Thursday, 10 January 2019

Climate change checklist

My belief is that climate change is likely over the coming decades, as it always has been, and that we should prepare for it, both  by reducing emissions and taking measures to protect us from floods and extreme weather events. This is doubly important as the population grows and becomes concentrated in cities, which are more often than not either next to the sea or a lake or a river. However, we need to retain humility and recognize that effects known only to the Creator could occur. The biosphere is orders of magnitude more complex than anything we can simulate, so there is always room for the unexpected.

The list below is a reminder of the complexity of the problem of predicting climate change. Please contact me (John Sears) via

if you think it needs modifying or have any information which might easily be added to the list.

Human activity. Carbon dioxide from fossil fuel burning and methane from livestock farming are the main human sources of global warming gases which appear to be tipping the global balance towards warming rather than the cooling we would expect according to the Milankovitch cycle (see below). However, the extent to which carbon dioxide is a major cause is obscured by the observation (my understanding as a layman) that the records over geological time show that CO2 levels lag behind rather than precede mean temperature trends upward. it could be that as temperature rises due  to other factors the CO2 held in sea water solution will be released thus reinforcing the the upward trend in temperature.

Radiant energy output of sun. This has increased by around 25% since earth was formed, i.e. over more than 4 billion years.  Remarkably, life was able to start, evolve and yield civilisation despite increases in luminosity.Very small variations occur over decades and centuries and bear some relationship to the number of sunspots (which is related to solar activity). The Little Ice Age  included  a period of low sunspot activity, with no sunspots observed over 1650-1700, when the mean temperature was lowest.

Milankovitch cycle. The amount of sunlight reaching the earth varies according to the changing shape of the earth’s orbit (eccentricity), the tilt of the N-S axis and the precession of this axis. The crucial factor appears to be the amount of sunlight falling on the northern hemisphere in any one year. Milankovitch (1970s, Serbia)  showed that the coming and going of ice ages over the last 600,000 years was due to these factors.  If there were no other factors we would expect to be entering another ice age now, instead of a warm period.

Heat from below the crust. The biosphere has more heat going into it than can be accounted for by the sun. The difference is believed to be due to  radioactive decay in the earth’s core. (see also Ocean Heat Sink below.) If this suddenly changed it could cause global warming or cooling.

Gravitational and astronomical effects.There are  gravitational influences on climate which could become large in certain situations (chaos theory shows that very small events, like the fluttering of a butterfly, can potentially have dramatic effects, such as a storm on the other side of the world). The gravity exerted at the earth's surface varies very slightly with time and position due to inhomogeneities in the crust, mantle and core. Even small changes in these factors could potentially set off major changes not allowed for by present climate models. Even small changes in the orbit of the moon and planets would have huge effects (E.g. If a large asteroid caused a perurbation in the sun-moon system. Jupiter's motion is also crucial to the stabiity of Earth's orbit).

Atmospheric composition. The importance of this arises from the way it affects the absorption and reflection of radiation coming in from the sun or being reflected back upwards from the earth’s surface. Carbon dioxide is the main gas responsible fo the greenhouse effect – it acts like the glass in a greenhouse to trap in heat. Methane is also a greenhouse gas, much more powerful than CO2 but also much less prevalent and much shorter lived.

Plants.  While alive these take in carbon dioxide from the air, thereby cooling it through the reduced greenhouse effect. But as they decay they give it out again,  but over a longer period. Large areas of trees affect the climate not only in this way but also by their moistening effect on the air.The Amazon rain forest appears to have a pivetol role in determining the global climate.

Animals . The main effect of these is due to the methane from  their defecated waste and rotting carcasses. Methane produced in this way is more of a problem than automobile greenhouse emissions as livestock herds grow in response to the westernization of diets in China, India etc.

Microscopic life. Bacteria and spores living in  land, sea and air sometimes affect rainfall. E.g. spores in the ocean can be whisked up into the atmosphere by strong winds and dispersed. Here they act as condensation nuclei for the formation of the water drops and thence clouds. Insects can reduce the balance of combustible debris in a forest and this in turn means fewer and smaller forest fires emitting CO2.

Clouds. The type of cloud, its thickness and its coverage affect the amount of sunlight striking the earth’s surface and the % of radiation reflected back to its surface instead of radiated away into space. These factors have been and still are a problem in creating climate models.

Aerosol pollution. Particles in the atmosphere from both natural and artificial sources can have a marked effect on the cooling or warming of the atmosphere. This can either be direct, by absorbing or reflecting incoming solar energy, or indirect by altering the type and distribution of clouds. The size, shape and colour of the particles affect the way they reflect, scatter or absorb radiant energy, Major sources of aerosols include volcanoes, forest fires, aircraft and large cities. Black and brown soot from the recent forest fires in California could have warming or cooling effects.  See this NASA source 

Atmospheric convection.  Heat from the ground boils up the air and the convection currents (i.e. wind) produced distribute warm air over the planet and also affect the cloud type, amount and global distribution. This in turn affects temperature, rain and snow.  Hurricanes, tornadoes, gales and the jet stream are all driven by atmospheric convection.

Ocean currents. The bulk of the heat in the biosphere which we inhabit is stored in the ocean and it is the global currents in the sea (e.g. the Gulf  Stream) which determine the global patterns of temperature in the air over the sea. Changes in these could dramatically affect the climate in some regions. E.g. Europe and the UK would be dramatically cooled if the Gulf Stream is stopped by sea salinity changes due to melt water from the arctic.

Ocean heat sink. As the net amount of heat input to the planet from the sun and from the earth's core (the latter being due to the decay of radioactive isotopes, e.g. U and Th) changes some is absorbed by the atmosphere and some by the oceans and the relative magnitude of each type of absorption is not clear, making it difficult to predict the nature of the resultant climate change.

Methane and water vapour.  As the climate warms it releases large bubbles of methane trapped in fozen deposits under the ocean or in tundra.  This causes further warming. It is 21x as powerful as carbon dioxide as a greenhouse gas and is produced by a certain kind of bacteria. It is much shorter lived than CO2, i.e. just over 10 years as opposed to over 200. Water vapour accumulating in the troposphere partly as a result of global warming also amplifies the warming.

Polar ice caps. Both Arctic and Antarctic  ice sheets reflect large amounts of radiant heat from the sun back into space. Small reductions in area cause significant increases in the amount of heat absorbed from the solar heat reaching the earth’s surface. Similarly, the greater the ice coverage  the more incident radiant heat will be reflected.

Snow cover. As with snow in the polar regions the snow settled on large mountain ranges like the Himalayas and the Alps affects the percentage of solar radiation reflected or absorbed by the earth’s surface.  The recent melting of arctic ocean ice sheets is causing large volumes of moisture to accumulate in the atmosphere which could potentially come down as snow, forming thick long lasting coverings over N America and Russia in the winter. If these don't melt in the summer we could even be on track for the next Ice Age. The time scale is, as usual, uncertain but could be much shorter than previously thought - a hundred years or less, rather than thousands.

Melting glaciers.  When a glacier melts it not only leads to possible flooding but reduces the area of the planet which reflects incident sunlight away from the surface, i.e. the ground retains incident solar energy instead of reflecting it  back into space. When melt water flows into the sea it dilutes the concentration of salt in the seawater and this has a major effect on ocean currents which in turn affects the climate. (The more salt the denser the water.)

Sea ice. As with glaciers and snow, melting of sea ice (icebergs) reduces the % of sunlight reflected back into space. It also reduces the salinity and hence density of seawater, which affects ocean currents which themselves affect the distribution of heat in the oceans.  However, melting icebergs maks no difference to sea levels.

Volcanoes. Eruptions from these inject huge amounts of sulphur dioxide into the air and, like carbon dioxide and methane, this produces a greenhouse effect. The ash and dust from eruptions also affects cloud formation and directly blots out sunlight.

Carbon dioxide absorption by weathering of rocks. About 1 billion tons per annum of atmospheric carbon dioxide is absorbed by weathering of silicate rocks. This compares to 30 billion tons emitted by civilisation. Such absorption is associated with the plate tectonic cycle which has been important in keeping air temperature constant over hundreds of millions of years.

Carbon dioxide absorption where ice has melted. Land and sea exposed by retreating ice is likely to be recolonized by plants and plankton which absorb carbon dioxide during photosynthesis. The surface areas involved are large and this could be a major factor in offsetting the heating effect of the reduced albedo. Conceivably it could even cause global warming to come to a halt or even reverse. (I will try to find some data on this.)

Meteor  impacts. Hits by large meteors can have global repercussions including climate change. If a large enough object hit the earth it would of course cause a mass extinction event, like the one which wiped out the dinosaurs 66 million years ago.

Cosmic rays.  These  can also affect cloud formation , since the particles which make up cosmic rays can cause nucleation of water drops.  There does seem to be some link between them and average temperature/rainfall.

John Sears
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Sunday, 16 December 2018

Blogging for Peace on Earth: Climate change checklist

Blogging for Peace on Earth: Climate change checklist: My belief is that climate change is likely over the coming decades, as it always has been, and that we should prepare for it, bot...

Monday, 10 December 2018

Interplanetary mining

This was originally published in 2012 but I can't see that the arguments have changed much. I have made minor modifications since then but the main argument is the same. There is plenty of room on the earth but humanity is now too demanding of resources and environment to sustain its expansion mode. Artificial intelligence and robotics have grown up very rapidly since 2012 and this kind of technology is enormously useful in space exploration.

There is an increasing shortage of minerals and metals needed in technology, especially in China, an inevitable consequence of

  • A rapidly growing world population (1.09% p.a., 145 per minute births minus deaths. (That was the data I had in 2012.)

  • A rapidly growing per capita demand for technology (GDP growth 5.9% p.a. means more money spent on goods and services which draw upon the Earth's  resources)

TThis investor report states that ‘dysprosium, terbium, europium, neodymium and yttrium are critical and face a looming shortage. These rare earth elements and their associated compounds are used in solar panels, fluorescent bulbs, electric car batteries, wind turbines and semiconductors. Platinum (Pt) and related metals are also in short supply and more expensive than gold.  Most of the world supply of Pt is used in catalytic converters and fine jewellery.

Iridium (Ir) is distributed thinly over the planet and expensive to mine, yet is in demand for its uniquely high resistance to oxidation, and as a hardening agent in alloys when combined with Pt and osmium (Os). Pt-Ir alloys are also in sparking plugs and Pt-Os alloys are used to tip fountain pen nibs, in pivot bearings such as those found in compasses, and in surgical tools.

In the past the supply of these materials has been more than enough. This would not have been the case if the Earth did not have such a variety of minerals: 4,500 vs 60 for the average rocky planet (data I found in 2012) brought to near the surface and within reach of civilisation by plate tectonics (again, of a kind unique to the Earth).

Providentially, all these substances are available in abundance in asteroids, which are now within reach of humankind at just the right time in history that they are needed and when we are close to developing the know-how to reach them. In fact we already rely mostly on past impacts for our supply of Pt. Even gold is heavily reliant on an asteroid which fell to Earth where the mines of Johannesburg are located today. Some asteroids comprise stainless steel, so pure that it requires no refining. Again, at least one extraterrestrial source has been used on Earth: the Inuits in NorthAmerica made tools and knives out of unrefined metals from meteorites. And Sudbury, Ohio is a mining town exploiting nickel, copper and other metals derived from an ancient impact.

So now is the time to start proactively seeking out this abundant resource rather than wait for it to come to us. A company has already been formed with just this objective: Planetary Resources Inc., The current website states there are 16,000 asteroids rich in resources, 2 trillion tonnes of water for life support and fuel, and that space exploration costs in the long term could be reduced by 95%.

It was set up by James Cameron (adventurer and film director) and Larry Page (co-founder of Google with Sergery Brin), who were able to put serious money into it – billions of dollars. It is being done as a money making venture, its viability deriving largely from the high and increasing price of platinum.  

Requoting from its website as of 2012: Some near-Earth asteroids contain platinum group metals in much higher concentrations than the richest Earth mines. In space, a single platinum-rich 500 meter wide asteroid contains about 174 times the yearly world output of platinum, and 1.5 times the known world-reserves of platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum).’ It is not just the very expensive materials that are being targeted. Quoting again from Planetary Resources: ‘Asteroids also contain more common metallic elements such as iron, nickel, and cobalt, sometimes in incredible quantities. In addition to water, other volatiles, such as nitrogen, CO, CO2, and methane, exist in quantities sufficient to warrant extraction and utilization.’

They are intending to park asteroids in orbit around either the Moon or the Earth. If the former they would choose ones having a large amount of ice since this could be used to support a lunar colony with water or the electrolysed components of water – hydrogen for fuel, oxygen for breathing. This would be a kind of contracted service for any number of manned lunar enterprises. Minerals could be sent back to Earth relatively cheaply and there are plenty of comet-like bodies having both ice and rock.  Platinum-rich bodies could be parked in Earth orbit for a good financial return.

The stainless steel asteroids, which can provide steel of higher grade than that from steelworks, could be used both on the Earth and for the building of spacecraft and space stations in orbit or at L2 Lagrange points. Iron and aluminium could also be used for construction work in space.

Not surprisingly, NASA is interested as, I suspect, are the space agencies of Europe, Russia, Japan and China.

Our planet is becoming overstretched not because of people per se but because of the resources they consume and the waste this generates. Equally important is a lack of awareness of just how precious it is and I believe that starting up major enterprises in the hostile environment of space, together with the rarity, if not the non-existence, of extraterrestrial life, will shock us into facing the reality that we and our world are special.

See also
 Destination Phobos?
Skylon: an opportunity for a venture capitalist?