This blog provides background for and explanation of current topics in science.

Saturday, May 12, 2012

Does Evolution Violate the Laws of Thermodynamics?

In short, no; evolution does not contradict any law of thermodynamics, nor does it contradict the law of cause and effect, another common objection to evolution by the scientifically challenged.  I will discuss each of these in detail and show how these objections arise from a misunderstanding of both evolutionary theory and thermodynamics.

The First Law of Thermodynamics can be stated as: "Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another." Living cells use energy from the sun (electromagnetic energy) or chemical potential energy to grow and repair themselves.  They change the form of energy but do not create or destroy it.  There is no violation of the first law.

The Second Law of Thermodynamics can be stated as: "In all energy exchanges, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state."  What those who think that the second law is violated omit is that the second law refers to closed systems, those which have no exchange of energy with their surroundings.  They thus ignore the fact that there is a constant stream of energy from the Sun that is captured by living organisms at the base of the food chain.  It is this energy input that allows an organism to increase its order.  Living organisms achieve order by using energy to grow and repair themselves.  In the process, they create energy in the form of heat that is ultimately radiated, conducted, or convected away.  This heat (electromagnetic energy in the infrared, i.e., IR radiation, and molecular motion) represents the entropy that is created as either electromagnetic energy from the Sun (photons) or chemical energy, such as some bacteria who use sulfur and iron compounds as a source of energy, is converted to another form of energy in the process of living.

The Law of Cause and Effect: "Nothing happens by chance." is the simplest way of stating it.  Firstly, it is violated by quantum mechanics.  "Spooky action at a distance" has been demonstrated experimentally.  The random nature of radioactivity has been demonstrated experimentally.  Those are just a couple of examples where the classical concept of causality fails.  Secondly, it is violated by the replication process of RNA and DNA when living organisms reproduce.

Here are two features of evolutionary theory that are random: copying errors when cells divide and acquiring the complete genome of another organism.  Both of these are amply documented in the scientific literature.  What is not random is natural selection.  If the change in the organism that results from a random change of its genome does not give it an advantage in the number of offspring with the same genomic change, then it will not survive as a new variant of the original species.  If it does provide an edge, then the change will spread through the population that shares the same environmental conditions.  If conditions change, a different variant may be favored.  If enough genetic changes accumulate, it may become a new species.  In the case of acquiring a new genome, such as in the case of an advanced set of symbionts like some lichens, it will become a new species.  But its survival and spread depends on how it adapts to its environment in comparison to other variants of the parent species.  This also is amply documented in the scientific literature.  Evolution clearly does follow causality at the organism level, although the changes to the genome may be random.

Tuesday, September 20, 2011

The Paleocene-Eocene Temperature Maximum (PETM)


Using a variety of temperature proxies, including the ratio of the different stable isotopes of carbon, 13C and 12C, where higher temperatures favor the lighter isotope, 12C and one would expect to see a negative δ13C. Another indicator is the negative δ18O > 1% present in foraminifera shells that grew both in the surface and deep oceanic waters that occurred during this same time period. Likewise, analyses of the foraminifera Mg/Ca ratio and ratios of particular organic compounds used for TEX861,2, a paleothermometer based on the composition of marine picoplankton, Crenarchaeota3. There is clear evidence of a massive injection of 13C-depleted carbon at the Paleocene-Eocene transition. First, the previously mentioned negative δ13C change in carbon compounds at this time, about 55 million years ago. Second, carbonate dissolution which indicates the acidification of the ocean that occurs when atmospheric CO2 increases. The source of this carbon dioxide is unknown. Massive volcanic activity might have been to blame, but there is no evidence of sufficiently large volcanic activity such as the ash and lava deposits one would expect. There are volcanic traps in Siberia that were formed about this time, but there that activity alone would not account for the volume necessary to account for the likely CO2 content in the atmosphere of over 1700 ppm (parts per million) at its peak. This is based on a base value of about 1000 ppm near the end of the Paleocene and an addition of about 3,000 GtC (gigatonnes of carbon). This amount of carbon was determined by taking into account the carbonate compensation depth (CCD), a value determined by the carbonate depletion of shallow ocean bottom cores.4 A comet or asteroid impact that caused continent-wide fires was considered and rejected because there is no layer of soot that has been found in ocean bottom cores as would be expected. Nor has a crater been found of the right age to account for this. A third possibility is that the large deposits of methane hydrate that exist on the deep continental shelves were destabilized and released. Methane hydrate is a single molecule of methane, CH4, enclosed in a "cage" of water molecules, H2O. This compound is only stable in a narrow range of temperatures and pressures. It would only have taken a small change in temperature or a physical disturbance of the water surrounding the methane hydrate to cause it to become unstable and release the CH4. Methane is 20X as effective as CO2 at retaining heat, so with a large release of methane, there would have been an immediate rapid surge in temperature. Methane decays over a period of about ten years to carbon dioxide which would then linger for over one hundred years, heating the atmosphere more slowly for a longer period of time. The total temperature of the ocean water, both shallow and deep was about 9<sup>o</sup>F,reaching 77<sup>o</sup>F in the surface waters near the poles.  There was virtually no ice anywhere on Earth at this time since the temperature had already been warm prior to the PETM.  The poles warmed more than the rest of the planet because with the lack of snow, the albedo increased, causing a larger temperature excursion.1

Save up to 90% on Used Textbooks at BarnesandNoble.com. Shop Now!The transition from the Paleocene epoch to the Eocene epoch Is marked by sharp decrease in the percentage of 13C, δ13C, dissolution of carbonate in all the ocean basins, the extinction of many terrestrial mammals, and foraminifera in the mud on the ocean floor (i. e., benthic).  It was also marked by the origin of several new mammalian orders, including primates, artiodactyls (even-toed ungulates), and perissodactyls (odd-toed ungulates). The δ13C and dissolution of carbonate indicate that the ocean experienced a geologically rapid acidification and temperature rise. The acidification strongly implies a rapid rise in the amount of carbon in the atmosphere. This increase occurred over a period of about 20,000 years, a rate that is about one-tenth of the rate of increase of CO2 that we have experienced during the past 150 years.
Humans are currently adding about 30 GtC annually. At this rate, anthropogenic carbon additions will equal what was released at the P-E boundary in 100 - 200 years, some 100 times faster than occurred 55 million years ago.1,5 because we have geologic evidence of what the climate was like during this P-E boundary time period, we have an idea of what the climate will be like in our near future if we continue on our current path. Periods of 100o temperatures in the North American Southwest will last for months around the clock. Drought will be longer and more frequent than now. Flooding will be worse in those areas that commonly flood. All the glaciers will melt, raising the sea level by about 200 feet - it was 220 feet higher at the P-E Boundary than it is now. Since there are vast stores of methane under the permafrost, if the permafrost melts, and that now seems inevitable, the released methane will just exacerbate the problem and hasten the warming. There are also large deposits of methane hydrate on the continental shelves that could be released if the ocean temperature exceeds the threshold.
Only broad features of the climate during the 150,000 year transition from the Paleocene to the Eocene until CO2 levels returtned to the levels of the late Paleocene after this large carbon dioxide excursion. One can hope that by further study, a more detailed understanding will be gained along with indications of how this scenario might be mitigated
  1. National Geographic, October 2011, pp. 90 – 109
  2. http://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum
  3. http://en.wikipedia.org/wiki/TEX86
  4. http://www.realclimate.org/index.php/archives/2009/08/petm-weirdness/
  5. http://www.realclimate.org/index.php/archives/2004/12/how-do-we-know-that-recent-cosub2sub-increases-are-due-to-human-activities-updated/ 
Gaiam.com, Inc

Wednesday, September 14, 2011

Scientist claims that he has created life-like cells based on metal

Lee Cronin at the University of Glasgow claims that he may have developed cell-like structures capable of adapting to changing environments.1 The materials that he has used to create what he calls iCHELLS (inorganic chemical cells) are known as polyoxometalates. These are compounds made with various metal atoms combined with oxygen (O) and phosphorous (P).  Tungsten (W) is the most common metal used.

One of the iCHELLs.
Image from NewScientist.com.
He creates large negatively charged ions of these metal oxides and creates a salt by mixing these ions with protons (positively charged hydrogen [H+]) or sodium (Na+).  He next injects a solution of this salt into a solution containing an organic salt with large organic cations (positive ions) and small anions (negative ions).  What results is a salt of the metal oxide anion with the organic cation that precipitates from the solution in the form of a small bubble-like structure.  He is able to manipulate the form of these structures to give them some of the characteristics of organic cell membranes such as selective permeability that will control what chemicals reside within the bubble.  He has created bubbles within bubbles to give the appearance of the internal structure of living cells.  He has attached photosensitive dyes to the iCHELLS which enabled them to mimic rudimentary photosynthesis, including the ability to split H2+ and O plus an electron (e-), an important step in the process.

It is during his current experiment, scheduled to run for seven months that he has given some indication that he has succeeded in modifying the iCHELLs so that they will adapt to the environment they are in.  The final results are still a few months away and the details have not yet been published.  Last year he also showed that polyoxometallates could serve as templates for self-replication analogous to how DNA and RNA operate.  Taken together, these could be good first steps toward creating artificial life.

Reproduction, self-repair, adaptation, growth, and evolution are all characteristics of single-celled and more complex life as we know it.  If Cronin is able to induce these iCHELLs to perform all three, would this constitute a new form of life?  It would seem to be.  If he is able to accomplish this, and it is not certain that he will, it would revolutionize our understanding of what life forms might be possible on other planets in our solar system and elsewhere in the universe.  It may expand the Goldilocks zone and drastically increase the possibility of finding other life.

1. http://www.newscientist.com/article/dn20906-lifelike-cells-are-made-of-metal.html



Tuesday, August 2, 2011

Contributions to Global Warming and Climate Change

The Sun and Global Warming

iconOf the many trends that appear to cause fluctuations in the Sun’s energy, those that last decades to centuries are the most likely to have a measurable impact on the Earth’s climate in the foreseeable future. Many researchers believe the steady rise in sunspots and faculae since the late seventeenth century may be responsible for as much as half of the 0.6o of global warming over the last 110 years (IPCC, 2001).


iconThe effects of orbital mechanics on global warming - the Milankovic cycle
The variation of insolation due to orbital mechanics was solved by Milankovich in the 1930's.
There are three relevant cycles and four factors that contribute: precession of the orbit, meaning that the location of the perihelion (point of closest approach of the Earth to the Sun) rotates around the Sun; precession of the Earth's spin axis relative to the orbital axis (like a top that is spinning with its axis of rotation at a tilt); change in eccentricity of the orbit between a perfect circle and an ellipse that is slightly different from a circle; and variation of the tilt of the Earth's axis between about 23o and 24.5o.
The iconcombination of the variation of the orbit's eccentricity and the Earth's spin-axis precession creates climate change on about a twenty-thousand-year cycle. The oscillation of the spin-axis relative to the orbital plane between 23o and 24.5o has a 40,000 year cycle. The eccenticity change by itself causes small variations in the insolation with a cycle of about 100,000 years, but its effect is only about 0.1 % of the others. These factors are known as Milankovich forcing.


These cycles were correlated with the the timing of the ice ages and hypothesized to actually cause them. Currently, these variations should have been cooling the Earth's mean temperature over the past 150 years, but the global mean temperature has in fact been rising.


Relationship between CO2 emissions and rise in temperature
iconThe relationship between CO2 emissions and rise in temperature, one tonne (one tonne = 1000 kilograms = 2200 lb = one long ton) of added carbon will cause 1.5 x 10-12 degree rise in temperature, is based on an article in Nature.  In the USA, one tonne of carbon is emitted per person annually. Assuming that worldwide emissions per person are one tenth of a tonne per person, then for just the additional carbon emitted each year and assuming that this rate is steady (It is not, it is increasing), then each year the temperature rise will be 9 x 10-4 oC. However, this also assumes that the temperature has reached equilibrium with the current level of CO2 in the atmosphere, but it hasn't.


This chart shows the normal lag of CO2 concentration to temperature rise and that the relationship has reversed in the present, i.e., the CO2 concentration has continued to rise even as the temperature has been relatively stable. Based on the past record from the ice cores, one would expect that the temperature would be dropping with the CO2 concentration either stable or decreasing as well:






















When the The Milankovich cycles cause an increase in solar energy striking the Earth, this will initiate a melting of some of the glaciers and at least one of the polar ice caps.(depending on the season). As the article states, 18,000 years ago, this increase in the intensity of the sunlight occurred during the spring in the Southern Hemisphere. This led to the Antarctic ice cap melting more than it had been. This decrease in the area of ice decreased the amount of sunlight reflected and a corresponding increase in the amount of sunlight absorbed. This initiated a positive feedback loop where reduced reflection and ocean warming lead to more temperature rise than would be expected from Milankovitch forcing. Currently, if Milankovitch forcing were the primary factor, global temperature should be falling.


As the temperature of the ocean increases, it can hold less carbon dioxide, so the carbon dioxide level in the atmosphere increases. This increased CO2 level creates a second positive feedback loop that also causes more warming than can be explained by Milankovitch forcing, oceanic warming, and reduced reflection alone. The lag in CO2 concentration from temperature rise has normally been about 600 +/- 400 years for the last 450,000 years based on several different sources (primarily ice cores).  For about the last one hundred years, the rate of increase of CO2 has been leading the rise in temperature.


iconAnother point is that with the melting of the permafrost, the risk of large methane releases increases. It isn't a matter of "if" but "when" if current trends continue. Methane has 25 times the warming effect of carbon dioxide. This is being studied in Alaska where new shallow summer lakes are forming on top of the permafrost and permafrost is meting more deeply than in recent history and increasing amounts of methane are being released. It is uncertain where the threshold is for large releases to occur.


For a more detailed explanation and the history of the theory that links CO2 to temperature rise, see http://www.aip.org/history/climate/co2.htm.

Wednesday, June 15, 2011

Maunder Minimum and Climate Change

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A Maunder Minimum is a period of low sunspot activity. The period from about 1650 to 1720 was the nominate Maunder Minimum and coincided with a period known as the Little Ice Age. Recently, Space.com posted an article, Sun's Fading Spots, that stated that we may be in the beginning of a new Maunder Minimum. In the following, I attempt to assess the probable influence this will have on the climate.

It is apparently correct that reduced sunspot activity is correlated with reduced solar irradiance. The Maunder Minimum during the latter half of the 17th century did lead to what was known as the Little Ice Age. However, there is also strong evidence that the rise in greenhouse gases has become the dominant agent affecting global temperature as can be seen in this graph:

Courtesy of http://lasp.colorado.edu/images/science/solar_infl/Surface-Temp-w-paleo.jpg

The golden line with diamonds is the measured or reconstructed total solar irradiance. The solid blue line is the reconstructed global surface temperature. The dashed blue line is the measured temperature in the Northern Hemisphere (NH). One can see that solar irradiance and the reconstructed global temperature follow one another fairly closely. The measured NH temperature also tracks total solar irradiance until the last 40 years when it starts to sharply diverge. This graph shows the recent data at higher resolution:

Courtesy of http://www.skepticalscience.com/pics/Solar_vs_Temp_basic.gif

The divergence is even more clear here since total solar irradiance has been declining as global mean temperature has been rising. One can see on the first chart that there is a very close correlation between solar irradiance and temperature. The effect of the three major volcanic eruptions that are noted caused an immediate drop in solar irradiance and a corresponding drop in temperature. So the implication of the second chart is that there must be at least one other factor that is influencing global mean temperature than solar irradiance and that this factor is overriding the drop in solar irradiance.

If we are indeed entering another Maunder Minimum of solar activity, it at most will give us a temporary reprieve and slow the rise in temperature. It will not cause a long term (i.e., greater than 100 years) cooling and it will not reduce the importance of reducing anthropogenic greenhouse gases.