-1=e^ipi

I disagree. Many people in the public may perceive that economists think this way, but public perception != reality. Based upon my own interaction with economists, as well as undergraduate and graduate studies in economics I assure you that the vast majority of economists (and by economists I mean real economists, not people like Stephen Harper) recognize the existence of the environment. Edit: For example, it is standard to try to monetize the value of environmental impacts when performing a cost-benefit analysis.

Earlier I referenced a Lunt et al. paper that suggested that the ESS is approximately 1.4 times ECS (it compared changes between the Pliocene and the Holocene). However, this was using an ECS of ~ 3.05 C. The ratio of ESS/ECS is unlikely to be constant. Rather, you can think of the ECS to be the 1.15 C no feedback CO2 sensitivity + fast feedbacks and the ESS to be the ECS + slow feedbacks. If we let a = fast feedbacks and b = slow feedbacks then: 3.05 C = ECS = 1.15 C / (1 - a) 1.4*3.05 C = ESS = 1.15 C / (1 - a - b ) This suggests that b = 0.108. Now if ECS is actually lower (say 2 C), then that means that the fast feedbacks, a, are lower (0.425), which would give a lower ESS for the same slow feedbacks, b, (2.46 C). In this case, not only has the ECS dropped, but the ratio of ESS/ECS has dropped (from 1.4 to 1.23).

Thought I would mention this because it has interesting implications. Bjorn Stevens has 2 papers recently, which help explain some of the discrepancy between climate model estimates, and observations. The first is that Bjorn Stevens has reduced the uncertainty & median estimate on aerosol forcing and the result suggests that climate models (as well as simple radiative balance calculations) have been overestimating climate sensitivity (since the negative forcing of aerosols somewhat offsets the positive forcing of greenhouse gases in the instrumental record). Nick Lewis' instrumental best estimate of climate sensitivity drops from 1.64 to 1.45 C (a 12% drop). http://climateaudit.org/2015/03/19/the-implications-for-climate-sensitivity-of-bjorn-stevens-new-aerosol-forcing-paper/ The other paper finds support for Lindzen's Iris hypothesis (which to my understanding means a stronger negative cloud feedback in the tropics). Since climate models aren't taking this effect into account, they are overestimating climate sensitivity. For example, this paper suggests that the climate sensitivity of ECHAM6 climate model decreases from ~2.8 to ~2.2 C. http://judithcurry.com/2015/04/22/bjorn-stevens-in-the-cross-fire/

No, it was a result of the melting of the North American, Eurasian and other ice caps + glaciers at the end of the ice age, which was caused by Milankovitch cycles + the GHG & albedo feedbacks, which increased sea levels by 105-120 m. Is this supposed to be a rhetorical question?

Some more thoughts on this: If I look at pleistocene ice core data, the CO2 difference between glacials and interglacials is ~100 ppm. But by Annan and Hargreaves 2013 the change in global average temperature is (4.0 +/- 0.8) C. This suggests that the CO2-temperature feedback is roughly (25 +/- 5) ppm/C. However, due to the non-linear temperature relationship of the CO2 in water Henry's constant, this is probably a slight overestimate of the temperature-CO2 feedback. Looking at the effect of water solubility alone suggests that as water holds 1.26% more dissolved CO2 as you decrease temperature (and the glacial periods are roughly 4C colder), one should multiply the above number by ~ 0.9874^2, which suggests that the CO2-temperature feedback at current temperatures is ~(24.4 +/- 4.9) ppm/C (95% confidence interval). Edit: now that I think about it, the CO2-temperature feedback that one obtains empirically from the pleistocene ice core data is the equilibrium change. However, for melting permafrost, that CO2 will first go into the atmosphere before the atmosphere has time to reach equilibrium with the ocean, so it might be possible for the short term feedback to be larger than the long term feedback (although not necessarily since it also takes time for the ocean to release CO2 to the atmosphere).

I tried to estimate the equilibrium climate sensitivity (ECS) from Pleistocene data again. I used the same data as post #371, and I used the de Boer 2010 sea level data (http://www.staff.science.uu.nl/~boer0160/Model_output/BdeBoer_etal_ANICE_5Myr_output.txt) rather than the Bintaja 2005 sea level reconstruction. For the sake of simplicity (and the fact that Pleistocene data occurs over such a long time period that I can use this simplified model), I use the simple linear model: Tt+10 = β0 + β1*(GHG forcing + Solar forcing due to eccentricity changes + Albedo forcing) + β2*Obliquity_Index + β3*Precession_Index + model error The lag of 10 years is to try to take into account the fact that it takes some time for climate to change temperature due to a change in forcing and the value of 10 years is based upon Ricke and Caldeira 2014 (http://iopscience.iop.org/1748-9326/9/12/124002/article) . Given the large timescale of ice ages, the choice of the lag doesn't significantly affect the results and some individuals such as James Hansen neglect time delays completely when obtaining estimates of ECS. I tried to combine GHG forcing, solar forcing and albedo forcing into a single parameter to make the model easier to estimate and to take advantage of a priori information. If I go with the claims of Hansen 2013 (http://rsta.royalsocietypublishing.org/content/371/2001/20120294), the albedo forcing (ice-albedo, sea level changes, vegetation changes) are roughly a linear function of sea level changes and the difference in albedo from the Holocene to the last glacial maximum is roughly 3.4 W/m^2 with an error of roughly 20%, then I can replace the albedo forcing in the regression with (1 +/- 0.2)*3.4/105*Sea_Level (105m is the change in sea level for the LGM according to the de Boer data). Earlier I argued that the effectiveness of solar forcing relative to GHG forcing would be less than 0.7/4 since solar forcing has a stronger effect in equatorial regions (thus by the Stefan-Boltzman law, the change in global temperature would be less than if solar irradiance were distributed more evenly). Based on calculations I have done earlier in this thread, plus all my earlier regression results, I think it is reasonable to suggest that to convert changes in solar irradiance to GHG forcing I can multiply by a factor of (0.10 +/- 0.05). This confidence interval seems a bit arbitrary (and I am sort of doing what James Hansen does), but the error isn't that large; it doesn't matter that much since eccentricity changes aren't that big. Anyway, performing a linear regression gives me estimates to my model. Climate sensitivity can then be calculated as β1*5.35*ln(2). My actual error is going to be model error + temperature error (which I can get from Annan and Hargreaves 2013) + error on solar parameter + error on albedo parameter. Overall, my 95% confidence interval for ECS based on this model is (2.46 +/- 0.48) C. However, this may be an overestimate of ECS because my estimate of the effect of the albedo feedback may be an underestimate. The reason I may be underestimating the effect of my albedo forcing is because in addition to causing less incoming solar radiation to be absorbed during an ice-age, the albedo effect will increase the unevenness of the distribution of incoming absorbed sunlight across the surface of the Earth. The reason for this is because the ice-albedo feedback occurs in polar regions, which already receive less sunlight than equatorial regions. The effect of this unevenness may be quite large as indicated by the strength of obliquity on explaining temperature changes (as obliquity affects the sunlight distribution). Another thing I would like to mention is that there may be a far amount of specification error for this model, so the above confidence interval is an underestimate of the true uncertainty. Though it does look like 1.5 C < ECS < 3 C.

More on Sea Level: During the Eemian (interglacial 120,000 years ago), global temperature was ~2 C warmer than the Holocene and sea levels were ~ 6 m higher than the Holocene. This would suggest that the equilibrium change in global sea levels is roughly 3 m per degree of warming (and of course getting to this would take a millennia or two because it takes a long time for the ice cap feedbacks). Edit: But the Pliocene had ~24m higher sea levels at 3 C higher temperatures, which would indicate roughly 8m per degree of warming. However, the Pliocene did not have as strong Antarctic circumpolar current and the Americas were not joined either due to differences in the positions of the continents, so a lot of the higher Pliocene sea levels may be due to the positions of the continents (which allowed for a more equitable climate for the same global average temperature) rather than due to changes in the global average temperature.

Another thought: If Greenland and Antarctica completely melted, sea levels would rise by ~ 68 m. If they have a 513 year decay time, this would suggest an upper bound on the rate of sea level rise of ~ 0.13 m per year (even if GHG levels became very high). Realistically, sea level rise is expected to be ~ 0.5 m this century. Edit: the 0.13m per year would be ~ the maximum sea level rise you would get if the ice albedo feedback where 'self-perpetuating', which it clearly isn't.

I thought I would do a rough upperbound of the timescale of the ice-albedo feedback. The upperbound should roughly be the time it takes the increase in radiative forcing from melting an ice cap to melt that ice cap. Mean annual solar insolation at the poles is ~ 55 W/m^2. The albedo of an ice cap is roughly 0.8. The albedo of water (which is what would replace the ice caps of Antarctica and Greenland if they all melted) depends on the latitude and other factors because reflectivity depends on the Fresnel equations, but is roughly 0.1 at high latitudes. This means that a lower bound for the increase in energy absorbed by the earth from melting a square metre of ice cap is (0.8-0.1)*55 W/m^2 = 38.5 W/m^2. The thicknesses of the Greenland and Antarctica ice caps are roughly 2 km. The density of ice is ~ 934 kg/m^3. The enthalpy of melting ice is 333550 J/kg. This means that it would take 2000*934*333550 = 623071400000 J to melt a square kilometre of Greenland/Antarctica ice cap. So it takes 623071400000/38.5 = 16183672727 s = 513 years to melt a square kilometre of Greenland/Antarctica ice cap with the feedback that would result from melting that ice. Given that the shortest feedback is roughly 0.5 years, this suggests that an Van Hateren impulse response function with decay times ranging from 0.5 years to say 1024 years should be more than sufficient coverage to represent the true impulse response function.

It is feasible to run the world's economy into the toilet. It is just not preferable.

I'm starting to get skeptical that a cost-benefit analysis is the best way to determine optimal policy (despite my earlier claims in this thread). Some of the assumptions that go into justifying cost-benefit analysis might be violated when it comes to climate change. In particular, the magnitude of impact of policy on the global economy can be quite large and there appears to be a fairly large amount of uncertainty when it comes to the impacts of different policy choices. Traditional cost-benefit analysis is basically risk neutral and tries to determine if a policy is potentially pareto improving (and it generally relies on having a low level of uncertainty). Perhaps a method that better takes into account risk aversion and preference for equality should be used.

The effect of climate change will have both costs and benefits. How one weighs the different costs vs the different benefits is ambiguous. The pareto principle alone isn't sufficient to judge if something is better. You are making two assumptions here. The first is that there exist people that actually do know the answers to these questions and the second is that the people claiming to know the answers to these questions actually know the answers to these questions. I do not believe that people that know what the optimal policy response to climate change exist (because I have yet to meet someone that has provided me with a satisfactory answer), and therefore I do not believe that the people claiming that they know the optimal policy response actually know the optimal policy response. If an imam claims to know that a god exists and an atheist claims to not know if a god exists, does that mean society should believe the imam simply because the imam is in a position of authority and claims to know the answer to the question on does god exist? There are costs and benefits to global warming. With respect to US agriculture production, I am unconvinced that lower production in California won't be offset by increased production elsewhere in the country. California + Texas != the entire world. Lower Californian agricultural production being offset elsewhere in the US does not imply that adaptation is the optimal policy response to climate change. One cannot exclude mitigation policy based on changes in US agricultural production. I do not know != no idea. Again, as far as I am concerned, these experts who know the optimal policy response do not exist. And yes, blindly using appeal to authority is a fallacy and when large amounts of people do it in society it becomes dangerous. I can give you countless examples in history if you want. I suspect that you lack a decent appreciation or understanding of the scientific method if you think it is based on blindly believing in what an 'expert' concludes. A group of people with the title 'scientist' making flawed arguments about what should be done with respect to climate change does not make their arguments somehow less flawed. Some 'scientists' do not follow the scientific method correctly, jump to conclusions, and make oversimplifications in their analysis. Furthermore, the scientific method alone does not tell people what to do. So it isn't possible to derive the optimal policy response from the scientific method + empirical method alone; you need additional premises. Again, my position isn't that we shouldn't do mitigation. Please do not misrepresent/strawman me.

You simply claim that I am wrong in my claim that there is no sudden tipping point and that this is an oversimplification of the impacts of climate change vs greenhouse gas emissions. But you do not explain why it is that I am wrong and proceed to go off on an unrelated tangent. Perhaps you simply do not understand the claim I am making, so I'll try to reword things. Basically, I think many people are treating the impact of climate change as a step function (http://en.wikipedia.org/wiki/Step_function), where as really the impact of climate change is a continuous function of greenhouse gas emissions (http://en.wikipedia.org/wiki/Continuous_function). The politics of the 2C target are a good example of people treating the impact of climate change as a step function. Maybe you are super privileged and $100,000 isn't much money to you. As a person on the verge of homelessness, a person who doesn't drive but rather walks or takes public transportation, I would certainly do that for $100,000. Heck, I would let someone piss in my mouth for $100,000 (provided they don't have aids or something). So you either have or expect to have kids and grandkids. Talk about privileged. Actually, this is a good reflection at how privileged our society has become (that people assume having kids and grandkids is a given). And deluding yourself into thinking that you are a righteous advocate of mother gaia fighting the hordes of evil greedy capitalists doesn't give you any sense of self importance? Yes, it's not like well intentioned people could have different opinions based upon the evidence available to them! They only disagree with us righteous gaia protectors because they are selfish and greedy! Therefore, we can dismiss any argument they ever make! *sarcasm* You are mixing Carbon up with Carbon Dioxide. But people not understanding basic chemistry is to be expected. We clearly have different definitions of 'costs'. Cost - cost is a metric that is totaling up as a result of a process or as a differential for the result of a decision. (from wikipedia)

The North American Cordillera, which lies between California and Texas acts as a barrier to moisture transfer. My understanding is that global warming may shift the jetstreams poleward, which should make wind more Easterly and less Westerly, is the reason why California may become drier. California has the Pacific Ocean to the west, where as Texas has the Atlantic Ocean to the East (with the Cordillera between them); so more Easterly winds should make California drier and Texas wetter. For similar reasons why a drier California is often considered a negative. Both California and Texas are at similar latitudes, receive plenty of sunlight and are warm. However, both states are relatively dry and a slight increase in soil moisture should be beneficial both for agriculture and for the state biosphere. This is a difficult question to answer. How does one judge something to be better? What emission scenario will we expect? How sensitive is the climate to increases in greenhouse gasses? Etc. I don't know. Why do you think I am an 'adaptionist'? I don't know what the optimal policy response with respect to global warming is. For all I know, it might be a combination of mitigation, adaptation and geoengineering. My 'disdain' for alarmism is due to many things including the willingness to jump to conclusions, the dogmatic approach to the issue of climate change, the constant strawmaning of differing positions in order to fit a false dichotomy, the usage of overly simplistic methodologies such as the precautionary principle to determine the optimal response to climate change, and the frequent lack of respect of the scientific method.

Nope, that would be 6 billion years.

Not really sure what you mean by 'burn itself out', but in 5 billion years the Sun will be a red giant and should be large enough to devour the Earth. Is that what you mean?

More than half of warming since WW2 is due to anthropogenic greenhouse gas emissions. If you want me to give you a more accurate number, I could obtain it from my Van Hateren impulse response model that I used to estimate climate sensitivity from the instrumental record. Science deals with uncertainty. I don't think it is fair to criticize scientists for being honest about their uncertainty. Although, it would be better if organizations like the IPCC simply made statements such as 'our 95% confidence interval is X' rather than 'X is very likely'.

If there were no measurable effects that are of concern to anyone, then people like Juddith Curry and Nic Lewis couldn't obtain estimates of climate sensitivity from the instrumental record. There is no guarantee that the sun will continue to rise. Yet people expect it to. I think your claim is worded too strongly. You shouldn't dismiss David Suzuki's arguments because David Suzuki isn't a climate scientist. You should dismiss David Suzuki's arguments because the arguments are nonsense and not supported by physics or empirical data. Please treat science as a methodology, not some sort of institution where 'truth' is determined authoritatively.

I don't understand your question and I'm not sure if you do either. The kilo-year events I was referring to were events that occurred 4.2, 5.9 and 8.2 thousand years ago. They didn't last for thousands of years or have kilo-year timescales.

This question relies on the premise that US food security is going to be at risk due to global warming, which I question greatly. California may become drier, but then Texas should become wetter. Most of the US will become wetter, you have the CO2 fertilization effect, longer growing seasons in most of the USA etc. The mongol invasion of Eurasia coincided with the the medieval warm period and a time when Mongolia was warmer and wetter than it is today. One of the reasons that the mongols had the ability to do what they did is because the climate changed to allow them to be more prosperous. During this time you also had vikings colonizing Greenland and growing crops there. I read science directly, as well as perform my own analysis. Scientists are flawed people and just blindly following the conclusions of someone with the title 'scientist' is giving in to the appeal to authority fallacy. The scientific method is not compatible with logical fallacies. Fortunately there are positions that exist outside of the alarmist-denier false dichotomy. Doesn't 'between' suggest that the space of positions on climate change is one dimensional (or can be well represented by a projection onto a single dimension)?

On guard for thee just did. Alarmists are consistently making absurd claims about the impacts of global warming. Obama claiming that the Earth will boil over is a good example.

So people in South Florida getting their feet wet = Earth becomes uninhabitable?

So your definition of destroying the planet is making it uninhabitable for humans? What is your perception of the global planetary conditions necessary to achieve this?

How do you define 'destroying the planet'?

But no such thing exists. There is no sudden tipping point or point where damages go from 0 to very large. Net cost is a continuous function of emissions.