Rising sea levels cause major problems as they erode and flood coastlines and as they mix salt water with fresh water. Coastal communities could face significant losses in fresh water supplies as saltwater intrudes inland.
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Dear EarthTalk: With all the talk of rising seas, what could happen to the rivers that flow into the oceans? Will they reverse flow? Will rising seas back up into fresh water lakes? And what happens to our groundwater should saltwater flow backwards into it?
-- Sandy Smith, concerned Michigander
The intrusion of saltwater from the sea into rivers and groundwater is a serious issue, but the threat is not from a reversal of flow, and our far inland lakes and rivers are not expected to be directly affected by the salty water of our oceans. However, the sensitive areas around the edges of our continents, where fresh water meets salt water, are at risk, and greater efforts must be taken to protect them. Some 40 percent of world population lives less than 40 miles (60 kilometers) from the shoreline.
According to the Intergovernmental Panel on Climate Change (IPCC), global average sea levels should rise eight to 34 inches by the year 2100, a much faster pace than the four to 10 inch increase of the past century. Seas rise because of higher global temperatures, melting mountain glaciers and polar ice caps, and other factors. Higher temperatures also cause thermal expansion of ocean water, intensifying the problem.
Rising sea levels cause major problems as they erode and flood coastlines and, yes, as they mix salt water with fresh. A November 2007 article in ScienceDaily posited that coastal communities could face significant losses in fresh water supplies as saltwater intrudes inland. And whereas it had been previously assumed that salty water could only intrude underground as far as it did above ground, new studies show that in some cases salt water can go 50 percent further inland underground than it does above ground.
Salty water invading groundwater can reach not only residential water supplies but intakes for agricultural irrigation and industrial uses, as well. Economic effects include loss of coastal fisheries and other industries, coastal protection costs, and the loss of once-valuable coastal property as people move inland.
Estuaries at the mouths of rivers have in the past handled rising ocean levels. Sediment that accumulates along the edge of an estuary can raise the level of the land as the sea levels rise. And mangrove swamps, which buffer many a coastal zone around the world, flourish in brackish conditions. But because of our preference for living in coastal areas, and our habit of re-engineering our surroundings accordingly, humans make matters worse by preventing natural processes from managing the change. On the coast, we build roads and buildings, and replace natural buffers like mangrove swamps with dikes and bulkheads to control flooding, which make the problem worse by preventing beach sediment from collecting. And as we dam rivers and create reservoirs, we trap the sediment that would naturally flow down to the sea.
In some places, changes are happening. Governments are beginning to restrict or prohibit building in setback zones along the coast where risk of erosion is the greatest. A newer policy of "rolling easements" is also being tried, where developers are allowed to build in restricted zones but will be required to remove the structures if and when they become threatened by erosion. The IPCC recommends more drastic actions, such as creating more marshes and wetlands as buffers against the rising level of the sea, and migrating populations and industry away from coastlines altogether.
CONTACTS: Intergovernmental Panel on Climate Change, www.ipcc.ch.
EarthTalk is produced by E/The Environmental Magazine. GOT AN ENVIRONMENTAL QUESTION? Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; submit it at: www.emagazine.com/earthtalk/thisweek/, or e-mail: earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php.
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36 Comments
Add Comment"Talk of rising seas" is exactly that; talk. I had to laugh the other night while watching the news. Some intrepid reporters were in Hawaii trying desperately to dig up something to justify their Obama related junket, so they invented a story about erosion in Hawaii and how global warming will erode the beaches.
Reply | Report Abuse | Link to thisPeople, look at a map. The Big Island is the only one that is actively growing due to volcanism from the underlying mantle hot spot. The islands to the NW were formed by the same hot spot, and get smaller as you move away from the Big Island, eventually becoming seamounts. It is the fate of them all to erode back into the sea after the hot spot has passed.
This type of story is what happens when reporters misinterpret basic geological processes and attempt to apply some type of AGW related issue to fill some dead air in a news show.
Obviously the earth's water levels have varied widely over its history. The White Cliffs of Dover, Grand Canyon, and Norwegian fjords come to mind. What climatic conditions are necessary to see such extremes?
Reply | Report Abuse | Link to thisGlobal warming?
Reply | Report Abuse | Link to thisJuneau just experienced it second avalanche in less than one year. It took out an electrical tower again, cutting off power to Juneau from the hydroelectric plant. We are on diesel generators for a couple of months again until the tower can be replaced by helicopter.
Juneau has had record snowfall for January. Our summer has been cooler than normal.
Reply | Report Abuse | Link to thisMan can survive global warming. A global cooling or an ice age will prove disasterous for man. Starvation, war, and lack of energy to provide heat and transportation of goods will cause the loss of billions.
Of course, if the rivers reversed themselves, the salmon would not have to work so hard to return upstream to spawn.
Reply | Report Abuse | Link to thisThis article contains at least one huge glaring error. Frankly I'm embarrassed for those at Scientific American. If the polar ice caps melted the sea level would NOT rise at all, in fact it would be lower. That is because ice is more dense than water.
Reply | Report Abuse | Link to thisExperiment:
Fill a glass with ice
Then fill the glass with water as close to the top as possible
Mark the water level on the glass
Let the ice melt
Check water level
The water level will be lower.
This global warming hysteria is getting out of hand!!!
Referring to it as global warming or global cooling is missing the problem. Either one causes climactic change and that's what's causing havoc. Severe storms, extended drought, heavy flooding. There are arguments back and forth about warming or cooling but virtually everyone agrees weather patterns have changed significantly in a relatively short period of time. Regardless of experiments in glass to mimic the Earth, melting ice caps would change salinity and currents which would add to climactic change.
Reply | Report Abuse | Link to thisWhy there is so much variability not only in the IPCC's estimates, but also in the measurements of the last 100 years? Could it be that statistical analysis of numerous measurements isn't very exact? Could the computer models the IPCC relies on be even less accurate?
Reply | Report Abuse | Link to thisAssuming that the IPCC is right and oceans rise as little as 8 inches in the next century and assuming also that the oceans really did rise 10 inches in the last 100 years, doesn't that mean that the rate of rise is decreasing and that it might even reverse? I'm not sure what all the worry is about if the estimates have so much latitude for error.
This is exactly what is happening to many communities in Bangladesh.
Reply | Report Abuse | Link to thisThis is real.
Someguysomewhere is wrong. Ice is less dense than liquid water. That's why is floats. Duh.
Reply | Report Abuse | Link to thisIn response to Someguysomewhere and the ice caps;
Reply | Report Abuse | Link to thisOnly the Arctic ice caps are currently "floating." The Antarctic ice, of which there is much, much more, is mostly over land. So the Arctic ice cap wouldn't affect sea level much, but the Antarctic certainly would.
If only a few of you would read the article... One of the ice caps is floating and (yes) the water level remains the same in that case. The other is not floating. In addition to the obvious problem of ice on Greenland and other glaciers melting in excessive volumes, we also have the thermal expansion issue to consider.
Reply | Report Abuse | Link to thisIn the case of IPCC estimates, they make them with an understanding that there are factors that will affect the outcome, including but not limited to human behavior changes. It doesn't invalidate the estimates to make these allowances.
laurenra7:
Reply | Report Abuse | Link to thisI think you are catching on. The reason that there is so much variability is that the computer models are all just that: models. Small changes in input parameters can have massive changes in output.
I'm just glad that Earth's climate is far more stable and less sensitive to input changes than any of the computer models yet devised, otherwise I wouldn't know whether to put on a snowshoes or a snorkel when I go out to work.
michaelohara:
Reply | Report Abuse | Link to thisI believe that you are wrong wrt to Greenland and Antarctic ice volumes. Do you have any references to support your assertions regarding ice volumes?
Ice is less dense then water and why it floats and takes up more space. but also ice in the caps is large and reaches deep, almost to the ground in many parts. so the melting of the ice would make a positive increase in the water levels. just the ice itslef is not what increases the levels but also drying streams and melting mountain glaciers. you got to think the glaciers on mountains are becoming smaller because the melting point of ice on mountains is rising. most of the climate changes are not these large changes that are the biproduct of most other cases. such as increasing tempature earlier and differing breading patters of bugs and birds. and so on. i tend to think that rising water levels is a least of our worries we can move and still find and obtain other sources of fresh water. there are already plants that can create fresh water from used water from humans.
Reply | Report Abuse | Link to thisAlternate headline: "Could the oceans fall enough to cause cataracts at the mouths of earth's mighty rivers?" As my alternate headline indicates, anything "could" happen. The continental shelf extends seaward from the current shoreline of many continental areas. Significantly lower sea level would steepen the grade of rivers near the current coasts, play havoc with harbors, sewer outfalls, etc. If I were a climate alarmist and big government advocate like Al Gore, should I demand that the government "do something" about it.
Reply | Report Abuse | Link to thisRe: ice melt on Greenland, Antarctica and glaciers, I refer you to a particular source:
Reply | Report Abuse | Link to thishttp://www.realclimate.org/index.php/archives/2006/03/greenland-ice-and-other-glaciers/
This in turn references several scientific studies about the topic. The "realclimate.org" is my favorite source of scientific data on this area.
Re: ice melt on Greenland, Antarctica and glaciers, I refer you to a particular source:
Reply | Report Abuse | Link to thishttp://www.realclimate.org/index.php/archives/2006/03/greenland-ice-and-other-glaciers/
This in turn references several scientific studies about the topic. The "realclimate.org" is my favorite source of scientific data on this area.
The Ice sheets on Greenland and Antarctica are on land. They are not floating on the ocean. When they melt the oceans will rise.
Reply | Report Abuse | Link to thisThe ice sheets on green land and Antarctica are on a land mass. They are not floating on the ocean. When they melt the seas will rise.
Reply | Report Abuse | Link to thisMichaelohara:
Reply | Report Abuse | Link to thisI can see why realclimate .org is a favorite site; it is a pro AGW site. I have visuited it several times and find it's articles politically motivated and underwhelming. Personally, I like to visit climatedebate daily.com which presents articles of both pro and con. It is on that website that you will find several articles referring not just to edge shrinkage of glaciers in Antarctica and Greenland, as reported in realclimate.org, but they also report on the thickening of the total ice sheet, which means that the entire mass of the ice sheet is growing.
The "denier community" prefers to interpret every statement that acknowledges (what the like to call) AGW as "political".
Reply | Report Abuse | Link to thisWhat I really like about "realclimate.org" is their response to questions with references to real scientific, peer-reviewed studies, rather than allusions to some paranoid fantasy - that all the thousands of scientists whose data seems to confirm climate change are in some great conspiracy to pad their collective pockets, impose one-world government and take away our freedoms.
michaelohara:
Reply | Report Abuse | Link to thisAs an aside, several things bother me about the AGW debate. I find the fluidity of the arguments from pro-AGW supporters unsatisfying. As an example, when the Al Gore touted ice core data asproving AGW and then when his conclusions were shown to be not only incorrect, but actually shown to disprove pro-AGW claims, the data and debate about these numbers suddenly slipped from the radar-screen and became a non-issue. Not good science.
When satellite data and temperature ballon data failed to find the expected "footprint" of AGW that the computer models projected, one of the logical course of action would have been to assume that the computer model was somehow incorrect. Instead, the researchers concocted an utterly unbelievable story about how "wind shear" measurements were more accurate at measuring atmospheric temperatures than thermometers and that the temperature increases were really there. Again bad science.
The one that bothers me the most is that the term "Global Warming" has somehow morphed into the much more generalized term "Climate Change". This only makes sense if you look at it from a fund raising perspective as then you can raise funds whether the temperatures go up or down. To me, it smacks of Creationism morphing into "Creation Science" and now re-branding itself as "Intelligent Design". Not just bad science, but the utter lack of science.
michealohara:
Reply | Report Abuse | Link to thisI see that you have shifted to ad hominem attacks. I take this to mean that you have run out of facts.
"ice core data as proving AGW and then when his conclusions were shown to be not only incorrect, but actually shown to disprove pro-AGW claims, the data and debate about these numbers suddenly slipped from the radar-screen and became a non-issue. "
Reply | Report Abuse | Link to this- I hadn't heard that 'ice core data disproves'. Do you have a link?
'satellite data and temperature balloon data failed to find the expected "footprint" of AGW... Instead, the researchers concocted an utterly unbelievable story about how "wind shear" measurements were more accurate'...
I'm familiar with the problems associated with comparing satellite measurements with ground measurements. Do you have a reference for this particular claim of "unbelievability"?
"bothers me the most is that the term "Global Warming" has somehow morphed into the much more generalized term "Climate Change". This only makes sense if you look at it from a fund raising perspective as then you can raise funds whether the temperatures go up or down. To me, it smacks of Creationism morphing into "Creation Science" and now re-branding itself as "Intelligent Design". Not just bad science, but the utter lack of science."
-Creationism (as you know) is not science, and (as been shown in their internal documents) the promoters of "Intelligent Design" were quite deliberate in their attempt to gain support with a less religious term. However, this specific intent to deceive doesn't apply to "warming vs. climate change", in my opinion. The term "global warming" doesn't really connect with the problem, which is that a slight increase in average annual temperatures causes long term changes in weather all over the world. The specific effects will vary depending on the geography. Some zones will get more precipitation others less. The shift is not represented by this morning's thermometer reading or this season's snow fall or hurricane (in spite of un-informed people's tendency to think so). The shift is world wide and long term and therefore it is more appropriate to call it climate change.
No - I have plenty of facts to work with and am only making an observation regarding comments of a sort that I'm sure you have also seen.
Reply | Report Abuse | Link to thisMichaelohara:
Reply | Report Abuse | Link to thisThe following link shows that that CO2 lags temperature increases in ice core data by 800 years, making Al Gore'a assertions impossible.
http://joannenova.com.au/global-warming/ice-core-graph/
As to unbelievability of using wind shear data to measure temperature; well this one just doesn't pass the sniff test. It makes no common sense. Explain to me how using an anemometer and running the data through a computer using a bunch of assumptions is more robust than reading a temperature directly off of a thermometer.
You can call it AGW, Climate Change or whatever you like; the onus is still on you to prove that something is happening. The problem that you face is one of credibility. It appears that you are changing the terms of reference whenever a new hurdle is encountered, and that is exactly the same type of tactic used by Creationists.
And at this stage it is hard to cry "Global Warming" when global temperatures are falling, counter to all IPCC models. I can see the need for re-branding.
An answer to this (frequently used) objection can be found at:
Reply | Report Abuse | Link to thishttp://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/
(it is too long a piece to post here)
The long term trend of world wide average temperature is up.
As for the "wind shear vs. thermometer" issue, this turns out to be a straw man argument. It wasn't actually positioned as "vs", but as "correlated with". See an extensive set of references on it at:
http://www.realclimate.org/index.php/archives/2008/05/tropical-tropopshere-ii/#more-562
michaelohara:
Reply | Report Abuse | Link to thisYou answered neither of the issues I put to you.
The issue are not whether the long term trend is up down or sideways, it is whether people are responsible. Over geological time scales, the Earth's temperature changes are up and down and up and down and up and down and up and down and up and down.
Nowhere are there any data to support that a static temperature environment has ever occurred in Earth's past climate, so it makes the whole concept of "Fighting Climate Change" somewhat megalomaniacal. Besides, who is the IPCC to decide what the "Optimum climate" for the planet is? It makes no sense.
As to your wind shear argument; your response also makes no sense. If you disbelieve thermometer data, then you must have data with which you have a higher level of confidence. Again, please answer the question: Why is measuring wind speed and processing the data through a computer program (packed with assumptions) to derive a temperature more accurate than measuring it directly?
Your correlation argument is also flawed. Correlations are only of interest when when real live measurements are missing. Real measurements trump correlations and computer models not some of the time, but every time.
"The issue are not whether the long term trend is up down or sideways, it is whether people are responsible. "
Reply | Report Abuse | Link to this- Keep track of your own questions (or comments). You mentioned the apparent problem with the data on ice cores and temperature measurements. I pointed to links that most clearly referred to those subjects. You only now bring up the anthropogenic issue. You also said " global temperatures are falling" and I pointed out that the long term trend is up. Some people believe as you do, that this variation is in line with the "normal and natural" variation over geologic time. However, the studies cited by the IPCC and others show that the (well known) forcing effect of human-generated greenhouse gases is the only way to explain the rate of temperature change we have seen since the beginning of the Industrial Revolution.
" Nowhere are there any data to support that a static temperature environment has ever occurred in Earth's past climate"
- This is a straw man argument, since "static" doesn't occur in nature. However, very long periods have gone by with relative stability in climate and temperature. Movements of the sort we have seen in the last 100 years are not explainable as natural cycles.
" who is the IPCC to decide what the "Optimum climate" for the planet is?
It's not the IPCC who decides. The climate we've been experiencing for all of recorded history (and quite a while back from there) is what we and the rest of the living world have adapted to. Certainly, we are capable of surviving in the snow or tropics, if need be. However, what tolerance do the plants and animals we depend on have for changes in rainfall? How do birds adapt to disrupted food supply in their seasonal migrations?
"...wind shear argument; your response also makes no sense. If you disbelieve thermometer data, then you must have data with which you have a higher level of confidence."
- Did you read either of the papers? I don't get that impression from your comment.
You're correct for the North Plar sea ice, but incorrect regarding the South Polar ice cap, which rests almost entirely on land. Melting of this ice would definitely increase sea levels. So too would the Greenland ice cap, which constitutes a significant fraction of the world's fresh water.
Reply | Report Abuse | Link to thisYou're correct for the North Plar sea ice, but incorrect regarding the South Polar ice cap, which rests almost entirely on land. Melting of this ice would definitely increase sea levels. So too would the Greenland ice cap, which constitutes a significant fraction of the world's fresh water.
Reply | Report Abuse | Link to thisFYI, the term "climate change" was introduced into general parlance by George Bush as a way to avoid speaking of "global warming", when he finally had to admit what his own administration's science advisors told him: the planet is indeed warming.
Reply | Report Abuse | Link to thisMichaelohara:
Reply | Report Abuse | Link to thisThe relavant issue is and always has been anthropogenic warming. To suggest that otherwise is misleading. Either people are responsible for warming that may or may not be occuring or we aren't.
As to static temperatures, I'm glad that you agree with me and admit that that static temperatures are not natural. This leaves both of us in the position to also agree, by extension that changes in climate are natural. This is the crux of my argument on why the term "fighting Climate Change" makes no sense. If you want to call it "Fighting Anthropogenic Global Warming" by all means feel free, but be prepared to prove that it is real first.
Your argument wrt to this climate being the optimum and that somehow we bear responsibility should it deviate is cherry picking. Plants and animals do this thing called "Evolution" and they've been very proficient at it for billions of years. I believe that you need to step out your appreciation of time scales from the 30 year average defined by the IPCC and look at things in the thousands or millions or billions of years.
As to wind shear, please stop evading my question: Is anemometer data fed into a computer and run through a computer program more accurate at measuring temperature than a thermometer? Yes or No?
Not sure what all this discussion and worry is about. We all know that global warming is nothing more than a f--king joke anyway. Right? Everyone knows it's just a silly little fabrication in the minds of idiot scientists.
Reply | Report Abuse | Link to thiswhat you wrote makes no sense. Think about it. Most of the ice on earth is not in the water. So try that experiment again but this time stack as much ice as you can until it makes a mountain on top of the glass and then see what happer.
Reply | Report Abuse | Link to this