EnviroLink Forum

No, there are a lot of ruins of population centers under the seas now. The civilizations to which they belonged also fell. That seems pretty catastrophic to them by anyone's standard.



That is an assumption which ignores the amount of land we might have used which we cannot now. The Saharah region is one that comes to mind.



Not all of the land, but the most populated regions. The destruction of the primarily island nations?

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With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

Is your position that pre-industrial human activity caused a 3-4 degree temperature rise due to CO2 increases?

Is your position that a similar change of 3-4 degrees c increase will cause large scale coastal flooding?

It seems strange to me that these 2 ideas don't conflict in your head. If our pre-industrial activity has had such a radical impact on the climate then why has our industrial activity which has done so much more to change the atmosphere had such a slight effect? If the previous AGW had such a warming without any catastrophy why would the same again do so much? I accept it's simple thinking but I always smell B.S. when the arguments of the other guy are un-necessarily complex and he starts with the ad-homm.

Do asteroid impacts in the unpopulated wilderness make a sound? For tens of thousands of years, we had but a fraction of the current world population. There's quite a difference in meaning when we talk human catastrophe then vs. now.

My position is irrelevant. My argument is with your analysis.



Admittedly, I threw in some ad hom. but I didn't start the discussion nor is anything I added unnecessarily complex. We have to account for more than one variable input.

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TANG SOO!

The basic idea of AGW is that;

1 Human activity produces CO2 (absolutley)

2 CO2 increases greenhouse warming of the atmosphere (Beyond me, let's assume so). The important question here is to what degree (sensitivity).

3 That increased temperature results in ice melting at the poles which increases sea level. Again how sensitive is this to temperature change being the key question.

If the pre-industrial activity of humans resulted in increased sea levels as a result of increased temperature (3-4 degrees c), as has been suggested,and the increase in sea level is demonstrated by the e3xistance of submerged villages off the coast of lots of places, then the sea level must have been of the order of 4m. That requires a melting of 1.4 million cubic killometers of ice.

Where was the big ice sheet which has disapeared in the last 7,000 years?

Or perhaps the land has a tendancy to move up and down. This could explain the drouned cities.

If humans have changed the climate by pre-industrial CO2 release then what we are doing now should have extreemly obvious results, the sort of thing which is quoted by the more insane alarmist types who speak of boiling seas etc.

The land does move up and down. Sometimes due to the impact of another tectonic plate and sometimes due to the weight of ice being added or removed from it.

The increase in sea level is not only due to less grounded ice, but also thermal expansion.

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With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

You need to go further than that the evidence is clear that human activity has increased the the level of CO2 in the atmosphere by 40% since the late 1700 and we are responsible for CO2 in the atmosphere continuing to rise by about 2 PPM per year.

The reason co2 increases temperature at the surface is simple co2 is opaque to the heat waves that the earth gives off when it tries to cool especially at night. From experiments we know that any doubling of the amount of CO2 in the atmosphere will directly increase the temperature by about 1 deg C + or - 0.2 deg C. We also know that any warming of the atmosphere will lead to knock on effects particularly an increase in the amount of water vapour in the air which is even more opaque to heat trying to escape from the surface. The best estimate is that a doubling of CO2 in the atmosphere will lead to surface warming of about 3 deg C.

The increased sea level is caused by:-
1 Thermal expansion of the ocean, the average depth of the ocean is 3.8 kilometre. A thermal expansion of just 0.01% will lead to a sea level rise of 38 cm or a bit over a foot.
2 The ice on land melting of which the Greenland , the Antarctic and glaciers at lower altitudes, are the major contributors.

I don't accept the 3-4 C figure as been correct although human activity may have been responsible for a small amount of the warming that took place prior to the industrial revolution.
It is however worth noting that for each doubling of the level of CO2 the temperature is expected to rise by the same amount.

From Roman times to about 1870 the amount of sea level rise has not been significant but since that time, the ocean levels rose on average at about 1.7 mm per year up to 1993 based on tide gauge data, after that time we have satellite data which indicates that current rate is about 3.4 mm per year. Note that where the two types of data overlap the results are consistent. This shows that the rate of sea level rise is accelerating.

The answer is yes the result are obvious. The temperature gradient of the atmosphere with height has changed dramatically and in line with that expected from greenhouse gases.
The temperature in the high latitudes has also increased by up 4 deg C which is also expected from increased levels of GHGs, but not from any other possible cause that we are aware of.

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Pollution is not the solution

ice is only a portion of the water that ends up in the oceans. The soil holds a lot of water especially frozen permafrost. The thousands of feet of sandstone formations under much of the continents hold a very large amount of water. These stores (all sub-surface water within the continental masses) are kept out of the oceans due to continued rainfall and glacial melting. Glaciers have melted back a lot and river flows have dropped accordingly. The lack of trees has already caused new desert areas that once were rain forest jungles. Now you are pointing to only 7000 years... it takes time for changes to have their effects. The energy needed to melt ice and frozen ground is several times the amount of energy to take that water from freezing point to boiling point. This is why it takes so long for temperature rise to show up in the form of melting ice and melting permafrost. An everyday example is your freezer staying frozen for a few days after a power outage but once it is melted, it gets hot very fast. The water table has been dropping in many parts of the world but rising in others. As the temperature rises, the weather will start acting like it does over the Sahara desert... the clouds dry up at the coast and run out of water by the time it gets to the desert. Compare this to the Amazon were the clouds continue to be rebuilt by the humidity release of the trees (as much as 5 times by the time the coastal cloud water reaches the Andes Mountains). This is the source of water we have not seen yet... the die-back of trees (or humans cutting them down) causing major water table drops.The do speculate that the movement of some mountains has increased due to being forced up by more water in the oceans which used to be more evenly distributed across continents during ice ages. This could slow the sea rise when the rate of added water to the oceans is small and close the speed that the oceans are sinking and mountains raising. If we change that rate of adding to the oceans, things will be out of balance and all that new rise will not be countered by the lowering effect of the continental drifts. Continental drifts are the cause of earthquakes and tsunamis so any rise in the oceans is going to also be accompanied by tsunamis that wipe out communities without a trace. Basically, don't expect to see skyscrapers under water but rather a shore line with no traces of past cities. The Mediterranean sea is too small for serious tsunamis so coastal cities were just submerged for us to find again but ocean-coast cities of old are never located as they are completely destroyed.

No. From memory it's 3.6 Joules / gramm for vaporisation and 4,2 Joules / gramm per degree c or K.

Melting permafrost or sub-surface water will at most account for 2m of sea level change. That is not enough to cover bronze age settlements. The ground moves up and down all the time.

we are not talking evaporation but melting.

Latent heat of fusion (to melt ice) = 333.55 J/g (heat of fusion of ice) = 333.55 kJ/kg
Sensible heat (moving water from 0 °C to 100 °C) = 4.18 kJ/(kg·K) x 100 °K = 418 kJ/kg

So, I was wrong... the melting energy needed is similar but slightly less then the latent energy to move water from melted to almost boiling. I need to point out my confusion though... the latent heat of vaporization IS several times the sensible heat... 2257 kJ/kg (or 5.4 times 418)

From Wiki;


That fits my very old memory from school of it needing 4.2 Joules per gramm per degree temperature increase but it's a lot higher than I rember for the energy of melting.

Getting back on subject;
"New(2005) evidence suggests that concentrations of CO2 started rising about 8,000 years ago, even though natural trends indicate they should have been dropping."
The average CO2 ppm for over a million years varied from 180 to 280 ppm, averaging 230 ppm. At the start of the use of fossil fuel in large amounts it had risen to near the upper variable, 275 ppm. Since then it has risen to now over 395 ppm. The agricultural plant hardiness zone map from the USDA in a separate thread showed a +5*F change from 1993 to 2012 (add 1/2*F rise from 1980 to 1993).
Human inputs or causes may have lead to perhaps a 40 ppm or more increase in CO2 in thousands of years, but in the past 180 years or so it has gone up geometrically another 120 ppm from human fossil fuel burning, and increasing slash and burn agriculture.
This lead to a stimulated mammal population crash curve during this recent period, and not in the past pre-coal era. In the pre-coal era human causes were an average increase per year of only ~.005 ppm, then once coal (then other fossil fuel) was burned profusely it accelerated to the present ~+3 ppm per year.

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"With every decision, think seven generations ahead of the consequences of your actions" Ute rule of life.
“We do not inherit the earth from our ancestors; we borrow it from our children”
― Chief Seattle

So a 40ppm increase in CO2 caused a 3 degree temperature rise whilst the next 120ppm had less than 1 degree effect?

Or perhaps there are factors other than CO2 involved. Perhaps these other factors are much more important than any gas you have to measure in parts per million.

Like particulate emissions or thermal equilbrium being a long process?



Perhaps not. Without that particular gas measured in ppm, we as a species and all of the other life in the planet would not be here.

http://www.nasa.gov/topics/earth/featur ... ature.html

Without non-condensing greenhouse gases, water vapor and clouds would be unable to provide the feedback mechanisms that amplify the greenhouse effect. The study's results will be published Friday, Oct. 15 in Science.

A companion study led by GISS co-author Gavin Schmidt that has been accepted for publication in the Journal of Geophysical Research shows that carbon dioxide accounts for about 20 percent of the greenhouse effect, water vapor and clouds together account for 75 percent, and minor gases and aerosols make up the remaining five percent. However, it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth’s greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth’s greenhouse effect.

_________________
With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

I never said the ~40 ppm CO2 rise from early humans caused a 3*C temperature rise 8K years ago. Like Wayne said, thermal equilibrium took time. 11K years ago the axis tilt was at a minimum and we entered this interglacial epoch. The complex of events for the next 3 K years included rapid shifts and a return of ice age conditions to northern Europe. The present AGW of +1*C has momentum of another 1/2*C if all CO2 input was stopped now. The AGW is not evenly distributed immediately. It is now +5*C at the north pole, +<3*C at the US latitudes, >1/2*C at the equatorial region, and going to <+2*C at the south pole.
The Earth is getting near maximum axis tilt and orbital elliptic, and was, for 2K years on a steady downward temperature average, toward the ice age return. That combination usually ended the interglacial at 12-14 K years, except once in the last 5 million years where the interglacial was double because the wobble and elliptic are not exactly synced (~23K yrs. for wobble cycle and ~100K years for elliptic cycle). Snow begins to stay in ever larger areas, especially in the Northern Hemisphere, changing the planetary albedo and bringing on ice sheets. Global temperatures average 5*C less.
This time, with the temperature rise induced by human increase of CO2 level at the tundra regions of the north has started geometrically rising methane releases, which will soon not need any more human CO2 input to keep an increasing greenhouse effect in that region, and spreading globally and to the latent heat of the oceans which also have sensitive methane hydrate deposits. Methane hydrate release sensitivity is from only +1 to +2*C. Methane in the atmosphere is 23 times as potent a greenhouse gas as CO2 and breaks down in 15 years to CO2 and water vapor with a net increase in AGW.
Now, most likely to me, the ice age cycle will be broken for two cycles or 200K years.
This is the biggest danger among many facing humanity, and other species. Other persistent pollutants, depleted resources, and the already high extinction rate caused by human habits are other long term problems. The main one facing humanity is the crash of the population around mid century, but after too many HGHGs are input (resulting in a much higher temperature rise well after most people die, and preventing several ice ages and causing the extinction of most species).
We used to joke about plumbers, that all they knew is that s**t runs downhill and the boss pays on Friday.

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"With every decision, think seven generations ahead of the consequences of your actions" Ute rule of life.
“We do not inherit the earth from our ancestors; we borrow it from our children”
― Chief Seattle

Well, if the ice starts to melt it will increase sea level so the methane ice will be at higher pressure making it less able to melt/evaporate/boil.

When the CO2 was at 12% or more in the triasic the earth did not boil. It was hot, fair comment but it did not get silly.

Strange that the plumber and the IPCC agree that this run-away scenario will not happen.