Matthew Flinders named Cape Leeuwin after the first known ship to have visited the area, the Leeuwin (“Lioness”), a Dutch vessel that charted some of the coastline in 1622. There are three Capes in the southern hemisphere that offer a landfall to sailors who take advantage of the westerly winds at this latitude.
Cape Leeuwin is surrounded by blue/green water. Its a long stretch from Cape Town to the south west corner of Australia and an even longer stretch to Cape Horn. There is very little land between 30° south and 70° south latitude. The wind blows vigorously from the west. When you gaze out to sea and and find yourself reaching for more clothing it is because the air is very fresh, it has the same temperature as a vast stretch of ocean.
This Ocean is the Earths battery. It is the chief and only means of storing energy from the sun. Whatever energy gets through the cloud layer penetrates deeply into the water and is given up slowly. The ocean warms and cools in the same way that it develops a long swell on its surface. When riding across the swell you rise up slowly and fall down just as slowly regardless of the surface chop. If we are looking for ocean, the location of the Earths energy store, you find it here. It is for this reason that Cape Leeuwin lighthouse is a good proxy for what is happening to the globe as a whole.
If a steady 33 mph (30 knots) wind blows for 24 hours over a fetch of 340 miles there is a 5% chance of encountering a single wave higher than 35 ft (11 m) among every 200 waves that pass in about 30 minutes. At the latitude of Cape Leeuwin a 50 knot wind is frequently encountered. No trees can grow in the vicinity of the lighthouse, just grass and low scrub. There is a layer of salt on everything.
If one looks for consistent high variability in the temperature of the surface of the sea it is here, in the southern hemisphere that one finds it, and at the equator. Here the variability is due to change in cloud cover and the direction of the wind. At the equator there is little cloud, little wind but a big variation in the in-feed of cold water from high latitudes according to the speed of the ocean circulation that is driven by wind and wave in high southern latitudes. It is in high southern latitudes that one finds the strongest wind belts on the planet, the roaring Forties, the Furious Fifties and the Screaming sixties.
The lighthouse at Cape Leeuwin dates from 1910 and so does the temperature record. A sample from 1915 to 1921 is presented below. There is a tiny diurnal and annual range but strong cycles of warming and cooling. The daily range increases strongly in summer when hot winds from the continent tend to arrive on a ten day cycle associated with the passage of anticyclones. In winter, these winds off the land can be cold suppressing the maximum and reducing the diurnal range. There is considerable variability in the daily minimums in winter within and between years. Winter is the time of the year when the Antarctic dynamic associated with the ozone content of the polar atmosphere causes marked swings in the relationship between surface pressure in the mid latitudes and the Antarctic circumpolar trough affecting the rate of flow of the westerlies and at times bringing cold southerly wind from Antarctica. Frontal rainfall falls in winter. Summers are arid as cyclones track well south. Autumn is a season of quiet air, and infrequent light showers when farmers clear up land for pasture and burn the native vegetation to reduce the risk of fire. With solid winter rainfall and deep soils the countryside supports the growth of large eucalyptus trees that drop leaves and twigs in summer, a worrying fire hazard but an essential store of nutrient for soil microflora and plants, tending to keep the soil cool and moist in the dry summers experienced on the western sides of the continents at this latitude. Not far away is a very large desert.
The red ellipses in figure 1 are intended to take your eye to features of interest, in particular the shape of the variability in the curve when temperature is least and the extreme variability in the daily maximum in the height of summer.
Plainly, the climate is like the road that curls through the Karri forest as seen below.
There is a conclusion that can be drawn from the data presented below: Between 1910 and 1992 the minimum daily temperature does not change. Between 1992 and 2015 it warmed slightly then cooled again, then warmed for about six years and cooled for another six and looks as if it will get back to the 1910 average of about 14.3°C in a few years time.
Straight up this tells us that either, there is no greenhouse effect due to carbon dioxide in the atmosphere or that some local influence is maintaining the status quo as the rest of the globe is warming. I believe that there is no greenhouse effect. I do know that there is a local factor enabling this place to retain the status quo as surface temperature increases elsewhere. Until we understand the latter influences we will not be free of fear of the former.
Carbon dioxide is plant food and it is greening the Earth and in particular the arid zones because a plant that is not starving for carbon dioxide does not have to open its breathing apparatus (stomata) as wide as an opera singer and it loses less moisture to evaporation in the process of acquiring its plant food. For godssake, plants are at the base of the food chain. We have the wherewithal to feed double the current population of the globe and yet global economies are in complete disarray, interest rates are negative, governments are printing money, nobody wants to invest, commodity markets are reeling and the whole system is teetering on the edge of an abyss. Something is very wrong in the way that we are ordering society. That something has a lot to do with climate scares.
In any case 14°C is too cool to support plant life properly. Photosynthesis is optimal at 25°C. The globe is too cold for comfort, too cold to support photosynthesis over the bulk of its area for too long in the annual cycle.
If the ‘climate sceptics’ could all read from the same hymn book there would be a much better chance of dismissing ‘climate change hysteria’ that is resulting in gross manipulation of energy markets and making it impossible for poor people in cold climates to keep warm in winter while denying many countries who are yet to industrialise the cheap energy that is required to fuel machines. That we have ‘luke warmers’ who consider that man is having some effect on the climate but can’t work out just ‘how much’ influence he is having plays into the hands of the so called ‘consensus’ claimed by the alarmists. This is like reaching down with a machete and cutting your legs off just below the knees. There is no need. Luke warmers…… forget about the theory and OBSERVE.
1910-39 THIRTY YEARS OF COOLING IN THE DAILY MINIMUM AND MAXIMUM
Above we see that the annual range varies a lot. This is because in the height of summer the ozone content of the air is much affected by what is happening in the Arctic stratosphere. Less ozone means cooler temperature aloft and more cloud. In the depth of winter the ozone content of the air and hence its temperature, cloud cover and the entire global circulation is driven predominantly from Antarctica. If ozone partial pressure falls temperatures at all levels in the atmosphere respond, first in the stratosphere and next in the overlapping region where ozone exists in the upper troposphere and finally at the surface.
Gordon Dobson put the matter in perspective when he calculated that if the entire atmosphere had the same density that it exhibits at the surface it would have a sharp top at 8 kilometres in elevation. I would remind you that you can walk 8 km in an hour and if you are a walker in the Olympics you could be there in half an hour.
1940-75 THIRTY YEARS OF COOLING DAILY MINIMUMS AND WARMING DAILY MAXIMUMS
There are two possible reasons why the daily maximum could rise while the daily minimums fall.
- Cloud cover could fall away in summer as surface pressure rises in the mid latitudes (along with upper air temperature and geopotential height) while the winds that drive the circumpolar current accelerate due to the enhanced difference in the surface pressure between the mid latitudes and the poles. This would bring colder water from the poles to the western coasts of the southern continents reducing the winter minimum temperature and in fact the summer minimum because when the sun is not shining it matters little whether there is cloud or not.
- If the wind blows more consistently from the continent in summer that wind will be hot. That could occur if the core of anticyclones tracked further south. When surface pressure rises in the mid latitudes that is what happens. It has been observed that the so called Hadley cell that takes in the convection in the tropics and the descending air in the mid latitudes has expanded in recent times. Notice the large fluctuation in the maximum temperature at Cape Leeuwin in summer. Notice that the pattern of extremes is quite different from year to year. This is what determines the level of success I have ias a wine maker in making wine from the early ripening Pinot Noir, a grape that is negatively affected by heat in the last month of ripening. Our ‘Three Hills’ vineyard is just 12 km north of the the lighthouse.On a hot day in February the temperature can climb to 42°C and the relative humidity drops from 60% to 30%. In just one day of this sort of treatment the grapes shrivel and sugar concentration rockets. Fortunately even if February is warm, most of the reds ripen in March and are picked in April. The chance of hot days is less in March, unheard of in April.
Above, we give a closer inspection of the temperature profile in the summer of 1958-59. It would not be possible to ripen grapes in such a year. Notice the low variability in the daily data in summer and the relatively high variability in spring. Quite atypical. The diminished area under the summer season temperature curve represents a reduced capacity for plant work.
Global data for the latitude band 30-40° south latitude is not necessarily representative of local conditions at Cape Leeuwin but neither of the summers of 1956-7 or 59-60 look particularly auspicious when we examine the geopotential height data for these years. Heights are likely to vary less with latitude than is sea surface temperature. Sea surface temperature depends on the circulation of the ocean that exhibits a south to north and north to south component whereas the movement of the atmosphere has a gently north east to south east movement that comes pretty close to following lines of latitude.
1975-1992 COOLING DAILY MAXIMUMS AND COOLING DAILY MINIMUMS
In this graph we have fewer years and the pattern of heightened variability in mid-summer and mid-winter is more apparent to the eye. Year to year variability comes from the same source as long term variability, the winter pole with peak variability in January-February emanating from the Arctic and July-August from the Antarctic. This is what is behind the variation in the seasons that keeps the farmers guessing.Its also what lies behind the long term variability, decadal and longer.
1992-2015 A STRONG WARMING CYCLE FOR THE MAXIMUM AND LESS SO FOR THE MINIMUM….OR IS IT?
Again the dotted line is the horizontal. Its easy to see that the minimum has increased at about half the rate of the maximum. There is nothing in the Earth system that takes away carbon dioxide overnight and puts it back in the daytime.
Magnification drives home the point that variability in temperature is strongest in mid winter and mid summer. Extreme summer variability is due the fact that Cape Leeuwin occasionally experiences hot winds from the East in summer but it is also due to a flux in the ozone content of the air above and with it, cloud cover. Autumn is a time of low variability, balmy pleasant weather with light winds. The coldest months of winter are not always cold and nothing in the shape of the curves in the bridging seasons provides any sort of an indication of what will happen in June, July, August and September. That depends on whats happening at the Antarctic circumpolar front.
Above is a different way of looking at the same data for the last 23 years. The trend curves are polynomials and they fit better the pattern exhibited by the extremes. The cooling trend of the last five years is given the weight it deserves. So far as the minimum is concerned we will soon be back at where we started in 1910.
THE VIRTUE OF DIS-AGGREGATION OF TEMPERATURE DATA
In the figure below we have data for the entire globe in the 30-40° south latitude band drawn from here.
Average monthly data conceals the interesting complexities that are only revealed in daily maximums and minimums. Is the temperature increasing during the day or at night? We are at a loss to explain anything and we are at the mercy of witch doctors who rush in to provide us with a global average.
At Cape Leeuwin the daily maximum is the chief driver of variations in the average temperature. Without a shadow of a doubt part of that daytime summer warming is associated with loss of cloud as the increase in geopotential height and air temperature aloft suggests. Part will be due to a more easterly component in the air in the summer that brings warm air from the warming continent during the day. In any case, its readily apparent that the direction of the wind can be critical to surface temperature in coastal locations. That applies, not only in coastal locations, but everywhere, when the wind comes more consistently from either the equator or the pole. Change the wind and you change the local temperature. For this reason we need to get a grip on what changes the global circulation if we wish to understand surface temperature change. Just quietly, we also need to get a grip on the degree of mixing of cold deep water with warm surface water due to the currents and the waves. We are measuring the temperature of our patient not in his anus or his mouth or ear-hole but at the extremities.
Some of the change in temperature at Cape Leeuwin may well be due to a change in the amount of cold water from the Southern Ocean being driven up the coast due to an increase in the speed of the southern ocean circulation. In that case, the enhanced current will tend to limit the increase in the temperature of the air as measured at Cape Leeuwin. The enhanced pressure differential between the mid and high latitudes has undoubtedly enhanced the circumpolar circulation and assisted to stabilise the temperature at Cape Leeuwin, a built in countervailing force limiting the rate of temperature increase due to loss of cloud cover and a generally enhanced flow of warm air from the tropics as the Antarctic circumpolar trough in surface pressure has deepened.