A few lucky souls have stumbled on diamonds in glacial debris around the Great Lakes and further north into Canada for centuries.  Geologists have known that the sources of those diamonds represented a vast wealth of hidden treasure somewhere in the frozen tundra of northern Canada, but it was not until the late 1980s that a couple of cowboy geologists, Chuck Fipke and Stewart Blusson, painstakingly ferreted their way back to the source. But I am getting way ahead of the story.

Diamonds are brought to the surface from deep within the upper mantle via unusual igneous rocks called kimberlites (and sometimes lamproites).   I recognize I run the risk of losing my readers by delving into the nature of kimberlites, but to a geologist like myself kimberlites are crazy types of rocks.  Typical magmas (and lavas) like basalt form by partial melting of the mantle.  Kimberlites, on the other hand, are geologically unique because although they form from partial melting of the mantle, the melting is significant enough for these rocks to resemble compositionally (not precisely) the mantle itself.  They are referred to as ultramafic rocks as compared with basalts which are mafic (mafic means rich in magnesium and iron – two of the most abundant elements in the mantle).

Diamonds actually don’t form in kimberlites.  Think of kimberlites as a conveyor belt bringing diamonds that form under high temperatures and pressures (from about 125 to 175 kilometers1) to the surface relatively fast, before they can reequilibrate (breakdown) into other compounds like graphite or carbon dioxide.  Diamonds are not forever.  Many an exploration program has had its hopes dashed with the discovery of kimberlite full of octahedral or other cubic forms of graphite — degraded diamonds2.

Exploration for diamonds can be excruciatingly frustrating.  There are 6,400 known kimberlite pipes worldwide but only 30 or so have become viable mines — that’s about 0.5% chance that a discovered kimberlite will turn into a producing mine.  It’s true, diamondniferous kimberlites are hard to find, but you don’t need many diamonds to make a mine.  High-grade diamond kimberlites only contain a few carats per ton of rock.  That’s enough to make any geologist rich beyond her dreams.  Kimberlites form at greater than 200 kilometer depths (200 to 600 km) and are enriched in volatiles (e.g., carbon dioxide and water) that make the magmas not only buoyant but explosive.  They literally “blow” through the upper mantle and crust in perhaps a matter of hours (rates postulated are about 14 km/hr) forming carrot-shaped pipes called diatremes (see the diagram below).  The faster the better for diamond preservation.  But they also have to pick diamonds up along the way or incorporate them as the magma forms.  Kimberlites can contain as much as 25 to 50 percent rock within their magma acting as an elevator to the surface for mantle material helping geologists understand the mantle3.

VolcanicPipeAsbestos Wikipedia

After half a century or more of serious diamond exploration. we have learned that diamond-bearing kimberlites form below the cratons.  The cratons are the ancient regions of continents containing rocks greater than 2 billion years old.  There is still great debate about how the cratons formed, but every continent is rooted in these ancient environs.   If you are looking for diamonds, go to the cratons.  Before the 1980s, diamond kimberlite mines had been developed on every craton of all the continents except Antarctica and North America.  Diamonds come from two major sources: mantle rock (e.g., peridotite) and eclogite (metamorphosed basalt).  Diamond formation in peridotites occurred primarily in the Archean centered on a time about 3 to 3.3 billion years ago but some dates are as young as 1.9 billion years ago.  Eclogite diamonds tend to be younger from 1 to 2.9 billion years ago.

Where does the carbon come from to form diamonds?  No one knows for sure, but most researchers think that the carbon along with sediments and volatiles were subducted through plate tectonics (the ecologites brought up by kimberlites are likely ancient subducted ocean floor)4.  I am interested, through my own research, on how the cratons formed and when subduction began.  Many geologists pooh-pooh the idea that subduction could have begun so early in earth history so it is satisfying to see how diamond research supports the early existence of plate tectonics and subduction.  My colleagues and I have contended for years that the cratons are the result of ancient subduction.

Imagine Chuck Fipke in the 1980s looking out over the vast expanses of northern Canada contemplating all the diamonds he believed had to be out there in the craton hidden below tons of glacial deposits.  Those damnable glacial deposits were the reason no one had discovered pipes in Canada5.  The map below shows the furthest extent of the glaciers 17,000 years ago and the site of the diamond pipes eventually discovered.  Fipke also had to contend with De Beers, the giant cartel that controlled the world’s diamond markets. They were actively exploring with their practically unlimited resources.  I worked for De Beers as a consulting geologist for a time in the mid 1990s in Russia, and I can assure you, they are a force to be reckoned with.

diamond countryBase map from Wikipeida

By the mid 1980s, geologists had discovered that the mantle material brought up by kimberlites could aid them in their exploration thanks to a geochemist named John J. Gurney at the University of Capetown.  Diamonds form in equilibrium at specific temperatures and pressures with other minerals more abundant than diamonds.  Gurney, funded by Superior Oil, analyzed extensive mineral assemblages from kimberlites with and without diamonds and found that there are chemical signatures in the minerals that show up when diamonds are present.   One of the more famous diagrams is that of the chromium and calcium concentrations in garnets from the mineral assemblages.  Garnets fall into two groups on the diagram called G10 and G9 and virtually all garnets that occur with diamonds fall within the G10 field shown below.  As mentioned before, diamonds can reequilibrate in kimberlites and become graphite or evaporate away as carbon dioxide.  The diagram shows the line of stability under chromium saturation where diamonds will breakdown.  Some diamonds remain stable in the graphite field because the conditions do not last long enough to degrade the diamonds.  But if G10 garnets fall above the diamond-graphite equilibrium line it is a pretty sure bet you are on the right track for diamondiferous kimberlites.  And that is precisely what Fipke kept finding in in his samples of glacial debris as he flew along with Blusson (who not only has a PhD but is a pilot) periodically sampling them.  The long-gone glaciers were pointing the way.

garnetAfter Nowicki et al., 2007

At the time in the mid 1980s, geologist understood the relationships between these indicator minerals and diamonds, but how could the information be used to find the kimberlites in the Canadian craton?  What was unique about Fipke and his partner Blusson was the way they approached the problem.  They knew that the glaciers were powerful enough to gouge out the relatively soft kimberlite and carry the indicator minerals long distances destroying any signs of the kimberlites at the surface and subsequently burying them under debris carried by the glaciers when they melted.  They reasoned that they might be able to sample glacial deposits and “walk” the indicator minerals back to their source.  Standard Oil liked the idea and funded their exploration at first.  No one knew then that it would take eight years, millions of exploration dollars, and several companies before they hit pay dirt.  De Beer’s geologists also knew the answer was in the glacial remains, but to them it was a nine to five job and the season ended after 8 weeks of summer collecting.  For Fipke, it was a life’s dream, and nothing terminated his resolve collecting well into the cold months of the far north.

Fipke and Blusson focused on eskers (see the esker shown below) which are sinuous ridges of stratified sand and gravel deposited by water flowing in tunnels of ice within or under the glaciers.  As the glaciers recede the ridges remain like compasses indicative of the direction the water and ice once flowed.  If the glaciers rumbled over kimberlites, the proof would be in the streams that carried the glacial till away.   They kept going even after Standard Oil called it quits.  The G10 garnets kept telling them they were on the right road and the mining giant BHP believed them when they began running out of money.  Dia Met, the company Fipke and Blusson formed, signed a sweet deal with BHP.  BHP agreed to fund the exploration for a 51% stake.  Within six months after teaming with BHP, Fipke had come to a point where the G10 garnets disappeared near Lac de Gras.  Fipke knew he was close to the source.  As the story goes, he noticed a lake from the air that looked like it sat in a bowl-shaped depression near where the G10 garnets disappeared.  He had to have a sample of the rock in that depression.  They landed the plane on the lake, rowed to shore, and started to dig, but after many hours they were still in glacial till.  They decided to walk the shoreline for a better place to dig.  That is when Fipke’s son Mark, found a piece of kimberlite.  They were all ecstatic — the lake must sit on the pipe.  Gurney eventually analyzed the mineral assemblage and verified that it was highly likely to be a diamond-bearing kimberlite.  BHP quickly flew a geophysical survey which showed a distinct structure below the lake.

FulufjalleteskerEsker in Sweden (Hanna Lokrantz Wikipedia)

BHP and Dia Met started quietly staking as much land around the lake as they could.  Kimberlite pipes frequently occur in bundles so it was imperative that they obtain rights to as large a region as possible before word got out of the find.  While they were staking, BHP flew a drill rig in by helicopter and cored 455 feet under the lake pulling out beautiful samples of kimberlite 33 feet below the glacial debris with 80 plus small diamonds. Canadian law requires that companies announce to their shareholders when a potentially profitable body is found.  On November 12, 1991 they announced the results from the core including the fact that a few gem-quality diamonds had been recovered from the core.  All hell broke loose, and the rush was on by large and small companies alike to stake as close to BHP’s claims as possible in the hopes that other pipes might be buried nearby.   BHP would go on to discover more than 150 kimberlite pipes helping to make Canada the third largest producer of diamonds in the world.  De Beers even found a few mines.  Fipke and Blusson became billionaires overnight (if you don’t count the 8 years of exploration).

The image below shows the Etaki mine – one of the producing mines staked within Fipke’s original claims.   The large circular depressions in kmberlite represent part of the open-pit mining operations BHP is running.

Untitled-1 copyEkati mines from the air (Google Maps)

  1. Shirey, S. B. and Richardson, S. H. (2011) Start of the Wilson Cycle at 3 Ga shown by diamonds from subcontinental mantle: Science 333, 434-436
  2. Pearson, D. G., Davies, G. R., Nixon, P. H., and Milledge, H. (1989) Graphitized diamonds from a peridotite massif in Morocco and implications for anomalous diamond occurrences: Nature, 338, 60-62
  3. Russell, J. K., Porritt, L. A., and Hilchie, L. (2013) Kimberlite: rapid ascent of lithospherically modified carbonatitic melts: In Pearson, D. G. et al, Proceedings of 10th International Kimberlite Conference Vol. 1 p. 195-210
  4. Nowicki, T. E., et al. (2007) Diamonds and associated heavy minerals in kimberlite: A review of key concepts and applications: Developments in Sedimentology, 58, 1235-1267
  5. Cross, L. D. (2011) Treasure Under the Tundra: Canada’s Arctic Diamonds: Heritage House Publishing Co

Last summer I attended the annual fourth of July parade in our local town with my family.  We enjoy watching the floats, pageantry (I am embellishing a bit here), and the copious quantities of candy thrown at us.  Nearly every local business has a float — well a truck with the company name on it serves as a float in many instances.  The local politicians, constabulary, high-school marching bands, queens of various vegetable festivals, local junior baseball teams, etc. join the queue.  The obligatory paper advertisements are handed out by the business participants lauding their merchandise.

During the parade, I had a paper shoved in my face about the problems with genetically modified organisms (GMOs).  I had just heard a wonderful Ted talk about how safe GMOs were by genetic scientist Pamela Ronald so the proclamation caught my attention.  I realized that the polemic was being passed out by a local health-food store.  There was an obvious conflict of interest – by creating suspicions that GMOs were unhealthy or even harmful the store benefited by encouraging people to buy the non GMOs they sold.  Disinformation to make a buck?  The World Health Organization, the United Nations Development Programme, National Academy of Sciences (US), American Medical Association, American Association for the Advancement of Science, Food and Drug Administration, American Cancer Society, and more than 270 other prestigious groups including many Academy of Sciences in other countries have gone on record through numerous reports that GMOs are safe.

I spent a bit of time in my last essay on global warming bemoaning how the subject has become a political hot potato because of disinformation by Exxon (and I mentioned other examples such as Big Tobacco, the National Football League with concussions, and creationists).  Was the radical left on a disinformation campaign also?  It certainly appears so.  As a scientist I know how difficult it is to achieve a consensus on a hypothesis.  Scientists have no time for unsupported opinions – they demand empirically supported results.  I don’t deny that politics plays a role, but I like to think, at the end of the day, that the accepted theories that make it through the labyrinth of scientific scrutiny are extremely sound.  Let’s not forget that scientists have egos and you get intellectual brownie points for debunking someone’s work.  It’s a jungle out there as I have discovered first hand as a research professor.  When I see the community of scientists fundamentally agreeing on a topic, I find it fairly convincing (scientists agreeing is an amazing thing in itself).  I don’t mean to imply that science cannot make mistakes – there are some notorious examples.  But I cannot think of a better way to make educated decisions – based on the research from the experts in the scientific community.  Unsupported opinions just don’t cut it even if the people are well meaning.

The case of Golden Rice demonstrates the horrendous impact anti-GMO groups can have in a rush to prevent GMOs from reaching the marketplace1.  According to Scientific American Golden Rice had passed the health and safety issues for commercial use by 2002.  Syngenta had genetically engineered Vitamin A from corn (beta-carotine) into rice.  Syngenta altruistically turned over all the monetary interests for the use of the rice to a non-profit organization to avoid any interference from anti-GMO groups that fight biotech companies for profiting on GMOs.  The only hurdle left was regulatory approval.  In 2015, Golden Rice was among seven products that won the Patents for Humanity award, but the rice is still not in use anywhere (The Golden Rice Now advocacy group tells me that the Philippines and Bangladesh are expected to have Golden Rice available in 12 months – some time in the middle of 2017).  Amazingly, the life-saving rice is strenuously opposed by environmental and anti-globalization activists who object to GMOs.

!1280px-Golden_RiceInternational Rice Research Institute (IRRI)

In 2014, Justus Wesseler of the Technische Universität München and David Zilberman of the University of California quantified the economic impact caused by the resistance2.  They estimate that at least $199 million dollars were lost per year over the previous decade just in India.  They likened the loss to a metric called life years which they calculated to be 1.4 million in India alone which reflects deaths, blindness and related health disabilities from not having access to Vitamin A.  Unfortunately children are the hardest hit.

I want to emphasize that the Golden Rice case is more than a battle over perceived danger by the anti-GMO movement in the face of contrary scientific evidence.  There are people dying while Greenpeace, the Sierra Club, and other misguided organizations wage war over unclear principles and leftists ideals.  And of course there is always the Non-GMO Project which was created by health-food retailers to sow seeds of doubt (I don’t know if the pun was intended or not) “who oppose a technology that just happens to threaten their profits” according to Scientific American.  I should make it clear that my criticism of Greenpeace and the Sierra Club is not done lightly.  They serve a real purpose in helping to preserve our environment.  But when the science argues against them and lives are at stake, we need to bring them to task.  Let me dive into the science that argues against radical and mindless battles over GMOs.

The National Academy of Sciences has just released a consensus 407-page report entitled Genetically Engineered Crops: Experiences and Prospects which reviewed decades of research on genetically engineered (GE) crops.  Their conclusions find that GE crops are economically beneficial, safe for humans and livestock, and have adequate regulation.  The data is overwhelming impressive and I will take the time to summarize some of the major points.

Humans have been modifying crops for 10,000 years.  A good example is the domestication of maize in Meso-America.  Teosinite, shown in the left of the diagram below, is a grass that went through a series of human selections of rare mutations to develop modern-day maize grown throughout the world (shown in the right part of the diagram).  The point is that humans have been modifying crops through selection of beneficial traits for millennia.

cornNAS

In 1985, the United States was the first country to approve a GE crop, and by 1994 a GE tomato, which delayed ripening, was produced for sale.  Through 2015 about 12 percent of the land available for crop production contains GE crops (the number goes to 50% in the US).  The figure below shows which GE crops are currently being produced and where.  Europe, Russia, and most of Africa have been particularly resistant to GE crops as you can see from the map.

gmoNAS

There are three major types of GE crops: 1) Herbicide resistant traits which allow the crop to survive herbicide application to kill weeds or insects.  2) Insect resistant traits which typically incorporate a gene code from Bacillum thuringiensis (Bt) to the crop, killing insects when they feed on the plant.  3) Virus resistant traits which keep the plants from being susceptible to specific plant viruses.  It is important to note that most of the crops are modified to resist one insect, virus, or herbicide.  Drought tolerance, nonbrowning (e.g., with potatoes and apples), various colors in flowers, stability of oil to suppress trans-fats, enhancement of omega-3 fatty acids are other examples of GE traits in commercial production.

The NAS report reviews studies conducted comparing the production of  GE crops to non-GE crops in mind-numbing detail.  But some clear important conclusions have been summarized below (I quote to avoid any misrepresentation of the information).  Please note that I have not included all the findings because many are quite esoteric.  I refer the reader to the NAS report for more details.

  1. “Although results are variable, Bt traits available in commercial crops from introduction in 1996 to 2015 have in many locations contributed to a statistically significant reduction in the gap between actual yield and potential yield when targeted insect pests caused substantial damage to non-GE varieties and synthetic chemicals did not provide practical control.”  Potential yield is the theoretical yield a crop could achieve if water and other nutrients are in adequate supply and there are no losses to pests and disease.
  2. “In areas of the United States where adoption of Bt maize or Bt cotton is high, there is statistical evidence that insect-pest populations are reduced regionally, and the reductions benefit both adopters and nonadopters of Bt crops.”
  3. “In all cases examined, use of Bt crop varieties reduced application of synthetic insecticides in those fields. In some cases, the use of Bt crop varieties has also been associated with reduced use of insecticides in fields with non-Bt varieties of the crop and other crops.”
  4. “The widespread deployment of crops with Bt toxins has decreased some insect-pest populations to the point where it is economically realistic to increase plantings of crop varieties without a Bt toxin that targets these pests. Planting varieties without Bt under those circumstances would delay evolution of resistance further.”
  5. “Planting of Bt varieties of crops tends to result in higher insect biodiversity than planting of similar varieties without the Bt trait that are treated with synthetic insecticides.”
  6. “Although gene flow has occurred, no examples have demonstrated an adverse environmental effect of gene flow from a GE crop to a wild, related plant species.”
  7. “Crop plants naturally produce an array of chemicals that protect against herbivores and pathogens. Some of these chemicals can be toxic to humans when consumed in large amounts.” I emphasized naturally here because the statement pertains to the production of chemicals by non-GE crops.
  8. “Conventional breeding and genetic engineering can cause unintended changes in the presence and concentrations of secondary metabolites.”  This is not only important but emphasizes the need for oversight in the approval of GE crops.  However, NAS also concluded: “U.S. regulatory assessment of GE herbicide-resistant crops is conducted by USDA, and by
    FDA when the crop can be consumed, while the herbicides are assessed by EPA when there are new potential exposures.”
  9. Regarding safety, NAS concluded: “In addition to experimental data, long-term data on the health and feed-conversion efficiency of livestock that span a period before and after introduction of GE crops show no adverse effects on these measures associated with introduction of GE feed. Such data test for correlations that are relevant to assessment of human health effects, but they do not examine cause and effect.”  In others words, GE crops appear to be safe for the animals that consume them and for humans that consume either these animals or the GE crops directly.
  10. “The incidence of a variety of cancer types in the United States has changed over time, but the changes do not appear to be associated with the switch to consumption of GE foods. Furthermore, patterns of change in cancer incidence in the United States are generally similar to those in the United Kingdom and Europe, where diets contain much lower amounts of food derived from GE crops. The data do not support the assertion that cancer rates have increased because of consumption of products of GE crops.”
  11. “The committee found no published evidence to support the hypothesis that the consumption of GE goods has caused higher U.S. rates of obesity or type II diabetes.”
  12. “The committee could find no published evidence supporting the hypothesis that GE foods generate unique gene or protein fragments that would affect the body.”
  13. “The committee did not find a relationship between consumption of GE foods and the increase in prevalence of food allergies.”
  14. “The similarity in patterns of increase in autism spectrum disorder in children in the United States, where GE foods are commonly eaten, and the United Kingdom, where GE foods are rarely eaten, does not support the hypothesis of a link between eating GE foods and prevalence of autism spectrum disorder.”
  15. “On the basis of its understanding of the process required for horizontal gene transfer from plants to animals and data on GE organisms, the committee concludes that horizontal gene transfer from GE crops or conventional crops to humans does not pose a substantial health risk.”
  16. “The available evidence indicates that GE soybean, cotton, and maize have generally had favorable outcomes in economic returns to producers who have adopted these crops, but there is high heterogeneity in outcomes.”
  17. “Exploitation of inherent biological processes—DNA binding-zinc finger proteins (ZFNs), pathogen-directed transcription of host genes (TALEs), and targeted degradation of DNA sequences (CRISPR/Cas)—now permit precise and versatile manipulation of DNA in plants.”
  18. “New molecular tools are further blurring the distinction between genetic modifications made with conventional breeding and those made with genetic engineering.”
  19. “Treating genetic engineering and conventional breeding as competing approaches is a false dichotomy; more progress in crop improvement could be brought about by using both conventional breeding and genetic engineering than by using either alone.”
  20. “In some cases, genetic engineering is the only avenue for creating a particular trait. That should not undervalue the importance of conventional breeding in cases in which sufficient genetic variation is present in existing germplasm collections, especially when a trait is controlled by many genes.”
  21. “Although genome editing is a new technique and its regulatory status was unclear at the time the committee was writing this report, the committee expects that its potential use in crop improvement in the coming decades will be substantial.”  I think this is an extremely important conclusion.  If we want to continue to feed the world we are probably going to become more dependent on GE crops particularly if population continues to increase at present rates.
  22. “Genetic engineering can be used to develop crop resistance to plant pathogens with potential to reduce losses for farmers in both developed and developing countries.”
  23. “Genetic engineering can enhance the ability to increase the nutritional quality and decrease antinutrients of crop plants.”
  1. There are similar accounts of environmental groups shutting down a genetically modified eggplant in India, Bangladesh, and the Philippines.  Another involved a genetically modified potato which was resistant to specific herbicides.  A large food chain under pressure from environmental groups refused to purchase genetically modified potatoes and the project was shut down.  Farmers then introduced a new herbicide for the non-genetically modified potatoes grown instead
  2. Wesseler, J. and Zilberman, D. (2014) The economic power of the Golden Rice opposition: Environmental and Development Economics: 19, 724-742

Disinformation has become a hallmark of companies and religious sects interested in undermining science.  Please note that I have used disinformation instead of misinformation because these organizations have purposefully spread wrong or bad information to mislead the public and cloud issues discovered by science.  The most famous example comes from the tobacco industry.  Richard Kluger’s book Ashes to Ashes1 won the Pulitzer prize and helped expose the ruse that nicotine is not harmful or addictive.   The tobacco industry funded hundreds of scientific research projects in an attempt to muddy the waters concerning the health risks of smoking.  Who will ever forget the seven CEOs of America’s largest tobacco companies swearing in front of Congress in 1994 that nicotine is not addictive (still on Youtube if you care to reminisce).   One of the leading examples of the travesty was the funding of the Harvard Center for Tobacco Research.  Big Tobacco, through its Council for Tobacco Research, gave millions of dollars to the Center and Dr. Gary Huber2

In a more recent exposé, Mark Fainaru-Wada and Steve Fainaru showed in their book League of Denial how the National Football League actively downplayed the seriousness of trauma to the head3.  For example, to offset concern over head injuries, the NFL and commissioner Paul Tagliabue set up the Mild Traumatic Brain Injury Committee (MTBI) in 1994.  The committee was notorious for denying that concussions did not lead to serious effects.  In 2003, the committee began publishing what would amount to 16 research papers in the coopted science journal Neurosurgery, supporting their contention that the concussion problem was minor.  It certainly helped that the Neurosurgery editor, Michael L. J. Apuzzo, was a major NFL fan4.  The MTBI fuzzy logic included statements such as: “A total of 92% of concussed players returned to practice in less than seven days … More than one-half of the players returned to play within one day, and symptoms resolved in a short time in the vast majority of cases.”   During the same period independent research was discovering chronic traumatic encephalopathy (CTE) in the brains of deceased football players that had suffered numerous concussions throughout their careers.

Then there is the whole creationist movement which has attempted to undermine science through such organizations as the Institute for Creation Research.  There is neither space nor time to delve into the movement’s attempts to promote creationism and more recently intelligent design.   If you want to read a riveting account of one of the recent battle fronts pick up a copy of Monkey Girl by Edward Humes5.  It documents the attempt by the Dover School Board to demand the teaching of intelligent design in science classes which resulted in Kitzmiller v. Dover Area School District legal brouhaha.

Does this sound familiar?  Exxon (now ExxonMobile) formed the Global Climate Coalition in the 1980s to lobby congress and actively dispute the claim that global warming was not caused by anthropic greenhouse gases6.  The organization shut down in 2001 under pressure from numerous groups, but by then, the term global warming had morphed into a political issue entrenched in right-wing politics.    But the time may be coming for ExxonMobile to pay up for its disinformation campaign.  More than a dozen state attorney generals are investigating ExxonMobile for attempting to obfuscate the facts about global warming.  The New York Times reported in March that new documents published by the activist group Center for International Environmental Law shows that  Exxon knew about the dangers of global warming from carbon dioxide through its own research as far back as 1957 and established a campaign that doggedly fought air pollution control.

Admittedly, politics always baffles me.  The science of global warming via anthropic greenhouse gases seems so obvious that I have trouble seeing how the issue could become such a heated-cantankerous argument.  Let me briefly outline the science and you decide.  I have no ax to grind in the debate.  I tend to favor middle of the road solutions.  What I am more interested in is how the issue could ever become hijacked by politics.  If you are the kind of person whose eyes glaze over when you see graphs, hang in there because it is all pretty straight forward.  Before we dig in, let me remind you of a phrase Thomas Henry Huxley, known as Darwin’s bulldog, said: “My business is to teach my aspirations to conform themselves to fact, not to try and make facts harmonize with my aspirations… Sit down before fact as a little child, be prepared to give up every preconceived notion, follow humbly wherever and to whatever abysses nature leads, or you shall learn nothing.”

Wavelength is plotted below on the x-axis (which is broken down into UV, visible, and infrared radiation) and the spectral intensity is plotted on the y-axis.  The red curve (top panel) represents the span of wavelengths transmitted by the sun and received at the top of the earth’s atmosphere.  Scientists refer to the electromagnetic radiation that comes from the sun as Planck black body radiation because they can reproduce it by heating an opaque non-reflective body (a black body) to a temperature of 5,525 degrees Kelvin.  The red region represents the extent of radiation that is received at the earth’s surface (i.e., not absorbed).  Note that most of the UV radiation is absorbed by the atmosphere (mostly due to the ozone layer fortunately) and most of the visible spectrum gets through.  Animals have evolved to “see” in the visible spectrum almost certainly because light comes to us in this range of the spectrum.

Atmospheric_TransmissionGlobal Warming Art, Wikipedia

The average Planck black body radiation of the earth is represented by the blue curve (255 degrees Kelvin)7   The blue area filled in under the blue curve is the amount of radiation from the earth that escapes into space (emitted by the top of the atmosphere) which is equal to about 15 to 30% transmission.  Virtually all of the near to far infrared is absorbed by greenhouse gasses shown in the panels in the above diagram for each of the gases.  Water plays the biggest role but carbon dioxide has an impact on the far infrared.  You can see this better in the diagram below.

CO2_H2O_absorption_atmospheric_gases_unique_pattern_energy_wavelengths_of_energy_transparent_to_othersNASA

Relatively small increases in carbon dioxide have a profound affect on the absorption of radiation (energy).  In fact, it is so sensitive that carbon dioxide closely follows the temperature changes during the past glacial cycles — the last 420,000 years are shown below.  As you can see, we are in an interglacial warming period and, under normal nonanthropic conditions would expect to enter another ice age in about 10,000 years8.  I should mention that carbon dioxide concentrations were measured from Vostock ice cores taken from Antarctica (the ice traps air bubbles locking in atmospheric concentrations).  Temperatures in the same cores were determined from hydrogen and oxygen isotopes9 10.

co2 NASA/NOAA

Now here is one of the most astounding graphs in environmental science – carbon dioxide and temperature over about the last 20,000 years11.   It shows global temperature in the blue curve relative to the Holocene mean between 6.5 and 11.5 thousand years ago (LGM is the last glacial maximum).  The red curve is an Antarctic composite core temperature profile.  Carbon dioxide concentrations (yellow dots) start to rise as we come out of the last glacial cycle along with temperature about 18,000 years ago and continue to rise until about 8,000 years ago when they become stable (temperature – red curve – and carbon dioxide in the cores lag a bit behind global temperature – blue curve).  Note that carbon dioxide concentrations have stabilized at about 260 ppm (parts per million) over the last 8,000 years or more (the current carbon dioxide changes are too new to be picked up in the cores).

natureShakun et al., 2012

Compare the graphs above to the carbon dioxide data measured directly from Hawaii since 1957 below.  The concentrations went above 400 ppm in 2015 (the annual variations are due to higher output in carbon dioxide by vegetation during the summer in the northern hemisphere – more land in the north), 140 ppm over the average of the last 8,000 years shown in the above diagram.  It is important to point out that carbon dioxide concentrations have not reached this level in more than 3 million years12!

co2_data_mlo

And here is why scientists think that humans are responsible for most of the carbon dioxide increase.  The graph is of temperature from 1880 (annual mean compared to the average between 1951 to 1980).  The red line is a five-year running average.  Temperature begins to increase significantly when carbon dioxide concentrations reach about 340 ppm in the mid 1970s.   The Intergovernmental Panel on Climate Change won the Nobel Peace Prize in 2007 and consists of thousands of the world’s finest scientific minds contributing to their reports.  The IPCC Fifth Assessment Report which was completed in 2014, stated: “It is extremely likely [90 to 100% probability in their words] that human influence has been the dominant cause of observed warming since 1950, with the level of confidence having increased since the fourth report”.

Global_Temperature_Anomaly.svgNASA

So why all the fuss?  Even if we admit that carbon dioxide and global temperatures are rising (and they are also rising in the ocean because carbon dioxide and heat are absorbed from the atmosphere), is this devastating for the future of the world?  To be honest, no one knows for sure.  I could list a plethora of examples of the impact from these changes – sea level rise, species habitats being pushed toward higher latitudes or higher elevations worldwide, ocean acidity, continued melting of the world’s glaciers, etc.   But the data that keeps me up at night (being overly dramatic here) is the tipping point.  Climate models show global temperatures rising between 1 to 2.5 degrees centigrade (1.8 to 4.5 degrees F) between 2050 and 2100.  We don’t know what might throw us into a tipping point – what Wagner and Weitzman call “tail effects” or “black swans” to designate statically low probability extreme events13.  They are referred to as tail events because they occur on the ends of a bell distribution curve (less than 2.1% in the figure below – greater than 2 standard deviations).  These events will be so potentially horrendous that we may not know how to combat them.

Wagner and Weitzman claim that tail events are “profound earth-as-we-know-it-altering changes”.  For example, they may lead to as much as a 30 percent decline in global economic output.  No one knows.  The only thing that is certain is that if we continue to ignore global warming and its effects, we are taking huge potential risks.

Standard_deviation_diagram.svgWikipedia

  1. Kluger, R. (1996) Ashes to Ashes: America’s Hundred-Year Cigarette War, the Public Health, and the Unabashed Triumph of Philip Morris: Vintage
  2. McGarity, T. O. and Wagner, W. E. (2012) Bending Science: How Special Interests Corrupt Public Health Research: Harvard University Press
  3. Fainaru-Wada, M. and Fainaru, S. (2013) League of Denial: Three Rivers Press
  4. Fainaru-Wada and Fainaru suggest that Apuzzo was drawn to the limelight of the NFL as the major reason for allowing dubious papers to be published by the MTBI
  5. Humes, E. (2007) Monkey Girl: HarperCollins Publishers
  6. The CCC was a major opponent to the Kyoto Protocol and was instrumental in persuading the US not to sign it
  7. The black curve is the upper atmosphere at 210 degrees Kelvin and the purple curve is the lower atmosphere near the earth’s surface at 310 degrees Kelvin.
  8. Novacek, M. (2007) Terra: Our 100-Million-Year-Old Ecosystem — and the Threats That Now Put It at Risk: Farrar, Straus and Giroux
  9. The ratio of hydrogen isotopes has a linear relationship with temperature.  The hydrogen isotope (hydrogen has one electron and deuterium has 2 electrons) is lighter than deuterium and preferentially evaporates relative to deuterium from seawater (it takes less energy to evaporate a water molecule with hydrogen than a molecule with deuterium).  In periods of high temperature, more water evaporates concentrating deuterium in seawater relative to the atmosphere.  The relationship between hydrogen and deuterium in the atmosphere is recorded in snow as it falls and becomes part of the glacier sampled.  Temperatures are extrapolated from the ratio of the isotopes of hydrogen.  Oxygen isotopes are used in a similar way to augment the hydrogen isotopes.
  10. Petit, J. R., et al. (1999) Climate and atmospheric history of the past 420,000 years from the Vostok ice core Antarctica: Nature, 399, 429-436
  11. Shakun, J. D., et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last glaciation: Nature, 484, 49-54
  12. Nordhaus, W. D. (2015) A new solution: the climate club: New York Review of Books, June 4
  13. Wagner, G. and Weitzman, M. L. (2015) Climate Shock: The Economic Consequences of a Hotter Planet: Princeton University Press