Thanks. I think it is best though to not put much faith in the more popular discussion forums, such as the "physics forum," where anyone can weigh in. I have repeatedly pointed out the fatal flaws in Hansen's later work. I take great pleasure, and breathe a sigh of relief, to note that he is now retired from serious scientific work. Sadly he is still dangerous as a polluter of young minds at Columbia. I think his published work became hopelessly flawed once he lost all objectivity by becoming emotionally involved in an unproven hypothesis that would turn out to be quite wrong and started promoting his flawed science through direct contact with the media. Once science becomes politicized objectivity goes out the window. This is a sort of human insanity that we humans are collectively capable of. So we end up with Republicans not believing in Hansen's hypothesis and Democrats preaching it as though it were a religion. How ridiculous! And we have just repeated the same sort of insanity in regard to a viral pandemic which is real for Democrats and a hoax for Republicans. We end up being able to tell someones political leaning by whether or not they are wearing a mask! This is collective human insanity for all to see. We should be embarrassed to admit we are Homo sapiens. Unfortunately the best sources of relatively unbiased and disinterested discussion of climate science is in the primary literature and the professional conference proceedings, sadly these sources are largely inaccessible to the layman or science hobbyist. I have tried my best to bring scientific objectivity to this is topic in these ET Forums, but I am fighting an uphill battle.
well, here are the issues I see as a casual: Shaviv at best has a Libertarian slant which is why he goes to speak to these think thanks, or just doesn't realize that the optics of speaking there will pollute his thesis. At worst, he's a paid actor by these groups to "find us the science" or is being shunned by the scientific community and these groups out of "magnanimity" are some of his few outlets. I posted the physics forum because that's where trained physicists hang out, even if anyone can join in, so I'd much rather put faith there than Elite Trader. Which brings me to the other red flag; the level of expertise needed to understand Shaviv's theories. I've seen intentional obfuscation when agendas or worse, quackery is being pushed, and if you don't get it, then "you're too dumb to question it". Why not simplify it for mass consumption? This reminds me of Eric Weinstein's "theory of everything".
Of course you are, for the very fact you state about the layman's lack of accessibility to the research. The laymen default to the prestige of the publications that do write for the public, and weigh the balance between believers and skeptics. Doesn't mean they're right in their conclusions, but that's the way to bet. Most scientists, the general public, government, and lately business are accepting the anthropogenic climate change hypothesis and taking action on it. For the practical layman, the proof of the pudding will have to be in the tasting.
Thanks. It tried that and here is the first search result that popped up. Solar Debunking Arguments are Defunct 11 Aug 2019 Solar Debunking Arguments are Defunct By shaviv An article interviewing me was removed yesterday from forbes. Instead, they published an article by Meteorologist Prof. Marshall Shepherd that claims that the sun has no effect on climate. That article, however, falls to the same pitfalls that pointed out on my blog yesterday. Specifically, why is Shepherd’s arguments faulty? Although I addressed them yesterday, here they are brought again more explicitly and with figures. First, and foremost, Shepherd ignores the clear evidence that shows that the sun has a large effect on climate, and quantifies it. This graph is from the Shaviv 2008 (#1 in the reference below): Figure 1: Reconstructed Solar constant (dashed red line) and sea level change rate based on Tide Gauge records as a function of time (solid blue line with 1 sigma error region in gray). As you can see, there is a very clear correlation between solar activity and the rate of change of the sea level. On short time scales most of the sea level change is due to changes in the heat going into the oceans, such that we can quantify the solar radiative forcing this way. It is found to be an order of magnitude larger than changes in the irradiance, which is what the IPCC is claiming is to be the solar contribution. After that work was published there was not a single paper that tried to refute it. Instead, additional satellite altimetry data covering two more solar cycles just revealed the same. In fact, the sun + el Niño Southern Oscillation can explain almost all the sea level variations minus the long term linear trend (caused by ice caps melting). This is from Howard et al. 2015 (see ref. #2 at the end): Figure 2: Satellite Altimetry based sea level (minus linear trend) in dashed blue points. Red is best fit model which includes solar cycle + el niño souther oscillation. Clearly, the sun continues to have a clear effect on the climate. Note that it is impossible to explain the large variations through a feedback in the system because that would give the wrong phase in the heat content response. What does that imply? First, since solar activity increased over the 20th century, it should be taken into account. Shepherd’s radiative forcing graph should be modified to be: Figure 3: Radiative forcing contributions (graph from Shepherd's article) with the following added. The beige is the real solar contribution over the 20th century. The green is the total forcing (natural + anthropogenic) we get once we include the real solar effect. The next point to note is that Shepherd claimed that because solar activity stopped increasing from the 1990’s it cannot explain any further warming. This is plain wrong. Consider this example in false logic. The sun cannot be warming us because between noon and 2pm (or so), solar flux decreases while the temperature increases. As a Professor of meteorology, Prof. Shepherd should know about the heat capacity of the oceans such that assuming that the global temperature is something times the CO2 forcing plus something else times the solar forcing is too much of a simplification. Instead, one can and should simulate the 20th century, and beyond, and see that when taking the sun into account, it explains about 1/2 to 2/3s of the 20th century warming, and that the best climate sensitivity is around 1 to 1.5°C per CO2 doubling (compared with the 1.5 to 4.5°C of the IPCC). Two points to note here. First, although the best estimate of the solar radiative forcing is a bit less than the combined anthropogenic forcing, because it is spread more evenly over the 20th century, its contribution is larger than the anthropogenic contribution the bulk of which took place more recently. That's why the best fit gives that the solar contribution is 1/2 to 2/3s of the warming. Second, the reason that the best fit requires a smaller climate sensitivity is because the total net radiative forcing is about twice larger. This implies that a smaller sensitivity is required to fit the same observed temperature increase. Here is my best fit to the 20th century. Solid line is model and dashed is the observed global temperate (See Ziskin & Shaviv, ref. #3 below). Figure 4: Best fit for a model which allows for a larger solar forcing and a smaller climate sensitivity than the IPCC is willing to admit is there. Top: Model = solid line, NCDC Observations = dashed line). The bottom is the different between the two. As you can see, the residual of the fit is typically 0.1°C, which is twice smaller than typical fits by CMIP 5 models. Once we fit the 20th century, we can integrate forward in time. Here I plot the expected warming for many realizations assuming a vanilla flavored emission scenario: Figure 5: Using best fit models for the 20th century, we can integrate forward in time while making random realizations for volcanoes, solar activity etc. The actual temperature increase witnessed is totally consistent with the observations. It is much smaller than the CMIP 5 models which the IPCC is using. See image capture from Roy Spencer’s ICCC13 talk: Figure 6: CMIP5 models vs. actual temperature change based on satellite (RSS/UAH) or reanalyses datasets. And average warming slopes, together with my predictions: Figure 7: Warming trends in CMIP5 models vs. actual warming trends based on satellite (RSS/UAH) or reanalyses datasets. The orange bar is our predicted warming trend. Error is from the range of realizations. Namely, our predictions are totally consistent with the satellite (RSS / UAH, whichever you prefer) and the Reanalyses datasets. Remember, this was obtained for a model which included the real solar contribution which requires a small climate sensitivity. Shepherd also mentions that the link through cosmic ray flux variations has been debunked. I point the reader to a summary of why those attacks don’t hold any water, which I wrote yesterday. To summarize, Shepherd did not debunk the solar forcing. His arguments are defunct. Unless he comes up with a very good explanation to the first graph above, he should instead advocate taking solar forcing into account. The fact that forbes hushes up any possibility for having a scientific debate should be considered truly bothersome by anyone who values free speech and scientific debate. Truth will prevail irrespectively. References: Shaviv, N. J. Using the oceans as a calorimeter to quantify the solar radiative forcing. J. Geophys. Res. (Space Phys.) 113, 11101 (2008) local version (not paywalled) Howard, D., Shaviv, N. J., Svensmark, H., The solar and Southern Oscillation components in the satellite altimetry data, J. Geophys. Res. Space Physics, 120, 3297–3306 (2015) Ziskin, S., Shaviv, N. J., Quantifying the role of solar radiative forcing over the 20th century, Advances in Space Research 50, 762–776, (2012). local version (not paywalled) shaviv's blog
It seems Shaviv's response to the Forbes Shepard article that I posted above is actually pretty accessible.
Science 30 years later, former NASA scientist wishes he hadn't been right about climate change 'I don't want to be right in that sense,' James Hansen says about warming planet The Associated Press · Posted: Jun 18, 2018 12:45 PM ET | Last Updated: June 18, 2018 Lol, you went to the outlier's argument to find that he holds a minority view?
https://www.cbc.ca/news/science/james-hansen-global-warming-1.4710713 Science 30 years later, former NASA scientist wishes he hadn't been right about climate change 'I don't want to be right in that sense,' James Hansen says about warming planet The Associated Press · Posted: Jun 18, 2018 12:45 PM ET | Last Updated: June 18, 2018 Dr. James Hansen, then director of NASA's Goddard Institute for Space Studies in New York, testifies on May 9, 1989, before a Senate transportation subcommittee on Capitol Hill in Washington, D.C., a year after his history-making testimony telling the world that global warming was here and would get worse. (File/Dennis Cook/Associated Press) James Hansen wishes he had been wrong. He wasn't. NASA's top climate scientist in 1988, Hansen warned the world on a record hot June day 30 years ago that global warming was here and worsening. In a scientific study that came out a couple of months later, he even forecast how warm it would get, depending on emissions of heat-trapping gases. The hotter world that Hansen envisioned in 1988 has more or less come true. Three decades later, most climate scientists who have been interviewed rave about the accuracy of Hansen's predictions given the technology of the time. Hansen won't say, "I told you so." "I don't want to be right in that sense," he told The Associated Press in an interview in his New York City penthouse apartment. That's because being right means the world is warming at an unprecedented pace, and ice sheets in Antarctica and Greenland are melting. Hansen said what he really wishes would have happened is "that the warning be heeded and actions be taken." They weren't. Hansen, now 77, regrets not being "able to make this story clear enough for the public." From Venus to Earth Global warming was not what Hansen set out to study when he joined NASA in 1972. The Iowa native studied Venus — a planet with a runaway greenhouse-effect run — when he got interested in Earth's ozone hole. As he created computer simulations, he realized "this planet was more interesting than Venus." And more important. In his 1988 study, Hansen and colleagues used three different scenarios for emissions of heat-trapping gases — high, low and medium. Hansen and other scientists concentrated on the middle scenario. The Arctic sea ice extent for September 2017 was 4.87 million square kilometres, 1.67 million square kilometres below the 1981 to 2010 average extent for that month, represented by the magenta line. The Arctic, warming twice as fast as any other place on Earth, has been the quickest to respond to climate change. (National Snow and Ice Data Center) Hansen projected that by 2017, the globe's five-year average temperature would be about 1.03 C higher than the 1950-1980 NASA-calculated average. NASA's five-year average global temperature ending in 2017 was 0.82 degrees above the 30-year average. (He did not take into account that the sun would be cooling a tad, which would reduce warming nearly a tenth of a degree Celsius, said the Scripps Institution of Oceanography's Jeff Severinghaus.) Hansen also predicted a certain number of days of extreme weather — temperature above 35 C, freezing days, and nights when the temperatures don't drop below 24 C — per year for four U.S. cities in the 2010s. Hansen's forecast generally underestimated this decade's warming in Washington, overestimated it in Omaha, was about right in New York and mixed in Memphis. Clara Deser, climate analysis chief at the National Center for Atmospheric Research, said Hansen's global temperature forecast was "incredible" and his extremes for the cities were "astounding" in their accuracy. Berkeley Earth's Zeke Hausfather gives Hansen's predictions a 7 or 8 for accuracy, out of 10; he said Hansen calculated that the climate would respond a bit more to carbon dioxide than scientists now think. A move to advocacy University of Alabama Huntsville's John Christy, a favourite of those who downplay climate change, disagreed. Using mathematical formulas to examine Hansen's projections, he concluded: "Hansen's predictions were wrong as demonstrated by hypothesis testing." Hansen had testified before Congress on climate change at a fall 1987 hearing that didn't get much attention — likely because it was a cool day, he figured. So the next hearing was scheduled for the summer, and the weather added heat to Hansen's words. At 2 p.m., the temperature hit a record high 37 C and it felt like 39 C. Hansen gives a briefing, on global warming, on June 23, 2008, in Washington. In 1988, Hansen warned the world on a record hot June day that global warming was here and worsening. Later, he forecast how warm it would get, depending on emissions of heat-trapping gases. (AP Photo/Susan Walsh/Associated Press) It was then and there that Hansen went out on a limb and proclaimed that global warming was already here. Until then most scientists merely warned of future warming. He left NASA in 2013, devoting more time to his "anti-government job" of advocacy. Hansen, still at Columbia University, has been arrested five times for environmental protests. Each time, he had hoped to go to trial "to draw attention to the issues," but the cases were dropped. He writes about saving the planet for his grandchildren, including one who is suing the federal government over global warming inaction. His advocacy has been criticized by scientific colleagues, but he makes no apologies. "If scientists are not allowed to talk about the policy implications of the science, who is going to do that? People with financial interests?" Hansen asked. CBC's Journalistic Standards and Practices
Again the question isn't whether we are currently in a warming trend, especially in regards to the Northern Hemisphere, the question is what's causing it. The first step to answering that question has to be the get the science right.
That's correct. Formulate hypotheses, and test them. Shaviv's hypothesis was examined and reported in Scientific American years ago, "cosmic rays cannot account for more than 10% of the last century of warming", etc. As far as I know the only hypothesis left standing is increasing CO2 concentrations. I'd be willing to look at something, from a respected source, supporting the "urban heat island" hypothesis, but at a glance that one doesn't help much to explain the melting of Greenland, or the loss of ice mass (not extent) in Antarctica.
While you may be correct in your assertion, Scientific American is not an authoritative source for peer reviewed science research journal articles. Neither is Popular Science. Bill Nye. Do you have any peer reviewed journal articles to substantiate your claims for us to take a look at?