|
What is natural climate change? By Floor Anthoni (2011) www.seafriends.org.nz/issues/global/climate7.htm
|
Note! for best printed results, read tips
for printing. For corrections and suggestions, e-mail
the author.
-- Seafriends home -- Climate
Index -- Rev:20110820,20171129,
introduction
This global climate chapter is very exciting because it deals with an important mechanism that has been overlooked or insufficient attention paid to. It is based on the work of the late Dr Joseph 'Joe' C Fletcher, known for his arctic research. Working for NOAA, he was OAR Deputy Assistant Administrator for Labs and Cooperative Institutes. Joe retired in 1993 and moved to Sequim WA where he passed away on July 6, 2008. Dr Gary Duane Sharp was a good friend of Joe and even organised a seminal lecture as part of his Maestros Legacy Lecture Series. This 100 minute lecture was filmed, and I proposed to have it transcribed and converted to HTML, for the world to read in perpetuity. Don't miss it! |
Joe's personal quest was to answer the question: "What is normal global climate change", based on the hypothesis that:
Nature will behave as it has in the past and will continue to do so. - Joseph Fletcher
To investigate this, he based his research on the COADS dataset (Comprehensive Ocean-Atmosphere Data Set) held by NOAA, to which he had access. This dataset was begun by a far-sighted individual, Matthew Fontaine Maury (1806-1873) who at that time headed the hydrographic office and built the sailing charts to help mariners sail at various places around the world. He realised the value of accumulating a dataset which would really document the behaviour in all the oceans. So in 1854 all the participating countries agreed on when to take observations, how to take them, how to archive them and so on. And this has been going on now for almost 150 years up to the present, resulting in over ten million observations which provide us with a good documentation of just what has been happening at the ocean's surface in all parts of the global oceans. |
The complexity of the climate system has been described by many people including such great scientists as Einstein and Von Neumann, pointing out that the ocean drives the atmosphere, and the atmosphere drives the ocean, and that the interactions occur on all time and space scales, with nonlinearities and thresholds and that the representation of all these interactions, are almost beyond comprehension. The simplicity is that nature knows all the rules, and knows all the boundary conditions and knows where the mountain ranges are, deep ocean ridges and trenches, and the rest of the geography, and nature's answer to that question is this average picture of winds (wind field). When you think of it in a holistic sense, you can think, if whatever is forcing this system, if it changes in magnitude, you can expect that the whole pattern will wax and wane in unison. And that is exactly what the observed record is showing as here with the wind field. As the forcing increases, the highs become higher, the lows lower, winds stronger, and vice versa. |
Not surprisingly, this is precisely what this chapter aims to do. First we'll look at some of the most popular signals like ENSO, AMO, PDO, to conclude that they do not make it. But what Fletcher discovered was the consistency and the enormous change in the wind field (wind speed), and this needs further study. But already major predictions (that have come true) can be made.The simplicity is that nature knows all the rules, and knows all the boundary conditions and knows where the mountain ranges are and the rest of the geography. - Joseph Fletcher
To understand the winds and barometric pressures, we need to understand the general global circulation and the differences between the two hemispheres which creates an entirely different situation.
Joe Fletcher pays much importance to the Tropical Warm Pool, and how it works as the greatest climate phenomenon on Earth.
In the end, we do not know where the main fluctuations come from, but it must be either from changes in sunlight or from an irregular out-radiation of Earth.
To begin with, one must understand that there are major and important
differences between sea and air, as shown below. Thus the sea is Earth's
main heat storage whereas winds are its main weather and climate motor.
property |
oceans
|
air
|
description |
heat capacity
mass momentum kinetic energy |
1600
400 4 0.04 |
1
1 1 1 |
Very large volume times
high specific heat capacity
Atmosphere only equates to 10m depth Speed times mass Ocean currents are slow and superficial. Winds are fast. |
The conclusion is that Joe's hypothesis is probably right, as one does not need Anthropogenic Warming to explain what happened in the past 150 years during the Industrial Revolution, because the changes in wind strength explain it all.
Winds also have a major influence on sea levels, year to year, decade to decade and on a century scale. Because modern sea levels are derived from satellites that do not measure the polar seas outside 66º N and S, a crucially important part of the oceans is excluded from observation.
In this graph we have brought some global signals together, that are on and off the flavour of the time. All signals have the bottom axis as zero, except for ENSO, AMO and PDO which are relative to the brown scale on right. There is ENSO (El Niño Southern Oscillation) also called SOI (Southern Oscillation Index), here the purple scribble, which is derived from a difference in air pressure from east to west equatorial Pacific. Due to local barometric pressure swings, it is very noisy, but related to how much water is pushed into the Tropical Warm Pool in the west equatorial Pacific, even though it does not swing in unison. |
The Tropical Warm Pool in light red, represents the pool of water warmer than 29ºC and because of this, capable of causing thunder clouds and deep convection into the highest reaches of the troposphere, transferring a massive amount of latent heat into the atmosphere (see later). The red curve above is its average, but is unreliable before 1900. Notable is the extreme rise between 1970 and 2000 from 100 to 170 (lefthand red scale), or an unbelievable 70%, which is hard fact. |
The green
squiggle in the graph above, represents the surface wind strength in the
South Indian Ocean, the world's weather power house. Winds here blow on
average at 9m/s (20MPH, 32km/h), with substantial year to year fluctuations
and a huge 150-year swing of 30%. The average wind speed over oceans is
6.5m/s with enormous geographic variation as the wave height map shows.
Remember though, that wave height is proportional to the third power of
wave wind strength. The map shows very calm areas in magenta and the Warm
Pool as poor in wind. Notice also tall waves near Canada and Greenland.
Also shown in the global signals graph is the average of the Indian Ocean (partly shown), which follows the southern winds in phase and pattern. The question is now: what about the other oceans? |
Sea Surface Temperature (SST) maps are usually shown in false rainbow colours, but when their isotherms (points of equal temperature) are plotted, a picture emerges with more information as shown here. Where these isotherms are close together, a steep gradient exists, inviting strong winds and a highly variable climate. Fortunately nobody lives in the Southern Ocean south of Africa, but in the NH three areas are battered: east Canada, Japan and west Mexico. Please note that these curves were not obtained from satellites but from actual measurements on ships (COADS). |
150 years of wind for (LtR) Atlantic, Indian and Pacific oceans. [Click on an image to see a larger version] |
October 2012
dust storm over central USA
Dr Fletcher calculated the periodicity of the wind cycle at 170-180 years but on 19 october 2012 a massive dust storm over central USA reminded us of the "Black Sunday" dust storm of 14 April 1935, suggesting a periodicity of 77 years (about half of 150), and a repeat of the "dust bowl" droughts of the 1930s with severe loss of topsoil and harvests, for years to come.This occurs just as a large part of the corn harvest is diverted to ethanol production.Note that another recent dust storm happened in Arizona on 5 July 2011. [1]: Scientific American Oct2012: link [2] wikipedia Black Sunday storm [3] The Daily Times: link. |
Between 1977 and 2003, average ocean evaporation increased by 11 cm per year from 103 to 114 cm per year (10%). This was caused by an increase in average wind speed of 0.1 meters per second [Yu, 2007].But hang on, one cannot have such large swings in energy without also a corresponding swing in sunlight. Since the sun is considered a constant light source with, give or take, 0.1W/m2 fluctuations (the solar constant), what is the story? Remember that sunlight arrives with an intensity of 1368W/m2 which averages out at 342 W/m2 due to day/night and summer/winter. So 30 W/m2 variation is enormous. Is that reflected in climate and weather, temperature and wind?
There exists as yet no reliable method to measure past fluctuations in sunlight arriving at Earth's surface, even though the new radioactive Beryllium-10 method looks promising [1]. The very light metal Beryllium occurs in the atmosphere as it is created from cosmic bombardment of larger molecules like nitrogen. As it dissolves in rain drops, it settles out on Earth's surface where it gets enclosed in ice and sediments. But the technique is young, its signal small and its interpretation uncertain. In the graph (Beer et al. 1994) is also shown the sunspot activity (Hoyt and Schatten 1998), which in 1650-1750 caused deep cold (the Maunder Minimum or Little Ice Age). A new minimum after 2010, appears to be coming. Note that these curves are not in agreement with the wind pattern. |
But who says that Earth's reradiation out to space is constant? Perhaps the energy is obtained by not reradiating as much back into space, which could be caused by an inherent instability of the climate cycles like:
more wind => more evaporation => less IR out => more warming => more wind
and the reverse, winding it down again. The frequency of such an oscillation
depends on the inertia of the whole, in this case the oceans. Then a +30%
and -30% cycle in 170 years amounts to only 0.3-0.4% per year which is
indeed undetectable.
Some support for the notion of reduced Outgoing Longwave Radiation OLR comes from a computer model by Pierrehumbert, the results of which are graphed here. Horizontally the temperature of the surface in Kelvin, and vertically the outgoing IR radiation. rh means relative humidity. The top solid black line treats the surface as if it were a black body, radiating out according to the Stefan-Boltzman equation. If the air contains moisture, OLR reduces because water vapour absorbs OLR. The more water vapour, the less OLR. Note that 273K is 0ºC and the Warm Pool of above 29ºC is to the right of 302K. Here moisture can make a 30% difference, supporting the notion that increased winds, cause increased evaporation, causes less OLR and more warming of air. Thus OLR can vary considerably over time and place, and is definitely not constant. In theory, changes of up to 30% can even happen on a yearly basis, but is not likely. Smaller yearly changes become more likely. |
So the bottom line is that we cannot show where the energy came from to cause such large swings in wind strength. We just need to accept for now that it is real and not altogether impossible, and figure out how the rest of the climate system reacts.
We can already predict that faster winds cause:
[1] More about radio-dating with Be-10 in Chapter
3.
North Pole, the Arctic, N hemisphere | South Pole, Antarctica, S hemisphere |
Is an ocean surrounded by continents | Is a continent surrounded by oceans |
Has sea mounts and ridges under water and a very large continental shelf (light blue) | Has mountains and volcanoes and a very small continental shelf. |
Has very slow ocean circulation | Has very fast ocean circulation |
Annual mean temperature is 0ºF=-18ºC | Annual mean temperature is -60ºF=-50ºC |
Human population north of 60ºN is more than 2 million | No human population |
Sea ice area 7 million square miles | Sea ice area 6 million square miles |
Westerlies more variable and not strong | Very strong circumpolar westerly winds and currents |
Northern Hemisphere has most land | Southern Hemisphere has most water |
Has many huge mountain ridges blocking winds while partitioning the troposphere | Has only one mountain ridge blocking winds, the Andes |
Here the global climate zones are shown in colours from left North Pole to right South Pole. Superimposed are temperature curves for the northern summer (red), average (green) and the southern summer (blue). Although both hemispheres behave quite similarly, it can be seen that the NH warms up in summer more so than the SH, while also becoming colder in winter, even though average temperatures are quite similar. In simple terms, the NH has a land climate (more extreme) and the SH a sea climate (more equitable). |
This diagram simplifies global atmospheric circulation as if it were symmetrical for both hemispheres. Around the equator, trade winds blowing E to W converge to a weak equatorial E-W flow and corresponding ocean currents (ITC= Inter Tropical Convergence). The convergence (clash of winds) causes air to rise, releasing heavy rain, travelling poleward and descending in the subtropic highs as very cool dry air, creating the desert zones of the planet. This is called the tropical Hadley circulation which spirals E to W around both sides of the equator. There is a counter flow in the upper troposphere in the form of jet streams. In the temperate climate zone, winds are dominated by the Coriolis force which deflects to the right on the NH and to the left on the SH. The winds here are mainly westerlies and they are very strong. Finally around the poles exist the polar Hadley cells, with strong winds spiralling around the poles in an E-W direction. We will now see that this narrative is not true in the real world. |
|
|
The map shows where people live, and their densities. It also shows the extent of the Inter Tropical Convergence zone which travels from the July curve (northern summer, red) to the January curve (northern winter, blue) and back each year, with variations in its extent. Where winds meet, air rises, causing rain. The ITC is essentially a rain band, which means that the people living between red and blue bands, experience two rainy seasons each year, which is most beneficial for agriculture and thus for humanity. About half the world's population lives here (dark colour). |
Looking at average barometric pressure, a huge difference is found between the two hemispheres. The graph shows how the northern winter and summer do not differ very much but south of 40ºS, barometric pressure tumbles into a consistent ever-present deep Antarctic low. This steep gradient forms perhaps the motor of the world's climate system, with very strong winds unobstructed by mountain ranges.. |
When the above barometric pressure is plotted as differential pressure between latitudes, it looks like this bar chart, the blue bars for the NH summer and the red bars for winter. The differences in barometric pressure, or the gradient in pressure, is what drives the winds. As one can see, the Southern Hemisphere has a huge wind field compared to the Northern Hemisphere. Strongest winds occur around Antarctica in the southern winter JJAS. |
These two graphs from Fletcher show another dramatic difference between the hemispheres. The blue curves correspond to the northern summer and the black dashed curves to the winter. Potential energy corresponds to sunshine which has a predictable swing for the NH but a steep decline in the SH due to cloudiness and ice albedo. Watch how ground albedo and cloudiness make the SH more reflective than the NH (righthand image). |
The tropical spiralling Hadley circulation is also a bit more complicated, as shown here along the equator. The yellow humps are from right to left the Andes, the Indonesian/ Papua New Guinea mountains, the African mountain ranges and the Andes again. Over the equatorial Pacific, a text-book Hadley circulation with its Walker component as shown here, blowing E-W over the sea and W-E through the troposphere. On the left, the equatorial Atlantic also follows this textbook scheme, but in-between are two opposing but weaker cells, one over central Africa and another one over the central Indian Ocean. |
As these graphs demonstrate, the size of the Warm Pool correlates well with wind speed. Note that the Warm Pool index is easily calculated from satellite sea surface temperatures (SST) by counting the number of 4x4 degree cells warmer than 29 degrees C. Although there is no long-term record of the TWP, it has been following the wind pattern since 1950 but less so between 1900-1950 for which no satellite data exists. |
The TWP is often depicted as shown here, with excursions from an 'average'. So please note that the blue and yellow shapes are not opposites and the curve should really have been shown as above. But it agrees with the temperature swings found in the meteorological record: warming between 1920 and 1940; cooling between 1940 and 1970; warming between 1970 and 2000. It is a reliable record of weather phenomena like the El Niño/ La Niña cycle as it is based on actual sea temperature and one of the most important drivers of global climate. It is much more reliable than the ENSO graphs which are derived from barometric pressure differences. |
GIF animation of the size of the Tropical Warm Pool by decade 1900-1984. This movie shows by decade the changes in the size of the TWP. Decade by decade it has been increasing steadily since the beginning of last century. 'Global warming'? |
These
two maps show the areas of deep convection (high rising rains), the TWP
and the Amazon basin, even though the Amazon basin does not have as much
water to evaporate. The blue low pressure areas are where most of the winds
subside, over the African desert and in oceanic doldrums (areas with little
wind).
The bottom image shows where most of Earth's heat is radiated out into space, corresponding with rain in areas of deep convection, the rising parts of Hadley cells. Of all these, the Tropical Warm Pool is of most influence. It also shows that out-radiation does not happen equitably all over the planet, but in places where it 'bursts out' due to deep convection, thus supporting the idea that surface cooling happens by conduction, convection and evaporation whereas in the upper troposphere infrared outradiation begins. Thus Earth's out-radiation is not constant but subjective to changes of 15-25% per decade and 30% per century. This process is highly sensitive to the behaviour of winds. |
|
These two graphs of sea level change, are from Pohnpei in the Western Pacific and from Baltra in the Eastern Pacific. As you can see, they are inversely related. When the level goes up in the east, it goes down in the west, as can be predicted from wind strength. The blue curves are from Topex/Poseidon satellites; the red ones from tide level gauges. |
The sea level at San Diego gives us a long-term record. From a flattish beginning around 1910, it rose and then flattened out from 1990 on. This 0.2m rise corresponds with the global wind pattern from the COADS dataset. |
The conclusion is that short-term (decadal) and mid-term (century) fluctuations in sea level are most likely from changes in wind speed whereas long-term (millennia) fluctuations arise from temperature changes. We need to remain very skeptical about popular claims and about any report using Topex/Poseidon sea level data, particularly in the light of recently discovered fraudulent 'adjustments' [3]
[1] Cabanes, Cecile et al. (2001): Sea level rise during
past 40 years determined from satellite and in situ observations. Science
2001;294, 5543.
[2] Floor Anthoni (2010-2011): Are sea levels rising?climate4.htm#Are_sea_levels_rising
[3] Sea level fraud:Analysis
finds satellite data has been continuously 'adjusted' to exaggerate sea
level rise. link