In past times we have had pulses of sea level rise that have seen many metres in a few decades and as we only need one metre for economic and human disaster a lot of research is being done to understand if it could happen again.

n many ways circumstances are very different from those in a previous pulse of sea level rise as we are just past the peak of a warm period. The previous sea level pulses came from the melting of huge land based ice sheets on the North American and Asian continents which have now gone. 

​The only remaining big ice sheets left are on Greenland and Antarctica and they can be divided into four different significant regions with very different circumstances and very different potentials for adding to sea level rise.

Antarctica is split into three regions of which by far the largest is East Antarctica with a potential to add about 60 metres to sea levels.
East Antarctica is fortunately very high and extremely cold so there is no surface melting and most of the ice sits on rock so there is very little melting from underneath except where ice flows move out over the ocean. There is melting from the underneath of ice shelves around the edges and these ice shelves are massive but as they are already in the sea they do not contribute to sea levels.  There is loss of ice but there is also snow falling in greater quantities on the shoulders of the continent and therefore there is only a modest loss of mass balance.

​The Antarctic peninsula is at a warmer latitude and is disintegrating, demonstrated by the ice shelves Larson A and Larson B having suddenly collapsed. The glaciers on the mountains behind these ice shelves have speeded up their progress to the sea, adding to sea level rise. Larson C has recently had a massive calving of 10% of its area and there are more splits in the remaining ice. Once again most of the ice loss is already in the sea and so, at the moment, it is a minor addition to sea level rise. Still all these bits add up and we only need one metre for disaster.

West Antarctica has a whole series of glacier streams of which the Thwaites and Pine Island are the most significant. Global warming has increased the heat differential between the South pole and the tropics and the katabatic winds at the coast are now stronger. As they blow offshore they blow surface water away from the coast and consequently warmer water is sucked up from the deep to replace it. 

​This deep water is relatively warm at +2C and is melting the ice shelf from below and this is where it starts to get interesting.
 
 
The warm water melts the ice from below and as the ice shelf thins it breaks up, just as Larson’s A, B and C have, and the ice shelf retreats. As it gets closer to the coast the ice is sitting on the sea floor and much thicker and higher than floating ice.
Ice is brittle and has a maximum size that it can maintain before it collapses. This would be a cliff face of 90metres above sea level and above that it will collapse. 

​This illustration is the classic profile of a glacier and ice shelf. 

​When the ice shelf retreats due to warm water melting and break up it will eventually reach this thicker ice, and then it will collapse very quickly because it is unstable. This ice will add to sea levels because some of it is not floating.
This process of rapid collapse would quickly get back to land based glacier which, without buttressing support would quickly start slipping into the sea. This scenario could produce a pulse of sea level rise.
The illustration leads you from A to F and shows how the warmer melts the ice from below, when the melting gets past a shallow ridge on the sea floor B the warm water reaches deep behind the ice face C and collapses the floating ice shelf. D + E shows how the retreating ice reaches thicker grounded ice. The last illustration F shows the unstable cliff face of the thicker ice and this is the point of rapid collapse.
​In summary the Antarctic region is currently has a nett loss of 125 gigatons of ice a year which would raise sea levels by 0.3 mm a year. 3 mm a decade does not sound much, but much of the current melting is of ice that is already in the sea, it is accelerating and when the shelve are gone the glaciers behind them will start to slip and they will add significantly towards the one metre disaster level.

Greenland is relatively accessible from the USA and Europe and so it is well researched. It is suffering a whole host of problems partly because it is closer to the warmer latitudes than Antarctica. By comparison Greenland spans from 60 Deg.  to 80 Deg., the North of Scotland is 60 Deg. and the Antarctic Peninsula spans 65 Deg. to 75 Deg.
The central plateau of Greenland is 3000 metres high and up until recently it did not melt but since the late 1990’s it has been melting quite frequently. Some of this is due to rising temperatures but it is made worse by dark soot from industry, aeroplanes and forest fires, covering the clean reflective snow, absorbing heat and encouraging melting. Once the snow has melted it is a darker colour and becomes significantly less reflective and more prone to absorbing heat.
The warm water melts its way down through the ice and forms holes called moulins which carry the water deep into the bed of the ice sheet. This warm water will unstick the ice from the bedrock so that 3-kilometre-thick ice will lurch suddenly towards the ocean. In some cases, the water makes its way to the sea and adds to sea level but in other cases it sits inside the ice as a reservoir of liquid water and may become part of a later pulse in rapid sea level rise
Satellite measurements show that the surface of Greenland is dropping noticeably and the meltwater is adding to sea level rise.
Around the coast of Greenland, it is suffering the same problems as West Antarctica with deeper warm water, melting from below the ice tails of the glaciers that sit in the water. As these glaciers melt and break up they no longer buttress ice from further up the valleys, which increases their speed to the sea.

​The four above scenarios illustrate the various threats of a sea level pulse and where the main culprits are. Overall there is no stopping sea level rise but the scientific community is trying to do research on the timing.  With over 400 parts per million of CO2 in the atmosphere we are committed to a 20-metre sea level rise.
 it’s all about the timing.

​The graph below by Tim Naith shows CO2 levels on the left-hand side with sea levels at the top and temperatures at the bottom.
The yellow dot represents today. The black dot is the peak of the last warm period with CO2 levels at 300 ppm and sea levels 7 metres higher than today.
The first large red cross is 3 million years ago when CO2 levels were at 400 ppm and sea levels were 20 metres higher and it was 3 C warmer.
The second red cross is where we are headed with CO2 at 500 ppm, sea levels 40 metres higher and the temperature 5 C higher.
This information came from core samples taken from the seabed in Antarctica in the Andrill research project. https://www.youtube.com/watch?v=oZHRwDHh4B0

There is always speculation on the behavior of the Polar vortex as the Arctic sea ice disappears and the way that it will affect the weather around the world.
One theory is that as the ice disappears and the Arctic ocean warms the next coldest spot would be the high plateau of Greenland and the polar vortex might centre on that with the subsequent chaos to weather patterns in the Northern hemisphere.
In the recent invasion of warm air into the Arctic when the temperature was 30C above normal a minor Polar vortex formed over Greenland which gives some credence to the theory.

Having just done a post on the unstable weather conditions due to the warm water in the Tasman Sea I had a quick look at Met Vuw.
​There is a tropical storm coming down from the Pacific, which is a bit early in the season but not unusual.

 What is interesting is that the storm is forecast to go down the West coast and over the warm water in the Tasman Sea where it picks up heat and energy, it intensives and the pressure drops tp 992.
​To make it worse the storms southwards path is blocked by a high pressure system and it gets stuck.
​Much like the hurricane that struck Texas.

This is a four day forecast and a lot can change but you can see the effects of the warm water in the forecast.

​The ocean water in the Tasman sea is up to 6 C warmer than normal and it will have an unpredictable effect on the weather. The first and obvious outcome would be that the extra heat will raise the moisture content of the atmosphere by 8% for every extra degree of temperature rise and the extra heat can drive stronger storms. 

Instead of rain we are in a drought so what’s happening?
New Zealand has a ridge of mountains down the West coast that effectively stops rain getting past them and we need easterly winds to bring us rain to our populated areas. The current drought is due to the increased prevalence of Westerly winds due to global warming in the Southern Ocean and the very warm weather is due to the warm water in the Tasman Sea warming the winds. 

We have also had sunny, clear skies due to the high-pressure systems coming from the west. High pressure systems are from dry air descending from 10,000 metres and effectively blot out low pressure systems which rise from the sea and rise to 3000 or 5000 metres shedding moisture and heat as they ascend.
Drought is the biggest killer to our environment and to our farming economy and food production. It can kill millions of trees, dry up streams and destroy grass and other farming produce.

​Powerful rainstorms wash away topsoil and flood our estuaries with silt as well as causing damage to our infrastructure and homes.
 So what can we expect?
The drought is already with us and we still have the warmest part of the summer months to come so we can expect it to intensify.
There must also be a big risk of powerful rainstorms causing flood damage but that is less predictable and are more likely to happen later in the summer or autumn.

The water in he Tasman sea is around 4C above normal which is a big worry. So much is unknown about this type of event. Will it be there long? What effect will it have on the weather?
Currently the weather is dominated by a high pressure system so we are having a spell of warm weather but an ocean with these extreme temperature must have an effect of some kind on our islands.
​Extreme drought or floods?. 

The very fast pace of change in our modern world means that one generation is not going to be the same as the last, as even the last ten years has shown. Planning for the future needs and open mind and a good sense of social awareness.
To get an idea of the changes that are very close to us now I suggest that you watch this video of Tony Seba and reflect on the many social issues that will come from it.
https://www.youtube.com/watch?v=2b3ttqYDwF0&t=93s&list=FLiUwiBc_bp0xCGnsJ2LL2Tg&index=4
The video portrays some massive changes, many of which are apparent today, which will bring massive disruption to our lives and if we are to avoid massive social unrest we need to be planning for the future with a completely different mindset.

Universal wage.
The election has brought to the surface retirement pensions and the thorny issue of what age to fix it at. We also have the problem of social benefits for illness and unemployment. Lurking around the edges is the idea of the universal wage, so some people are considering changes to our social structure already. For those not familiar with the concept of a Universal Wage here is some text from Wikipedia
Basic income is potentially a much simpler and more transparent welfare system than the one existing in the welfare states around the world today.[11] Instead of having numerous welfare programs, it would simply be one universal unconditional income. This strategy for introducing basic income is controversial because some basic income supporters argue that it should be added to the existing welfare system rather than a replacement for it. 
Many hard working people do not take kindly to some people getting a living and not working, but there are bigger issues at stake and mass unemployment is a distinct possibility and it could lead to political and social instability.
We currently have unemployment rates of around 5% but governments, worldwide are notoriously devious about those figures and hide it with education and retraining plans which, in a way, accepts that there are not enough jobs to employ all those who want to work and so they go for retraining to take them off the unemployment lists.
One of the big advantages of a universal wage is that it takes the pressure off people and they then start using their creative ability to start small enterprises to earn extra money or to do good social or environmental work.

Pensions
​Here are some thoughts on the where we could have a floating retirement age where, you can choose your own retirement date starting from age sixty but the longer you leave it the more you get. The average actuarial age of death is well researched and so the government know how much they will have to pay out to the retired population. If you are a New Zealand male you are going to die (on average) at 79.1 years old. Currently pension is paid from 65 and so there are about 14.1 years of payment at $691.44 a fortnight totalling $253,481.90. If you chose to retire early at 60 you would get 19.1 years of pension and so you would get $510.43 a fortnight. If you had a hard life or illness you might prefer to retire early and make the most of it.
If we can get more people to retire early it will make room for younger people to get jobs.
As mentioned at the beginning there are massive technological social and environmental changes coming and we need to have a very open mind to avoid big social problems.

Recent analysis has revealed that the Southern Ocean has increased its speed by 30% in recent years and this will serious consequences for us all.
​It means that the climate models will be underestimating the rate of melting to the ice in Antarctica and the strength of the wind in places like New Zealand will have a higher proportion of strong Westerlies.
This year in particular New Zealand has had a succession of strong westerly winds which has brought flooding to the west coast but also drought to the populated areas in the east.
The technical reasons for the drought are dealt with here. ​http://www.climateoutcome.kiwi.nz/drought.html
The report on the original research is here. 
​https://eos.org/research-spotlights/notorious-ocean-current-is-far-stronger-than-previously-thought#.WIbgaF8rGdU.twitter

When discussing an ice free Arctic we dont need to be too particular about the minimum amount and one million square kilometres would be considered so low that it might just be ice free.
The effect on the weather in the populated regions just South of the Arctic region can be devastating. North America, UK and Europe, Russia and China can all have extreme weather with floods, freezing winters or drought which can put a huge strain on the economies and the lives of the people.
The loss of Arctic ice is the fastest reaction to climate change. There is no waiting for half a century for the ice to melt and sea levels to rise. This is almost instantaneous.