and erosion, navigation, tidal energy extraction, sediment movement and the extent of species in coastal ecosystems. Therefore, the changes we have identified have wider ranging practical and scientific implications, particularly if they increase in the future.”
“The cause of these changes is complex and appears to be a combination of mechanisms from local to global, with the primary driver being the rise in sea level associated with climate change,” says co-author Dr Neil Wells, Associate Professor in Physical Oceanography and Meteorology. “Further research is required to more fully understand the mechanisms causing these changes and to understand how tides might further change in the future.”
###
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
So the ocean levels are increasing 10mm per decade? Did I get that right?
Less than 1/2″ every ten years?
hahahahahahahahhahahahahahahhahahahahhahahahahha
So in 100 years it’s less than 5″. And I would guess there’s no way to tell if there’s some component of the earth/coast subsiding as some of that.
Yet NYC and other places will be inundated according to the chicken littles.
Why do we continue to allow those people to govern the discussions?
They are looking for anything to claim we must go back to the caves for the sake of saving ourselves. Frankly if that’s the choice, I’m going to buy some property inland and set up a few lifeguard towers and docks.
I think that title of the post was based on a misreading by Mr. Watts of a passage from the article. The paper concluded that there WERE significant changes in the tides. The preceding statement that “tide levels, HAVE GENERALLY BEEN CONSIDERED to have undergone little change on decadal time scales” was merely a statement about what prior assumptions had been made regarding tidal changes, and not a conclusion of the paper. In other words, the article claimed that the study contradicted what had previously been assumed or what had “generally been considered.”
That’s not to say that I agree with the premise. I don’t understand how one could assume that sea level is rising, while at the same time not inferring changes in tidal levels that accompany the sea level change. This seems like puffery in the paper – trying to make the result of the study seem to break new ground when it really just confirms the obvious.
As I said, mass and volume (expansion) does not explain sea level rise.
I suppose most are unaware that half of the sea level rise ‘rise’ is due to assumed deepening of the oceans due to the extra mass of the water. Come on man.
ftp://falcon.grdl.noaa.gov/pub/bob/2004nature.pdf
I read recently that there are 38000 bulk carriers (ships) displacing 100,000 thousand tons or more. I wonder how much the displaced water causes sea level to rise?
I would completely discount that except that it never occured to me that groundwater extraction raises sea level. But it does. Best to keep an open mind on this stuff… except for chemtrails…LOL
No. The ocean is too large to show that change. To illustrate.
Do the math if all of those 38,000 ships were 100,000 tons dispalcement, but all very in the Hudson Bay (area 1,200,000 sq kilometers) at one time.
1. How much water would this event cause Hudson Bay “spill” out into the Atlantic Ocean?
2. If that much water caused Hudson Bay to increase in height, how far would it increase to balance?
220 sea level records from around the world, so we back to the idea that one grain of sand from one beach can tell us about all grains of sand from ever beach , because its ‘better than nothing ‘
And it is before we get to the issue with collecting the data , the changes in land use and even geographical changes that makes statements like ‘ increases in average high water of over one millimetre per year have occurred around the world’ hilarious.
One mm accuracy from 150 years ago!
Let me guess they ‘corrected for errors although they have little idea what the errors where in the first place , well such is the nature of magic .
When i read these stories of scientists predicting and pretending to measure the coming inundation of our lands I am reminded of Noah and his ark. We have more problems than Noah he only needed some good cedar from Lebanon, some shittem wood and tar to pitch within and without.
We on the other hand have to forgo all freedoms of choice, live in a bark hut, worship Gaia and only eat vegetables to fix the problem.
What to do if sea levels rise?
Move 10 meters inland.
it is total BS
Datum from only one sea level gauge suffices to inform about sea level change, if that gauge is located on a stable coast, i.e., no isostatic adjustment or subsidence. There are numerous such gauges around the world and these agree that sea level is stable. See NOAA Mean Sea Level Trends for the west coast, Gulf coast, and east coast (south of Chesapeake Bay). These show no trend for past 15-20 years. Satellite SL data is not reliable.
Claims of sea level rise of, say, 1.9 mm or 2.4 mm or 3.1 mm is horsegrunt, as many have so commented here.
A suggestion,
Just as all advanced classes have prerequisites, it might be a good idea to have any researcher interested in writing a paper like this one that claims sub-millimeter accuracy in SL measurement to complete certain prerequisites. I propose the following:
A. Camp out on the shore of the Bay of Fundy for 1 week. (average tides > 14 meters) may accept King Sound as an alternate for SH applicants (> 11 meters)
B. Crew a small craft (less than 35 meter) across the North Atlantic in winter.
C. Work a season as a deck hand on a crab boat in the Bering Sea.
D. Fly at least 3 missions with a Hurricane Hunter aircraft penetrating a Cat 4 or larger storm while recording average sea level to 0.1mm.
E. Demonstrate proficiency at surfing the Oahu North Shore with at least 3 rides on 15 meter waves while simultaneously recording the distance from the board to the wave crest to an accuracy of 0.1mm.
F. Compete as a crew member in the The Antarctica Cup Ocean Race.
G. Demonstrate a proficient understanding of the following: radio altimetry, Laser altimetry, GPS altimetry, plate tectonics including a field trip to Alaska to review the effect of the 1964 earthquake (some areas near Kodiak were permanently raised by 9.1m), tide gauge construction, operation and maintenance including hands-on experience with 19th century equipment, meteorology including the effect of high and low pressure systems on local sea level, orbital mechanics including all applicable effects of lunar cycles, masscons etc.
The survivors will have a new appreciation of the profound difference between their comfy little academic cubbys and the Real World they so glibly profess to measure micro-metrically.
So that’s how Bass Strait got filled up with water just over thousand years back!
Give these people a Peace Prize or an Emmy or something.
I meant to say ten thousand years back, but I homogenised. Or something.
The most commonly quoted 20th century sea level data derived from tide gauges has the average rise rate at about 1.8 mm per year, but the satellite data since 1993 has the rise rate at about 3 mm per year. I have always wondered if those two facts could be reconciled. If they are both true, does that mean there has been an extreme acceleration in sea level rise rates at the tail end of the 20th century? Shouldn’t such an acceleration be apparent in the tide gauge data?
I have taken an honest look at this question, and developed a scheme to analyze the data in search for and answer. For all my searching, the outcome is still somewhat ambiguous. If such an acceleration exists at all, then it is very subtle, not some obvious danger that people in tie-dyed tee shirts are so sure about.
Here is a series of posts on this search…
https://climatesanity.wordpress.com/the-search-for-acceleration/
The unformation is in the errers.
Being from this area, there has been NO sea level rise in hundreds of years. Gosport, Emsworth, Havant, Southampton, Portsmouth, Exeter, Plymouth etc etc etc etc…most of which are very old sea ports. It’s bullcarp!
“The cause of these changes is complex and appears to be a combination of mechanisms from local to global, with the primary driver being the rise in sea level”
‘Holy Climate Change, Batman!!’ … If the ocean level increases, the ocean level at high tide increases!!
Who would have thunk?
———–
Excuse me for asking, but we are dealing with a highly fluid system and basic gravitational forces, right? So other than the nuances of a little sloshing around in the “bath tub” of the world’s oceans, the author’s are simply stating the obvious.
I am thinking this might get an Honorable Mention at the Hampshire County high school science fair competition (they love the socially responsible projects), but not a Ph.D.
“If the ocean level increases, the ocean level at high tide increases!!
Who would have thunk?”
If you read the paper, you would know that this it NOT what they are finding. The RANGE between high tide and low tide is INCREASING (more often than it is decreasing). They are finding the high tides are more often increasing and the low tides are more often decreasing!
Who would have think that actually reading the paper would be more informative than creating strawmen! /sarc
tjfolkerts
It’s all that dark matter impacting the Far Side of the moon. Oh. And we left them lunar landers, the lunar crashers, and few vehicles up on the moon between 1966 and 1978. Gotta be making it heavier.
nothing to worry about – “A new geological study has shown that many low-lying Pacific islands are growing, not sinking”
http://www.bbc.co.uk/news/10222679
The phrase “a drop in a bucket” comes to mind.
An important variable which seems to be missing is Atmospheric Pressure. On a day-to-day basis this can (and often does) amount to a foot or more on tide levels. Without taking it into account it how can projections in terms of single millimetres have any significance?
“Lead author Robert Mawdsley, postgraduate research student in Ocean and Earth Science…”
“Science” by yet another kid with a fresh install of “Marxist World-View v2.0”, trying to be “relevant”.
Wow. Such an amazingly empty ad hom attack based purely on ideology. What specifically in the paper do you disagree with?
Everything. Other commenters have explored the problems quite well. I was just offering an explanation way such an unscientific paper would even be produced. “Marxist World-View v2.0” contains so many invalid equivalencies and fallacious dichotomies as to yield the platform unable to produce rational thought. like it or not, the researcher IS part of the measurement system. Speaking of measurement systems, It is impossible to derive deltas smaller the the measurement uncertainty of the systems used to collect the data.
“Everything [is specifically wrong with the paper].”
I just have to laugh at that. Presumable that would include the font used and reporting results in millimeters instead of meters.
““Marxist World-View v2.0″ contains so many invalid equivalencies and fallacious dichotomies as to yield the platform unable to produce rational thought. “
Then once again, it should be easy to find specific scientific problems, but you instead double down on ad hom political rebuttals. What in the paper is irrational?
“Other commenters have explored the problems quite well. “
Some commenters consider the work so simple and obvious that it should be a high school project; others think it is hopelessly flawed an over-reaching. Most commenters are discussing other things altogether.
Please find even ONE SPECIFIC EXAMPLE where you think the commenter explored the problem quite well.
“It is impossible to derive deltas smaller the the measurement uncertainty of the systems used to collect the data.”
The results were on the order of 1 mm/yr for on the order of 50 years = 50 mm change. While changes from one year to the next might be very hard to detect, trends over the course of several decades can become quite apparent. Sure, it is a small change, that is what the data shows.
I think he got ya.
Again, for anyone actually interested in the original science, the paper is available here: http://onlinelibrary.wiley.com/doi/10.1002/2014EF000282/pdf
* The paper is NOT about global warming.
* The paper is NOT about global sea level rise.
““The cause of these changes is complex and appears to be a combination of mechanisms from local to global, with the primary driver being the rise in sea level associated with climate change,” says co-author Dr Neil Wells, Associate Professor in Physical Oceanography and Meteorology.”
It is not the paper itself that is important, but its utility as a vehicle for generating propaganda. The paper itself is pretty weak tea, high school science project stuff.
But it does claim to use levels historic of accuracy unlikely to exist in reality , while the range of measurements it has is hopelessly limited given the vast size of that its claiming to measure. They effectively do a count of cats in their street then claim they can tell you to high degree of accuracy the total number of cats in the world .
Its nonsense .
Having read the paper I have to disagree about the seal level rise.
The paper is very much about MSL rise, with the necessary addition of a reference to global warming.
I quote ” water column stratification
[Kang et al., 2002;Müller, 2012] (Note: the latter could have a large influence over longer time-scales as
global warming causes widespread changes in the global oceans)”
The whole theme of the paper is to do with changes in MSL the trend in MSL is mentioned all the time.
But do they have the actual data needed to make such a judgement
If I need 1000 points to make a valid judgement but I only have 10 because that is all there is , can I actual make a valid judgement in the first place.
A C Osborn,
But they are referencing LOCAL changes in the mean sea level (MSL) and the LOCAL tidal changes. For each of the 220 locations, they do find the local trends in the local MSL, and explore how that trend might be related to the changes in tides. But they are not determining how the local MSL changes might give a global MSL changes, and they are not determining how global MSL changes relate to specific locations.
The closest they seem to come to studying/discussing global MSL changes are
1) noting that others have reported global MSL are rising
2) noting that more of the 220 locations have rising MSL than falling MSL
Given ANY set of data in the form of Ordered Pairs, i.e. (measurement) vs (time), one can ALWAYS perform a linear regression to find a ‘trend’. The ‘removal’ of the trend, subtracting the values calcuated for each ordinate using the secular ‘trend’ from the original raw data, will leave an ‘adjusted’ data set with only non-secular variations, which Fourier’s Theorem tells us can be *exactly* described as a linear compbination of *periodic* functions.
Any effort to assign significance to any part of this procedure without a rigorous examination of the variances, signal-to-noise ratios, etc. involved in linear regressions (which I have YET to see in any such discussion of the measurable quantities associated with climate) can only lead to self-delusion through pareidolia.