With a diameter of 12,700 Km the Earth has an area of 510 million Km ², or 51 billion Ha. Sea area is 362 million Km ² :land 148 million Km ², of which 128 million Km² is dry. In what follows we shall be concerned with two different levels of scale: our human scale: against which changes are huge, and the global scale, at which they are tiny.

The greatest height is 8850m: the greatest depth of ocean 11000m. The average depth of the oceans 1s about 4Km. which is also the height of the atmosphere useful to us. The atmosphere is essentially vacuum by 50Km. above the earth's surface.

On a 300mm diameter globe the average ocean depth would be about 1/10mm. The outermost wisps of atmosphere would eddy just over 1mm above the surface. The ozone layer, about 20Km up, would hover .5 mm above the surface. A billiard ball, at scale, would be rougher than the earth.

That is the global scale.

The Basis

In deriving what follows, two fundamental principles have been applied. The first is that we continue our present 'do worse' scenario: greenhouse emissions have increased about 50% since 1980 and are expected to have doubled within a decade or two. The second is that basic real world measures of what is going on are more telling than theories, hypotheses, or derived argument. This is not to discourage these necessary aspects of approaching an understanding of what is going on around us, and they have been used. The basis of this presentation. however, derives from measured data more than calculation, wherever it is possible and appropriate.

In addition, data for oceans and earth are preferred to those for atmosphere: air is too scarce (1/1000 oceans), and has too low a specific heat (1/800th water). It is also too volatile.

The Core Data

In 1965 ice loss was about 600 Km³. In 1980 it was about 1,200 Km³. In 1986 ice accumulation was about 2,000 Km³ p.a. and loss about 1,450 Km³ p.a. In 1992 ice accumulation was about 2,140 Km³, and loss was about 2.530 Km³. In 1965 ice shelves moved about 400 m p.a. In 1980 this figure was between 900 and 1300 m p.a.

The 1999 figures give 7 mm p.a. level increase, not allowing for thermal expansion, and 6 mm decrease. Net + 1 mm. It is estimated that the Greenland cap is retaining up to 2 mm p.a. worth of sealevel rise.

Satellite data gives a present rate of sealevel rise of up to 2-3 mm p.a., up from 1-2. Temperatures have risen 2.5°C in Antarctica in 40 - 50 years. Seaice is retreating about 1.4% per decade in Antarctica (now statistically significant) and northern seaice 4.3% per decade, up from 2.5%.

The Present rate of ocean temperature rise, over decades is about .04°C p.a.: more around Antarctica.

The Conclusion

This presentation is headed into uncomfortable territory: its thesis is that there is a growing probability that our manmade warming will cause Antarctica to melt on a timescale of a few centuries at most and that within the lifetimes of the children now at school we will begin to suffer the major consequences. We are dealing with the unknown and with a multitude of nonlinear processes. There is an unquantifiable probability that we have already triggered it and can only move to slow it down. Another probability is that if we act swiftly and stringently enough we may be able to avert it. I do not know: noone knows.

The scale of risk, however, is so great that we cannot afford it, no matter what those probabilities may turn out to be.

This is not an experiment, nor a rehearsal. This threat is real, and it is now. It is beyond the scale of our ability to cope, other than by avoidance. The great white wolf may well provide the carcase for all the environmental vultures we have been breeding to feed on.

THE GLASSLESS GREENHOUSE

To liken the greenhouse effect to a greenhouse is a perfect example of a misleading oversimplification of a false analogy. It isn't like a greenhouse at all. What happens is that gases in the atmosphere absorb photons of heat and reradiate them. They receive them from all directions, and reradiate them in all directions. There are two directions, however, where the flow is greater: that coming in from the Sun, and that going out from the Earth. The presence of the gases causes more of the radiation to be retained: it causes the Earth to warm. To this effect owe the habitability of the planet: in particular we owe that habitability to the balance struck between the increasing temperature, which increases outward radiation, and the effect of the gases, which determines how much escapes. The 'original equipment' gases were C02 and, tripling this effect, water vapour. These left a region of the energy spectrum where a lot of heat could escape, misleadingly called a window, which we are filling with gases which prevent that loss The windows in our greenhouse act in reverse to those of a real greenhouse! There isn't any glass to break, and the door is stuck.

The timelags between adding gases and the final state of balance are long: so any risebydate figure you may see you can about double for the final effect, provided that no more greenhouse gases are being added: that is zero growth.

Before maninduced warming, of the 390 j radiated from each m² of Earth 237 j escaped into space, about 61%, exactly balancing the heat input from the sun and leaving 153 j to raise the planet's temperature to a range appropriate to us. The earth is some 31-33°warmer that it otherwise would be (expert estimates differ). A simple sum suggests that 1°C can be expected for each 5 j/m².

The figure climate modellers often give for the additional greenhouse effect is 2.5 j/m², sometimes 4 j/m². Deriving this is a complex calculation and the exact figure is a matter of opinion and debate. The lower estimate will be used here.

But how much energy is involved? The 'before' figure was 153 j/m². One third of this, 5l j, due to CO2, amplified by feedback from extra watervapour in the air, and at least half of the CO2 doubling effect will be due to other gases.

If CO2 is increased by 50% from 280 to 420 ppm, then the extra heat retention is 7.5%, or about 4 j/m². Thus the present route for CO2 alone will be something over 2.5 j.

To get a figure for the energy added at CO2 doubling we need to double this for the other gases and then triple it for the watervapour effect. 4 x 2 x 3 -> 24 j/m². To this must be added an amount for the extra UV due to the worldwide depletion of the ozone laver. All the extra UV absorbed will manifest as heat.

Between 7 and 9% of the solar flux is in the UV bands, or 30 j/m². Allowing for 20% of this to be added, 6 j, gives a total of about 30 j/m² of additional greenhouse effect. This suggests a final equilibrium state of + 6°C. Were the present CO2 rate 4 j/m² as is sometimes used, the effect would be 42 j/m² and the final state 8 deg. warmer.

Current annual rates of deep ocean increase are of the order of .04°C. maintained for decades as a check: just for the ocean. 3730 (depth m) x .04 (annual increase °C) x 4.2x 106 j (energy required per m²) / 3.15x10&sup7 (seconds in a year) > 20 j/m²). Oceans lag the atmosphere. and will not be registering strongly yet.

Other energy inputs additionally retained include direct human energy use (<.1 j/m² but locally much higher. > 4 j/m²) and energy reaching the surface from the core (.05 j/m²). These and others are small and total well within the range of uncertainty of our figure.

There is plenty of damage left to be done: if we've restricted escape by an eighth there are seven eighths left to go.

THE GASES

The 'original equipment' greenhouse gases, to which we owe the habitability of our planet, are CO2 and H2O as water vapour.

In relating the warming effect of gases CO2 is taken as 1, and the factor is the warming effect over the gases' atmospheric lifetimes, tonne for tonne (relative warming constant).

To illustrate this, 12 thousand tonnes of domestic CFC consumption in l986/1987 had 2/3 the effect of 87 million tonnes of domestic coal consumption (producing CO2 and N2O): 100 million tonnes CO2 equivalent vs 155 million tonnes. Note that the N2O element virtually doubles the greenhouse effect over the tonnage of coal itself. Coal is as damaging an export as uranium.

CO2

An abundant and relatively ineffective greenhouse gas easily regulated by biosphere. This makes use of it as a warming reference standard a very dangerous red herring.

It absorbs in the 13 -19 micrometre band and in that range already absorbs so much that relatively large increases in concentration will lead to quite low additional absorption, this goes up as the logarithm of the concentration, about 7.5% for a 50% increase.

Water Vapour (H2O)

A natural greenhouse gas and heat and water transport. Absorbs right across the band so that as the Earth warms with more watervapour in the air, increased radiation at higher energies will be increasingly blocked. It is about 10-40,000 times as abundant as CO2 and triples the heating effect due to other gases. It is the prime warming feedback mechanism.

Ozone (O3)

A greenhouse gas, powerful poison and UV shield. Depleting at high levels (less shield), while increasing at low levels.

About 10% of ozone is at low levels: the gas is especially toxic to plants and can be lethal at concentrations not far off today's. Concentration has about doubled in the last century, from 10 to 20 ppb. Can reach 200 ppb.

At sea level the stratospheric ozone would form a layer about 3mm thick: there isn't much of it. Ozone depletion increases UV at the surface, both UVA and UVB, markedly deleterious to many species. Despite earlier disbelief the effect is both marked and worldwide. UV penetrates water deeply, and has a marked effect on plankton and fish larvae (a 20% increase at l0m for 15 days killed all of one species). Ozone depletion will continue for many decades after we cease to produce the agents of change.

Damage to biological systems is essentially the same as that from any treeradical producing event such as exposure to ionizing radiation, and has to be seen as at least additive to such effects. It has different effects on different forms of phytoplankton the most useful CO2 absorbing and O2 producing being worst affected.

Since the band used to be saturated, the energy absorbed increases as about 1.6 times depletions. 2.5% > + 4% UV where there is virtually no ozone, as over Antarctica in spring virtually all the UV penetrates. This more than counters the loss of greenhouse effect due to ozone depletion.

Ozone loss is a powerful warming agent, particularly at the poles. Models have consistently underestimated the ozone effect by a factor of two. It is critical, decreasing overall by 4-5% per decade from 1979 between 40 and 600 N and S.

Some 7-9% of the solar energy is in the UV bands about 112 j/m². Adjusting this for angle, ozone variation season and reflection suggests an average energy input to the Antarctic of 4-10 j. This will increase if any high ice faces are created by melting, since the angle presented to the radiation will come closer to the perpendicular.

Methane (CH4):

Increasing due to human population growth (forest clearing, rice paddies, cattle, mining, energy use and refuse) and termites, but gigatonnes locked up in frozen (thawing) tundra and in the oceans (500-1000 Gt) as clathrates (a c. is a solid in which one component is enclosed in the structure of another). Increasing very rapidly. The critical temperature for large releases is unknown, but there is evidence that it has begun. If so this will be an enormously powerful positive feedback on warming.

Methane is 'metabolised' into CO2 and H2O by hydroxyl (HO) but blocked by CO2, which HO also cleanses. At 3 deg. C. .5Gt p.a. is released from oceans. l2X as powerful as CO2.

Also involved in ozone destruction is the stratosphere ice being] broken up and taking up oxygen, leaving water vapour or ice. Doubling water vapour in the stratosphere is as powerful as doubling CO2 in the troposphere where we live.

Residence time is l5 yrs: doubling the concentration will increase heating effect hv about 40-50%.

Chlorofluorcarbons (CFCs)

We are not phasing out all CFCs, only those most damaging to the stratospheric ozone. Others such as HCFCs, 1/3 as damaging to ozone, but still powerful greenhouse gases, are being substituted. Meanwhile there is a thriving black market, smuggling at over 20,000 tonnes p.a. into the USA and continuing production: 360,000 tonnes in 1995.

Methyl bromide, responsible for about 15% of ozone loss, is expected to increase by 8% p.a.

Some of the CFC replacements have atmospheric lifetimes of about 50,000 yrs. and one, sulphur hexafluoride, is reported as the most powerful greenhouse gas that the IPCC has yet tested. That makes it more than 27,000 times as powerful a greenhouse gas as C02 . Due to the low concentrations doubling CFCs in the atmosphere will about double the heating effect.

Due to long lifetimes, ozone depletion will not end quickly, and CFC-derived warming will continue for the foreseeable future.

Nitrogen Oxide (N20)

With a lifetime of about 125 yrs, N2Ois 470 times as powerful as CO2, doubling its concentration will increase heating 40-50%.

Slowly processed by anaerobic bacteria and lightning.

Others

Greenhouse gases such as CF4 and C4F6 are produced in quantity in aluminium processing for example, and others by other manufacturing process. No data on the amount. Overall emissions have gone from 3,900 million tonnes in 1970 to 6,000 million tonnes in 1993, and a predicted 8,600 million tonnes by 2010, mostly, but not entirely, in the developing world.

THE WARMING

Arrhenius (1890) Predicted about 5°C for CO2 doubling effect, now expected before 2O30. He got the temperature about right. We are now more than 2/3 of the way to the doubling and will almost certainly get more; researchers are already investigating the effects of a tripling.

Temperature rise was detected and reported in 30s: then there was down-swing. The world cooled markedly between [I940 and l965]. Debate then was over possible reglaciation. Already since [1965] we have more than recovered the warmth.

Modelling suggests that when the climate has stabilised, it will be least in the tropics. l/3 to 1/2 the average middle latitudes will get about the average and the poles 2 or 3 times the average, although the tropical stability is at present being debated.

The polar amplification is usually explained as due to ice melting and therefore more heat absorption (which is both true and least alarming) but is also due to the physics of heat exchange: heat flows from warm to cool except in the presence of some phenomenon such as life which temporarily reverses the trend. The greater the difference in temperature, the greater the flow and readier and swifter heat exchange mechanisms exist in the tropics to transport heat polewards than to transport cold away from the poles. The figure does not allow for additional changes.

UV

Climate regions will move polewards: the air and sea at the poles will steadily become warmer. As to the extent: with three scenarios: do nothing; restrained and heavily restrained - 3 to 5°C by 2015, 2O30 or 2O75: the middle scenario gives 5 - 8°C rise by 210O. The do nothing scenario, a 10 to 16°C increase in temperature.

The very least we can really hope for by then is about 4°C. conservative rate will be anything less than .5°C per decade - 5°C per century. We know absolutely nothing about how the world will respond and there is no necessary 'off' switch.

How much so far? At least 1°C since 1880, and more before, probably c. 1.5°C total. 3°C therefore minimum expectable. Up to 4°C estimated by 2O30-2050. The more optimistic estimates often include the downswing of the 1940s-1960s in their trends. As a longterm reference line this is fine, but the rate since 1965 has been closer to .3°Cper decade.

In addition, the atmospheric series is often curtailed by eliminating questionable data from earlier periods: which is also fine, as long as it is understood that there is good evidence from treerings, sealevels and warming glacial and tundra recession and boreholes that the process has been in hand for some time, probably since the beginning of the clearing of the American forests about 200 years ago: whether the effect was manmade or not is irrelevant. The overall warming so far is 1-2°C.

Oceans (+ .1°C p.a ) are said to lag the atmosphere by 20 yrs, but are increasing faster this may abate if it is due to spasmodic energy exchange. Cool summers are not a source of either hope or ripe tomatoes: they merely mean the heat has gone polewards, either quickly via the air, or more slowly via the ocean.

The temperature difference between an ice age and an interglacial is about 6°C, with an associated 30% increase in CO2. We are already at the top of that temperature range and have already increased CO2 alone by more that 33%. This makes prediction based on historical evidence shaky, as does the unnatural speed with which we are achieving it.

The Earth was 5°C cooler during the last ice age, with sea level about 100 m lower. In the last interglacial temperature was 1-2°C higher, sea level 5-7 m higher. This is the minimum historical estimate of sealevel rise, in the short term.

The critical factors are first: whether and at what point will Antarctica 'break' and second; will there be a stopping point?

Noone knows.

Any rise of more than the 3°C we have already got (although not all of it has vet arrived) will alert the world to levels which have not existed for millions of years and take us into utterly uncharted and unpredictable regions of effect.

Noone can know.

Changes will become evident as an increasing rate and severity of 'extreme events' such as El Ninos floods and cyclones, rather than graded alterations. It is perhaps worth pointing out that when the cyclone came ashore at Townsville major disaster missed us by hours: the storm came ashore at low tide. When a storm comes ashore at high tide on the steepto shelf South of the Reef as the ocean warms, we will then maybe know that we have been hit.

But perhaps the melting of Antarctica will cool the surface enough to prevent the storms coming that far South. Then the ocean will come ashore.

And so to the wolf.

ANTARCTICA

The continent and its iceshelves make up some 10% of the earth's land area  87% of this is ice sheet, 11% was ice shelves. 2% exposed rock. There are two land parts, East and West plus seaice, plus ice shelves.

The interior has lakes which melt seasonally. The ice sheet holds almost all the fresh water on earth. The interior of the ice sheet has volumes of liquid water, some of it quite warm, 35°C which contrary to recent news reports was known in the sixties.

It is not all ice: it is not all cold.

One main mountain range 5000 Km long divides E. & W. Highest peak is the 5140m Vinsen Massif. This is a major fault line with normal mantle on one side and hot mantle on the other.

It is not geologically and seismically stable and unchanging and there is ample evidence of volcanic and geothermal (produced by the internal heat of the earth) activity below the ice surface. The average surface height above sea level is 2300m  this is the highest continental average and is almost all ice. Most of the land surface has been weighted down to below sea level.

The Antarctic continent is not even land.

Climate

Precipitation is less than 50 mm (c. 5 mm rain) snow annually, and higher towards the coasts. The average is about 140 mm of rainfall.

Temperature: the coldest surface temperature ever recorded was -84.6°C (1983) at Vostok, elev. 3500mm: cold is height.

Over 0°Cin high summer at Mawson, over 0°C for more than 4 months at Palmer (on Peninsular, at a lower latitude.

Temperatures on the Antarctic Peninsula rose to more than 4°C between 1951 and l99O. The mean from 1951 to 1960 was -12.9°C from 1981 to 1990 -7.5°C.

Vostok has a mean temperature of -55°C with a range of 65°C. At Mawson both mean and range are less than half, bringing the high above 0°C.

Mean summer 0°C in the mid eighties was just off the coast except by Mawson and on the peninsula.

Much is often made of the temperature difference between the N and S polar regions: most of this is due not to climate but to height.

Ice can (and does) melt with air temperature less than 0°C. Coastal snowfields melt in summer and there is life in the summer meltwater lakes of the interior.

The West wind belt 'isolates' Antarctica from warmer air and sea circulation delays heat transfer to the continent.

The Land

East Antarctica will rise slowly following any melt to establish a continent the size of Australia. It holds 88% of the ice sheet with an average thickness of 2.5 to 2.8 Km and a maximum thickness of 4700m  twice the height of Mt. Kosciusko.

West Antarctica is several continental fragments pressed together and against the East. It will become an island group after the land rises.

Between the two runs the highest fault of its kind on earth.

Sea Ice

The seaice is in significant and increasing retreat. Since it serves as a heat reflector and air conditioner, its absence will rapidly increase local sea temperature. It also stabilises local subsurface environment at 1.8°C and provides foodchain base on the underside.

Sea ice reaches its maximum extent in September (c. 20 million Km²), receding to about 4 million Km² at the end of February. The maximum winter thickness is 3-4 m. It is a transient phenomenon.

-6% (1975 to 1988) and decreasing about 1.4% per decade 1977-1994, including the Pinatubo cooling; but not the major iceloss events of 1994. In the North, [4.3% per decade, up from 2.5%]. In the spring, water where once was ice can absorb 50 j/m². and loss of area means, as a corollary, more water available to absorb for longer.

Salt water freezes at-1.8°C leaving heavier, saltier, colder water to sink (as a circulation pump) and nearpure water as ice. That is the maximum possible temperature difference. Current summer temperatures are approaching 0°C.

Either Deep Thought got it wrong or the answer to our life, our universe and our everything is 1.8, or we, the biological computer, are busy finding the answer to the wrong question. With people like us about, who needs Vogons?

Ice shelves

There are several ice shelves where glacial flow reaches the coast and spreads laterally and thins. The main ones are the Ross and Ronne. They are called shelves because they consist of ice over water anchored on islands of rock. The thickness increases out from the coast. and they melt chiefly from the bottom up until they are thin enough to fracture and float away.

Shelves block most glacial outlets to the sea. Present melting on some shelves is over 3 m (upwards) p.a. and reported rates of movements have about tripled between 1965 and 1980. Thus they appear to be disappearing more swollen than they are. All of the extra ice comes from the ice sheet.

Melting (upwards) of well over 10m/yr (as in tens of) is now predicted. Shelflife would be less than 50 years and the loss of shelves will increase glacier flow rates.

Thinking of them as entities, however, is wrong: where they melt slowly enough times they are replenished by interior iceflow.

Land Ice

Average thickness is c. 1.6 Km: more than enough over a wide area, with a maximum of 4.7 Km (Peak of E.) extending to 700m below sealevel. Aged to 230,000 yr (max. drill depth) but most ice has a residence time of about 1,000 yrs. Little stays longer than 100,000. travelling in a curved path from deposition, down and edgeward. It fractures both across the flow and along it. and is layered. It has an inherent fractured structure.

There are 5 drainage bowls for glaciers, almost all blocked by ice shelves. The large Lambert Glacier usually referred to drains more than 1 million Km². 400 Km long by more than 40 wide, extended by 300 Km of iceshelf. With a flow of 35 Km³ p.a. It is 200Km wide at the coast, moving 230 m p.a. inland, 1 Km p.a. at the coast even though it is slowed by the shelf.

With the iceshelf gone and a moderate increase in flow rate this one glacier could release 10% of the present total icerelease from the continent.

There are extreme inconsistencies within streams, with rates from O to 2 Km p.a. In the words of the reporter "Things are wildly deviant from a steadystate system".

There are well over 80 glacial outlets, large and small and this number will increase as the ice shelves go and the ice retreats, since glaciers merge their courses like rivers, although mixing their contents far less.

As a simple introduction to understanding glaciers they are often divided into 'cold' and 'warm'. Cold glaciers are stable and relatively uniform, warm glaciers are much less stable: they are volatile and unpredictable, containing bodies of liquid water.

Warm glaciers make and breach dams of ice and earth, create and cut off underice rivers. To those who love them they are capricious, unpredictable and exciting creatures.

To be cold and stable a glacier must have a mean surface temperature of -40°C when 1500 metres thick, -80°C at 3000 metres. It is thus necessarily true that much of the thick ice in Antarctica must be in the warm classification.

The ice was 100-500m thicker in last ice age suggesting a 'not quite enough that time' scenario.

Icebergs

Ends of glaciers shearing off - 80%. Tabular bergs - parts of ice shelves - 20%. These proportions have reversed since 1965. One tabular berg 31000 Km² in 1956. one of 3000 Km² and a group totalling 11,500 Km² in 1986, one l5O x 40 Km (6OOO Km²) x 23Om thick in l987. This continues with heavy calving from the Larsen shelf and the disintegration of the Ross and Wordie shelves.

Climate History

Has sustained animalian life (dolphins, Vestfold Lake near Davis and Princess Elizabeth Land) and extensive beech forests for millions of years while in its present polar location: stable ice state has probably been determined by ocean temperature and circulation.

There is increasing evidence that the area was at least partly icefree until 2.5 - 3 million years ago, and that for long periods, with a tropical to polar temperature difference only half that of today, summer temperatures were well above 0°C.

Ice cover probably finally took over c -2.5 Ma, following opening of the gap from S. America and establishment of the present ocean and air circulation patterns isolating the continent. although there is evidence and argument that the process was not that simple.

A +5°C mean summer climate with a top of 10°C is sustainable.

The ice cap is not an inevitable or necessary feature of the earth: It is necessary to our wellbeing on the earth, but not inevitable.

There is evidence that 9,5000 yrs ago there was 'surge' of the E. Antarctic icecap that raised sealevels 15-20 m over a century, probably due to the buildup of ice during glaciation. 125,000 yrs ago the W. Antarctic ice did disintegrate, raising sealevels by 5-6 m within l00 years. There is much to suggest that this happened three times.

During the last deglaciation, within the slow melt of a large landbased icesheet, the central part, bedded below sealevel and with a single face open to the sea, disappeared within 500 years.

There is life in the present melt-water lakes e.g. the present meltwater lakes e.g. Deep Lake in Vestfold Hills.

Stability and iciness are not dependable features or a defensible argument.

At the beginning of the Triassic there is evidence of sealevels rising tens of cm p.a. Loss does not have to be slow.

The process will almost certainly be selfaccelerating: probably following some critical detail change in balance, and is most likely to be swift, as in a few centuries.

MELTING ANTARCTICA

This is not a new concern: the Wordie iceshelf calved large areas in the 1970s and another in the George VI channel receded.

By 1970 it was being predicted that an irreversible retreat of the W. Antarctic sheet had begun in the Pine Bay area. and would proceed to completion within 200 years.

The icebodies are so different that it is likely that totally different mechanisms of melt will apply to the East and West components, with the West far more likely to go quickly  a 6 - 8 m. rise in sea level within 100-200 years.

Water upwelling in the Weddell sea delivers 23 j/m² over 100,000 Km² the Austral winter.

Energy requirements

Think of the 0.lmm thickness of the oceans on the 300 mm globe: think of a 90 m rise. That's just 2.5% more ocean depth. a 1/400th of a mm on our 300mm globe. That is the global scale of a full melt. That is not large.

Sum 1: how much energy is needed to melt the Antarctic ice?

It takes 4.18 joules for l second (l Watt) to raise 1 c.c. of water 1°C. It takes 335 W to melt it. So to raise ice 40°C and melt it needs about 500 j. Thus each Km³ needs 500 x lO¹5j/Km³ = 5xlO¹7

3.62 x lO8 (water area) x .062 (depth) x 5x10¹7= 1.10 x lO²5 j.

But the ice already holds 3.62 x 108 x .062 x lO¹3 (newtons) x lO (g) x 8OO (height) = 1.8 x 10²4 of potential energy (gravity) so the added energy needed is l.12 x 10²5- l.8 x lO²4 = '9.4x10²4. High ice already contains potential energy to meet about 80% of its melt requirements.

Sum 2: how much of the additional energy can be expected in Antarctica?

Area = 14 x 10ۦ/ 5.lO x lOۨ x 100 = 2.7%. Differential to mean 2.5: 2.7 x 2.5 = 6.75%. Adjust for seaice area: 6.75 x 2 = 13.5%. No adjustment is made for extra W from ozone depletion at the poles: at least 5 j/m² of UV input can be expected locally above the global average.

Sum 3: how long to accumulate the energy to melt the Antarctic ace?

Assume that half the CO2 doubling value is the average for the whole process. Energy applied per year: 5.10 x10¹4 (area m²) x 13.5% x 15 j x 3.15 x 10¹7= 3.25 x 10²2 W. Time taken to add enough energy to the system: 9.4 x 10²2 / 3.25 x lO²2 = 290 yrs, from 108-50 years ago at best: this is another Sshaped curve

These sums are not definitive, but suggest that the necessary energy will be available well within the timescale of even a rapid melt. This remains true even if the rate of energy addition given here is too high.

Additional energy as for the equivalent tripling of CO2 to which we are headed, will increase both the energy available and efficiency of transport and reduce melt duration.

Based on the low estimate of greenhouse warming, the energy figure then will be of the order of 50 x .125 x 2 x 3 + 7 > 45 - 50 j/m².

This is the true nature of our problem: it is one of distribution rather than availability.

Note also that we are not discussing reflectable shortwavelength radiant energy with which the status quo has come into balance, but the transfer of additional lowtemperature heat energy by air and water. The albedo [the proportion of light or radiation reflected by a surface] of ice would enhance this by limiting re-radiation.

The danger is present, and real.

Much of the melt so far has been invisible. The point at which it becomes apparent depends on the local reaction to the energy application. Thus the shelves have been melted upward with little apparent effect because most of the ice being melted is below sealevel. The decreasing seaice is causing no increase in sealevel for the same reason.

This account of the view that a melt must necessarily be slow is given as presented in the late eighties with the addition of the implicit assumption that rapid glacial flow depends on temperature transmission to the bedrock.

Mass balance is probably slightly positive, within limits of uncertainty. Residence time of snow typically > 1000 yrs except near the coast. With warming, precipitation may increase 30%, which would lower sea-level by 2mm p.a. Therefore increased flowrates are of more concern. Rate of flow depends on temperature at bedrock, which will be slow to increase With 4°C warming (+200 sea), most of iceshelves would be gone within 1OO yrs .

This will increase glacial flow rates since the shelves dam the flow. Flow, currently hundreds of m p.a., will rise to several Km p.a. but not tens of Km as in surging glaciers thus it will take several centuries for ice to drain from central regions.

That data suggests a real and present threat, albeit not quite as immediate.

A model was then used to explore the process.

The conclusion was that there will be a maximum sealevel rise of 1m in the 500 years following the disappearance of the iceshelves, leading to an overall rise in 1000 years of 3.4m and a new equilibrium after 5000 years at + 4.5m with the E. Antarctica ice thicker over more of its area.

Well, at present rates the ice shelves will certainly be gone well within a century.

A 30% increase in precipitation was predicted for expectable temperatures following a doubling of the CO2 effect, with a possible 1.7 mm p.a. sea level drop  this is the basis of the time estimate, together with the assumption that it would remain on the icecap for a long time.

1.3 x 140 is 186 mm, yielding an increased in accumulation of 600 Km² p.a., equivalent to a 1.7 mm p.a. sea level drop to compensate for rises due to iceloss. There is no way this can begin to compensate even for a slow melt, even if residence time is long: current data indicate that this slack has already been taken up.

The added weight inland even if precipitation reaches there will not stay: it will act to accelerate the iceflow and since most precipitation occurs close to the coast, it will be back at the coast within a few decades or centuries at most, as will the heartland ice.

Surging glacier speeds of tens of Km p.a. are possible, even if they are not likely, as iceflow will not be over bedrock (most of it being below sea level) but by shearing over ice, the friction of which will generate the melt water to lubricate the flow.

In addition, warm seawater will be eating away at the ice mass in exactly the same way as the shelves are being consumed but with an increasing faceheight and much more rapid shearing. At the end of the last iceage the ice was thicker than now' i.e. warming decreased the ice volume: Antarctica did not store an excess. The thicker cap theory does not correspond to historical data.

In order to survive the W. Antarctic ice may need a temperature 10°C colder.

Holding gas levels is not enough: our goals must be far more stringent.

If iceoutflow were doubled while accumulation increased slightly, sealevels would rise by 7.8 mm p.a. For a quadrupling 21 mm with no allowance made for thermal expansion or land rise. Small change in balance, large change in effect.

Process

The real question of the Antarctica ice, of course, is how it can be there, not how it can melt.

The first answer to this we have already eclipsed: height, and the storage of energy. The potential energy of the high ice is about 80% of the energy needed to melt it.

The second answer is probably the seaice, which cools and removes water from air flowing over it and provides a buffer to minor and shortterm changes.

The third answer is likely to be the present air and ocean circulation patterns which further delay energy exchange, evening out minor changes.

The circulation pattern of the oceans is likely to be disturbed as energy distribution continues and meltwater arrives at the ocean margins. There is no way of foretelling the effects, or critical point. There are signs of fundamental change, such as El Nino frequency and the frequency of 30 m waves in the N. Atlantic and the 50% increase in wave size between the 1960s and 1980s, but none that can be interpreted with certainty. There are signs of imminence. There is evidence of frequency and rapid climate change, 70°C in years at most, in the North. There is only one fundamental ocean circulation pattern.

Apropos of Antarctica, however, since the present ocean and wind circulation patterns are held to keep it frozen, any change seems unlikely to be beneficial.

What is important is that it used to be in balance with relatively low rates of energy input. This has already, clearly, been disturbed. There may be other, new. balance points: noone knows. What seems likely: however, is that the speed of the present rise will act against any balance becoming established.

What also seems likely is that the process has been continuing for some time, and we may have passed through the accumulation exceeding melt stage.

So what are the mechanisms of melt? There are several. First there is radiative energy. Particularly important is its reflection by snow vs absorption by ice, sea rock or life. That absorption is increasing and will continue to do so. Ice is not white. but blue, due to differential absorption.

If the melt starts inland from the coast, creating ice cliffs or steps, these will present at an angle to overcome the slant due to latitude, which gives high reflection and start absorbing radioactive energy more or less at right angles. That will be very high and will increase with increasing cliff or step height.

Then there is sea water: increasing sea-temperature will melt ice more rapidly. At 10°C it will take 80 cc to provide the energy to melt 1 cc of ice. At 20°C, 40cc, and so on. Friction from flowing water is already melting ice and will continue to do so. Antarctica already manifests as heat.

Then there is water vapour. Here are the claws of the wolf.

What is in a raindrop?

From the surface of the sea water vapour is evaporated: this takes a lot of energy over 2,000 j per gram. This may then be convected high into the air, say 3,350 metres, taking .01 x 10 x 3350 =.335 j per gram. It may then be transported polewards. If it arrives on ice, and condenses, it will release enough energy to melt nearly seven times its own weight of ice. If it has maintained its altitude and condenses on an ice crystal to make a raindrop it will release the same amount of energy, warming the air, and then fall onto ice, releasing enough energy to melt its own weight. If, in addition. it lands at 10 °C, then 8O raindrops will melt one raindrop's weight of ice; 40 at 20°C, etc.

Air temperature is important first because of the temperature of the water vapour, and second because of the .amount of water vapour it can contain. Warm air over ice means melting far greater than the temperature change.

If the vapour condenses somewhere high and cold enough to absorb its energy, without melting the heat will warm the surface: the gravitational potential energy will be stored until the ice starts moving downwards. The high ice already contains 8O% of the energy needed to melt it.

So what might slow it down?

Volcanic activity dust cooling vs decreased albedo and 'salting' ice with contaminants to lower melt temperature this is a known effect plus the energy released from the mantle. Not to be relied upon.

Energy reflection and absorption as ice melts at sea and icemelt water warms. This will probably be no more than a temporising effect since it effectively increases the area of ice easily receiving energy.

The disruption of the oceancirculation pattern shutting down the Gulf Stream and reglaciating Europe. Probably too slow.

Major Earth trauma  not a solution.

Stringent human activity on greenhouse emissions, bighealth and egality and sharing with impoverished peoples.

Sea Level Rise

This is very difficult to measure in small amounts, even with satellites. Land is rising in places, falling in others, and it is affected by sloping seas, and long period waves, as well as climate events and trends, and resonance effects.

So far up to 3 mm p.a. has been measured, with some stored in Antarctica and Greenland thus any increase can gain rapidly with balance shift.

First reports of 'defences' against rise being built or strengthened: land loss is through erosion by waves, especially beaches and particularly during storm surges. Thus it is seen more often as an event rather than a process.

Rise for total melt: 55m E. Ant; 6-8m W. Ant.; 8m Greenland: + temp> 73m. To that add the water displaced as the Antarctic land-mass rises, an average of about 600m. say 20m to be conservative. Between 90 and 100 metres, which is of course irrelevant. On the 300 mm globe, that would thicken our 1mm thick skin of water by less than 3/100ths mm. That is all the global scale we are discussing. Land loss for 90mm rise: 90 million Km²+ erosion: 13 to 15 x Australia, almost all prime land, cities, nuclear power stations and such.

The centrifuge effect will probably result in a greater equatorial rise and lower polar rise. Australia will probably experience about the global average, to whatever extent that matters.

Rise so far? At least 200-300 mm, depending on the start date. We are at the beginning of a noticeable increase and effect. Most so far is due to sea temp rise and S. coastal and N. melting, moderated by up to 2 mm p.a. by increased ice. The later data indicate that levels have risen an average of 20 mm per decade, this century.

Rate Of Rise

The Marvin curves

In the beginning there was lots and lots of ice and very little melt. Melting was therefore slow. Mass balance was positive so rise was even slower.

At the end there will be lots of heat and very little ice, so rise will be slow, but the sea will be expanding most rapidly due to the heat, which will increase the rate.

As a result the rise will follow some 'S' -shaped curve which can be simply constructed to demonstrate the manner of the rise with all the accuracy that is meaningful. The shape conforms with what is known of previous major sea-level rises.

The actual curve, of course, will have bumps and flats, since it derives from the interaction of several quite different processes involving many non-linear processes, some often minor, and this happening quite quickly. The physics of the process and lag times, suggest that it will be easier to switch from slower to faster in the lower half.

The upper and lower average curves will almost certainly not be the same, but the detail of the upper curve is of no present consequence to us.

These curves are not adequate to any prediction: there is too much uncertainty in the rise so far and the present rate attributable to Antarctica. They may serve only to demonstrate main features. The most likely fits to present data suggest a period of between three and five hundred years, but at this stage the data is very loose. Without the correction to the satellite data, the period could be less.

The figures give, for each duration and rise so far, the rise in metres in the next 100 years, the maximum rate of rise per year, the average rise for the middle one third of the curve, and the present annual rise attributable to melting of the big ice. in mm.

To fit slower rates, the rise so far must be greater. or the start time earlier or the rate today lower. The minimum estimate would be about 1.5 mm the maximum 3, depending on what ice is melting where.

Unfortunately, however, if the duration is to be short, by the time the process can be verifiably demonstrated (as with population growth and greenhouse cas rises) it is too late for any simple controls to he effective. Wait and it may be seen but by then it can't be stopped.

Remember too that the last interglacial melt was from the bottom of the temperature cycle amid a correlated increase in greenhouse effect. The present melt, if triggered, will be from the top of the temperature cycle upwards, with greatly enhanced energy absorption already in place, and growing. The only sustainable argument is that the melt is likely to be more rapid.

We may know quite soon: the final set of curves are those for the next 100 years. These curves are just a section of those already given, the 600 year curves being left out simply for clarity: within 50 years it will be difficult to distinguish between them. The 400 year curves show annual rises of about 150mm p.a. within the next century, lOOmm p.a. well before that. Devastating direct and reflected effects could be expected within the lifetimes of the children now at school.

As can be seen, if we get rises of anything approaching lm by 2050 we will indeed be up to our necks in it.

If this seems excessive, consider: there are knowledgeable observers who would not rule out a 100 year melt in some circumstances, and 500 years is easily within our grasp, given the lack any significant and effective intervention at the global scale.

In 20 or 30 years we will be able to tell if we have unleashed a rapid melt, in 70100 years time we may be able to demonstrate a slower rise. In neither case would there then be much we could do to change it.

The Consequences

The consequences of a 90 m rise in sealevels in terms of land. city, resource, trade and technology loss need not concern us. The negative effects will strike far earlier.

At some stage we can expect a marked increase in seismic and volcanic activity: the fault line across Antarctica will be unevenly stressed as the land rises, and the rise itself is likely to trigger spectacular effects.

We are becoming increasingly aware of how subtly and thoroughly linked fault activity is worldwide. In addition, the added weight of the water, as it disperses, will make the whole world crust try to shrink a little. It is after all only floating on the mantle.

Even that probably need not concern us much. The early stages of rise well under a metre, will affect hundreds of millions of people and they will not happen in a political vacuum. Some of the countries adversely affected are nuclearcapable if not already so equipped.

Countries close to us will be under enormous pressure resource loss and population displacement. Australia is likely to be to be seen as a paradise, which will be relatively true even if it is in reality false.

Even if direct local consequences are relatively minor, the world effects will be marked. Even if the loss of the Gulf Stream and a reglaciation of Europe should save us from flooding, it would be naive to expect that we would escape unaffected.

That is why it is urgent.

Lupus Antarcticus Sum sheet

Sum A: how much energy is involved?

The 'before' figure was 153 j/m². One third of this. 5l j' due to CO2.

If CO2 is increased by 50% from 280 to 420 ppm, then the extra heat retention is 7.5%, or about 4 j/m². The present rate for CO2 alone: something over 2.5 j.

To get a figure for CO2 doubling, we need to double this for the other gases and then triple it for watervapour. 4 x 2 x 3 -> 24 j/m². Add to this extra UV.

Between 7 and 9% of the solar flux is in the W bands, or 30 j/m². Allowing 20% added, 6 j/m² gives a total of about 30 j/m².

This suggests a final equilibrium state of +6°C. Were the present CO2 rate 4 j/m² as is sometimes used, the effectwould be 42 j/m² and the final state 8 deg. warmer.


Sum B: a check

Current annual rates of deep ocean increase are . 04°C, 3730 (depth m) x .04 (annual increase °C) x 4.2x10ۦ j (energy required per m²) / 3.15 x 10&sup7 (seconds in a year) > 20 j/m²).

Sum 1: how much energy is needed to melt the Antarctic ice?

It takes 4.18 joules for 1 second (1 Watt) to raise 1 c.c of water 1°C. It takes 335 W to melt it. So to raise ice 40°C and melt it needs about 500 j. Thus each Km³ needs 500x10¹5 j/Km³ = 5 x10.

3.62x10ۨ (water area) x .062 (depth) x 5x10¹7= 1.12 x 10²5 j.

But the ice already holds 3.62x10ۨ x .062 x 10¹3 (newtons) x 10(g) x 800 (height) = l.8 x 10²4 j of potential energy (gravity) so the added energy needed is 1.12 x 10²5 - 1.8 x 10²4 = 9.4x10²4. High ice already contains potential energy to meet about 80% of its melt requirements.

Sum 2: how much of the additional energy can be expected in Antarctica?

Area = 14 X 10ۦ / 5.10 X 10ۨ x 100 = 2.7%. Differential to mean 2.5: 2.7 x 2.5 = 6.75%. Adjust for seaice area: 6.75 x 2 = 13.5% No adjustment is made for extra UV from ozone depletion at the poles: at least 5 j/m² of UV input can be expect locally above the global average.

Sum 3: how long to accumulate the energy to melt the Antarctic?

Assume that half the CO2 doubling value is the average for the whole process.

Energy applied per year: 5.10 x 10¹4(area m²) x 13.5% x 15 j x 0.15 x 10&sup7 = 3.25 x 10²2 W. Time taken to add enough energy to the system: 9.4 x 10²4 / [missing text]. 25 x 10²2 = 290 yrs, from 100-150 years ago at best: this is another Sshaped curve.

OCR and emendation performed by JMBarnsley@Ferny Creek: March '97. jmbarnsley@cO31.aone.net.au

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