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-- Seafriends home -- climate index -- global issues -- Rev:20100515,20101105,20110124

introduction Water is the strangest substance on Earth, by far. It should be a gas at Earth's temperatures, yet it occurs as a liquid, a solid, a gas and as cloud. Take for instance a related substance, hydrogen sulfide (H-S-H), which is as close as one can get to water (H-O-H). H2S has molecular weight 1+32+1=34, whereas water H2O has 1+16+1=18, and is thus substantially lighter than hydrogensulfide. Yet water occurs as a liquid and H2S only as a gas.  It is evident that water molecules like to cluster together to form bigger clumps, and this property is attributed to its unique shape and electrical polarity, shown in the drawing. Its peripheral H+ atoms attract the central O- from another molecule, and vice versa so that four molecules form a pyramid. This pyramid is not entirely symmetrical, such that it attracts to other pyramids and so on.

Other properties of water are no less spectacular:

• tasteless, odourless: water is so 'neutral' that it has neither taste, nor odour.
• transparent: water is very transparent, more transparent than glass or other known substances. But its own colour is slightly blue. Light interacts with water molecules in what is known as Rayleigh scattering, which gives it its blue colour by day (not by night).
• three phases: water occurs on Earth in three phases, as liquid, ice and vapour. In addition it forms stable aerosols called clouds in many forms. It also forms snow crystals of many forms and ice aerosols.
• affinity: water has an uncanny affinity to most substances, but is also phobic to others.
• capillary action: due to its affinity, water rises inside capillary pipes - the thinner the capillary, the higher it rises.
• neutral pH: water is chemically neutral, being equally an acid as a base at pH=7, or neither acid nor base.
• universal solvent: due to its universal affinity, it is also a universal solvent for biochemical substances (except fats and oils), and minerals. Thus it is the medium of transport in living organisms.
• high heat content: water has a very high heat content, able to store energy from heat.
• high latent (hidden) heat: even though water occurs in all three phases, it requires/releases much heat when changing from one phase to another. In this manner it has a high heat transfer capacity in the atmosphere and an 'inertia' in changing from one phase to another.
• available in large quantities: water is the most common substance, covering 71% of Earth's surface with a staggering volume of 1,360,000,000 km3 (1.36E9 km3)
• water changes its properties with size: a water droplet, cupful, swimming pool, lake and ocean have different properties. A droplet is dominated by surface tension; the sea has waves, currents, tides and stratification (thermoclines).

Important points:

• the points mentioned above
• water is weird - stranger than we can imagine
• water is the main actor in climate and life
• all life is based on water
• it is the main transporter of what plants and animals need

Note that the words warmth and heat are often used interchangeably, but there is a difference. Warmth is the energy content of a substance, whereas heat is the energy in transfer from a warm object to a cold object. Cold is identical but opposite in the way it is used. Hence our introduction of the word coolth which is equivalent to lack of energy stored, similar but opposite to warmth.

Water, ice and vapour Water is the most important substance on Earth, but is rather difficult to understand. Let's begin with a diagram showing how it changes to ice and vapour, depending on temperature (horizontal) and pressure (vertical). For ease of understanding, the conventional graph is mirrored upside down such that higher pressures are found lower in the graph (as on Earth). We use the unit of pressure of bar (for barometric pressure or atmosphere), which is 1 on Earth's surface. There are three red lines that separate water from ice and vapour, coming together in the triplepoint where water exists in balance with ice and water vapour. Note that these three lines represent the boundary conditions where an equilibrium (balance) exists, such as can be done in an experiment. The thick black horizontal bar represents the surface of Earth, where barometric pressure is one atmosphere. It extends from -50ºC to +50ºC, roughly the maximum range of surface temperatures. The diagram also shows four coloured shapes, which make the picture more interesting.

The blue shape for water runs between 0 and +50ºC, narrowing towards higher pressures because it becomes colder in the deep sea. The pressure under water changes by 1 bar for every 10 metres, so that 1000 bar (1E3) is found in deep ocean trenches. Should a volcanic vent produce hot water of +200ºC (far right bottom), it can exist as steam because its location in the phase diagram is above the red curve separating water and vapour.

Although the whole ocean covers over 70% of the planet's surface, mostly at temperatures above 0ºC, the phase diagram shows that this is in the vapour phase, indicated by the lighter triangle named evap for evapotranspiration. What it means is that surface water is not in balance anywhere on Earth, and that it will always be 'eager' to evaporate, the rate of which depends on temperature (and wind + waves). Water can exist in rivers and lakes above sea level, but this means that it will be even more out of balance. Fortunately, temperature decreases with altitude by 0.6ºC per 100m.
Life owes its existence to evapotranspiration because it enables plants to draw water from the soil, all the way to their leaves. In addition, all oceans are continually evaporating moisture which then rains down on the land, thus supplying terrestrial life with a steady supply of water. More about this below.

On its left in the graph, water is bounded by ice which can exist in thickness of several kilometres, and thus high pressures. The line down from the triplepoint, tilts slightly such that high pressures do melt ice. A female ice skater places 50kg on a square centimetre skate, which amounts to 50 bar, enough to melt ice of -2ºC.
Ice can be found in high mountains, where it can sublimate (evaporate direct from ice to vapour) to the air, but in order to melt, its temperature must increase to above 0ºC. Ice is about 9% less dense than water, so the vertical pressure scale is 10 bar for 11m of ice. Note that in salt water the red melt line runs somewhat to the left because salt lowers the freezing point.
From the diagram it can be seen that ice, unlike water, is not out of balance at the surface pressure of 1 bar. It is thus a very stable form of water. However, with altitude, ice sublimates as shown by the missing triangle, and cold air can still hold a sizable amount of moisture (see diagram below). However, a substantial amount of latent energy is required to do so (623 cal/g) compared to melting (80 cal/g).
 
 

Water vapour pressure and temperature Water vapour, better known as steam, is a gas that serves civilisation in its use for steam engines and steam turbines (and much more). The graph shows how steam pressure increases rapidly with temperature, to such extent that above 120 degrees, it can do work, like converting heat to electricity in power plants. But at earthly temperatures, it cannot do so. Even so, water remains the most important substance for transferring heat and for equalising the temperature of the planet (blue shape). In the next graph we'll examine how it works.

Water vapour is found only in air, which rapidly thins with altitude, shown as the purple shape below and the light blue shape above, following the dashed temperature line in the phase diagram. Notice that at some stage the temperature of the air crosses into the ice phase, above which clouds may turn into ice (snow). The troposphere ends at 0.2 bar (11km) where the tropopause is, then warms to just below freezing point in the stratosphere which ends at 0.01 bar in the stratopause (47km).
 
 

Water content of air The amount of water found as water vapour is very small, no more than an ocean of 3 cm deep (0-7cm). It is found only in air. The graph shows the amount of water in air, against temperature, in red as a percentage and in green as grams per cubic metre. Cold air holds substantially less water than warm air, and not shown, this amount decreases rapidly with altitude. Shown are also the ranges for three habitats: the ice caps extending below 0ºC; the oceans from 0 to 27 ºC (overlapping the world's green plant belt); and the deserts which could produce much water vapour if only they had water.  Also shown is water vapour's partial pressure 0-40mbar which corresponds to 0-4% (purple curve, 4% of 1 bar = 40 mbar). This curve represents the water's 'eagerness' to evaporate.

Below 10ºC it roughly follows the red curve, which implies that the water 'space' in air (saturation fraction) equals its 'eagerness' (vapour pressure) to occupy that space, resulting in 50-60% relative humidity. But above 10ºC water's 'eagerness' to evaporate gradually exceeds the air's capacity for it. As a result, towards the tropics, the air rapidly becomes fully saturated to 90-100% relative humidity. And as can be seen, the situation with deserts becomes rather extreme, hence their paucity (few) of life. But the consequences of this go much further.

Surrounding the purple curve is drawn a light purple shape, meaning that the temperature of the ocean (purple) usually differs from that of the air. The right-hand side of this purple shape corresponds to a cold ocean under warm air, and obviously, the water is unable to fill the air's capacity for water, resulting in low relative humidity, dry air. The left-hand side of the shape corresponds to cold air over warm water, which causes high relative humidity, damp air.

Important points:

• ocean currents have a major effect on coastal climates because they transfer warmth to cold places and coolth to warm places. The El Niño/ La Niña variation in ocean currents has a significant influence on global climate.
• where cool water meets warm air, such as in all places of ocean upwellings, the air is dry, resulting in drought (Galapagos, Chile, California, Namib Africa's west coast, etc.)
• where warm water meets cool air, the air is moist, resulting in rain and snow (NE USA, Ireland/England, etc.)
• cold seas cause dry, hot summers with cold nights. Warm seas cause the opposite.
• the summer can begin only when all surface moisture of the winter has evaporated.
• if the atmosphere heats more than the oceans, precipitation decreases. If oceans heat more than the atmosphere, precipitation increases.
• the principles discussed here may be the main driver of  ice ages, see further below.

Our extensive section about soils and their ecology, analyses the importance and consequences of evapotranspiration. The world map below shows where moisture is found in the air, as expected, mainly around the equator.

Global relative humidity Humidity of the air has been measured by weather balloons, which give accurate results. Their data shows that relative humidity has been decreasing in the upper troposphere, particularly at 0.3 bar at the uppermost boundary. But even at 0.7 bar (?km) it has decreased by 4% over 50 years. Why this happened or what it means, is not known, but since water vapour is thought to be the most potent greenhouse gas, a decrease may have contributed to cooling of the atmosphere.

Decreasing humidity in air could be explained as follows (not proved):

• as we produce more greenhouse gases, water vapour decreases, so that the total out-radiation remains constant. This saturated greenhouse theory comes from Miscolzcy.
• the sun has reached its solar maximum when cosmic rays are minimal. Now the sun's protective shield is diminishing, and cosmic rays increasing, turning vapour into cloud. At the moment (2010) the sun is going through a minimum. See the chilling stars.
• as we produce more aerosols and dimethylsulfide, more vapour is turned into cloud and rain.

Important points:

• only at 0ºC is water in equilibrium with ice and vapour. At lower and higher temperatures it is either sublimating or evaporating.
• the rate of evaporation depends on the difference between vapour pressure and relative humidity, which increases rapidly with temperature above 10ºC.
• the amount of water in the atmosphere is very small but it transfers most of the heat by condensation to cloud and rain/snow.
• evapotranspiration is the most important factor in plant life, and thus the habitat zones of the world.
• examples from daily life:
• the washing dries much better when warmed slightly (in the sun), while air passes over it.
• before putting on your dive mask, make your face cool in the water. This reduces evaporation from the skin and helps prevent the glass from fogging. (spitting and rubbing is also needed)
• more rain falls by night than by day. Because the night cools the air.
• When water vapour (a gas) condenses to cloud/rain (a liquid), it creates a sudden vacuum of up to 40mbar which drives winds and tropical cyclones (hurricanes). Meteorology assumes that winds move from high to low pressure areas but this may well be wrong as winds create lows and highs while chasing rains (condensation).

Reader please note that this aspect of climate has been overlooked or under-reported.

Latent heat, specific heat and heat capacity The name latent heat (concealed heat) is used for the heat required to change from one phase to the other (e.g. melting, evaporating) without changing temperature, whereas heat capacity (=specific heat) is the amount of heat required to warm a standard unit by one degree, without changing phase. In the diagram we are using the conventional units for warmth (energy), the gram-calorie or cal (not to be confused with the food-calory which is a kilo-cal =1000cal). To warm a block of ice of 1000g from -10ºC to 0 ºC takes 5000 cal because heating ice requires 0.5 cal/g/ºC as shown in the diagram under <->. The latent heat of 80 cal/g must be provided (=80,000 cal) to melt the block, still at 0 degrees. To heat it further as water, to 100 degrees, requires 1000 x 1 x 100 = 100,000 cal because water's heat capacity is 1 cal/g/ºC. To evaporate this water requires a whopping latent heat of  540 cal/g, amounting to 540,000 cal. From there on, as pure steam without air, requires 0.5 x 1000 cal per degree.

When water vapour exists in air at 2%, it adds 0.02 x 0.5 = 1% to the air's heat capacity, which is negligible. However, by changing phase from vapour to cloud, it releases a latent heat of 0.02 x 540 = 10.8 (cal), equivalent to 10.8 / 0.5 = 22 degrees of warming. Water vapour is thus a considerable player in the transfer of heat through the atmosphere.

Juan G. Roederer: "In a highly nonlinear system with large reservoirs of latent energy such as the atmosphere-ocean-biosphere, global redistributions of energy can be triggered by very small inputs, a process that depends far more on their spatial and temporal pattern than on their magnitude"

Note that cloud condensation nuclei CCN are typically smaller than infrared wavelength but larger than light wave lengths, sometimes a single molecule can do it. Thus raindrops begin at this size, rapidly growing to a typical size of 10 micron. As droplets grow, also their terminal velocity (hitting Earth) (speed) increases progressively. Note that raindrop volume (weight) is proportional to radius to the third power, thus increasing very progressively. During heavy rainfall, rain drops are heaviest and they are also fastest, resulting in unexpected soil damage. A 5mm rain drop is 5x5x5 = 125 times heavier than a typical 1mm rain drop, and its speed is twice faster, resulting in 600 times more kinetic energy, reason why most soil erosion happens during heavy rain storms. See soil/erosion/rain

The way snow forms is more complicated as discovered by Bergeron-Findeison. Water does not eadily convert to ice, such that droplets occur in an under-cooled state colder than ice. Snow crystals can then form instantaneously from the undercooled water droplets. The formation of ice releases heat which moderates the process. Ice crystals also grow from more water droplets and water vapour, but also from collision and coalescence. Once their speed exceeds the cloud's updraft, they fall out as snow, or rain in case lower altitudes are warm.
 
 

Interestingly, clouds, water vapour and rain are transparent to Earth's microwave radiation in the 5.0 mm band. Using this property, satellites can measure land and sea surface temperatures, even though this signal is very weak.

This graph, obtained from the Vostok (Antarctica) ice core, shows the capricious, yet cyclical nature of the past 4 ice ages as temperature (red) suddenly dips, then declines in large oscillations to a glacial minimum of some -8 degrees (at Vostok Antarctica). With it also the gases of life, carbon dioxide and methane, follow in step. On a more detailed time scale, the gases follow the temperature rather than the other way, which is an important observation refuting man-made global warming.

We'll explore the glaciation mechanism by assuming that it depends on the run-away (positive feedback) effects of:

and the end of an ice age:

There are a number of important factors:

• the large amount of land around the north pole which suddenly changes albedo (dark to light).
• the north polar climate depending more on radiation than the south pole.
• the polar area increasing with the square of latitude covered(surface of a circle is proportional to radius squared), extending away from the pole. Thus albedo increases rapidly.
• temperature being very dependent on latitude, see graph below.
• the very short summer season for melting the ice.

These two maps show the cardinal differences between north and south polar regions: antarctica is a continent surrounded by ocean, whereas the arctic is an ocean surrounded by continents. Whereas temperature varies little over oceans, it varies enormously over land. The inner black circle covers roughly the maximum ice extent during an ice age (see further down).

In this graph the average temperatures for both hemispheres are shown and their summer and winter variations. The top shows how little the oceans change from north to south (25 degrees) and from summer to winter (6 degrees) and even less so near the poles and the equator. By contrast, the land temperatures change vastly more, from north to south (50 degrees) and from winter to summer. Notice how the polar north varies the most, due to the large amount of land, compared to that of the oceans. In other words, radiation (in and out) is an important part of arctic climate, reason why an ice age has such large effect. Notice that towards the poles, the difference between air and sea temperature becomes an important driver of precipitation and climate.

This graph shows the incoming radiation by month for three latitudes. Note that during the summer months, the mid-latitudes and polar regions receive more sunshine than the tropics because of their long days and short nights. Notice the very short summer months for the poles. Note also in the right-hand graph how radiation changes most rapidly in the polar regions. Thus the effect of the summer months is rapidly negated by shorter summers and less warming, which is what happens in ice ages.

These two maps (from Wikipedia) show the minimum (black) and maximum extents (shaded) of ice during the past four ice ages. Note how Antarctica (right) is hardly affected, whereas the arctic is profoundly so. Note also how Alaska and Siberia remained exempted. This suggest that evaporation does not occur from the Arctic Sea but from the North-Atlantic, fed by the warm Gulf Stream. Note also how the mountain ranges block the transport of water vapour. Also note that north America drains its water to the east and north Europe to the west, both continents drain into the north Atlantic. This keeps the north Atlantic cool once melting begins.

Because the air can contain only a few centimetres of water, the bulk of the water is stored in oceans and ice caps. Thus mass transfers of water can occur only between these two. Ironically, ice is mainly stored on land whereas water mainly in the oceans. So an ice age can happen only by the transport of moisture through the air, from the oceans to the ice caps. It is a slow process, even though it appears to happen suddenly. The scenario behind ice ages could be as follows:

• first the oceans should have warmed sufficiently during a warm interglacial, before a new ice age can begin. When and where an ice age begins, the air is cool and the oceans warm, resulting in lots of moist air and rain/snow.
• it takes only a few years of sudden cold, to cover the northern continents in a wide swath of light-reflecting snow which does not melt in summer. (a deep sunspot solar minimum could do it)
• local runaway cooling sets in because more heat is reflected away into space
• heat moves quickly upward but slowly downward; the lower atmosphere cools
• the north has an enormous area of land that can be covered in snow and ice, in an ever widening circle that increases rapidly in its surface area (pi * radius * radius) and thus reflecting heat back to space ever more rapidly as it expands. Note that the snow's thickness is unimportant, but its extent is.
• the warm oceans initially have an unlimited supply of moisture to precipitate as snow
• the water cycle speeds up as more moisture condenses over the ice caps, returning cooler and drier air to the warmer regions.
• although local air temperature cools quickly and also the surface of the oceans somewhat (making it seem to happen suddenly), it takes thousands of years to reach a new equilibrium
• contributing factors are:
• CO2 flows back from land to sea, creating larger deserts and grasslands, which reflect more light to space. (see Chapter1/daisyworld and the carpon pipe hypothesis)
• as sea levels go down, more of the continental shelves emerge, becoming reflecting land where once radiation-absorbing sea was. About 8% of oceans is continental shelf, but the Arctic ocean has very large continental shelves.
• as ice builds up on continents, these tip downward towards mid-latitudes (London e.g.) and upward in the Arctic. As a result, the arctic continental shelves become shallower and eventually freeze over entirely, thereby ending the ice age.
• when an ice age ends, the oceans have cooled sufficiently to significantly reduce the moisture in the air and hence the transfer of water to snow/ice. A warm inter-glacial begins. Because the melt water flows direct to the sea, the sea surface cools rapidly, inhibiting evaporation in arctic regions. Thus warming is fast and an ice age ends fast.
• the south pole is not affected much by an ice age because it is surrounded by oceans and is already fully covered by ice, but the ice there could grow thicker
• because the process described here depends on physical quantities that do not change (properties of evaporation and condensation, sea surface, sea volume, heat content, land surface), one ice age resembles much the next one and even their timing is similar. No extraordinary explanations are necessary.

From the Vostok (Antarctica) ice core, which goes back for 4 ice ages, it can be seen that the temperature goes through very similar swings. In this graph, the five interglacials have been superimposed, aligned by their maximum temperatures. The magenta-coloured squiggle is our present interglacial warm period, which has been remarkably level over time. It has lasted now for over 6 millennia and the next ice age can begin any time soon (give and take a millennium). The Eemian is the previous warm period, some 110,000 years ago.

Arctic Jacuzzi There exists a possibility that an ice age can begin only once the arctic ocean opens up and its ice sheets have melted away. It then becomes a source of moisture by evaporation, where before, little moisture existed. As the water evaporates, it is replaced by warm water from the warm Gulf Stream, thereby accelerating evaporation. As soon as the air crosses the cool continents, all its moisture precipitates as snow. The arctic then behaves as a warm Jacuzzi (hotpool), transferring water to surrounding continents at an abnormal rate. An ice age ends once the sea level drops below -100m, and the warm Gulf Stream is choked off from reaching the arctic ocean.  The Arctic ocean has very large continental shelves (light blue on map), which would gradually reduce the jacuzzi effect, eventually freezing over entirely.

Oceans have around 1000x the heat capacity of the atmosphere. If the atmosphere transferred so much heat to the oceans that the air temperature went from an average of 15°C to a freezing -15°C, the oceans would heat up by a tiny, almost unnoticeable 0.03°C. The atmosphere cannot heat the oceans, because it does not have enough heat capacity and heat wants to rise rather than sink.

Reader, please note that the above scenarios are forms of speculation, based on physical principles. To our knowledge, the above scenario has not been reported before, and it is here that you first read it. Even if this scenario proves to be wrong, it still remains a good exercise showing how many factors work together: solar radiation, cosmic radiation, physical properties of water, physical properties of carbondioxide, curvature of Earth, geography of land and sea, tipping continents and the presence of life.

Ice shelves Ice shelves are found only where the sea water becomes cold enough to freeze over during winter, such as at both poles. Because the arctic (north pole) is an ocean surrounded by land, all arctic ice consists of ice shelves (except for Greenland, Iceland and north Canada). During summer as the sun light becomes stronger, the ice shelf warms up, particularly where melt water pools form, because water absorbs infrared warmth whereas snow reflects it. The higher temperature also causes the ice and melt water to slowly ablate (evaporate). Because ice is a good insulator and does not conduct heat easily, the melting below happens later and more slowly (top-down). However, because the ice experiences intensive contact with water, which transfers heat very effectively (bottom-up; heat moves upward), the melting below the ice proceeds rapidly, depending on sea temperature and currents. In the process, a layer of fresh water forms under the ice shelf, protecting it from salt water attack. In this condition, the melting process is very sensitive to wind, waves and currents, resulting in quite unpredictable 'erosion'. Think of sea ice as a very thin sheet, sandwiched between two worlds of air/wind/sun and water/waves/currents, both rather unpredictable.

sea ice extent is not a good measure to judge global warming by.

In winter the ice shelf thickens from two sides: snow falls on top and seawater freezes from below. As the seawater freezes, it leaves its salt behind, creating a salt lens underneath the ice shelf. Because cold salt water is very dense, it sinks to the bottom where it begins a long journey over the bottom of the oceans, as part of the ocean thermo-haline conveyor belt.  The diagram shows how cold water sinks both around antarctica and the North Atlantic, because both cold and salinity make it maximally dense. Travelling across the equator inside deep ocean trenches, it resurfaces somewhere in the north Pacific and Indian Oceans, as a warm water girdle closing the loop.

Note that a layer of ice over the ocean changes its properties quite considerably. For instance, the wind can no longer make waves and surface currents, although it can move ice shoals. Also the water can no longer evaporate to bring more snow, and sunlight is reflected back into space. A solid ice shelf is thus a rather stable condition. As it melts and more and more open water appears, the wind, waves and currents can suddenly accelerate the melting while the open water warms by absorbing light and heat. In addition, the life in the sea begins to bloom, making its own contributions.

In the debate about global warming, much ado is made about the extent of sea ice, but it is not a good indicator of warming/cooling because it depends on so many factors that influence one another, particularly on ocean currents. Note that sea ice, which floats on the water, cannot cause the sea level to rise when it melts.

Important points:

• it is wrong to pay much attention to ice boundaries like sea ice extent because they are highly variable
• melting sea ice cannot contribute to rising sea levels
• sea ice depends very much on currents and their temperature and speed
• a loss in ice cover does not mean a loss in ice volume
• sea ice expands and shrinks considerably, forming cracks and stacks.
• wind force over large areas can stack sea ice high and this reduces their area covered.
• when ice forms in winter, dense salt water sinks to form deep water currents.
• the mass of sea ice is more important than its extent. Yet scaremongers report on extent only.

Glaciers Glaciers are rivers of ice, found on the coldest slopes of mountains. They grow in thickness by snow, which becomes compressed to ice and then to hard ice. At a depth of about 50 metres, the hard ice deforms into metamorphic ice, capable of distorting slowly. In this manner, the glacier indeed 'flows'. For instance, at its bottom and sides, it flows around obstacles, but downward of the obstacle, the negative pressure turns the flowing ice again into hard ice, 'plucking' at obstacles. Glaciers flow faster near the surface than near the bottom. Below the summer frost line, glaciers can melt in summer, and below the winter frost altitude, they melt continuously. Because ice has a high latent heat (coolth) content, melting happens slowly, and because ice is a good thermo-insulator, it stays cold near the bottom and inside.

A glacier's erratic behaviour can be thought of as follows:

Much ado is being made of glaciers shrinking due to global warming, but glaciers are not really good indicators because their size mainly depends on the amount of snowfall and thus the moisture content of the air. Earlier in this chapter we saw that land use change has a major influence on the water cycle, causing land-locked glaciers to shrink but leaving coastal glaciers unaffected. Ironically, most glaciers are land-locked, seemingly supporting the global warming argument.

When glaciers end in the sea, they may still be 'locked' onto the bedrock because the ice can float only when 90% is submerged. Such glaciers can spawn ice bergs by breaking off small pieces, small enough to float.
 
 

Are glaciers melting due to global warming? The melting of glaciers has been cause for concern, fanning the fear of global warming. This graph pictures both humanity's use of fossil fuels and glacier shortening which began almost a century earlier and which is steadily progressing. Because glaciers shortening began before the industrial age, human emissions of carbondioxide and their associated global warming, cannot have caused their shortening. In this graph also the increase in sea level is shown, tracking along the glacier-shortening curve.

Important points:

• it is scientifically wrong to measure on habitat boundaries because they are changing due to many factors.
• glaciers grow and shrink naturally.
• a loss in length does not always mean a loss in mass.
• land-locked glaciers shrink due to loss of moisture from human change of land use (deforestation).
• sea-bordered glaciers depend on the amount of sea wind that brings moisture.
• a small altitude change of the frost level affects a large distance of terminal ice.
• glaciers have high latent heat (coolth) and so do ice shelves.
• glaciers began shrinking at a steady rate over a century ago, before the industrial age.
• CO2 and 'global warming' have not caused them to shrink.

http://www.appinsys.com/GlobalWarming/GW_4CE_Glaciers.htmAn excellent summary of the world's glaciers.

• The usual temperature, climate and weather for any place on Earth, in any month of the year, is mainly dominated by the amount of sunshine and the amount of moisture. Latitude and season determine the amount of sunshine and thus warmth, whereas moisture has a moderating effect. Heat-waves are unusual spells of unusually warm days.
• All moisture comes from the sea. It is transported through the air onto the land and some returns through rivers to the sea. Thus places near the sea receive more moisture than places far inland, reason why all continents have deserts in their centres.
• Global temperature is dominated by the oceans because they have a much larger heat capacity than the land. Thus global temperature is best measured at sea.

Important points:

• climate often works contrary to intuition.
• measuring land temperatures is not a good way of measuring global temperature.
• a cool(ing) sea makes heat-waves, droughts and bushfires more likely.
• wherever cold seas flow past continents, they cause desert climates (California, Chile, Galapagos, etc.)
• global cooling has an immediate effect on the land, and affects oceans much later due to their heat capacity.
• global cooling makes heat-waves and droughts more likely, as well as bush fires.
• global cooling diminishes agricultural production.

Important points:

• Ocean circulation plays an important role in the heat transfer from equator to poles (30-60%).
• Ocean circulation stagnates durning an El Niño event, for one or a couple of years.
• Oceans circulate during La Niña period of 9 years, which used to be 27 years (before 1960), transporting heat to varying degrees.
• During an El Niño, oceans warm in the tropics and cool in temperate areas, resulting in droughts, heat waves, cold winters, bush fires.
• When an El Niño ends (or La Niña begins), a pool of warm water travels towards the poles, causing the opposite: rains and snow, depending on summer/ winter in temperate climates.
• The longer El Niño lasts (currents stopping), the bigger and warmer the pool of tropical water, and the bigger its effect on the weather once currents begin circulating again.
• This weather disruption affects agriculture almost everywhere, and dependent on the timing of events, can be catastrophic.

Important points:

• The imminent food famine is global.
• A crisis can explode within months rather than decades (unlike 'global warming').
• Global cooling and droughts will intensify as the sun enters a dormant period.
• There are many complicating factors (population growth, growth in demand, higher energy prices, soil degradation, water crisis, urbanisation, politics, economics, corrupted markets, futures speculation, fuel from food).