If global warming is going to flood the world, why does the ocean not rise every Spring, when snow melts?

All of the flood the world stuff is just to scare people into paying money to the global warming people.

Well, "flood the world" is a bit of an exaggeration. Though by the end of the century, low lying coastal areas may well be flooded.

But to answer your question--its a matter of sheer quantity. Here's an abstract example, jsut to illustrate (abstract meaning its not the actual figures--I'm using figres for snow melt tha tare greatly exaggerated, just to make the point clear--the actual amount of snow melt is far less).

Lets say 15 million squae miles in the Northern Hemispere have 5 feet of snow on the ground come spring. That's a ridiculous figure--we'd be in another Ice Age if that happened. That convverts to about 10 inches of water. Now--there is more than 150 million square miles of ocean. So, by the time all that snow melted and ran into the ocean, it would raise the water level by all of 1 inch.

Remember, thats a gross exaggeration of how much show there is in a given year. Plus--there's a BIG ofsetting factor--when its spring in the Northern Hemisphere, its Fall in the Southern--so there, sno is falling and taking water out at the same time spring melt in the North is putting it back in--so there's reallly very little difference.

There does tend to be more sno pack in the Northern Hemisphere--there's a lot more land for it to form. But the actual difference due t o seasonal variations in sea level is very, very small--maybe a hundredth of an inch. Not enough to notice.

If this seems odd--and it may, if you live someplacewhere you can look out and see miles and miles of thick snow on the grund--its a good lesson on just how big and complex our panet is. All that snow--and its barely a drop in the gigantic bucket tha tis the world's oceans.

There is also the possibility that the resulting increase in temperatures will create huge melt water discharge from the ice caps and will cause a shut-down of the thermohaline current, which is the deep underwater currents that transfer heat around the oceans. This could cause rapid cooling in the North Hemisphere, which would mean an actually drop in sea-level as ocean water is locked up in growing ice sheets. Of course this is all speculative and there is much debate on the subject, given the many variables to account for. Its a huge topic of discussion and I could go on all day!

The ocean level stays constant because althoughh it may be spring/summer here, it is winter elsewhere. Water evaporates from the ocean, and precipitates in the form of snow somewhere other than here, keeping that amount of water on the surface until it melts in that regions spring. And when it becomes spring there, it becomes winter here.

Plus, not all of the snow melts during a spring. The arctic regions have snow and ice year round, althoug due to global warming, the sea level is rising slowly, but not in phases/levels that you suggested should be happening.

Artic regions do not completely thaw currently, which may happen with global warming. The seasonal variation in ocean water volume is much smaller than the difference between current ocean volume and the maximum that may occur during the upward trend over the next century caused by global warming.

Global warming is not going to flood the world, just low lying coastal areas (best guess is less than 1m above current sea-level by the end of this century). But even 0.5m, with storm surges will be harmful to many areas.

But to answer your question, the sea-level does rise and fall every year in response to accumulating and melting snow & ice. It's on the order of 8 mm. That's imperceptible to the human observer without scientific instrumentation.

Edit:

Dana - it's awfully hard to get the first correct answer posted with people like you and Bob around ;-)

Edit 2:

Tomcat - Your plot has quite a different shape than the 7 peer-reviewed scientifically published studies plotted on the link below. Is it possible there's some bias in yours, or should we simply assume the other 7 were wrong (and NOAA doesn't know that)?

http://www.ncdc.noaa.gov/paleo/globalwarming/image...

Congrats on asking the first new question I've seen here in a long time. Dana's answer covers it.

Tomcat's answer misrepresents the research summarized at the link he provided:

"while instrumental data are not strictly comparable, the rise in 29-year-smoothed global data from NASA GISS from 1935-1992 (with data from 1978 to 2006) is 0.34°C," and that "adding this rise to the 1935 reconstructed value, the MWP peak remains 0.07°C above the end of the 20th-century values, though the difference is not significant."

So the comparison stops in 1992, unable to fully consider (due to the methodology used) significant warming during the past 15 years (clearly a significant omission).

That the Medeival Warm Period may have been 0.07°C warmer than 1992 is statistically insignificant (smaller than the degree of error in the estimation method), but nevertheless warming since 1992 has eclipsed that minor amount so this should put an end to the folks that claim that "it was warmer during the Medeival Warm Period." (whatever that's supposed to mean... I've never seen a skeptic explain what mechanism caused that so they can claim to ahve proven something about anthropogenic global warming).

Yesterday a skeptic complained that the thousands of temperature sites around the world were inadequate to measure global temperatures and warming. Today we have one claiming that 18 historical records from things like pollen counts in ice cores are accurate and adequate to disprove global warming, to an accuracy of 7 hundredths of a degree!

As the author puts it, "It must be emphasized, of course, that this result is based on limited data."

The author's actual conclusion, corrected in 2008 with the help of skeptic poster child Steve McIntyre (an energy exploration industry insider who apparently claims he is not involved in the oil industry) is:

"The main significance of the results here is not the details of every wiggle, which are probably not reliable, but the overall picture of the 2000 year pattern showing the MWP and LIA timing and curve shapes. Future studies need to acquire more and better data to refine this picture."

In other words, according to the author the Medeival Warm Period and the Little Ice Age do seem to show up in the types of recrods he looked at. Did we really need a sceintific study to tell us that? Probably not.

There is nothing offered to explain or disprove anything related to anthropogenic global warming. In fact, one of the author's previous papers is:

"Geologic Methane as a Source for Post-Glacial CO2 Increases: The Hydrocarbon Pump Hypothesis," C. Loehle (Environ. Res. Div., Argonne Nat. Lab., Argonne IL 60439), Geophys. Res. Lett., 20(14), 1415-1418, July 23, 1993.

"Using a simple dynamic model, the hydrocarbon pump, evaluates the hypothesis that historical CO2 levels could have been governed by releases of methane from clathrates and as natural gas. This is likely; confirming evidence is presented."

So his interest in comfirming past temperatures appears to be related to his hypothesis that these sorts of warmings in the past may be related to natural methane releases... and the subsequent greenhouse gas warming.

Add man's greenhouse gasses to that, as we have for the past 150 years, and we're simply reinforcing the earth's demonstrated tendency to warm in response to increased greenhouse gasses.

Global warming is just a natural cycle which has already peaked, it did not flood the world in 900 AD when temperatures were much warmer.

http://www.co2science.org/scripts/CO2ScienceB2C/ar...

Antarctica has been growing colder and colder and accumulating more and more snow. Antarctica and Greenland are the only source that could lead to a significant change in sea level.

http://www.worldclimatereport.com/index.php/2008/0...

EDIT JS.

.07 Hugh? try .3. And do you really think averaging the low temperature with the high temperature at each surface station has any significance to reality as far as the average global temperature is defined. That is what is generally called a kludge, and it is pathetic to see so many alarmists hang their hat on such a shaky piece of data as proof of AGW. The surface temperature of the planet does not provide any proof as far as the cause is concerned.

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The oceans doesn't rise every spring because global warming is a gradual event. It does not happen over night.

It's not going to flood the world. Some low areas may get their feet wet, but that's about all.