New study about the rise in global sea levels

[lomidrevo]

Here is the BBC article, I've read today.
Conclusion from the original study:

... We find it plausible that SLR could exceed 2 m by 2100 for our high-temperature scenario, roughly equivalent to business as usual. This could result in land loss of 1.79 M km2, including critical regions of food production, and displacement of up to 187 million people (38). A SLR of this magnitude would clearly have profound consequences for humanity.

This sounds really alarming to me.

 

[davenn]

This sounds really alarming to me. How many warnings/studies is needed to make politicians (and people in general) listen to the scientists?

You are treading on thin ice with this subject
Generally, the topic of global warming is a forbidden subject

https://www.physicsforums.com/threads/climate-change-global-warming-policy.757267/Dave

 

[lomidrevo]

Thanks Dave, I realize that the topic might be perceived sensitively. But is it a sufficient reason to avoid any discussion?

I have carefully read the Policy, and I believe that I haven't break any rule so far. I have provided a reference to a peer-review journal. Also, I rather submitted the thread under General Discussion, because I haven't come with any technical/scientific question. I am more or less curious about the sociological/psychological aspect of this topic. What particularly I cannot understand is the passivity, lethargy or understatement that I can observe when discussing this topic in my surroundings or when I see politics to deny the threat.

If mentors decide that the thread is not consistent with PF rules and close the discussion, I will accept it, of course.

 

[lomidrevo]

ah, I see the thread was moved to Earth Sciences meanwhile...

 

[fresh_42]

Thanks Dave, I realize that the topic might be perceived sensitively. But is it a sufficient reason to avoid any discussion?

I have carefully read the Policy, and I believe that I haven't break any rule so far. I have provided a reference to a peer-review journal.

Which is fine.

Also, I rather submitted the thread under General Discussion, because I haven't come with any technical/scientific question. I am more or less curious about the sociological/psychological aspect of this topic.

Which is not so fine, because here you open the doors for political statements and anything will be allowed to say, since you cannot reason on psychological effects unless supported by a study.

What particularly I cannot understand is the passivity, lethargy or understatement that I can observe when discussing this topic in my surroundings or when I see politics to deny the threat.

Which again is about human behavior. I cannot understand murder, nevertheless it happens all the time.

If mentors decide that the thread is not consistent with PF rules and close the discussion, I will accept it, of course.

That's why I moved it to earth. We can debate the paper and its implications, but not the politics behind.

 

[lomidrevo]

Thanks @fresh_42, I understand that.

 

[berkeman]

I recently participated in "Hazard Mitigation" studies for two local cities, and since they border the San Francisco Bay, SLR and inundation were part of the studies. One complaint from the folks on the committee (including some representatives from the local Water Boards) was that the studies of SLR in the Bay Area varied quite a bit in their models and results. Still, we looked at various models and used them to bracket the minimum and maximum expected SLR in our area, and used that in our Hazard Mitigation planning (and infrastructure improvement planning).

The USGS website has some good resources, including links to recent studies. We used the 1.0m to 1.9m SLR predictions by 2100 and the USGS Inundation Maps in our planning...
https://www.usgs.gov/centers/werc/s...ce_center_objects=0#qt-science_center_objects

Rising Concerns

Accelerating sea-level rise (SLR), shifting precipitation patterns, and frequency and intensity of storms will affect coastal ecosystems, including salt marshes. Global sea-level rise projections range from 1.0 to 1.9m by 2100 (IPCC 2007; http://www.agu.org/pubs/crossref/2010/2010GL042947.shtml; Vermeer and Rahmstrof 2009), which will result in the loss of salt marshes and their associated wildlife species.

It is the aim of our program to provide site specific sea-level rise predictions to land managers through the intensive collection of field data and innovative predictive modeling. In 2009 and 2010, thousands of elevation and vegetation survey points were collected in salt marsh at 12 sites surrounding San Francisco Bay. The elevation data was synthesized into a continuous elevation model for each site, providing land owners valuable baseline data.

 

[Evo]

To the OP - We humans need to understand that as we come out of the last ice age that melting will continue . Human activity may be accelerating what would happen anyway. We need to realize that just because we planned cities on coasts and like things the way they have been the past couple of generations does not mean that they can or should remain that way. Things always change.

Look at history. Look at all of the cities we are finding under water. Look at the settlements we are finding that were destroyed under glaciers. Look at the sea fossils we are finding at the top of mountains. Where I live now was once a sea. New York City was once under a glacier 2,000 feet high.

We need to accept that we planned and built without understanding the impact that natural climate change would eventually make. Now that it may be speeding up, people are saying that it can't happen?

Anyway, enough of the panic about changes, change will happen. We don't discuss the repercussions of the changes, we only discuss the science if you wish to understand the science behind what is happening.

 

[Evo]

I recently participated in "Hazard Mitigation" studies for two local cities, and since they border the San Francisco Bay, SLR and inundation were part of the studies. One complaint from the folks on the committee (including some representatives from the local Water Boards) was that the studies of SLR in the Bay Area varied quite a bit in their models and results. Still, we looked at various models and used them to bracket the minimum and maximum expected SLR in our area, and used that in our Hazard Mitigation planning (and infrastructure improvement planning).

The USGS website has some good resources, including links to recent studies. We used the 1.0m to 1.9m SLR predictions by 2100 and the USGS Inundation Maps in our planning...
https://www.usgs.gov/centers/werc/s...ce_center_objects=0#qt-science_center_objects

This is the type of common sense things we should be doing to address the changes and how we should adapt.

 

[BillTre]

Look at the settlements we are finding that were destroyed under glaciers.

I don't know of any settlements that have been found that were destroyed under glaciers.

Anyway, enough of the panic about changes, change will happen. We don't discuss the repercussions of the changes, we only discuss the science if you wish to understand the science behind what is happening.

This is the type of common sense things we should be doing to address the changes and how we should adapt.

These two statements seem to be in conflict with each other. Discussing repercussions is preliminary to addressing the changes and how we should adapt to them.
The panic aspect just accentuates the seriousness of the conditions that some people perceive.

The main difference between our current climate crisis and previous changes in climate that did not involve humans is the rate of change. Outside of the Chicxulub impact and some catastrophic events like the formation of the Columbia gorge, most of these changes are thought to have occurred slowly over extended periods of time. The rates of change we are seeing today are on a human's historical time scale, no on a geolgoical time scale that previous big changes are thoguht to have occurred over.
The rapid rate of change is what is seems really threatening to me, since the biological processes that we all depend upon will not be able to keep up with ordinary evolutionary processes. This is added to by non-climate changes that humans have been involved in like, distribution of invasive species and habitat destruction. We therefore may have to make our own changes to organisms to maintain their important ecological functions in the face of these changes. This is an approach that is slowly being developed.

By the way, here is a NY Times story about a town in the mid-west where a similar approach to @berkeman's, in a Republican (or conservative if Republican is too political) area where they want to make changes to deal with ongoing weather issues (has to do with floods), but do not want to get into climate change issues for political reasons. I support this approach because it is currently more feasible in the real (and political) world in which we live. It does not seem to me to be the best approach since it is ignoring certain relevant information that could be useful.

 

[jim mcnamara]

@BillTre - history link https://notalotofpeopleknowthat.wordpress.com/2015/01/25/glacial-advance-during-the-little-ice-age/
The village Chemonix was overrun by glacial advance during the little age age. The link is more like story telling than what we normally post here. But. It is documented history.

Also see : https://en.wikipedia.org/wiki/Little_Ice_Age see section
'Geophysical and social impact by region'

 

[lomidrevo]

We humans need to understand that as we come out of the last ice age that melting will continue .

By "last ice age", do you mean Last Glacial Period (ending around 11,700 years ago)?
I am not sure you are correct with the continual melting since then. Let me quote from this study:

Early Holocene (10,000 to 5000 years ago) warmth is followed by ~0.7°C cooling through the middle to late Holocene (<5000 years ago), culminating in the coolest temperatures of the Holocene during the Little Ice Age, about 200 years ago.

... it suggests a cooling trend lasting over 5000 years in this interglacial period. See also the graph of Global Temperature Anomalies (figure B) taken from the same study:
Mod note: Graphs removed due to paywall violation, see link for graphs.

 

[lomidrevo]

Human activity may be accelerating what would happen anyway.

Yes, maybe. But saying "that would happen anyway" looks to me like we are refusing to take responsibility for that...

We need to realize that just because we planned cities on coasts and like things the way they have been the past couple of generations does not mean that they can or should remain that way. Things always change.

Agreed, the current living style is not sustainable from long-term point of view.

We need to accept that we planned and built without understanding the impact that natural climate change would eventually make.

It is hard to blame humans at the the earlier stages of the industrialization, because they didn't understand the possible consequences of combustion of fossil fuels and other negative activities. No data and no studies were available to predict climate changes. But now, we are in different situation. We have many proofs that currently observed climate changes are caused mainly by human activities. We have also many studies predicting negative scenarios of the further climate evolution (within some uncertainties of course). Despite of that, we do very little to mitigate the consequences. I don't find any excuse for such behavior.

And that annoys me, because in my opinion, humans are capable to take responsibility for their actions and to mitigate the negative impacts of their behavior if there is enough of will-power. Let me provide a positive example: Montreal protocol, which led to the reduction of substances that deplete the atmospheric ozone layer. It is not perfect, but it is working, quote from this report:

The Montreal Protocol is working: There is clear evidence of a decrease in the atmospheric burden of ozonedepleting substances and some early signs of stratospheric ozone recovery

I am not naive, we cannot revert all negative changes which were already done. But we should do our best to not continue in this trend.EDIT:
In the sense of post #5, I will not contribute in this line of discussion anymore. It is truth, it could be never-ending story. I will constrain my contributions only to the scientific papers, and facts.

 

[Evo]

By "last ice age", do you mean Last Glacial Period (ending around 11,700 years ago)?

I am not sure you are correct with the continual melting since then

I should have referred to it as the Holocene for clarity. "The Holocene, starting with abrupt warming 11,700 years ago, resulted in rapid melting of the remaining ice sheets of North America and Europe. The retreat of glaciers altered landscapes in many ways and is currently still acting as a result of climate change. " As I said.

The Holocene ( /ˈhɒləˌsiːn, ˈhoʊ-/)[4][5] is the current geological epoch. It began approximately 11,650 cal years before present, after the last glacial period, which concluded with the Holocene glacial retreat.[6] The Holocene and the preceding Pleistocene[7] together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch.[8] (
An interglacial period is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene interglacial began at the end of the Pleistocene, about 11,700 years ago.)

https://en.wikipedia.org/wiki/Holocene
But, let's both get back to the science of understanding why climate changes. You sounded a bit worried and I wanted you not to be. As Berkeman pointed out, there are level headed people that are using the information to make decisions to mitigate damage and make proper decisions going forward, so yes people are addressing the issues.

 

[Evo]

By "last ice age", do you mean Last Glacial Period (ending around 11,700 years ago)?
I am not sure you are correct with the continual melting since then. Let me quote from this study:

... it suggests a cooling trend lasting over 5000 years in this interglacial period.

That study is from 2013! Sorry you should check your sources to make sure they are not outdated. See my reply to you above.

 

[lomidrevo]

"The Holocene, starting with abrupt warming 11,700 years ago, resulted in rapid melting of the remaining ice sheets of North America and Europe. The retreat of glaciers altered landscapes in many ways and is currently still acting as a result of climate change. " As I said.

This text you have updated to your post #14, does it come from this wikipedia article: Holocen glacial retreat? Just at the beginning there is a warning:

This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)

This article needs additional citations for verification. (July 2011)

This article possibly contains original research. (July 2011)

Could you please provide a more reliable source? On my side, I have requested access to this article and waiting for approval:
The early Holocene sea level rise (DE Smith, S Harrison, CR Firth, JT Jordan)
This figure should come from the article (I will confirm once I get the access):

EDIT:
I have removed the figure, in order to not violate any copyrights. However, the same figure can be seen on this wikipedia link.

It looks like during last 2000 years the sea levels were approximately constant, which suggest that retreat of glaciers during this period was zero, or at least very close to zero. To confirm, it would require more detailed data. Moreover, between 4000 and 3000 years ago, the data suggest that the sea levels might be even decreasing!

 

[lomidrevo]

That study is from 2013! Sorry you should check your sources to make sure they are not outdated. See my reply to you above.

It doesn't mean the study is outdated. As per Info&Metrics of the article, I don't see any significant decreasing trend in the usage of the article since 2014. It seems it is still being frequently quoted. In the wikipedia articles you can find much older references.

 

[lomidrevo]

For future discussions in the topics related to climate changes, is it OK if I use wikipedia articles as a reference?

From the policy/rules mentioned in the post #2:

CC/GW threads in this forum are intended for discussion of the scientific content of well-researched models of weather, climatology, and global warming that have been published in peer-reviewed journals and well-established textbooks.

So I thought that wikipedia is not accepted reference for the CC/GW topics. But as it was already used in this thread, I am wrong apparently. To work with peer-reviewed papers requires much more effort, and many times the papers are not available to public users. So indeed, it might be more easier and quicker to use wiki (although not fully reliable).

Thanks in advance for your feedback!

 

[Evo]

Could you pls provide a more reliable source?

What, an explanation of Holocene being the interglacial warm period we are currently in?

Currently, we are in a warm interglacial that began about 11,000 years ago. The last period of glaciation, which is often informally called the “Ice Age,” peaked about 20,000 years ago. At that time, the world was on average probably about 10°F (5°C) colder than today, and locally as much as 40°F (22°C) colder.

https://geology.utah.gov/map-pub/su.../ice-ages-what-are-they-and-what-causes-them/

It doesn't mean the study is outdated. As per Info&Metrics of the article, I don't see any significant decreasing trend in the usage of the article since 2014. It seems it is still being frequently quoted. In the wikipedia articles you can find much older references.

Your study wasn't relevant to my response, I was addressing the current warm interglacial (now) and you were posting graphics dating back thousands of years, why, I have no idea.

 

[Evo]

For future discussions in the topics related to climate changes, is it OK if I use wikipedia articles as a reference?

From the policy/rules mentioned in the post #2:

So I thought that wikipedia is not accepted reference for the CC/GW topics. But as it was already used in this thread, I am wrong apparently. To work with peer-reviewed papers requires much more effort, and many times the papers are not available to public users. So indeed, it might be more easier and quicker to use wiki (although not fully reliable).

Thanks in advance for your feedback!

I wasn't addressing the climate change science issue of the thread, I was addressing "you" to try to put "you" at ease, and I went on to say to move past the panic as we only address the science, if you wanted to learn.

So the answer is no, if you wish to discuss the science, then please go by the rules.

 

[fresh_42]

I wasn't addressing the climate change science issue of the thread, I was addressing "you" to try to put "you" at ease

I just read in a serious news magazine (https://www.spiegel.de/wissenschaft...oeser-fckw-emissionen-entdeckt-a-1268733.html) that China still produces CFC-11, 32 years after China signed Montreal.

It is difficult to keep calm if you read those news on a regular basis. Three countries are responsible for the vast part of emissions and neither of them actually cares.

 

[Evo]

I just read in a serious news magazine (https://www.spiegel.de/wissenschaft...oeser-fckw-emissionen-entdeckt-a-1268733.html) that China still produces CFC-11, 32 years after China signed Montreal.

It is difficult to keep calm if you read those news on a regular basis. Three countries are responsible for the vast part of emissions and neither of them actually cares.

It's upsetting, but panic and despair won't help, it will just make you sick, level headed action is the best course if you want to get involved.

Anyway, we're still going off topic.

 

[BillTre]

Here is a Science mag news article on the CFC-11 issue.

They seem to be coming from certain areas of the country and not really legally.
To quote the rticle:

“The Chinese have been doing the best they can” to identify and shut down the rogue operations, Rae says. “But regulators have real trouble keeping tabs on what is going on” throughout the country.

Its my feeling that this will probably be corrected.

 

[lomidrevo]

I wasn't addressing the climate change science issue of the thread, I was addressing "you" to try to put "you" at ease, and I went on to say to move past the panic as we only address the science

Evo, I appreciate your concern, but I can assure you that I do not panic. I live around 500 km from the nearest coast, so the increasing sea levels are not the immediate or direct threat to me. What makes me worried (but not panicking yet) are the further consequences of such evolution. With all due respect, this discussion is not making my worries to disappear. But that is OK, it is not the aim of this discussion.

Your study wasn't relevant to my response, I was addressing the current warm interglacial (now) and you were posting graphics dating back thousands of years, why, I have no idea.

Looking back at the previous posts (starting from #8), I think we both have talked about the same period: after last glacial period, which means current interglacial period, or Holocene in another words, i.e. period from 11 700 year ago till now. So I don't understand how were the studies I referred not relevant.

 

[StandardsGuy]

Forecasts have been very wrong before. Instead of panicking about a forecast, please provide some data that shows how much change there has been in the last 50 or 100 years. Be sure to provide data that has uncertainties, so that we all can evaluate the situation together.

 

[NTL2009]

Here is the BBC article, I've read today.
Conclusion from the original study:

This sounds really alarming to me.

I recently participated in "Hazard Mitigation" studies for two local cities, and since they border the San Francisco Bay, SLR and inundation were part of the studies. ...

Based on the ranges in those studies, what were your ""Hazard Mitigation" action items (I'm curious is all)?Related to this, I started a thread about 9 months ago:

https://www.physicsforums.com/threads/42-of-sea-level-rise-due-to-human-water-use.953422/
It was surprising to me that it seems within the realm of possibility that ~ 40% of sea level rise is related to human water use, rather than global warming. Yet, we don't seem to hear of that, or actions to take?

 

[Sherwood Botsford]

Forecasts have been very wrong before. Instead of panicking about a forecast, please provide some data that shows how much change there has been in the last 50 or 100 years. Be sure to provide data that has uncertainties, so that we all can evaluate the situation together.

Truth. The problem with extrapolating from past data is that the same data with uncertainties can fit multiple curves. The advantage of models is that they can give you a basis for 'which curve?' It's still a crap shoot.

In military strategy, you plan not for what you think the opponent will do, but instead plan for what you think he can do. You plan for capability, not intent.

For planning public policy, you plan for worst outcomes, at least to the point where you aren't totally gobsmacked when it happens. FEMA's for Katrina is a good counter example.

Another consideration is the reputation of the forecasters. The IPCC has consistently under reported the situation. Trends have been just beyond their most pessimistic estimates.

Were I in a planning role, I would take the most pessimistic prediction available, and make it 20% worse, and use that as my main scenario. E.g. If now the worst forecast is 6 feet, I would plant for 7.2 to 8 feet SLR.

First tier planning is often cheap. It's a change in policy, change in building codes.

Consider New Orleans. If new construction were on stilts, with the under story used for storage, parking, and a place for the kids to play on a rainy day, then when the evac order comes, the boxes of stuff come upstairs, the car takes people out of town. If the under-space is on a separate subpanel and devices such as furnace and water heater and air conditioner are on the main floor, then the house is habitable as soon as the flood waters recede. Cost: Building code change.

 

[berkeman]

Based on the ranges in those studies, what were your ""Hazard Mitigation" action items (I'm curious is all)?

I think the results of our study/report were two-fold with respect to the rising Bay water levels. First, the results enabled the local cities to apply for additional FEMA funds to increase the height of existing levees, and perhaps adding more of them. Second, it probably will prevent building permits for new home developments in some areas that are expected to be inundated in the future. Good question.

 

[russ_watters]

It was surprising to me that it seems within the realm of possibility that ~ 40% of sea level rise is related to human water use, rather than global warming. Yet, we don't seem to hear of that, or actions to take?

It's probably because that's past sea level rise, not projected future sea level rise.

 

[russ_watters]

Another consideration is the reputation of the forecasters. The IPCC has consistently under reported the situation. Trends have been just beyond their most pessimistic estimates.

Really? I thought we were tracking below their median estimates? Do you have any sources for this?

 

[Vanadium 50]

I'm interested in that too. IIRC, IPCC-1 seems to be a factor of 2 above what we see, and a factor of maybe 4 above what we see given recent CO2 numbers. (It's true that more modern model do a better job of retrodicting)

 

[NTL2009]

... It was surprising to me that it seems within the realm of possibility that ~ 40% of sea level rise is related to human water use, rather than global warming. Yet, we don't seem to hear of that, or actions to take?

It's probably because that's past sea level rise, not projected future sea level rise.

But wouldn't that be continuing to contribute, probably at an even higher rate (more population, more crops being irrigated)? I can't think of any reason it would hit some sort of equilibrium, or stop altogether.

 

[russ_watters]

But wouldn't that be continuing to contribute, probably at an even higher rate (more population, more crops being irrigated)? I can't think of any reason it would hit some sort of equilibrium, or stop altogether.

If I read it correctly the study said it is because of the pumping of groundwater out of the underground aquifers. In the US anyway we've severely depleted them and have started managing them better to avoid running out. Also, population growth is slowing whereas AGW is accelerating. That said, I don't think I saw a prediction about the future.

I'm not very familiar with this issue though.

 

[votingmachine]

To the OP - We humans need to understand that as we come out of the last ice age that melting will continue . Human activity may be accelerating what would happen anyway. We need to realize that just because we planned cities on coasts and like things the way they have been the past couple of generations does not mean that they can or should remain that way. Things always change.

Look at history. Look at all of the cities we are finding under water. Look at the settlements we are finding that were destroyed under glaciers. Look at the sea fossils we are finding at the top of mountains. Where I live now was once a sea. New York City was once under a glacier 2,000 feet high.

We need to accept that we planned and built without understanding the impact that natural climate change would eventually make. Now that it may be speeding up, people are saying that it can't happen?

Anyway, enough of the panic about changes, change will happen. We don't discuss the repercussions of the changes, we only discuss the science if you wish to understand the science behind what is happening.

Your assuming we are along an increasing temperature path currently. As an analogy, if you are in spring and had some fires to warm yourself, the natural temperature the next few weeks is warming from the season change, with the fire contributing little to the months later highest temperature. If you have a fire on the hottest day of the year, you are indeed raising the temperature of that highest temperature.

I find your comment a bit like "in the long run we're all dead". It is true, but hardly useful. I still plan on taking a shower today, even though in 100 years, my walking around stinky is unimportant. I will get my flu vaccine, even though getting sick and dying is largely unimportant historically. I might even bother to eat.

People should not panic about things they cannot change. But they also should not assume they are unimportant and can affect nothing. You may be right ... there may be nothing that humans can do to constrain Earth temperatures within a preferred range. But it certainly looks like we could allow more heat to escape earth, and keep temperatures lower. I'm not sure we are as powerless as we once were.

 

[Evo]

People should not panic about things they cannot change. But they also should not assume they are unimportant and can affect nothing. You may be right ... there may be nothing that humans can do to constrain Earth temperatures within a preferred range. But it certainly looks like we could allow more heat to escape earth, and keep temperatures lower. I'm not sure we are as powerless as we once were.

If you read my responses I said

It's upsetting, but panic and despair won't help, it will just make you sick, level headed action is the best course if you want to get involved.

Anyway, we're still going off topic.

and

This is the type of common sense things we should be doing to address the changes and how we should adapt.

In response to Berkeman's post

I didn't say that there was nothing that could be done, I said that there were sensible ways to approach the issues. Drastic, panic driven responses by humans have a long history of making things worse. Just look at all of the invasive species we introduced in order to control problems that have created much worse issues.

 

[jim hardy]

Before i panicked i'd have to go back and check all the 20th century data to see whether it is based on the 1929 or the 1988 sea level datum and if it's all been adjusted to the latter or did the computer plots just smooth out the step change.
https://www.ngs.noaa.gov/datums/vertical/national-geodetic-vertical-datum-1929.shtmlhttps://www.ngs.noaa.gov/datums/vertical/north-american-vertical-datum-1988.shtml
I started that exercise once but gave up when i read that around the US gulf coast much of apparent water level rise is due instead to land sinking.

I decided geophysics is not my area of expertise
so now i just dismiss anything related to climate that i sense is trying to arouse my emotions. old jm

 

[Steelwolf]

Something that was noted in times past, but the Mississippi delta and the surrounding coastlines have been dropping due to oil extraction for over a century and was rather well documented and pegged to the volume of oil pumped. And places like Jakarta they are having a constant, losing battle to loss of land due to fresh water extraction.

 

[Genava]

It was surprising to me that it seems within the realm of possibility that ~ 40% of sea level rise is related to human water use, rather than global warming. Yet, we don't seem to hear of that, or actions to take?

There is a review with a different conclusion here: https://link.springer.com/content/pdf/10.1007/s10712-016-9399-6.pdf

It seems that the study from Pokhrel et al. is overestimating greatly the contribution from water use.

To the OP - We humans need to understand that as we come out of the last ice age that melting will continue . Human activity may be accelerating what would happen anyway.

Actually, the Holocene temperatures are cooling for 6'000 years. See the following papers:

Pacific Ocean Heat Content During the Past 10,000 Years
Moderator edit: link replaced - original link is copyright violation of paper behind paywall.

Use this link if you have access https://science.sciencemag.org/content/342/6158/617

Deep Heating
Global warming is popularly viewed only as an atmospheric process, when, as shown by marine temperature records covering the last several decades, most heat uptake occurs in the ocean. How did subsurface ocean temperatures vary during past warm and cold intervals? Rosenthal et al. (p. 617) present a temperature record of western equatorial Pacific subsurface and intermediate water masses over the past 10,000 years that shows that heat content varied in step with both northern and southern high-latitude oceans. The findings support the view that the Holocene Thermal Maximum, the Medieval Warm Period, and the Little Ice Age were global events, and they provide a long-term perspective for evaluating the role of ocean heat content in various warming scenarios for the future.
Abstract
Observed increases in ocean heat content (OHC) and temperature are robust indicators of global warming during the past several decades. We used high-resolution proxy records from sediment cores to extend these observations in the Pacific 10,000 years beyond the instrumental record. We show that water masses linked to North Pacific and Antarctic intermediate waters were warmer by 2.1 ± 0.4°C and 1.5 ± 0.4°C, respectively, during the middle Holocene Thermal Maximum than over the past century. Both water masses were ~0.9°C warmer during the Medieval Warm period than during the Little Ice Age and ~0.65° warmer than in recent decades. Although documented changes in global surface temperatures during the Holocene and Common era are relatively small, the concomitant changes in OHC are large.

A Reconstruction of Regional and Global Temperature for the Past 11,300 Years
Moderator edit: link replaced - original link is copyright violation of paper behind paywall.

Use this link if you have access https://science.sciencemag.org/content/339/6124/1198.full

Forecasts have been very wrong before. Instead of panicking about a forecast, please provide some data that shows how much change there has been in the last 50 or 100 years. Be sure to provide data that has uncertainties, so that we all can evaluate the situation together.

There is an article by professor Clint Conrad on the European Geosciences Union's blogs about the accuracy of the previous forecast. Here the link:

How good were the old forecasts of sea level rise?
https://blogs.egu.eu/divisions/gd/2017/09/13/modern-day-sea-level-rise/

 

[MikeeMiracle]

Most of our historic cities are built near the Sea as transport of goods relied on shipping. Movement of goods from ships to the population centers is trivial if the ports if next to the city. Imagine hundred of years ago trying to move enough goods for a city of 1 millions people any distance.

In this day an age we still rely mostly on shipping but there is nothing stopping us building on higher ground just having our ports at sea level as transportation by road/rail back to the population centers is a trivial concern and easily achievable.

Opinion: Sea levels continue to vary, even without human inteference we will eventually have another Ice Age and another period where all the Ice melts. There is no point in trying to fight nature as we can't win, the best we can do is plan around it so that we are less affected when not if that change occurs.

 

[davenn]

In this day an age we still rely mostly on shipping but there is nothing stopping us building on higher ground just having our ports at sea level as transportation by road/rail back to the population centers is a trivial concern and easily achievable.

Not every country has higher ground to retreat to !

And so by your way, all/many of the existing ports become unusable and zillions of $$ rebuilding
new infrastructure that no one ( very few) can really afford to do

 

[Genava]

Sea levels continue to vary, even without human inteference we will eventually have another Ice Age and another period where all the Ice melts. There is no point in trying to fight nature as we can't win, the best we can do is plan around it so that we are less affected when not if that change occurs.

I don't think it is the question the humanity is facing. Climate change and sea level rise will happen anyway (and is happening now), the question is more about how far we should go in the increasing of the phenomenon. Basically we have simply the control of the thermostat and our decisions will define the temperatures of the next decades and centuries.

 

[Evo]

Ok, I don't want to get involved in this thread, but seriously, there is something that needs to be said here, if it hasn't already. Sea level rise is not the same everywhere, it actually can lower in some areas.

Regional effects cause sea levels to increase on some parts of the planet, decrease on others, and even to remain relatively flat in a few places, including, in recent decades, on the California coast.

https://sealevel.nasa.gov/understanding-sea-level/overview
On the misnomer of "global" sea level rise.

Understanding trends in sea level, as well as the relationship between global and local sea level, provides critical information about the impacts of the Earth's climate on our ocean and atmosphere. The image above shows sea level change since 1993 and demonstrates the variation globally.Most people are surprised to learn that, just as the surface of the Earth is not flat, the surface of the ocean is not flat, and that the surface of the sea changes at different rates around the globe. For instance, the absolute water level height is higher along the West Coast of the United States than the East Coast.

You may have heard the term “global sea level,” which refers to the average height of all of the Earth's ocean basins. "Global sea level rise" refers to the increase in the average global sea level trend.

"Local sea level" refers to the height of the water measured along the coast relative to a specific point on land. Tide stations measure local sea level. "Relative sea level trends" reflect changes in local sea level over time. This relative change is the one most critical for many coastal applications, including coastal mapping, marine boundary delineation, coastal zone management, coastal engineering, sustainable habitat restoration design, and the general public enjoying their favorite beach.

https://oceanservice.noaa.gov/facts/globalsl.html

 

[MikeeMiracle]

I was not suggesting that we actively try and relocate everyone, as rightly stated the cost would be stratastophic. Merely that going forward we plan accordingly. Climate change is a global challenge that needs a global response from humanity as a whole. We are all currently silo'd into our own countries and that just does not work for this challenge.

 

[Genava]

Ok, I don't want to get involved in this thread, but seriously, there is something that needs to be said here, if it hasn't already. Sea level rise is not the same everywhere, it actually can lower in some areas.

Yes sure. It is the same problem than the temperature, regional changes are different than global change in average. This is why you need to look at the whole picture, with global data.

"Sea-level data since 1994, taken by the TOPEX and JASON missions, reveal complex changes in sea level that vary across the globe — but the overall trend is a strong increase."
https://www.space.com/30379-nasa-sea-level-rise-model-video.html
Here the visualization from NASA: https://svs.gsfc.nasa.gov/11927

 

[lucas_]

https://edition.cnn.com/2019/06/14/...ZsRyg9ZQBPPBEw6n8Nztejeu5S0F2zSr3WOtB5tKb_sAw
"Greenland lost 2 billion tons of ice this week, which is very unusual"

How bad?

 

[russ_watters]

There is no point in trying to fight nature as we can't win, the best we can do is plan around it so that we are less affected when not if that change occurs.

If you mean we ultimately can't control the climate on a geological time scale, sure, but we are proving we can control it (currently to our detrement) on a generational scale.

And on a day-to-day scale I'd say we spend the majority of our time and resources fighting nature and mostly winning.

 

[lomidrevo]

Opinion: Sea levels continue to vary, even without human inteference we will eventually have another Ice Age and another period where all the Ice melts. There is no point in trying to fight nature as we can't win, the best we can do is plan around it so that we are less affected when not if that change occurs.

The main point is that rapid climate changes that we can observe recently are almost surely driven by human activities, and there is a consensus about that in scientific community, see this article:

Multiple studies published in peer-reviewed scientific journals show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are extremely likely due to human activities.

So the current situation is not about "trying to fight nature". It is the mess that we ourselves have produced that we should fight against. The best we can do (for beginning), is to reduce the emissions of greenhouse gasses (mainly CO2), but we are constantly failing in this task: https://www.iea.org/geco/emissions/

 

[MikeeMiracle]

To clarify, I was not suggesting the current climate issue are not human induced, neither am I stating that we shouldn't try to reduce our impact as much as possible.

I am saying we should start planning for life away from the coasts in addition to doing everything we can to try and reduce human related warming.

Cities have lifespans in the thousands of years. We now have the technology and foresight to appreciate what might happen in those timescales, why not plan accordingly for the long term future?

 

[DrStupid]

I am saying we should start planning for life away from the coasts in addition to doing everything we can to try and reduce human related warming.

It is quite trivial that we need to adapt to the changed climate. However, living away from the coasts would include abandoning entire countries. Nobody knows if something like that is possible at all and if yes, how it would impact the rest of the world. At least Netherland prefers to flee forward and supports floating cities instead.

 

[Frosted Flake]

He who evokes Star Trek in a serious discussion loses.

But...

This discussion smells exactly like ONE Vulcan displaying "intellectual superiority" before a LARGE group of "irrational humans". Not in 'real life', but on TV. FICTIONAL. And not because it makes sense, but in order to illustrate the difference between humans and Vulcans, who understand (sorry, ran out of scare quotes) everything yet seem to care about nothing. Except intellectual superiority. And not because there is any truth behind or reason for it, but rather, as a plot device intended to piss the audience off. I had no idea this forum prohibited discussion of the existential crisis of our times, not nuclear war, no ==> global warming <==. And why? Because ===> it's political <===. As existential crises tend to be...

Oh, for christs sake. (swear, not prayer). I would like a clear headed, Vulcan style explanation of how we are going to solve problems we are not permitted to discuss.

Thank you.