The Bray (Hallstatt) Cycle

By Andy May and Javier

The evidence for a persistent irregular climate cycle with a period of 2400 ±200 years is strong. There is compelling evidence of a solar cycle of about the same length and phase; suggesting that the solar cycle might be causing the climate cycle. We will present a summary of the evidence, beginning with the original paleontological evidence, followed by the cosmogenic radionuclide (10Be or Beryllium-10 and 14C or Carbon-14) evidence. For more information, a bibliography of many papers discussing topics relevant to the Bray (Hallstatt) cycle can be found here. Only a small portion of the relevant papers are mentioned in this summary post.

In the November 16, 1968 issue of Nature, James R. Bray first proposed the idea of a 2600-year solar-driven climate cycle based primarily upon evidence of Holocene global glacier advances and retreats. We prefer to call this period the Bray Cycle after him, but the same cycle is often called the Hallstatt Cycle. In this post, we will use both names interchangeably to refer both to the climate cycle and the solar cycle. Bray only considered the maximum advance of a glacier field or a major re-advance that reached the near vicinity of the maximum. He used glacier fields in North America, Greenland, Eurasia, New Zealand and South America in the study. The glacial advances were dated using tree rings, lichenometry and radiocarbon dating. Glacial events for the last 13,700 years suggested an optimum interval of 2600 years. He used a “solar index,” based upon sunspots, sunspot cycle length and auroral records that covered the period from 700BC to the present day to show the cause might be a solar cycle. Over this period, the chi-square statistic tied the glacial events to solar activity with a score of 28.6 (P<0.001).

One inescapable conclusion, from the evidence presented, is that solar variability is an important cause of climate change in the centennial to millennial time frame. Therefore, it must have contributed more to recent warming since the last Bray low ended at the end of the Little Ice Age than the IPCC suggests.

This post is in response to Willis Eschenbach’s posts entitled “Sharpening a Cyclical Shovel” and “The Cosmic Problem with Rays.” His posts were in response to our previous posts on natural climate cycles: Impact of the ~ 2400 yr solar cycle on climate and human societies, Periodicities in solar variability and climate change: A simple model, and Solar variability and the Earth’s climate.

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#bray-cycle, #climate-change, #hallstatt-cycle

Solar variability and the Earth’s climate

By Andy May

According to Javier and the IPCC total solar radiation output varies little, less than 0.1%. This is only 0.7 to 1.4 Watts/m2 and converted to incident radiation striking the Earth this is reduces to about 0.05 to 0.4 W/m^2.  The latter values can be compared to an IPCC anthropogenic effect estimate of 2.3 Watts/m. They believe it has a small effect on the Earth’s climate. Others, like Abdussamatov, think solar output is more variable, perhaps varying 3 Watts/m2 (their Figure 3). Other variable stars, similar to the sun, seem to have 3% dimming in their minima, which is certainly significant. Both of the latter two examples are larger than the IPCC estimate of man’s influence. We don’t want to get any further into this debate here other than to note the IPCC may be significantly underestimating the effect of solar and ocean cycles in their models. The key point is we don’t know what drives the Earth’s climate. There are a bewildering number of natural and man-made factors that influence it.

While variations in total solar irradiance (TSI) may be small, there is clear evidence that Earth/solar cycles affect our climate. This is discussed in detail by two well referenced posts by Javier here and here. While measured TSI variations are small, the solar UV (ultraviolet) output varies by up to 10%, this affects ozone heating in the stratosphere which may have an influence on the troposphere. The varying UV radiation from the sun and other solar impacts on climate are discussed by Dr. Isaac Held and others at an NRC workshop here.

An interesting quote from the NRC (National Research Council) workshop in 2013:

“In recent years, researchers have considered the possibility that the sun plays a role in global warming. After all, the sun is the main source of heat for our planet.”

Well duhhh! They follow this with the preposterous explanation that solar influence is regional, how exactly does that work? The sun is 109 times larger in diameter than the Earth and 93,000,000 miles away, how can its influence be regional? The Pacific Ocean covers almost one third of the Earth’s surface and 68% of the landmass is in the northern hemisphere; so changes in the surface that the solar radiation hits are bound to cause uneven warming in the short (hundreds or thousands of years) term. This fact does not mean incident solar radiation changes are regional any more than a tornado leaving two walls of a house standing only affected part of the house. As they correctly note, solar changes cause changes in precipitation and in air circulation. Uneven warming can be expected to do this. However, an uneven warming effect does not disprove solar-caused global warming. It just means global warming of a heterogeneous surface cannot occur evenly everywhere instantaneously. The main means of heat distribution are through water phase changes, that is evaporation, circulation and precipitation. The adjustment of the Earth’s surface to a change in solar activity takes a long time, thus we have long term ocean cycles like the 1,500-year cycle.

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Comparing early 20th Century warming to late 20th Century warming

By Andy May

This post was updated August 25, 2015 to clarify the text on sea surface temperatures, provide a correlation coefficient between the two warming periods and to discuss the Planck parameter.

Many writers, including Professor Richard Lindzen and Ed Caryl have noticed the remarkable similarity in global warming observed from around 1910 to 1944 and 1975 to 2009. The similarity in slopes exists in all global surface temperature datasets. Figure 1 shows the HadCRUT version 4 dataset and the NASA GISS land (GHCN v3) and ocean (ERSST v4) temperature dataset. We’ve identified the two periods of interest on the figure. All datasets also show some cooling between 1945 and 1975.

Figure 1

Figure 2 shows the two periods overlain with data from the HadCRUT version 4 dataset. This display is scaled to actual average temperature. Unlike Figure one this figure uses monthly smoothed data. In that way, we can see some of the variation within each year.

Figure 2

The left side of Figure 2 represents 1910 for the blue line and 1975 for the orange line. On average the earlier blue line is 0.36°C cooler than the later line. The later line also has a steeper slope, the earlier represents 0.144°C of warming per decade and the later line shows 0.192°C warming per decade. Figure 3 shows the yearly HadCRUT v4 anomalies from the mean with the two means forced to be the same.


Overlay of the two 20th century HadCRUT warming periods

Figure 3

Now we can easily see the similarity in the two warming periods. The linear correlation coefficient (also called the Pearson product moment correlation coefficient) between the two periods is 0.81, so they are highly correlated.  Yet the IPCC in their AR5 Summary for Policy Makers states on page 17:

“It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”

On page 14 of the Summary for Policy Makers they provide a description of the anthropogenic “radiative forcing” from man’s emissions and other actions. This is shown in Figure 4.

Figure 4

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#climate-change, #early-20th-century-warming, #ipcc

Review and Summary of “The Moral Case for Fossil Fuels”

By Andy May

The best-selling book The Moral Case for Fossil Fuels was first published November 27, 2014 by Penguin. The author, Alex Epstein, took a BA in Philosophy from Duke University in 2002. He is the President of the Center for Industrial Progress, a former fellow of the Ayn Rand Institute and an adjunct scholar at the Cato Institute. He was also named as one of the top 10 in Rolling Stone’s 2013 “Global Warming Denier Elite.” High praise indeed! He was fourth on the list.

Epstein presents a very well written discussion of the climate change debate. He destroys the 97% consensus myth, explains that the carbon dioxide greenhouse effect decreases logarithmically with concentration and shows that the climate computer models used to compute man’s influence on climate have never successfully predicted anything. He also shows that global warming has not increased extreme weather of any kind and that the dangers from extreme weather are less today than at any time in man’s history largely due to fossil fuels. He discusses Craig Idso’s pioneering research proving that increasing carbon dioxide acts as a powerful fertilizer for many plants. But readers of this review know these facts, so we will focus on his discussion of the merits of fossil fuels. He is a good writer and has superhuman skills at laying out a compelling logical argument. He would have put Daniel Webster and Clarence Darrow to shame. I highly recommend the book.

According to ExxonMobil’s 2016 report, in 2014 fossil fuels produced 82% of the energy in the world. Fossil fuels have produced more than 80% of the energy used in the US for over 100 years according to the EIA. They predict that in 2040 fossil fuels will still produce 78% of the world’s energy. Oil will grow at a 0.7% annual rate and natural gas will grow 1.6% per year. Coal will slightly decline. Yet, many in society think fossil fuels are bad for us and the world.

Figure 1: Energy demand in 2014 and 2040, by source

The book challenges this idea that fossil fuels have a negative effect on society. It is a fascinating, fact filled and well-reasoned discussion of the impact fossil fuels have had on our world since they were introduced on a mass scale over 120 years ago. There are 7 billion people on the Earth today and we are better fed, live better and longer than nearly every one of the 900 million people who lived in 1800. It is worth remembering that the average life expectancy, at birth, in 1800, in the UK was about 39 years. Epstein argues that with fossil fuels:

“We don’t take a safe environment and make it dangerous; we take a dangerous environment and make it far safer.”

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#climate-change, #value-of-gasoline

Using R and JAMSTEC NetCDF Files to Examine Ocean Temperatures

By Andy May

It doesn’t matter if you think fossil fuel CO2 emissions are going to end the world or lead us to a greener and more beautiful one. Either way, to be a true climate change geek you need access to climate data! Unfortunately, much of the climate raw and gridded raw data comes in a very difficult to read format called NetCDF. Worldwide temperature data is complex, the dimensions of climate arrays are latitude, longitude, depth (or the equivalent pressure in the atmosphere or ocean), year, and month. It is very hard to simplify it more than that. NetCDF does handle data of this complexity in a machine independent way, but you will not be able to read it with Excel. So how do we do this?

R is a wonderful statistical package that is free. It is very widely used and lots of books and websites offer help. It is not easy to learn, but with work you can get a lot out of it. You can download it here. If you plan on working with climate data I recommend the 64 bit version, which requires a 64 bit computer running 64 bit Windows. The arrays are very large, often larger than the 32 bit limit of 2 GB. Try and use a computer with at least 12 GB of memory. The computer I use for this work has 18 GB and runs 64 bit Windows 10.

You can use the gui or text based interface built into R for all of your work, but I’ve found that RStudio is a better environment. RStudio can be downloaded here. It is also free for personal use. There are numerous books on R and I’ve certainly not read them all, but two books stand out for most R users. A good beginning book is R for Dummies. Once you’ve gotten started and you want to get in deeper you will need The R Book. R has powerful map making modules, called “packages,” and you will want to learn them, start here.

The NetCDF files we will be working with contain the JAMSTEC MOAA GPV worldwide grid of ocean temperatures to 2000 meters. You will want to download all of the files with names like “”. There are 176 files to download so I suggest using an ftp utility that offers multiple file downloading like Filezilla, which is also free. Each file contains the temperatures for one month, for example contains a world-wide grid of ocean temperatures from the surface to a depth of 2,000 meters for August, 2015.

JAMSTEC Ocean Temperature Dataset overview

The final lines of the R program described below build a summary matrix “MTYr” that holds the yearly mean global temperatures for 25 depths. Below is a plot of ocean depth versus temperature for 2001, 2005, 2010, and 2014 from the summary matrix.

The lines are indistinguishable at this scale below 100 meters. According to the JAMSTEC MILA-GPV grid, which can also be downloaded and read with a similar R program, the average mixed layer depth is about 59 meters. The mixed layer begins immediately below the surface layer, which is affected by the “skin” layer. The skin layer is less than a millimeter thick, but it can affect the surface water temperature down to 10 meters or so in some conditions during the daylight hours. Below 10 meters we encounter the sea surface foundation temperature.

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#climate-change, #jamstec, #netcdf, #ocean-temperatures, #r

The Exxon Climate Papers

New York Attorney General Eric T. Schneiderman has accused ExxonMobil of lying to the public and investors about the risks of climate change according to the NY Times and has launched an investigation and issued a subpoena demanding extensive financial records, emails and other documents. Massachusetts, the US Virgin Islands, and California are also investigating ExxonMobil. It is interesting that all but one of the attorneys general are Democrats. The remaining attorney general is Claude Walker of the US Virgin Islands who is a Green leaning Independent. So, this is a very partisan investigation, carefully coordinated with anti-fossil fuel activists. How much is there to it?

I’ve reviewed the 22 internal documents from 1977 to 1989 made available by ExxonMobil here. I’ve also reviewed what I could find on 104 publications (most are peer-reviewed) with ExxonMobil personnel as authors or co-authors. For some of the peer-reviewed articles I only had an abstract and for some I could find the reference but no abstract or text without paying a fee. Below this short essay is an annotated bibliography of all 22 internal documents and 89 of the published papers. The documents are interesting reading, they fill in the history of modern climate science very well. Much of the current debate on climate change was being debated in the same way, and often with the same uncertainties, in 1977.

Between 1977 and the fifth IPCC report in 2013 ExxonMobil Corporate Research in New Jersey investigated the effect of increasing CO2 on climate. If they withheld or suppressed climate research from the public or shareholders, it is not apparent in these documents. Further, if they found any definitive evidence of an impending man-made climate catastrophe, I didn’t see it. The climate researchers at ExxonMobil participated in the second, third, fourth and fifth IPCC assessment reports making major contributions in mapping the carbon cycle and in climate modeling. They calculated the potential impact of man-made CO2 in several publications. They investigated methods of sequestering CO2 and adapting to climate change. They also investigated several potential biofuels.

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#climate-change, #climate-sensitivity, #investigation-of-exxonmobil-on-climate-change

Climate and Human Civilization over the last 18,000 years, updated

By Andy May

This is an updated timeline of climatic events and human history for the last 18,000 years. The original timeline was posted in 2013. The updated full size (Ansi E size or 34×44 inches) Adobe Reader version 8 PDF can be downloaded here or by clicking on Figure 1. It prints pretty well on 11×17 inch paper and very well on 17×22 inch paper or larger. To see the timeline in full resolution or to print it, you must download it. It is not copyrighted, but please acknowledge the author if you use it.

Figure 1

References to the images and data are given in this essay as hyperlinks. I’ve done my best to verify the accuracy of the content by checking multiple sources. When references had different dates for the same event, I chose the most commonly cited date or the most prestigious source. All dates (except some in the modern era) are given as “BP” or before the year 2000 for simplicity, using 1950 (the radiocarbon zero) was too cumbersome.

The heart of the poster is the timeline of historical and climatic events. The Last Glacial Maximum (LGM) ended around 19,000 BP, the illustrations on the lower left of the poster illustrate what the world was like then. Much of the land area of the world was under ice or desert at the time and the exposed land had less precipitation than we do today.

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#climate-change, #milankovitch-cycles, #younger-dryas