chubbs

Agreed.  And for the most part they still fall in the 2.2-3C range for ECS.

 

The whole debate about ECS becomes a bit more muddied when one considers increasing feedbacks ala methane, albedo drops.  To date these feedbacks have been likely muted, but tipping points will make a generally linear temperature rise more exponential in the future.

GHG forcing has increased by 0.66% per year since 1979, this rate of increase produces a doubling in a little over 100 years.This makes it easy to do the math when relating temperature to forcing.  Surface temperature has increased by 0.0158 per year on GISS in the same period. Ignoring aerosals, other non-GHG forcings and natural variability, this gives a very rough TCR estimate of 1.6C, which is consistent with a mid-range ECS.

GHG forcing from here: http://www.esrl.noaa.gov/gmd/aggi/aggi.html

The bold is where you make a leap...that's only half of what determines the weight of the ratio. Remember that the temperature at which evaporation occurs determines the initial O^16/O^18 ratio before the precipitation process occurs..polar SSTs are usually too cold to sufficiently evaporate O^18 at the ratio observed in the cores. A good portion of the O^18 that precipitates over the poles has a tropical/subtropical source. These isotopes are subsequently rained out during the condensation process and relatively few are transported to the poles. So, warmer tropical/mid-latitude oceans will lead to more O^18 being transported poleward.

For all intents and purposes, ice cores are hemispheric SST proxies.

You are underestimating the importance of condensation vs evaporation. Here is a plot of current mean annual temperature vs isotope ratio for samples collected at different locations in Antarctica and Greenland. Note the Antarctic data is Deuterium and Greenland is O18. There is a very good correlation between isotope ratio in current snow samples and the local mean annual temperature.  O18 is removed preferentially over the  lowest and warmest portions of the ice sheet so by the time water vapor reaches the highest and coldest locations it has been significantly depleted in O18.

Lets go back to the original point. The lines in this plot, or similar, are used to convert the measured isotope ratio in the ice core to a local temperature value. So when the paper that started this discussion reports ice core temperature variation of 0.97C it doesn't mean that the mean global temperature has varied by 0.97C.  Similarly when an ice core shows a temperature change of 10C in a short period of time during the Younger Dryas it doesn't mean that the mean global temperature varied by 10C - obviously the oceans can't warm or cool that quickly.

However I do agree that ice cores are good proxies for temperature change over broad regions. There had to be large changes in NH jet stream configuration and climate during the Younger Dryas and similar periods with rapid variation in ice core temperature.

I think 2 different concepts are being argued over, especially the second point:

 

1.) O^18 / O^16 ratio is indicative of changes in global SST / change in global ice volume --> relate to global surface Temps, although not directly 

2.) O^18 / O^16 ratio corresponds to temperature of snow when the snow fell, which isn't necessarily where the snow fell .. 

 Yes The ice core records are broadly indicative of  regional and hemispheric temperatures but are most closely related to cloud temperatures when snow condenses. The measured oxygen isotope ratios in the core are usually converted to temperatures by collecting current ice sheet snow and temperature data  and correlating the local isotope ratios and temperatures

I'm sick of rehashing preschool science to you. Arguing that the O^18/^16 ratios are regionally representative is analogous to arguing that CO^2 is not well mixed, or that the dust concentration in the ice pack is regional.

http://www.econ.yale.edu/~nordhaus/homepage/documents/icecore_review.pdf

http://eo.ucar.edu/staff/rrussell/climate/paleoclimate/ice_core_proxy_records.html

 

Quotes from p6 of your first reference below. It is very clear that the ice core temperatures are regional.

 "As these water molecules are evaporated, primarily from the oceans, the lighter molecules, those having fewer neutrons, are preferentially evaporated over the heavier ones, due to a slight difference in vapor pressure caused by the extra neutrons. This causes the vapor to be depleted in heavy molecules but enriched in lighter ones. As the air mass cools and condensation occurs, the heavier molecules preferentially condense due to the same principle The condensation is then assumed to fall out of the cloud as precipitation. Thus, the oxygen isotopic ratio of rain and snow is strongly related to condensatIf the temperature of the air mass should continue to fall, the condensation will contain decreasing concentrations of the heavy molecules, resulting in a depletion of 18O relative to precipitation that condensed in a warmer environmention temperature. . ....In the context of ice cores, this technique allows scientists to estimate the actual air temperature of condensation when the snow fell".

I agree that the paper is fatally flawed, but too many people misunderstand what ice core proxies are actually measuring. The isotope ratios used to reconstruct temperature are governed by processes over the tropical, subtropical, and extratropical oceans, not over the Arctic. The heavier O^3 isotopes are mostly rained out by 50-60N, in fact.

The isotope ratios within ice cores are, for all intents and purposes, hemispheric SST proxies. The Arctic cores depict SSTs over the Northern Hemisphere, while the Antarctic cores depict SSTs over the Southern Hemisphere.

No the temperatures are regional. Changes in isotope ratio during vapor transport are more important than changes at the source. The heavier isotopes are preferentially removed as water vapor is transported, lifted, cooled and percipitated. A local calibration is performed to relate isotope concentration to temperature on the ice sheet. Note that a part of the variation in the isotope record is due to changes in moisture transport to the ice sheet and not temperature.

The article is rubbish research.  It's published in Energy & Environment, the pal-reviewed denialist journal, and it's methodology is fatally flawed.  The author used a cherry-picked portion of ice core records, performed a number of questionable statistical operations, and conflates his finding to represent the entire globe.  

 

The Denier Choir has posted this on various forums, and will certainly continue to do so, but the kindest review one can make of this paper is that it represents the views of one of the 3%ers.

You can tell by reading the abstract that the paper is junk science which that journal has a habit of producing. The abstract  equates ice core variability to global variability. There are several problems with that.  First variation in the arctic is much larger than the tropics. Second variability in one region is not the same as global variability. . Regional variability can arise from variation in mean wind or ocean circulation. However circulation variability balances out over the globe. Large variation in global mean temperature requires a change in forcing or a major change in ocean circulation and there is no evidence for that in the holocene. Secondly the paper doesn't identify any natural cause for the global warming over the past 150 years. Natural variability can be warm or cool. To conclude that natural variability has been a major factor in warming a natural warming effect or combination of effects comparable in magnitude to the over 2.5 W/m2 of man-made GHG forcing would have to be identified.

Even if climate change ranked higher on the list of concerns for the general public, the technology problem would still

be there. It's going to take a much more concerted effort on the part of the global community to find a viable replacement

for fossil fuels as our primary energy source. There is just nothing in the near term which can meet the majority of

the worlds energy needs and significantly reduce emissions. People relate to money so a serious push in R&D 

spending would have to be marketed to the public as a way that it's going to save them money in some tangible manner.

You are right there is no short-term easy fix. However today's actions will determine whether we can make a significant move away from fossil fuels in the longer term. The best way of reducing the cost of renewable energy sources is to increase deployment to benefit from cost learning curve and economies of scale. A carbon tax or carbon credits would move us in the right direction.

The biggest problem in tackling climate change is that the most extreme voices tend to be the loudest. You have a camp that tries to argue that we haven't warmed at all or even if we have, it is all natural. Then you have a camp that basically blames every weather event on climate change and pimps RCP 8.5 scenarios that are extremely unlikely but they sound disastrous. Then from these two groups, you get mud slinging and the strawmans begin to get built. It's counter productive.

It is no wonder that a lot of the general public has a very tepid attitude toward it. Their attitude toward climate change starts to mirror their attitude and dissatisfaction toward the state of American politics.

That certainly contributes but if climate change was easier for people to come to grips with there would be less motivation to deny, ignore.or exaggerate. 

Climate is not the perfect cognitive challenge but its amorphous nature creates the ideal conditions for human denial and cognitive bias to come to the for

DANIEL KAHNEMAN is not hopeful. “I am very sorry,” he told me, “but I am deeply pessimistic. I really see no path to success on climate change.”

Kahneman won the 2002 Nobel prize in economics for his research on the psychological biases that distort rational decision-making. One of these is “loss aversion”, which means that people are far more sensitive to losses than gains. He regards climate change as a perfect trigger: a distant problem that requires sacrifices now to avoid uncertain losses far in the future. This combination is exceptionally hard for us to accept, he told me.

http://climatedenial.org/2014/08/20/climate-change-the-slippery-problem/

MINNEAPOLIS (The Borowitz Report) – Scientists have discovered a powerful new strain of fact-resistant humans who are threatening the ability of Earth to sustain life, a sobering new study reports. The research, conducted by the University of Minnesota, identifies a virulent strain of humans who are virtually immune to any form of verifiable knowledge, leaving scientists at a loss as to how to combat them.---------More worryingly, Logsdon said, “As facts have multiplied, their defenses against those facts have only grown more powerful.”

http://www.newyorker.com/humor/borowitz-report/scientists-earth-endangered-by-new-strain-of-fact-resistant-humans

GlobalWarmer , being a proud American doesn't take anything away from the facts of how much damage were doing to our climate....atleast in my opinion. 

 

Were right up there with China....as one of the biggest offenders .

 

 

 

yeah, he kind of throws every option out there.  I can never tell which way he's leaning, but was surprised he invested so much towards global cooling being imminent. (with so many current indicators....*yours included*  pointing opposite) 

 

His main points were valid though...how nobody really knows what's going on, and which direction were heading...corruption and lobbying from all directions , etc.   

That video was unwatchable.. Full of misinformation.

People have to remember ice sheet melting is a long term feedback. Happens on the time scale of centuries not decades. Simply exceeding the Eeemian baseline isn't going to suddenly melt all the the ice in Greenland. Takes heat energy (and time) to convert the ice back into a liquid state. That being said, on our current CO2 emissions path sea levels will rise toward (and potentially beyond) Eemian levels over the next few hundred years.

 

Key point of uncertainty is when chokepoints in places such as the West Antarctic Ice Sheet (WAIS) give way resulting in an acceleration of SLR. The WAIS, not Greenland holds the key here as the volume of water stored is much larger and the factors influencing the SLR contribution are different. Appears we could start to see this acceleration as soon in the latter half of this century but this is still an area of research up for significant debate and even such an acceleration on this time scale is very unlikely to result in an additional 8 ft over 80-90 years.

 Yes its going to take thousands of years for Greenland and Antarctica to come back into equilibrium with the atmosphere and ocean.  Our science isn't good enough to predict with any accuracy future long-term SLR trajectories. Recent work generally indicates that both Greenland and Antarctica are less stable to warming than thought previously. This means that potential sea level rise rates and long-term sea level endpoints are both increasing. All this makes dealing with SLR is a very good field to get into.

10 feet is too high but the recent IPCC assessment is also too conservative on the upper end. IPCC did not include marine ice sheet instability in Western Antarctic which is now thought to be in the early stages of collapse. Timing for collapse though is unknown.

For another view here is a recent TED talk on the impact of SLR on S. Florida. Note SLR in S Florida is currently faster than the global average due to local subsidence, changes in ocean currents etc..

it took the staff almost a year to figure out the obvious

 No big deal its just the CC forum

The link doesn't work for me.

 

I'm guessing it might show an increase in global methane concentrations paralleling the increased use of fracking? 

It doesn't address global methane concentrations only emissions associated with NG production and use and comparison to other fossil fuels. 

A new paper:

http://onlinelibrary.wiley.com/enhanced/doi/10.1002/ese3.

shows that leakage from fracking operations may be so extensive that rather than using the 100yr equivalent figures for CH4 to CO2 the much higher 20yr figures will come into play.

The paper is not long and it's an easy read.

 

Terry

This is an update of an earlier controversial paper. Paper has a clear discussion of methane emission estimates and does a good job of supporting the factors used. The main takeaway is that there is not much advantage for NG over coal when methane leaks are accounted for.