Donnerstag, 30. Januar 2014

Global Temperature Graphs: Is the temperature rising or even accelerating?

Look: Just a this time at the beginning of 2014 there seems evidence, that the global temperature is steadily rising. A many newspapers and internet magazines showed that graph, which shows clearly that the temperature is rising, isn't it?


It's from NASA. But why do they have another Graph than seen on WFT? NO, it's the same. Just check:

They have put a low basic line, showing few beams or area for the first 25 years. After that the area of beams are increasing, and the three trend lines look like a marker of the rising area. It is not really visible that the rise has stopped for some time. Compare to the graph like it is used on WFT. I have also plotted RSS and WTI for comparison.
So GISTEMP has a steady rise, as it looks. but if you check for the last 12 years, you will see that there is a flatline. The same with WFT with 13 years.

Especially Satellite RSS data (undisturbed by human settlements) have a longer temp pause of neary 17 years.

The question is: Does this matter or not? Or, to ask in another way: Is a period of 12-17 years to be considered a just a short delay, or can it show something about global warming?

Here is another chart which might explain something:

We have here the HADCRUT3 graph starting in 1964. The green line is the amount of sunspots which can be counted from earth by looking through a dark glass (which has been counted for 400 years now. High number of sunspot means high solar activity, which could be radiation, magnetic field or sun wind).

You see a certain pattern with the sunspots and somehow a pattern in the same manner: everytime when the sunspots are low, there is a spike down in temperature, about every 11th year. Just let's look for the years:
  • 1965
  • 1976: less than 0.05°C up from 1965
  • 1988: 0.2°C up within 11 years
  • 1997 (there is already a down-spike around 92/93, but we know about the Mt Pinatubo Vulcan outbreak): again 0.2°C up from 1988
  • 2009: 0.15°C up from 1997
  • next down-spike would be around 2020, so what will bring the future? We can already see a very low solar activity, could mean that the temperature will stay down as well.

There are about 3 up-spikes during every sunspot cycle. Maybe we could get the average of every triple:

  • The average of 1965-1977 is -0.125
  • The average of 1977-1986 is 0 (0.125 higher)
  • The average of 1986-1996 is 0.15 (0.15 higher) note that we have herein the Mt Pinatubo outbreak
  • The average of 1996- 2008 is 0.4 ( 0. 25 higher) note that the 1998 El Nino high is included.
  • The average of the half cycle from 2008 is 0.4

If we try to equalize Mt Pinatubo and El Nino we could come to a half sinus wave:

0.125 - 0.2 - 0.2 - 0.1 , in total 0.525 like today. If that is true, the present half cycle is the top of that sinus wave.

This is just an idea. We can only come closer to reality, if we look for former solar cycles and how they behaved, or how the temperature worked out then.

What we have found out up to now is:

  • Temperature is following the solar cycles (sunspot numbers) of about 11 years.
  • There seems to be another bigger cycle, roughly like a sinus wave of about 60 years , on which the temperature/solar cycles are going up and down.
  • The last two Sunspot cycle temperature trends are on the same level, but the last one is not finished, we may find out in few years if the temperature will go up again or is declining, following the cycle.





Medieval warming globally or only in Europe?

In the climate chance course video of week two we saw a graph showing the medieval warming quite lower than the modern warm period. Also in the video from the end of week two the professor draw a graph like this and explained, that the medieval warming was just locally. Other sources say that it was global and the temperatures even higher than today.

Even in Germany now the media talk about this. Here is a graph from ARD Television (similar to the BBC):

http://wetter.tagesschau.de/wetterthema/2013/12/27/klima-macht-geschichte.html


According to this graph there have been various times before as warm or warmer than today.

So I looked for science papers about that topic and found a lot, e.g. one in science:

http://www.sciencemag.org/content/342/6158/617
Here the editors description:

Global warming is popularly viewed only as an atmospheric process, when, as shown by marine temperature records covering the last several decades, most heat uptake occurs in the ocean. How did subsurface ocean temperatures vary during past warm and cold intervals? Rosenthal et al. (p. 617) present a temperature record of western equatorial Pacific subsurface and intermediate water masses over the past 10,000 years that shows that heat content varied in step with both northern and southern high-latitude oceans. The findings support the view that the Holocene Thermal Maximum, the Medieval Warm Period, and the Little Ice Age were global events, and they provide a long-term perspective for evaluating the role of ocean heat content in various warming scenarios for the future.

And here another one:

http://scienceandpublicpolicy.org/images/stories/papers/originals/medieval_warm_period_russia.pdf
The description:

Excerpts:
The Medieval Warm Period (MWP) was a global climatic anomaly that encompassed a few centuries on either side of AD 1000, when temperatures in many parts of the world were even warmer than they are currently. The degree of warmth and associated changes in precipitation, however, varied from region to region and from time to time; and, therefore, the MWP was manifest differently in different parts of the world. How it behaved in Russia is the subject of this Summary.
In contradiction of another of Mann et al.'s contentions, Krenke and Chernavskaya went on to unequivocally state - on the basis of the results of their comprehensive study of the relevant scientific literature - that “the Medieval Warm Period and the Little Ice Age existed globally.”
The fact that the warming that brought the world the Current Warm Period began around 1750 AD, or nearly 100 years before the modern rise in atmospheric CO2 concentration, should be evidence enough to argue that the planet's current warmth is the result of nothing more than the most recent and expected upward swing of this natural climatic oscillation.
From approximately AD 1200 to 1410, they concluded that temperatures in the region of their study were “probably higher than today,” providing yet another example of times and places when and where low-CO2 Medieval Warm Period temperatures were likely higher than high-CO2 Current Warm Period temperatures.

In conclusion, and considering the full spectrum of studies included in this Summary, it would appear that a goodly portion of the Medieval Warm Period throughout Russia was somewhat warmer than what has so far been experienced there during the Current Warm Period. And since the MWP held sway when the atmosphere's CO2 concentration was something on the order of 285 ppm, as compared to the 400 ppm of today, it would appear that the air's CO2 content has had essentially nothing to do with earth's near-surface air temperature throughout the entire Holocene, when the air's CO2 concentration at times dropped as low as 250 ppm. Other factors have clearly totally dominated.



The number of papers about that topic appear to be about 100, but I have not checked them all. Seems an interesting area for further search.

Temperature went down by 0.7°C in Germany. Source: kaltesonne .de

png (877×555)

Sonntag, 26. Januar 2014

Global Temperature Graphs: Which is the right one? Part two.

Global Temperature Graphs: Which is the right one? Part two.

In part one we have seen that choosing a global temperature graph and not only see surface or land only seems not to be a good idea. In the long run, the data seem to give a clear picture. But now we should check what differences are there between the various global temp curves.

Let's go to www.woodfortrees.org and compare some of them:


Red: is the Woodfortrees index, which combines the for following graphs:

Green: GISTEMP from NASA Godard Institute
Blue: HADCRUT, which we know already, from Hadley Centre, UK
Pink: RSS, satellite measurements of land and sea surface from Remote Sensing Systems
Turquoise: UAH, satellite measurements from University of Alabama in Huntsville

You see, they differ not much in the time span from 1979 until today. So we could use one of them, or to show neutrality, only the WTI index. So the answer to our former question is:

If you want to go back to the nineteenth century, you have to choose either HADCRUT (from 1850) or GISTEMP (from 1880). From 1979 Satellite data are also available, so you can add RSS or UAH, or use the WFT Index.

Note: Of course, there are some differences, but you can't go really wrong with any of them.

AS we have the graphs available now, we could check how they look like. There is no clear line up or down, but some zigzagging with an upward trend. Just let's try to describe the pattern.
  • We can see something like double spike and a through, a double spike and a through, and so on.
  • We can also see a very high spike in 1998, which was the El Nino weather pattern.
  • And if we know about the Mt Pinatubo eruption in 1991, we see a deep through after that year, in 1992and 1993. Some say that the volcano caused the whole decline of 0.5°C, but as we see with the other troughs, some part of it could be because of other variations, so only 0.2 °C are left.
It's just a very small look into that topic, but we can see patterns in temperature graphs, and there seem to be possible ties to natural incidents on our earth.


Global Temperature Graphs: Which is the right one? Part one.

Global Temperature Graphs: Which is the right one? Part one.

If you see discussions on global warming, one thing is always present: Temperature graphs in various shapes and colors, ready to proof the assumption of the presenter of an idea. But whom to believe? And how - as a non-scientist - to check if there is something wrong with the data?

One thing is to mention: Temperatures measured with instrument are available for about 250 years, but only from about 1850 there are enough to get a global picture. So official graphs start from this date or later.

A good way is to go to official sources and there are a number of graphs which are considered as sound. We will check later which one are most common.

If we want to compare various graphs of temperature or with other data like CO2 or sea ice, we need a tool to get the whole picture. One of the best and easiest to handle tools is www.woodfortrees.org. In this tool all relevant data sets are already included, and you can make very impressive work with it. Note: This tool and the web site is neutral, not taking a certain stand in the climate warming discussion.

Just let's go straight to the website and check the most important temperature graphs:


Here we see three very common temperature graphs:

Red: HADCRUT 3 from Hadley Centre combining sea surface and land temperature (air temp 2 meters above surface)
Pink: Hadcrut trend over 160 years: 0.8°C, which is 0.5 per century and 0.05 per decade.

Green: HADSST 3: sea surface global temperature
Turquoise: HADSST 3 trend over 160 years: 0.65°C, which is 0.4 per century

Blue: CRUTEM3 only global land temperature
Brown: CRUTEM 3 trend over 160 years: 0.95°C, which is 0.6 per century

So why the differences?

Possible answers:
  • The ocean temperature is more stable in the long run, so changes are not so easy achieved.
  • Temperature stations on land often have been surrounded by cities or human-induced heat, which could have accelerated the recording of the blue CRUTEM curve.
  • Remote stations (with few human disturbance) have been abandoned, thus giving more weight to stations near towns.

If someone wishes to reduce human influences to temperature measurement, sea surface temperature cold be the choice for long-run observation, especially as the ocean surface is two third of the earth's surface.

If we take the average from land and sea, the HADCRUT, we have 0.6°C rise per century. Added this to the already started century, we would have a temperature 0.5°C higher than today, which would be no problem then.

So the question is: Is the global accelerating, or remaining, or declining?
This question we should look for at a later time. And it will be another chapter in the Layman's Climate Course

Now back to our Question: What is the right temperature curve?

The answer so far: Land and Sea surface temperature curves differ from each other. Land temperature seem to show human influence to the data, whereas sea surface data show a smoothed and delayed record. So the best seems to stick to the combined global data, which is also standard in science.

Sonntag, 19. Januar 2014

"Treibhausgase" und "Treibhauseffekt"

Wie sieht der Wärmehaushalt unserer Erde aus und was passiert dabei innerhalb der Atmosphäre?

Dieser Frage bin ich aus persönlichem Interesse nachgegangen. Ich habe als Laie versucht, meine Ergebnisse für Nichtwissenschaftler verständlich darzustellen. Mögliche Irrtümer meinerseits bitte ich, mir mitzuteilen und zu diskutieren. Schauen wir uns dazu mal die untenstehende Grafik an:

Vom eingehenden Sonnenlicht werden
  • 77 w/m² von der Atmosphäre reflektiert
  • 78 w/m² von der Atmosphäre absorbiert (diese wird dadurch wärmer)
  • 23 w/m² von der Erdoberfläche reflektiert
  • und 160w/m² von der Erdoberfläche und vom (Land und Wasser) absorbiert, diese wird also wärmer

Die Erdoberfläche gibt diese Wärme im Laufe von Tag und Nacht wieder ab und zwar:
  • 80 w/m² durch Verdunstung
  • 17 w/m² durch Thermik (von der Erdoberfläche erwärmte Luft steigt wieder auf)
  • 40 w/m² emittieren, d.h strahlen als infrarote Wärmestrahlung direkt in den Weltraum
  • und 23 w/m² strahlen in die Atmosphäre und werden dort von Treibhausgasen absorbiert (diese werden wärmer, und durch Kontakt mit den anderen Luftmoleküle auch die Atmosphäre)

Wir sehen hier auch noch andere Wärmeströme, und zwar
  • 396 w/m² von der Erdoberfläche hin zur Atmosphäre, davon durchdringen 40w/m² die Atmosphäre ohne Widerstand durch das sog. atmosphärische Fenster.
  • 333 w/m² von der Atmosphäre hin zur Erdoberfläche
Zieht man von den 396 w/m² die 40 w/m² und die 333 w/m² ab, dann bleiben die o.g. 23 w/m², die von der Atmosphäre absorbiert werden. Warum das so dargestellt wird, und nicht einfach die 23 w/m² genannt werden, dazu die folgende Erklärung.

Die Atmosphäre besteht größtenteils aus Stickstoff- (N2) und Sauerstoffmolekülen (O2), die eine Besonderheit haben: Sie können weder Wärmestrahlung absorbieren (aufnehmen) noch emittieren (abgeben). Deshalb ist Luft ein so guter Isolator.

Weiterhin gibt es aber in der Atmosphäre Spurengase, die das können, nämlich Wasserdampf, Kohlendioxid, Methan, Ozon und Distickstoffmonoxid. Sie werden auch Treibhausgase (kurz THG genannt) genannt, weil sie zu einer Erwärmung der Atmosphäre beitragen können. Das hat aber nichts mit den Funktionen eines normalen Gewächshauses zu tun. Sie können aber noch mehr, denn sie kühlen sie auch. Auch wenn der Name nicht ganz stimmt, wollen wir ihn hier verwenden, da er allgemein verwendet wird.

Die Grafik zeigt etwas sehr Vereinfachtes, nämlich die Atmosphäre als Blackbox. Es wird nur beschrieben, was in sie hineingeht (gleich oberhalb der Erdoberfläche) und was aus ihr hinausgeht (und zwar von der A. zur Erdoberfläche und von der A. zum Weltall hin). Was in ihr geschieht, wird dabei nicht beschrieben.

Auf der blauen Erdoberfläche in der Grafik sind auch noch 0,6 bzw. 0,9 w/m² angegeben. Dabei handelt es sich um einen angenommenen negativen Wärmeabfluss. Es wird hier angenommen, dass weniger Wärme abfließt, als hereinkommt, die Erde sich also erwärmt. Das dies aber in unserem beginnenden Jahrtausend ( je nach Temperaturkurve seit 8-17 Jahren) noch nicht ereignet hat, wollen wir diese Zahl mal beiseite lassen und von einem ausgeglichenen Wärmehaushalt der Erde ausgehen.



Was geschieht nun in der Atmosphäre?

Vom warmen Erdboden gehen Wärmestrahlen Richtung Weltall. Ein Teil geht durch die Atmosphäre hindurch (atmosphärisches Fenster), ein anderes Teil trifft auf THG und wird von ihnen absorbiert. Die Atmosphäre (vor allem die unteren Schichten) erwärmt sich dadurch etwas. Die Atmosphäre hat auch schon etwas Wärme durch
  • Absorption von einfallendem Sonnenlicht
  • Verdunstung / Wasserdampf und
  • Thermik (Luftbestandteile werden von der Erdoberfläche durch direkten Kontakt erwärmt und steigen auf)
erhalten. Durch Kontakt (Stoß) erwärmen sich alle Luftbestandteile gegenseitig.

Nur die Spurengase können Wärmestrahlung abgeben. Wie jeder andere Festkörper über 0 K (-273°C) strahlen sie in alle Richtungen. Dabei geht theoretisch jeweils die Hälfte Richtung Erdoberfläche und die andere Richtung Weltall. Natürlich gehen auch Wärmestrahlen nach links und rechts, aber die treffen wieder andere THG, die dann letztendlich auch wieder nach oben und unten strahlen.

Der Netto-Energiefluss

Es kommt jedoch mehr Wärmestrahlung von der Erdoberfläche, als von der Atmosphäre auf die Erdoberfläche, deshalb geht der Netto-Wärmefluss von 23 w/m² nach außen ins All. Muss man das denn so wie in der Grafik beschreiben, oder würde der Netto-Fluss genügen? Eigentlich schon, aber die Sache hat einen kleinen Haken: Durch das Aufheizen der THG-Moleküle und durch die Kontakt-Wärmeübertragung auf und von anderen Molekülen (auch Sauerstoff und Stickstoff) geht Zeit verloren, die Wärme fließt also langsamer ab, als wenn die Wärmestrahlen mit Lichtgeschwindigkeit ins All strahlen würden. Deshalb ist die Atmosphäre über der Erdoberfläche etwas wärmer als wenn alle Bodenstrahlung direkt in den Weltraum abfließen würde.


Theoretisch etwas wärmer

Betrachten wir das Ganze noch etwas feiner: Von der Erdoberfläche ausgehende Wärmestrahlung trifft schon nach den ersten Millimetern auf THG und wird von Ihnen absorbiert. Andere Strahlen erst nach vielen Metern Höhe. THG werden erwärmt und strahlen wieder ab. Manche Strahlen davon komme wieder auf die Erdoberfläche, manche gehen Richtung Weltraum und treffen dort wieder auf THG, die dann wieder nach oben und unten strahlen. Eine Art Pilgerschritt: zwei vor, einer zurück.

Dadurch wird dasselbe bewirkt wie beim echten Pilgerschritt: Es geht langsamer voran oder: Die Wärme fließt langsamer ab. Und dadurch bleibt die Atmosphäre etwas wärmer, und dementsprechend die Erdoberfläche auch.


Man kann diese Strahlung, die sogenannte Gegenstrahlung, die von der untersten Schicht der Atmosphäre zurückkommt, auch auch mit einem Pyrgeometer messen.
http://de.wikipedia.org/wiki/Atmosph%C3%A4rische_Gegenstrahlung

Wie gesagt, man misst hier nicht, was in der Atmosphäre abläuft, sonder was man von der Erdoberfläche aus, also am unteren Ende des Strahlen-Pingpongs eben mitbekommt.

Die andere Seite der THG:

Sie helfen auch, die Wärme in der Atmosphäre wieder loszuwerden. Sie können ja auch IR-Wärmestrahlung abgeben, also kühlen. In der Atmosphäre steckt sehr viel Wärmeenergie:
  • die 77w/m², die beim Eintritt des Sonnenlichts in die Atmosphäre absorbiert wurden
  • die 80 w/m², die durch Verdunstung in die Atmosphäre kamen
  • die 17 w/m², die durch die Thermik (aufsteigende Warme Luft) dazukamen
  • und die 23 w/m², die als Netto-Abstrahlung der Erdoberfläche absorbiert wurden.
  • Macht zusammen 197w/m². (also 8 mal soviel, wie die Nettoabstrahlung)

Nach der obersten Schicht der Atmosphäre, die ca. 100 km hoch ist, kommt nichts. Zumindest keine Materie, die die Wärme ableiten kann. Nur durch elektromagnetische Strahlung, in unserem Fall infrarote Wärmestrahlung, kann die Wärme abgeleitet werden. Und das können nur die Spurengase oder THG. Sie schaffen es, die Wärme wieder komplett abzustrahlen, also die Erdatmosphäre abzukühlen. Ohne sie würden zwar die 23 w/m² nicht abgebremst werden. Diese könnten dann einfach in das All strahlen. Aber die Energie, die sonst noch in der Atmosphäre steckt, könnte nicht ins Weltall abstrahlen. Die Atmosphäre würde überhitzen und in Folge davon die Erde auch.

Wie schaffen es nun die THG so effektiv, die Wärme abzustrahlen? Nun, einerseits kommt ja vom Weltall keine Strahlung zurück, andererseits wird die Atmosphäre nach oben hin immer dünner. Dadurch werden auch die Abstände zwischen den Molekülen immer größer, und die IR-Strahlung wird immer weniger von THG absorbiert. Wird sie dann doch einmal von einem THG absorbiert, strahlt dieses zur Hälfte in des Weltraum ab, wo nichts zurückkommt, weil dort keine Wärmequelle ist. Die andere Hälfte geht Richtung ErdoberflächeW, wo vom nächsten Molekül wiederum nur die Hälfte nach unten geht, die andere Hälfte aber wieder Richtung All, und zwar wahrscheinlich ohne von einem andere THG absorbiert zu werden.

Während also die Strahlung von der Atmosphäre zur Erdoberfläche hin von der Oberflächenstrahlung übertroffen wird, kommt aus dem All gar nicht zurück. Durch das Dünnerwerden der Atmosphäre wird darüberhinaus die Abstrahlung nach außen hin kaum mehr behindert. Das zeigen auch die niedrigen Temperaturen der oberen Atmosphären schichten.

Übrigens kann man die Abstrahlung der Atmosphäre nach außen ins All auch messen, und zwar mit Satelliten. Darüber gibt es Messreihen über viele Jahre.

Nun noch einige Nebenbemerkungen:

Die Hauptfrage, die uns bei dieser Thematik beschäftigt, ist:
Wird es bedeutend wärmer, wenn die Menge der THG in der Atmosphäre erhöht wird?

Oder wie die Wissenschaft diese Frage formuliert: Um wieviel Grad erhöht sich die Globaltemperatur, wenn der CO2-Gehalt von vorindustriellen 280ppm auf 560ppm verdoppelt? Die Antwort lautet ziemlich übereinstimmend (sowohl vom Weltklimarat, als auch von kritischen Wissenschaftlern): um ca. 1 °C +/- 0.5. Auch Berechnungen kommen zu einem solche Ergebnis. Mit diesem kleinen Wärmeplus kann man gut leben in unserer Nacheiszeit. Worüber man sich nicht einig ist, ist die Frage, was sonst noch passiert.

Einige Wissenschaftler befürchten eine sogenannte Wasserdampf-Rückkopplung. Sie besagt, dass durch die Erhöhung der Temperaturen auch die Verdunstung zunimmt. Dadurch hat man mehr von dem THG Wasserdampf in der Atmosphäre und auch eine verstärkte Abbremsung des Wärmeabflusses, ergo noch höhere Temperaturen, noch mehr Wasserdampf-THG und so weiter, bis das Klima komplett umkippt und die Erde überhitzt.

Es gibt aber auch noch andere Rückkopplungen:
  • Mehr Wasserdampf bedeutet mehr Wolken, also weniger Sonneneinstrahlung und damit eine Abkühlung.
  • Eine erhöhte Temperatur bedeutet auch eine exponentielle (also vervielfachte) Wärmeabstrahlung, wodurch sich sich die Temperaturen kaum erhöhen.
  • Eine erhöhte Temperatur bedeutet mehr Verdunstung, also Abkühlung der Erdoberfläche
  • Eine erhöhte Temperatur bedeutet mehr thermische Konvektion, also Transport der von der Erdoberfläche erhitzten Luft in die Atmosphäre - und der Gelegenheit, sich dort abzukühlen.
Mit diesen der Erwärmung entgegenwirkenden Funktionen sieht es so aus, dass die Erde diverse Regelmechanismen besitzt, um eine Überhitzung zu verhindern.

Was ist aber die wichtigste Regelfunktion? Das sind mit Sicherheit die Wolken. Der Gegensatz zwischen Wolken und strahlendem Himmel können viele Grade Temperaturunterschied ausmachen, genauso wie zwischen bedecktem und sternenklaren Himmel in der Nacht.

Folgende Beobachtung konnte man bisher machen:
  • Trotz beschleunigt ansteigendem CO2-Gehalt sind in den letzten 17 Jahren die Global-Temperaturen nicht mehr angestiegen, und in den letzten 12 Jahren um 0,1 °C gefallen. (Satellitendaten RSS untere Troposphäre)


Noch eine Nebenfrage:

Gibt es einen globalen Treibhauseffekt und den menschengemachten Treibhauseffekt?

Nicht im wahren Sinn des Worte. Die Erde ist kein Gewächshaus mit einer transparenten Abdeckung. Jedoch bremsen Spurengase oder THG den Wärmeabfluss durch Energieübergänge innerhalb der Atmosphäre ab. Erhöhte Mengen THG bremsen eventuell noch etwas mehr, so dass es dadurch zu einer um ca. 1 Grad höheren Global-Temperatur kommen könnte. Erst eventuelle Rückkopplungen entscheiden darüber, ob es zu einem Klimakollaps kommt oder nicht. Bis jetzt hat man noch keinen praktischen Nachweis für eine solche Theorie gefunden.





Freitag, 17. Januar 2014

The Layman's Approach: What will happen if the backforcing through Greenhouse Gases will be increased?

I try (and I encourage everybody to do the same) to understand and to find by myself out what's real in the climate debate. I will do it at a very easy understandable level. Being a foreigner to English will help me to keep this, as well as the fact that I always worked in the field of education.

Here we have a well-known graphic about the Global Energy Flow:


Let's just repeat and explain the facts: (all figures approximately in watts/m²)

1. Incoming global shortwave radiation: 340
- Reflected by clouds, atmosphere and surface 100 (Note: surface reflection is only 23 of the general budget,6.7%)
- Absorbed by atmosphere: 80

-Remaining 160 w/m² absorbed by the surface.

2. Now how to get rid of the surface heat:

- Transported into the atmosphere by thermal convection: 20
- Transported into the atmosphere by evaporation: 80
- Surface radiation through the atmospheric window
   (these IR waves are not trapped by greenhouse gases): 40
- Remaining Surface Radiation 360 minus Back Radiation from the greenhouse gases 340:
   Rest 20, wich are absorbed from the atmosphere.

-All of the 160 w/m² which heated up the surface, are now in the atmosphere.

3. Now we have in the atmosphere 75 from the incoming sunlight, 20 from convection, 85 from evaporation in total 200 which is radiated from the Greenhouse Gases towards open space. (or 240 together with the 40 which escaped through the Atmospheric Window.

Only 20 w/m² are radiated towards the atmosphere and are hopping like Pingpong balls between the greenhouse molecules. But as the outer space is about -270 centigrades (There is nearly nil Back Radiation from the space, except the sun), and as the distance between the molecules in the upper layer of the atmosphere is steadily growing with the distance from the surface, most of the heat will be radiated into the space.



So, what would happen, if we had no Greenhouse Gases?

Remember, Greenhouse Gases can absorb longwave IR radiation and get heated up. They can also be heated up though contact with the O and N molecules of the air, which are first heated up by the surface, convection and incoming sunrays. The hotter they are, the more they are radiating and as there nothing comes back from the outer space, they will cool the atmosphere.

In the contrary, O and N molecules cannot absorb nor radiate heat. But they can collect heat from other molecules and the earth surface through contact. This is why the air is a such a good insulator. Bu the heat, once trapped, cannot radiate, and the molecules stay hot. To cool down, they need the help from greenhouse gases.

Now we look at our Earth Surface, heated up with 160 w/m². 80 we get into the atmosphere trough evaporation, 20 through thermal convection. No greenhouse gases in the air, except water vapour. 40 will vanish through the Atmospheric window, and 20 don't go into the atmosphere but straight into space, as there are no disturbing GG.

Now we have a problem: There are 100 w/m² in the atmosphere, and they can't escape. No help from the GG. So the temperature will climb up to the hottest tempeartures on Earth, about 60°. The poles will melt, and we will be boiled. Thank God, we have the greenhouse gases! They don't heat up, they mostly cool.

Okay, there is something wrong with my model, as water vapour is also a greenhouse gas, and it can help in cooling a bit. But it will not help with all the 100w/m². Even some Watts are dangerous. Why? look at the graphic: There is mentioned a 0.6 or 0.9 w/m² net absorbed energy, which is't released from the surface. Which means even this small amount is considered as dangerous as it will remain in the atmosphere and heat it up. But we have to handle 100 w/m²!


Now we come to our first question: What will happen, when the green house gases are growing together with the Radiative Backforcing? 

Only 20 w/m² will go through the atmospheric pingpong, all others have their own way. At the moment I have no good numbers, which amount of CO2 will increase the backforcing by 1 watt. But just lets get the picture: 1/8 (160 w/m² surface heating : 20 radiation into the atmosphere) of each additional Watt has to go through the greenhouse gases, the rest has other ways to come into the atmosphere or to the space.

But even this slightly hotter surface means:
1. More heat causes more evaporation, ergo more heat transport.
2.More heat causes more thermal convection, ergo more heat transport.
3. More heat causes more radiation, ergo more heat transport into space or the atmosphere.
4. Hotter atmosphere means more temperature difference to the space, ergo more heat radiation from the Greenhouse gases going there.
5. More heat causes more vapour in the air, ergo more clouds, which are reflecting incoming sunligth.
6. More GG in the atmosphere means more heat transport on the outer edge of the atmosphere to the space due to more heat collecting and emitting GG molecules.
7. What has not yet been discussed are the phases of heating and cooling. The model acts like a flat earth with all processes going on at the same time, wich is not true. Directly below the sun (e.g. on the equator) the incoming radiation is 1300+ w/m², wheras on the poles it is near to nil. There are cold and warm regions (where cold or warm winds can transport heat). Heating up during the day is followed by many hours for sufficient cooling. (in the dessert a boiling day can be followed by a real cold night) When it is hot, the outgoing radiation is much stronger than the backradiation, helping to get rid of the excess heat quickly. Also thermal convection during heat is much stronger.

Seems there are a lot of thermostatic functions here on our Earth to keep the climate in good shape. Seven physically well known effects seem more than sufficient to regulate the Earths climate. So from a theoretical point of view increased Greenhouse Gases seem not to be the big problem.

It's fair to add one possible obstacle: Some scientists believe that increased water vapour (=greenhouse Gas) in the atmosphere will lead to more radiative backforcing, which will increase the greenhouse effect. This is a not yet approved theory. In reality, steady expotentially rising CO2 has neither caused higher temperatures nor more water vapour during the last 17 years. The opposite cold be: More clouds (which reflect sunrays) through more vapour. One study (I have to look for the data) observes regularely clouds during hot hours in the tropics, which will exactly avoid overheating, when necessary.

So far my theory. I encourage to countercheck everything.









Dienstag, 14. Januar 2014

The layman's approach: The properties of greemhouse gases

The layman's approach: The properties of greenhouse gases

In my course about climate change I got some explanation about the so-called greenhous gases. But this is not sufficient to see the complete picture and the role they play within the climate system. Being a layman, I want to find out how these work and try to get an easy to understand but yet exact enough picture for everybody. As an example I use the CO2, but the other GG are working after the same principle.

What are the properties of CO2?

  • CO2 can absorb a vast spectrum of infrared (heat)rays. The CO2 molecule gets hotter and radiates again infrared radiation, partly toward the earth's surface, partly towards space.
  • The time between absorbing heat for IR radiation and emitting it again lies in the fraction of a nanosecond.
  • CO2 can collect heat from the earth surface or from other surrounding non-greenhouse-gas-molecules through physical contact. Even this heat is radiated in both directions.
  • CO2 content of the air is about 400ppm (parts pe million, 1 ppm = 0.0001 %). In very direction of an air filled space, every 16th molecule is CO2. So it is unlikely that infrared radiation doen't meet such molecules. In fact, even after only few cm, a big amount of the  IR radiation has already met CO2 molecules.
In short, CO2 can absorb and emit IR/heat rays. Or: I can be heated up and will cool down by itself. The proinciple is like that: Two matters are emmiting heat/IR rays, one is hotter than the other. As the hotter one radiates more than the cooler one, the difference between both heat transfers is the net amount, which will heat up the cooler one.

How is CO2 in the atmosphere working?

near the earth surface: CO2 is hit by a IR ray, is heated up and emits half of the extry energy toward the surface and half of in direction of the space. But there are lots of other CO2 Molecules, wihch also re-direct the half amount from this fraction towards space and half of it towards the surface. The next one does the same, etc. So the fractions redirected are getting smaller and smaller.The more the IR rays are comming to the outer layers of the amosphere, due to the thinner air let CO2 molecules ar hit and most of it will go out into the space.  CO2 can be considered as brake for the IR radiation, which slows down the cooling process of heat transfer through IR radiation.

on the outer edge of the atmosphere towards the space: CO2 is absorbing heat rays comming from the earth via other CO2 molcules and extra heat from physical contact to other non-CO2-molecules. As the temperature of the space is -273 centigrad, it radiates as long energy towards space, until it is exhausted. But still some few IR is comming from the earth. Here on the outer edge CO2 is helpng to send any energy away from the earth, which means that it cools the atmosphere. Yes. some few IR rays are still sent back to earth, but they are few compared to the net sum of those who are directed towards space.

What are the properties of the NON-greenhous gases O2 and Nitrogen? 
  • They can collect heat through physical contact to the earth's surface and to other air molecules.
  • They can't neither absorb IR rays nor emit/radiate heat away. They are insulating.
How would an atmosphere work without Greenhous gases?
  • IR radiation could pass through towards space, causing more heat loss.
  • But O2 and Nitrogen are also heated up by contact to the surface, but this heat can't escape from the atmosphere, because both cannot emit heat through IR rays.
  • So the whole atmosphere would have the same temperature as the surface.the only cooling could happen through contact to colder parts of the earth, heating them up, and causing them to radiate the excess heat towards space.
In consequence, an atmoshphere without Greenhouse gases could be hotter than with, as it misses the cooling through IR emitting gases. Is it really like this? Consider the fact, that now at the outer edge of the atmosphere are temperatures of -100 centigrades or lower. Without cooling, those areas would have the same temperature as the surface.

Reflections: How cold/hot it would be without Greenhouse gases?

 It depends on the amout of heat which is emitted from the earth's surface vs. the the amount of heat which is collected from the atmosphere through contact. We understand, that wind / convection is steadily bringing new air molecules to the surface to be heated up.

The heat is only radiated away, when the surface has been heated up. In deserts the day temperature will go up to 70 centgrades or more. At the same time the air has chance to get heated up by surface contact. And it is trapped as long there, as it hits a colder area of the earth, say, the poles. Using the poles to cool down the hot desert air, would cause them to melt. 

Possibly it's ´not so bad to have some CO2 in the air. And possibly the rate of it is not so crucial. More heat mean more convection / exchange with the outer layers of the atmosphere, allowing there the CO2 to do some cooling work.

Anway, a good scenario to start a discussion.