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32,000 scientists dissent from global-warming “consensus”

Well, I see that this post, made hours ago, has been greeted with deafening silence.



01-07-2008, 08:17
Johnny Canuck2 Johnny Canuck2 is online now
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Quote:
Cloud feedback is currently approx half the size of of the 21st century CO2 temperature effect, but there is no agreement on whether it will cool or warm the climate.
IPCC 2001a:7.2.2.4.1
 
Image above: C02 (Carbon Dioxide) is a critical component of the Earth's atmosphere. Since the beginning of the industrial age, the concentration of CO2 has increased by about 25%, from about 280 parts per million to over 370 parts per million. Scientific studies indicate that CO2 is one of several gases that trap heat near the surface of the Earth. These gases are known as greenhouse gases. Credit: NASA/JPL

CO2 is increasing, and CO2 can cause higher temperatures, but the question is, what will happen in future? The problem, as I've pointed out, is that current models don't adequately take all factors into account in determining how much, if any, the temperature will rise.


I talked about clouds above. Now let's see what the IPCC says about aerosols/particles:

When increases in greenhouse gases only are taken into account in simulating climate change over the last century, most GCMs...produce a greater warming than that observed to date4, unless a lower climate sensitivity than that found in most GCMs is used.

...There is growing evidence that increases in sulphate aerosols are partially counteracting the [warning] due to increases in greenhouse gases.

IPCC 1996a:295
 
Sulphates released into the air/atmosphere might be touted by manufacturers/producers/PR groups as a partial-counteraction to greenhouse gas warming, however, the other factors invovled in production that releases sulphates into the atmosphere/air probably nullifies any miniscule gains.

I think it's wishful thinking, sorry.
 
Well, I see that this post, made hours ago, has been greeted with deafening silence.
This doesn't change anything. Essentially, high-level clouds tend to reflect more of the short-wave radiation of the sun back out into space and less of the longer-wave radation of the earth back to earth, and so tend to cool the planet. low-level thick cloud does the reverse. Therefore, climate modellers are unsure how increased cloud cover will affect warming - and warming does increase cloud cover because it increases evaporation from the oceans. Basically the feedback from clouds could accelerate global warming or it could slow it down. Water vapour is a greenhouse gas, and if the warmer air can hold more water vapour, this feedback could accelerate warming.

It is a complex picture, and modellers build this complexity and uncertainty into their models. Your point is not really a point.
 
our interpretation that observed global warming has been caused mainly by non-CO2 GHGs. Although this interpretation does not alter the desirability of slowing CO2 emissions, it does suggest that it is more practical to slow global warming than is sometimes assumed......

Climate forcing by CO2 is the largest forcing, but it does not dwarf the others. Forcing by CH4 (0.7 W/m2) is half as large as that of CO2 and the total forcing by non-CO2 GHGs (1.4 W/m2) equals that of CO2. Moreover, in comparing forcings due to different activities, note that the fossil fuels producing most of the CO2 are also the main source of atmospheric aerosols, especially sulfates, black carbon, and organic aerosols.

Aerosols cause a climate forcing directly by reflecting sunlight and indirectly by modifying cloud properties. Forcing by atmospheric aerosols is uncertain, but research of the past decade indicates that it is substantial (IPCC 1996). The aerosol forcing that we estimate (4) has the same magnitude (1.4 W/m2) but opposite sign of the CO2 forcing. Fossil fuel use is the main source of both CO2 and aerosols, with land conversion and biomass burning also contributing to both forcings. Although fossil fuels contribute to growth of some of the other GHGs, it follows that the net global climate forcing due to processes that produced CO2 in the past century probably is much less than 1.4 W/m2.

http://www.giss.nasa.gov/research/features/altscenario/
 
This doesn't change anything.

So you say, but to get back to the IPCC, here's what they say:

there is no agreement on whether it will cool or warm the climate.

They agree that the cloud effect will equal half of the CO2 effect in the 21st century, but they can't agree as to whether the effect will be to cool, or warm, the climate.

Surely you can understand the significance of that.

It's like saying, there's a pill you can take, it will either cure you, or kill you.

You say they've built the uncertainty into the models.With respect, you can't build that much uncertainty into a model.


To go a step further with your point, which model do we go with, the one that says clouds will cool, or the one that says it will warm?
 
It's not my point. It's an admission by the IPCC that they don't understand some of the fundamental climate influences.
All global warming scientists will fully admit that they are not sure of everything. Yet despite this, they are sure that anthropogenic global warming is occurring - and there is compelling evidence of this based on the last 50 years. Your quibble is marginal really.
 
All global warming scientists will fully admit that they are not sure of everything. Yet despite this, they are sure that anthropogenic global warming is occurring - and there is compelling evidence of this based on the last 50 years. Your quibble is marginal really.

One of the things the professional contrarians like to do is exploit the uncertainty inherent in the science, along with a few outright lies about what actually is uncertain, to create the illusion that it's *all* uncertain.

The science predicting the ‘greenhouse effect’ has been around a long time and is not in doubt (I’m going to take the phrase ‘among qualified scientists writing in peer reviewed journals … ‘ etc. as read here to save repeating it every paragraph) That we humans have significantly changed the quantities of greenhouse gasses in the atmosphere is not in doubt. We also understand pretty well the additional amount of solar energy these gasses trap in the climate system. We know that the Earth’s surface temperature has warmed significantly since we started burning fossil fuels and destroying forests etc. We can model the recent historical data with enough accuracy to be pretty damn sure that more emissions mean more warming. There is uncertainty to be sure, but not about any of that stuff.

The uncertainty starts to creep in when we try to project the models forward because we're constantly refining the estimates of how sensitive the climate is and when we try to predict consequences. We know we'll cause some warming and we've got an approximate idea how much for any given emissions scenario, but things get fuzzier as you project further forward and as you add more variables (like what we do to control emissions, interactions with other issues like resource depletion, soil erosion etc.)

There are some consequences that are fairly straightforward to predict, for a given rise in temperature. For example, a 0.5-1.5m rise in sea level for the emission scenarios considered by the IPCC is pretty straightforward to predict and hence can be considered high-probability, which also means a couple of hundred million refugees from places like Bangladesh and Egypt are also high probability.

Other changes are triggered at some hard to determine threshold though. For example the irreversable melting of major ice sheets adding several more metres to sea level and the switching off of the Atlantic Thermohaline Circulation are predicted to happen at some point if greenhouse gas levels continue to rise, but we’re not really sure a) what that point is and b) how much more emissions will actually rise given that we don’t yet know the outcome of the struggle between those who want to mitigate the effects now and those who want to keep emitting

The thing is, the science does prove this is happening, but it’s harder to show exactly what the effects will be. Some of them are regional for a start. So it’s not just a matter of uniform warming. It’s also a matter of changes in weather patterns and knock on effects like the extinction of species providing valuable ecosystem services or the wider spread of disease causing species.

So there is a sort of cascade of uncertainty. The basic climate models have some uncertainty in them but we pretty much understand how much. There are questions about how big the effect is, but we already know enough to say that it's going to cause a lot of problems. There are also limitations in computing power that mean the models have to work in units rather larger than Belgium and you need to model much smaller units to get an accurate idea of what effect a given mountain or forest has on local conditions. Once you get down to knock-on effects, like where and when crop failures will occur, or just when Wales becomes malarial, the uncertainty is also magnified by the inherent uncertainty of predicting behaviour in complex natural systems.

In addition, we have some potential problems with very grave impacts (like the major ice sheets melting or some big natural carbon sink turning into a carbon source) where the problem occurs at some undetermined threshold. One might use smoking as a metaphor here. We know it can cause cancer, but we can’t say with confidence just exactly how many cigarettes a given individual needs to smoke to get sick. We can say with confidence that smoking is a bad idea though.
 
That's from an article called, "Global Warming in the 21st Century: An Alternative Scenario" and then adds - in the the part of the quote you omitted to highlight in bold - that "Although this interpretation does not alter the desirability of slowing CO2 emissions, it does suggest that it is more practical to slow global warming than is sometimes assumed"

I'm aware of the title. Since it's positing non CO2 causes to warming, it makes some sense to call it 'an alternative scenario'.

The important part of the quote is this:

our interpretation that observed global warming has been caused mainly by non-CO2 GHGs. Although this interpretation does not alter the desirability of slowing CO2 emissions, it does suggest that it is more practical to slow global warming than is sometimes assumed......

Climate forcing by CO2 is the largest forcing, but it does not dwarf the others. Forcing by CH4 (0.7 W/m2) is half as large as that of CO2 and the total forcing by non-CO2 GHGs (1.4 W/m2) equals that of CO2. Moreover, in comparing forcings due to different activities, note that the fossil fuels producing most of the CO2 are also the main source of atmospheric aerosols, especially sulfates, black carbon, and organic aerosols.
 
All global warming scientists will fully admit that they are not sure of everything. Yet despite this, they are sure that anthropogenic global warming is occurring - and there is compelling evidence of this based on the last 50 years. Your quibble is marginal really.

It's not my quibble. It's IPCC's 'quibble'. Their 'quibble', is that cloud effect equals half of CO2 effect for the 21st century, but they can't agree as to whether that effect will be a cooling effect, or a warming effect.

Some quibble.
 
Yet despite this, they are sure that anthropogenic global warming is occurring - and there is compelling evidence of this based on the last 50 years. .

You're aware that the temperature increase over the last century, has taken place in two 'bundles', one from 1910 - 1945, and the other from 1975 - present?

This isn't consistent with CO2 driven temperature increase, given the steadily rising CO2 levels over the century, and the earlier temperature increase is basically unexplained.
 
Temp over the last century has apparently risen .6C.

But you're aware that this temperature increase is mostly accounted for by an increase in minimum [night] temperatures, as opposed to increased maximum [day] temperatures.

Also, more warming has taken place in winter as opposed to summer, and this rise in winter temperatures has occurred the most in colder locations, and that 3/4 of winter warming has taken place in two relatively confined places: the cold high-pressure systems of Siberia and northwestern North America.

In other words, the 'warming' isn't just hotter days, and more hot days, it's higher nighttime temperatures, higher winter temperatures, with that last one occurring in specific locations, skewing the average.
 
You're aware that the temperature increase over the last century, has taken place in two 'bundles', one from 1910 - 1945, and the other from 1975 - present?
Yes, we are aware of that...
The mid-century cooling appears to have been largely due to a high concentration of sulphate aerosols in the atmosphere
[...]
The clean air acts introduced in Europe and North America reduced emissions of sulphate aerosols. As levels fell in the atmosphere, their cooling effect was soon outweighed by the warming effect of the steadily rising levels of greenhouse gases.
http://environment.newscientist.com/channel/earth/climate-change/dn11639
 
There are some consequences that are fairly straightforward to predict, for a given rise in temperature. For example, a 0.5-1.5m rise in sea level for the emission scenarios considered by the IPCC is pretty straightforward to predict and hence can be considered high-probability, which also means a couple of hundred million refugees from places like Bangladesh and Egypt are also high probability.
But is it?

On the other thread it's claimed that increased temp leads to increased snow fall in the antarctic that is causing the ice sheet to get bigger and as a lot of the antarctic is land and increased snow fall on the land will effectively lower sea levels as you're removing water from the seas by increased evaporation and depositing it on land where it stays.
 
It's not my quibble. It's IPCC's 'quibble'. Their 'quibble', is that cloud effect equals half of CO2 effect for the 21st century, but they can't agree as to whether that effect will be a cooling effect, or a warming effect.

Some quibble.

It's good isn't it.


"The IPCC are right"

"Quote from IPCC report by JC2 and suddenly you're talking out your arse". :D
 
increased snow fall on the land will effectively lower sea levels as you're removing water from the seas by increased evaporation and depositing it on land where it stays.
You are apparantly claiming that the amount of snow deposited in one area will exceed the amount melted from other areas. That is a quantitative claim, but you have provided no numbers. On what basis are you making the claim?
 
You're aware that the temperature increase over the last century, has taken place in two 'bundles', one from 1910 - 1945, and the other from 1975 - present?

This isn't consistent with CO2 driven temperature increase, given the steadily rising CO2 levels over the century, and the earlier temperature increase is basically unexplained.
As I understand it, the lull between '45 and '75 can be explained by aerosol emissions. Since the 1970s, industry has become cleaner, manmade aerosols have been reduced, and this has lessened the global cooling effect of aerosols in the atmosphere.
 
You are apparantly claiming that the amount of snow deposited in one area will exceed the amount melted from other areas. That is a quantitative claim, but you have provided no numbers. On what basis are you making the claim?

I've not said that at all. Trapping snow on land will have a lowering effect on sea levels. Wether that is outweighed by the melting elswhere is to be seen.

You also need to take into account that most of antarctica is land whereas most of the arctic is ocean and it makes no difference how much ice forms or melts in the arctic ocean to sea levels.
 
On the other thread it's claimed that increased temp leads to increased snow fall in the antarctic that is causing the ice sheet to get bigger and as a lot of the antarctic is land and increased snow fall on the land will effectively lower sea levels as you're removing water from the seas by increased evaporation and depositing it on land where it stays.

You are right that increased evaporation could lead to more water being held in the atmosphere at any one time. However, the single biggest factor affecting sea levels is that water expands as it is warmed. Plus, of course, the melting of the continental ice sheets is an important factor.

To me the most convincing evidence comes from the past. Essentially, the picture that emerges from all the evidence, from ice cores, archaeology, palaeontology, genetics, etc, is a simple one - the warmer the planet, the higher the sea level.
 
You also need to take into account that most of antarctica is land whereas most of the arctic is ocean and it makes no difference how much ice forms or melts in the arctic ocean to sea levels.
Are you claiming that the IPCC has not taken it into account?
 
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