chubbs

According to skeptical science this is an internet myth that has been propagated by Anthony Watts. Hanson's original statement needs to be placed in the proper context. He was asked to speculate in a 1988 interview what the view from his office might look like in 40 years if CO2 doubled. The interviewer published Hanson's response in a book 10 years later, but in a subsequent interview for Salon the interviewer left out the doubled CO2 and shortened the time to 20 years. A key learning over the past few days - don't believe what you read on the internet about climate scientists. http://www.skepticalscience.com/Examining-Hansens-prediction-about-the-West-Side-Highway.html

Yes its silly to blame scientists for their communication limitations - that is what politicians and PR experts are for. Climate change happens over very long time frames and there is large uncertainty. Scientists who have a little clearer vision into the future have a huge communication challenge that they are not prepared for. The potential WAIS collapse is a good example.The impact is so large that it is difficult for most to fathom and our current science cannot provide any timing estimate. So messaging is difficult. No matter what is said most people find it too alarming to contemplate or far enough in the future to ignore. The flip side is effective communication by deniers/skeptics. Their job is much easier since they mainly aim to confuse and discredit. The key components are a few simple talking points repeated in a consistent and reinforcing manner combined with villains that many can identify with (liberals, lying scientists, big government etc).

I can see where it would be misleading if snippets were taken out of context. These posts stimulated me to read portions of his 1981 paper. While portions are dated and missed the mark, many of his 1981 predictions are very accurate. His discussion of WAIS could have been written today but was way ahead of his time. It would be the height of irony if his warning of a WAIS collapse turns out to be correct - and yet leads to inaction per the theory outlined above

I wasn't familiar with Hanson's testimony so I googled and came up with the document linked below based on his 2007 testimony. Its not nearly as bad as you suggest. Its very scientific in tone - unlikely to cause a reaction in anyone except those already of a skeptical bent. His temperature projections are close to consensus. Some of his effect projections are high end but I wouldn't call them outlandish. He says SLR could be 2 meters in 100 years due to mainly to WAIS.. At the time this was quite aggressive.Since then however much more has been published on ice sheet instability and WAIS in particular. His projection is still high end but it is moving into the range of possible outcomes. Blaming Hanson for climate denial/skepticism is a big exaggeration. I discuss climate with many skeptics. They mainly stick close to the denier talking points:: the data is fudged, the scientists are in cahoots to get grant money, temperatures haven't increased in 18 years, climate has always varied etc.. No one ever mentions Jim Hanson. For the most part people believe the story lines that fit in with their preconceived views. http://arxiv.org/abs/0706.3720

That is a ridiculous assertion. These predictions made by Hanson in a 1981 paper before global warming was even an issue have proven to be quite accurate. Unfortunately we didn't make much use of them. Hansen, J., D. Johnson, A. Lacis, S. Lebedeff, P. Lee, D. Rind, and G. Russell, 1981: Climate impact of increasing atmospheric carbon dioxide. Science, 213, 957-966, doi:10.1126/science.213.4511.957. The global temperature rose 0.2°C between the middle 1960s and 1980, yielding a warming of 0.4°C in the past century. This temperature increase is consistent with the calculated effect due to measured increases of atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar luminosity appear to be primary causes of observed fluctuations about the mean trend of increasing temperature. It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980s. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.

That's the rub though no one can identify a natural factor that fits the long-term pattern of warming as well as AGW.

I looked at the abstracts and didn't see anything that makes me want to read further. Why should I go to the trouble of reading and critiquing obscure papers. Would be much easier if you summarized the key science in the papers that supports low sensitivity.

The final report summarizing the recent Ringberg ECS workshop has been posted. The report is not earthshaking. The main recommendation is to focus research on the science needed to justify ECS below 2C and above 4C. The unstated implication is that ECS between 2 and 4C are reasonable in the absence of new science.. http://www.mpimet.mpg.de/en/science/the-atmosphere-in-the-earth-system/ringberg-workshop/ringberg-2014.html

Sure I just used 1979 because the NASA GHG forcing series starts then on the website. However we've been locked into a relatively steady T increase since around 1970. The rate of temperature increase per unit of forcing was lower before 1970 and particularly before 1900. That is one reason the energy balance ECS estimates that go back that far are lower.

Yes.I do not advocate estimating ECS or even TCR this way. It is just useful in producing mileposts to check progress. If temperature trends diverge from recent history then there is evidence for a change in behavior.

Sure it could be off, but the longer we maintain a relatively steady warming the more likely the the middle estimates are correct.

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

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.

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

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".

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.

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.

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.

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

That video was unwatchable.. Full of misinformation.

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..