EnviroLink Forum

In the way the statement was framed, yes there was 97% agreement amongst 50% peer reviewed climate scientists.


http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf

1. When compared with pre-1800s
levels,
do you think that mean global temperatures
have generally risen, fallen, or
remained relatively constant?
2. Do you think human activity is a significant
contributing factor in changing
mean global temperatures?


Results show that overall, 90% of participants
answered “risen” to question 1
and 82% answered yes to question 2. In
general, as the level of active research
and specialization in climate science
increases, so does agreement with the two
primary questions (Figure 1). In our survey,
the most specialized and knowledgeable
respondents (with regard to climate
change) are those who listed climate science
as their area of expertise and who
also have published more than 50% of
their recent peer-reviewed
papers on the
subject of climate change (79 individuals
in total). Of these specialists, 96.2%
(76 of 79) answered “risen” to question 1
and 97.4% (75 of 77) answered yes to question
2.

http://en.wikipedia.org/wiki/Climate_sensitivity

delta T = lamda * RF

delta T = change in earth's surface temperature

lamda = climate sensitivity

RF = radiative forcing

For a doubling of co2 we get 1*C without climate feedbacks RF would be 3.7watts/M*2

Taking from wiki here with feedbacks included there is a consensus that 3*C +-1.5*C then would give
lamda= delta T/RF

lamda = 1.5*C/(3.7w/m*2) = .4*C/(w/M*2)
lamda = 3.0*C/(3.7w/m*2) = .8*C/(w/M*2)
lamda = 4.5*C/(3.7w/m*2) = 1.2*C/(w/M*2)

http://en.wikipedia.org/wiki/Climate_se ... l-age_data

If Earth were to experience an equilibrium temperature change of ΔT (°C) due to a sustained forcing of ΔF (W/m2), then one might say that x/(ΔT) = (3.7 W/m2)/(ΔF), i.e. that x = ΔT * (3.7 W/m2)/ΔF

x = ΔT * (3.7 W/m2)/ΔF

ΔT= .8*C = industrial change in temperature since 1750
ΔF= 1.6w/M*2 after taking into account all the different forcings
H = -.2w/M*2 ocean heat uptake

x = ΔT times (3.7 W/m2)/(ΔF-H)

x = .8*C times (3.7 W/m2)/ (1.6W/m2 -.2W/m2) = 2.1*C

Rahmstorf qualified that there was a great deal of uncertainty in these calculations.

Here is the low ball estimate and he is on the payroll of the oil companies with the co2 site

Other experimental estimates

Idso (1998)[21] calculated based on eight natural experiments a λ of 0.1 °C/(Wm−2) resulting in a climate sensitivity of only 0.4 °C for a doubling of the concentration of CO2 in the atmosphere.


http://earthsky.org/earth/heartland-ins ... enial-gate


Documents surreptitiously obtained from the Heartland Institute and then leaked to public websites in February 2012 disclosed the names of a number of donors to the institute – including the Charles G. Koch Charitable Foundation, tobacco companies Altria and Reynolds American, drug firms GlaxoSmithKline, Pfizer and Eli Lilly, Microsoft, liquor companies, and an anonymous donor who has given $13 million over the past five years – as well as the recipients of the institute’s largesse – climate skeptics including Craig Idso, physicist Fred Singer, Robert Carter, and Anthony Watts. The Heartland Institute maintains that the documents, which were first published on Desmogblog, were fraudulently acquired, and that the particular document detailing the alleged plans to influence school curricula is a forgery.

There is only one negative feedback that has been clearly demonstrated and that is the simple fact that objects at higher temperatures radiate very much faster than those at lower temperatures. In other words the hotter something is the faster it cools down. For example you might want to claim that clouds are a negative feedback, but if we look at Venus which has a 100% more cloud cover, and lower a total for incoming radiation, yet it has a much higher surface temperature than earth.

On the other hand there are numerous positive feedbacks. Particularly that higher temperatures increase the amount of water vapour in the air (7% per 1 deg C) which is again a stronger GHG than CO2. Loss of ice cover over the sea changes the surface from reflecting 90% of the radiation to absorbing in excess of 80%.
Higher temperatures of themselves also increase the amount of carbon based GHGs in the atmosphere EG forest fires, increased methane emission's from tundra and peat areas




No you don't get it that just because the size of something is small does not mean that it can't have a big impact for example a catalyst can completely change the outcome and speed of chemical reactions even though they may be present in very small quantities. On the other side of the coin nitrogen has fairly minor effects on the atmosphere despite being the largest component.

In the case of your cell phones if the heat from them is not allowed to escape the room, the temperature will rise, but the reality is this becomes harder and harder as the temperature rises. As a simpler example buildings have been designed which are heated only by the heat from the occupants.






The figure is 1.3 deg C based on sensitivity of 3 deg C.
The equivalent of 0.4 Deg C ended up in the oceans and 0.9 Deg C in the atmosphere. Bear in mind that the ocean increase in temperature is in fact much less as water has a much higher heat capacity than air. Just be patient we are getting there.

If you do not accept that level of sensitivity then how are you going to explain the ice ages of the last 4 million years or for that matter how the earth was much hotter than today, 100s of millions of years ago, despite the fact that the sun was not emitting as much heat as today.


Ah you don't understand that the warming caused by other GHGs in the atmosphere such as methane and NO2 etc are balanced by the aerosol cooling effect.




The southern hemisphere is warming faster than the northern hemisphere when you take into account the deference in proportions of land and sea.
The temperature of a city is strongly influenced by local weather conditions ie how windy it is and its latitude. The major effect of Aerosols is to increase cloud cover and to make clouds more reflective therefore it is reasonable to assume that the effect lasts several days by which time the airmass may well have gone 1/4 of the way round the globe.




There is nothing wrong with being skeptical but it must be tempered by the current state of our knowledge and the level of understanding of those people making various claims.
I am not wrong or right I simple accept that the vast majority of climate scientists have made a convincing case that the current and future levels of GHGs will lead to higher surface temperatures. Whereas those who claim this is not the case have not, and is best summed up by the saying " The devil can quote scripture for his own purposes"

_________________
Pollution is not the solution

Most of the studies you posted do not even cover the timeframe of the MWP...

A new study authored by Dr. Jan Esper and colleagues throws the whole MWP did not exist/was a regional event junk under the bus.

Esper et. al 2012 documented that the Medieval Warm Period and the Roman Warm Period have both been underestimated in previous studies, and according to the author, Dr. Jan Esper:

“Such findings are also significant with regard to climate policy, as they will influence the way today’s climate changes are seen in context of historical warm periods.”

They also find a cooling of -0.3 Degrees C per millenia:

Their findings demonstrate that this trend involves a cooling of -0.3°C per millennium due to gradual changes to the position of the sun and an increase in the distance between the Earth and the sun.”This figure we calculated may not seem particularly significant,” says Esper. “However, it is also not negligible when compared to global warming, which up to now has been less than 1°C. Our results suggest that the large-scale climate reconstruction shown by the Intergovernmental Panel on Climate Change (IPCC) likely underestimate this long-term cooling trend over the past few millennia.”

http://www.uni-mainz.de/eng/15491.php

The paper can be viewed here:


http://www.nature.com/nclimate/journal/ ... e1589.html

Solar insolation changes, resulting from long-term oscillations of orbital configurations1, are an important driver of Holocene climate2, 3. The forcing is substantial over the past 2,000 years, up to four times as large as the 1.6 W m−2 net anthropogenic forcing since 1750 (ref. 4), but the trend varies considerably over time, space and with season5. Using numerous high-latitude proxy records, slow orbital changes have recently been shown6 to gradually force boreal summer temperature cooling over the common era. Here, we present new evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (−0.31 °C per 1,000 years, ±0.03 °C) than previously reported, and demonstrate that this signature is missing in published tree-ring proxy records. The long-term trend now revealed in maximum latewood density data is in line with coupled general circulation models7, 8 indicating albedo-driven feedback mechanisms and substantial summer cooling over the past two millennia in northern boreal and Arctic latitudes. These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times.



Also, since the forcing that was 4 times as much as the anthropogenic forcing over a 2000 year scale produced a total temperature change of -0.6 Degrees C over the past 2000 years, this means that the total anthropogenic forcing would produce a temperature change of around 0.15 Degrees C, which is consistent with the 10-11 w/m^2 sensitivity I talked about in my prior post.

FWIW, this would actually mean that only about 18-19% of the recent warming of 0.8 Kelvin can be attributed to the anthropogenic forcing.

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Meteorology Undergraduate

I think you are throwing a red herring in here.

The authors mentioned briefly that solar activity correlates to periods where temperatures were warmer, and where temperatures were lower, suggesting a solar-climate relationship.

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Meteorology Undergraduate

It is not a possible mechanism. I have posted many times that the mechanism is confirmed, but it is uncertain with regard to the degree of how strong the mechanism is, just like with the CO2 mechanism.

http://science.au.dk/en/news-and-events ... skydaekke/

“Before we can say how great the effect is, it’s clear that our results must be verified – just as more measurements and model computations need to be made. However, we can already reveal with no doubt whatsoever that there is an effect.”

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Meteorology Undergraduate

I would answer yes to both questions.

Do you know what that means?

This poll documenting any "consensus" is worthless.

This is because a "significant contributing factor" is an extremely subjective term. A significant contributing factor could mean 10%, 40%, or 90%.

It does not prove anything about what most climate scientists believe is the dominant cause of the 20th Century warming.

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Meteorology Undergraduate

SSN is the Sunspot Number.

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Meteorology Undergraduate

There is generally a 7 year lag between changes in solar activity and temperatures on Earth due to the large thermal lag of the oceans.

I expect us to begin to decline in temperatures by around 2013-2014.

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Meteorology Undergraduate

I actually agree with a sensitivity close to this estimate.

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Meteorology Undergraduate

I'll reply to your lengthy post tomorrow, Warmair.

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Meteorology Undergraduate

Based on tree rings, which is why we were told Mann was so incorrect. Supposedly on tree rings over a certain altitude, which made them essentially summer only data points. How can one be so wrong and the other so right using the same "flawed" methods? Other than one being something you like and the other not, of course.

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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

I know you are incorrect in that thought because the author specifically referenced the Mann paper. If the Mann paper is wrong the correlation is wrong even if you wish to cherry pick statements and try to make them out to be something they cannot be because they reference warm and cool periods you and others have already said did not exist as the reconstruction indicates. Thus, any such correlation is also inaccurate to the same degree. It is really that simple.

_________________
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