ClimateChange.pdfCan Global Warming Amplify Natural Disasters?

[Mike Davis]

This disaster has come on humanity way too early in our understanding. We don't know what the consequences will be, and we don't know how much CO₂ it will take to set them off.

We are seeing oceanic acidification, and we are seeing a return of the Ozone holes. We are seeing an increase in Methane concentrations, either from formally frozen marshland or from clathrates. Hopefully marshland, although there is anecdotal evidence that some of it is bubbling up from the ocean floor. (http://www.iarc.uaf.edu/highlights/2008/ISSS-08/)

We don't know what any of this will do. Models predict a collapse of the Amazon rainforest and the Boreal forests with about 3°C of warming, but the northern summer sea ice has been hit harder and faster than models showed was possible.

It might be that Australia is being hit harder than most places, but every time I talk to an ecologist, their community of study is being devastated, and southern ocean communities are also suffering invasion by temperate species.

But there are some things that we do know.
We know the warming is greenhouse warming, and we know that it's anthropogenic. We know that human activity has raised atmospheric CO₂ concentrations from the pre-industrial 280ppm to current 385ppm, and we estimate that the climate sensitivity is about 3°C per doubling. HadGEM1 finds 2.8°C per doubling. That would be 1.3°C of warming due to CO₂ increase.

We are seeing anthropogenic warming. As the exhaustive literature review that is the IPCC reports have pointed out (to a 90% CI).

Bored Wombat:
You seem to have the same problem. Claiming to know what you do not know.
There is no verifiable evidence to support your claims.
Estimate= We do not know,We think. IF, Maybe. Pick your meaning.

 

[Mike Davis]

Well realclimate is not out of whack with published research, and the authors are not funded by bodies with a business interest in seeing the debate dragged out.

I believe you failedd to fully research your information. Who is funding Real Climate and what interest would they have in seeing the debate ended. Some one is hosting that web site/backng their opinion.

 

[WeatherRusty]

You seem to have the same problem. Claiming to know what you do not know.
There is no verifiable evidence to support your claims.

Mike,

In the strictest sense, I am not aware of empirical, verifiable evidence that increasing greenhouse gases are in fact applying a positive radiative forcing on the climate system.

I don't believe it possible to determine an exact future climate sensitivity to the initial forcing of increasing anthropogenic greenhouse gases given the complexity of the system.

http://en.wikipedia.org/wiki/Complex_system"

Trying to apply a strict adherence to the deterministic scientific method will not get you far in understanding complex systems such as weather and climate. You don't necessarily find one for one cause and effect relationships.

These complex systems are better understood in terms of probability with ranges of diversity and variability which entail uncertainty. We can be very reasonably confident that adding long sequestered carbon to the atmosphere/oceans will lead to warming in much the same way we believe tobacco use to cause cancer.

 

[Skyhunter]

Bored Wombat:
You seem to have the same problem. Claiming to know what you do not know.
There is no verifiable evidence to support your claims.
Estimate= We do not know,We think. IF, Maybe. Pick your meaning.

Mike,

There is no need to attack Wombat for his opinion.

If you disagree then state specifically what you disagree with and offer evidence to support your alternate claim. Telling Wombat he has a problem is a personal attack.

 

[Mike Davis]

Well!
Lets put it this way:
If a person claims to know what the future holds with 90% certanty And uses words like ESTEMATE as proof or models as proof.
In my opinion anyone claiming there is enough evidence to proclaim disaster has a problem with reality.
Weather Rusty: I agree with the statement that there is not enough evidence to proclaim anything one way or another.
Continuing to proclaim disaster is approching will only back fire on the whole scientific comunity!

 

[sirchasm]

These complex systems are better understood in terms of probability with ranges of diversity and variability which entail uncertainty. We can be very reasonable confident that adding long sequestered carbon to the atmosphere/oceans will lead to warming in much the same way we believe tobacco use to cause cancer.

But, there is strong evidence the ice sheets are changing - shelves are shrinking. Ice-sheet dynamics is complex but we have a general view, based on solid physics. It goes roughly: "if you warm ice, it will melt"

The denialist stance is based on an exceptionalist argument, which might be summarised: "the last time sea-levels were 70ft higher was 400,000 years ago, except 1000 years is a long time, except there's a 1/400 chance = 1000 years they will be 70ft higher again, except we don't really know, so I can except our activity contributing to this happening, except we don't really know, except..., ..., except, etc"

 

[Skyhunter]

Well!
Lets put it this way:
If a person claims to know what the future holds with 90% certanty And uses words like ESTEMATE as proof or models as proof.

Wombat did not use the word proof once in his post.

And where are you pulling the 90% from?

In my opinion anyone claiming there is enough evidence to proclaim disaster has a problem with reality.

The operative word in this sentence is opinion. Your opinion is not reality. Therefore you are being terribly presumptuous as well as rude.

Weather Rusty: I agree with the statement that there is not enough evidence to proclaim anything one way or another.
Continuing to proclaim disaster is approching will only back fire on the whole scientific comunity!

I don't believe you actually agree with Rusty.

It is my opinion that you are only reading the words that fit your bias.

 

[WeatherRusty]

Weather Rusty: I agree with the statement that there is not enough evidence to proclaim anything one way or another.

That is not quit what I meant to imply!

There may not be incontrovertible evidence but the evidence in support of AGW is numerous.

Atmospheric CO2 has increased due to human activities. Not much question about that.

Atmospheric CO2 is without a doubt a significant absorber of infrared radiation contributing approximately 12% to the global greenhouse effect. A doubling of the stuff will impose an additional positive radiative forcing of 3.7W/m^ within the troposphere.

The atmospheric greenhouse effect is responsible for about 33C/50F degrees of surface warming beyond that of direct solar insolation alone. The Earth's surface receives nearly twice the warming radiation from it's own atmosphere than it does directly from the Sun.

Direct insolation has not increased over the past 50 years, the very period of greatest warming.

Water vapor, the principle greenhouse gas, is primarily dependent on preexistent temperature for it's atmospheric mixing ratio. It acts as a feedback to varying temperature. It cannot by itself alter climate.

Coupled atmosphere/ocean phenomena such as the PDO, ENSO and AMO etc. are examples of internal climate variability rather than external forcings and cancel out over their positive and negative phases.

You can always play the uncertainty card and claim small climate sensitivity to initial warming by poorly documented cloud albedo effects and clear sky upper air drying (Linzden & Spencer). You can assert without strong confirmation a connection between galactic cosmic rays and low level cloud formation (Svensmark). These ideas and others should not be disregarded out of hand, however they lack supportive evidence to a much larger degree than CO2's known physical qualities and the importance of radiative forcing on the climate system.

Because of the great complexity of the climate system, we should regard AGW to be real by strong inference, if not positive proof. If science is forced to prove to a certainty the emergent qualities of such a complex system, we will be waiting for a long, long time and be effectively paralyzed to act.

 

[Mike Davis]

I guess I misunderstood what you all were trying to convey. I thought some realized that not enough reliable information is available to make any predictions/forcasts/projections/scenerios regarding future climate. I misunderstood and thought some realized that we do not have enough reliable historic evidence to understand what are the causes of climate variability. I thought some would understand the issue of model uncertainties.
I wish you all luck in your world of fiction.

 

[WeatherRusty]

I thought some realized that not enough reliable information is available to make any predictions/forcasts/projections/scenerios regarding future climate.

Understanding of the climate system is not such that precise and accurate predictions can be made, but that is not to say we know so little as to preclude an expectation of a general trend toward warming over time. I can not at this time inform you of your weather forecast at your location for July 4, 2009, but if you live in the northern temperate zone I can with great confidence tell you that day will likely be warmer than today. The month of July will average warmer than February.

We know why that is. It involves solar radiation distribution over Earth's surface. The science of AGW is all about radiative forcing of climate. Skeptics claim uncertainty primarily associated with feedbacks, claiming they are weakly positive or even negative. Yet temperatures have varied greatly in the past, at least 10C and feedbacks were strongly responsible for the lions share of the temperature change. How did climate change so severely in the past if feedbacks were not strongly positive and climate sensitivity high?

 

[mheslep]

...Atmospheric CO2 has increased due to human activities. Not much question about that.

Atmospheric CO2 is without a doubt a significant absorber of infrared radiation contributing approximately 12% to the global greenhouse effect.

Do you have source for that 12%? I read numbers as low as 2% (Lindzen IIRC).

A doubling of the stuff will impose an additional positive radiative forcing of 3.7W/m^ within the troposphere.

Careful. As stated this implies that is all directly from CO2. The ~4W/m^2 figure is for CO2 and ALL other sources combined, including feedbacks. Radiative forcing directly from increased retention of longwave radiation due to CO2 alone is much less:
http://www.ipcc.ch/graphics/graphics/syr/fig2-3.jpg

...The Earth's surface receives nearly twice the warming radiation from it's own atmosphere than it does directly from the Sun.

Huh? 1266 W/m^2 space, nearly 1000 W/m^2 insolation received at the surface, low latitudes. Where is there room for 'twice' more radiation from the atmosphere?

Direct insolation has not increased over the past 50 years, the very period of greatest warming.

I've always wondered over what part of the EM spectrum solar radiation is measured.

Coupled atmosphere/ocean phenomena such as the PDO, ENSO and AMO etc. are examples of internal climate variability rather than external forcings and cancel out over their positive and negative phases.

I don't believe you can isolate the two (internal/external) in a useful way. PDO, AMO, etc can temporarily change factors (i.e. ice and surface albedo) that increase or reduce the heat radiated away from the planet, i.e., which also makes them 'external' forcings (as you use the term), and its not clear to me that the peaks and troughs of the oscillations always 'cancel' each other out rather than having some net radiative effect over time, in particular when they operate over different average temperatures.

 

[WeatherRusty]

Huh? 1266 W/m^2 space, nearly 1000 W/m^2 insolation received at the surface, low latitudes. Where is there room for 'twice' more radiation from the atmosphere?

Averaged globally, day & night, the Earth's receives 342W/m^2 direct solar radiation.
168W/m^2 is absorbed by the surface.

The atmosphere radiates as integrated globally, day and night 324W/m^2 to be absorbed by the surface.

http://asd-www.larc.nasa.gov/SCOOL/energy_budget.html"

 

[WeatherRusty]

When these gases are ranked by their contribution to the greenhouse effect, the most important are:

* water vapor, which contributes 36–70%
* carbon dioxide, which contributes 9–26%
* methane, which contributes 4–9%
* ozone, which contributes 3–7%


Major Greenhouse Gas % of Greenhouse Effect
Water vapor
36% to 66%
Water vapor & Cloud droplets
66% to 85%
Carbon dioxide
9% to 26%
Methane
4% to 9%
Ozone
3% to 7%

Looking for a more convincing source but: http://www.windows.ucar.edu/tour/link=/earth/climate/greenhouse_effect_gases.html&edu=high"

 

[WeatherRusty]

The forcing of a doubling of CO2 is 3.7W/m^2 as measured from the tropopause before feedbacks and should with everything else remaining equal result in a 1.2C increase in global average temp at the surface. Climate sensitivity to that forcing is what is more at issue. How feedbacks react is where most of the uncertainty lies, but is generally considered to about double the effect resulting in ~3C degrees.

 

[mheslep]

Averaged globally, day & night, the Earth's receives 342W/m^2 direct solar radiation.
168W/m^2 is absorbed by the surface.

The atmosphere radiates as integrated globally, day and night 324W/m^2 to be absorbed by the surface.

http://asd-www.larc.nasa.gov/SCOOL/energy_budget.html"

Alright, averaged night and day.

 

[mheslep]

The forcing of a doubling of CO2 is 3.7W/m^2 as measured from the tropopause before feedbacks and should with everything else remaining equal result in a 1.2C increase in global average temp at the surface...

Yes, sorry, I was not careful here - missed the doubling.

 

[John Creighto]

Do you have source for that 12%? I read numbers as low as 2% (Lindzen IIRC).

Here's a good visual:

http://brneurosci.org/spectra.png
http://brneurosci.org/co2.html

 

[mheslep]

Here's a good visual:

http://brneurosci.org/spectra.png
http://brneurosci.org/co2.html

Yes, ok, and then CO2 is ~380ppm, 0.04%, and H2O goes up to maybe 3% at saturation, and we're still not accounting for clouds. It is not clear to me how to account for both the absorption bands and the concentrations.

 

[John Creighto]

Yes, ok, and then CO2 is ~380ppm, 0.04%, and H2O goes up to maybe 3% at saturation, and we're still not accounting for clouds. It is not clear to me how to account for both the absorption bands and the concentrations.

For a rough estimate multiply the fraction transmitted for each gas. Of course it should be obvious from this that you can't really say what percentage each gas contributes to the absorptivity. However, I guess you could still define a percentage of the back radiation that comes from each gas.

 

[Skyhunter]

Yes, ok, and then CO2 is ~380ppm, 0.04%, and H2O goes up to maybe 3% at saturation, and we're still not accounting for clouds.

Clouds are not water vapor and their sign could be positive or negative. Water vapor is rare in the upper troposphere. Carbon dioxide has a greater absorption potential at higher altitudes.

 

[mheslep]

Clouds are not water vapor and their sign could be positive or negative. Water vapor is rare in the upper troposphere. Carbon dioxide has a greater absorption potential at higher altitudes.

Yes I understand, first clause was on water vapor, 2nd clause on clouds.

 

[Skyhunter]

Yes I understand, first clause was on water vapor, 2nd clause on clouds.

Clouds are opaque to almost all incoming and outgoing radiation.

Here is a better visual for atmospheric transmittance.

http://www.globalwarmingart.com/wiki/Image:Atmospheric_Transmission_png

 

[Bored Wombat]

Carbon dioxide has a greater absorption potential at higher altitudes.

Why's that?

You get greatest pressure broadening of the absorbance spectrum at lower altitudes.

 

[Skyhunter]

Why's that?

You get greatest pressure broadening of the absorbance spectrum at lower altitudes.

Because at lower altitudes water vapor dominates the absorption spectrum. There is only a small part of the CO² spectrum that is not saturated by water vapor. Higher up where WV is rare there are more available photons of the proper energy to be absorbed.

 

[Bored Wombat]

Because at lower altitudes water vapor dominates the absorption spectrum. There is only a small part of the CO² spectrum that is not saturated by water vapor. Higher up where WV is rare there are more available photons of the proper energy to be absorbed.

So on days or regions with low humidity, the CO₂ at lower altitudes dominates?

Surely radiant energy from the Earth would have to pass through the humid zone anyway to get to the upper atmosphere.

 

[WeatherRusty]

Study this page carefully.

http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/irwindows.html"

You will note that water vapor and CO2 block infrared transmission through the lower atmosphere by absorption at discreet wavelengths to extinction. This is Sky Transparency.

You will also note that the atmosphere radiates in the infrared because of it's particular temperature profile according to Planck's Law. This thermal radiation is Sky Brightness in Infrared.

 

[Skyhunter]

So on days or regions with low humidity, the CO₂ at lower altitudes dominates?

In the absense of water vapor CO² accounts for 36% of a the GE.

Surely radiant energy from the Earth would have to pass through the humid zone anyway to get to the upper atmosphere.

The bulk of what is absorbed by the upper atmosphere is emitted from the atmosphere itself.

 

[WeatherRusty]

The bulk of what is absorbed by the upper atmosphere is emitted from the atmosphere itself.

Correct. In infrared (excluding the IR windows) the surface of the Earth is invisible from the top of the absorbing region. The "view" is clouded both up from the surface and downward toward the surface. The region is opaque to IR. Energy in the form of IR radiation is emitted and absorbed countless times within the absorbing layer. Every new emission is a new photon produced within the gaseous envelope itself directed on average in all directions and carrying no information pertaining to the surface where the energy originated.

 

[John Creighto]

For the physics of global warming this like looks good:

http://patarnott.com/pdf/IRemissionTheory.pdf

which I got from here:
http://patarnott.com/atms749/