Ice and climate change.
A lot has been said and written about humankind generated climate change and whilst most people are very concerned about this, a few are sceptical and/or deny its reality, preferring to think it a conspiracy theory and/or an anti-western / capitalistic anarchistic plot.
As an astronomer I thought it may be helpful to write a straight-forward short article about how global warming is happening. And why the deniers are wrong.
There are 2 major processes which affect global temperature, the amount of heat we receive from the Sun and the amount of heat retained in our atmospheric 'blanket'. I am not an atmospheric chemist and thus cannot write with authority on the latter. But I can for the former, and on how sea ice, the polar ice caps and mountain glaciation are critical for a global temperature equilibrium (balance).
If an object receives more energy than it reflects/radiates, it will get hotter. When we come inside on a cold day we warm up to the temperature of the room. We don't overheat because our bodies become heat-balanced with the room.
Except for gravitational potential and orbital energy (which do not affect global temperature), all the energy received by the Earth's atmosphere is from the Sun (...astronomical friends will allow me to ignore stellar radiation as miniscule in comparison, and geophysical friends please allow me to ignore mantle and core geothermal energy).
The energy received from the Sun into the Earth's atmosphere is called the solar irradiance. This is very stable/consistent. See our blog post of January 2017 for more on this
(Although very small variations are seen in the solar irradiance...short term through the slight eccentricity of the Earth’s orbit and the approximately decadal solar cycle, and long term in orbital changes such as the Milankovitch cycle, these do not account for temperature rises observed.)
Some sunlight is reflected by the Earth's atmosphere, including clouds, and the surface, and not absorbed. It is reflected back into space and does not contribute to the temperature 'budget' of the Earth.
The amount of light an object reflects is call the albedo of the object. The Earth is a relatively shiny planet and reflects about 30 to 35 % of the sunlight incident upon it. The moon is duller, and reflects a more consistent 12% of incident sunlight.
Dark rocks such as charcoal has an albedo of typically 4%, fresh snow is very reflective at circa 90%. Sea water is dull at about 6%, whilst sea ice varies from 50 to 70%. So the duller an object, the more heat it absorbs.
The problem we have is that the reduction in area (by melting) of the ice caps, sea ice and mountain region glaciation is reducing the global albedo. This means that our planet is no longer in thermal equilibrium (heat balance) and our atmosphere is heating up.
It’s analogous to us living in a greenhouse. We have reflective foil on our roof which means our greenhouse doesn't heat up too much. But what is happening is our reflective foil (ice) is being removed. So we're heating up. And life in our greenhouse will change.
This is why ice is so important to us. And why we need to be both very worried AND active in every which way we can to ensure we do not compromise our icy regions.
The second major process governing global warming is retention of heat. Retaining heat is rather sensitive to atmospheric chemistry, with water vapour, carbon dioxide and heavier 'greenhouse' gases such as methane all adding to heat retention. We will each have heard lots on these latter processes. In our greenhouse analogy, not only have we ripped down our reflective foil, but we've decided to put a warm coat on too!
There is very much more to this topic and many atmospheric aspects than this short article can provide. But albedo, and thus ice is absolutely critical.
I've included a few links below from the popular media for further info. as to the issues we're facing, and a link to my ideas as to what we each individually can do.
The last 3 of these links show, in my opinion, how the current US administration (who you will probably know has withdrawn from climate change commitments and accords) should be considered as a global terrorist, aided and abetted by the UK Johnson administration.
Strong words I know, but please read this and the links below and you'll understand why I use such rhetoric.
The rate of loss of ice in Greenland
Himalayan glaciation loss
The accelerating rate of loss of Artic permafrost
How the US administration are actively supporting reduction in Artic ice.
How the UK government response is a sham
How little importance the UK PM Johnson considers this matter to be
But what can I do to help? Plenty!
Auguste Charlois, seeker of asteroids (26/11/1864-26/3/1910)
Auguste Charlois was a French astronomer born on the 26th November 1864 at La Cadière-d'Azur, a town in the south east of France about 50km from Marseilles.
He is famous for discovering 99 asteroids while he was working at the Nice observatory. After finishing his secondary education at the l’Institution des Frères de la Doctrine chrétienne in Marseilles, he began to work at the Nice Observatory for Joseph Perrotin, its first director. He was employed to help Perrotin in finding the difference in longitude between the observatories of Nice, Milan and Montsouris in Paris.
Charlois discovered the 99 new asteroids between 1887 and 1904, and 27 of these were detected by direct visual observing. This means of observation needed many hours patience but Charlois was a dedicated and tireless observer. In 1891 the German astronomer Max Wolf introduced astrophotography, a much more efficient method of observation which allowed astronomers to discover much more than they would by visual observation.
The work and the discoveries of Charlois contributed to the excellent reputation of the Nice Observatory from its beginnings. But his life ended tragically. At the age of 45 he was assassinated in the middle of the night by an individual who arrived at his door on the pretext of delivering a telegram. He is buried in the cemetery at la Cadière d'Azur. He was without doubt a dedicated and talented astronomer, and today the asteroid (1510 Charlois) in his honour.
Auguste Charlois circa 1900
Image above courtesy of Jean-Francoiis Consigli
Auguste Charlois, chasseur d’astéroïdes (26/11/1864-26/3/1910)
Auguste Charlois est un astronome français né le 26 novembre 1864 à La Cadière-d'Azur, une ville située dans le sud-est de la France à 50km de Marseille.
Il est connu pour la découverte de 99 astéroïdes pendant qu’il travaillait à l’observatoire de Nice. Après avoir fini ses études secondaires à l’Institution des Frères de la Doctrine chrétienne à Marseille, il a commencé à travailler à l’Observatoire de Nice pour y assister Joseph Perrotin, le premier directeur, dans la détermination des différences de longitudes entre les observatoires du mont Gros (Nice), de Brera (Milan) et de Montsouris (Paris).
Charlois a découvert les 99 nouveaux astéroïdes entre 1887 et 1904 dont 27 par observation directe. Cette moyen d’observer nécessitait de très nombreuses heures d’observation, mais Charlois était un observateur assidu et infatigable. Ensuite, en 1891 l’astronome allemand Max Wolf a introduit l'utilisation de l’astrophotographie, une méthode d’observation beaucoup plus efficace qui a permis aux astronomes d'en découvrir bien plus qu'ils n'auraient pu par la détection visuelle.
Le travail et les découvertes de Charlois ont contribué à la réputation excellente de l’Observatoire de Nice dès son ouverture. Mais sa vie est terminé tragiquement. A l'âge de 45 ans il est assassiné au milieu de la nuit par un indivu qui est arrrivé à sa porte sous le pretexte de lui remettre un télégramme.
Auguste Charlois est inhumé au cimetière de la Cadière d'Azur. Il était sans conteste un astronome travailleur et talentueux. L’astéroïde (1510 Charlois) est nommé en son honneur.
The discovery of Chiron
Regular readers of our monthly blog will be aware of the Centaurs. Today marks the discovery of the centaur Chiron, or to give it it’s complete designation 2060 Chiron (1977UB). Aujourd’hui marque la découverte du centaure (2016)Chiron ou 2060 Chiron (1977UB).
Chiron a été découvert par l’astronome américaine Charles Kowal (8/11/1940 à 28/11/2011) à l’aide d’un télescope de 1,2m pendant qu’il travaillait à l’observatoire de Mont Palomar en Californie. L’iimportance de cette decouverte a été bientôt reconnue. Avant la découverte de Chiron, Hidalgo était considéré comme quelque chose d’exceptionnel. Mais les similarités entre l’Hidalgo et Chiron a permis l’identification d’une nouvelle classe d’objets – les Centaures.
It was discovered by Charles Kowal using a 1.2M telescope from the Mount Palomar observatory in California. The importance of the discovery was soon recognised. Whereas prior to Chiron’s detection the anomalous object Hidalgo (944 Hidalgo (1920UB) was considered as a one-off, the close orbital similarities Chiron showed brought the identification of a new class of objects, the Centaurs.
Chiron is a fascinating object. With an aphelion distance (furthest distance from the Sun) of almost 19 AU (nearly as far as the planet Uranus) it was at the time of its discovery the most remote asteroidal object detected.
It is relatively large for an asteroid and has a diameter of 166km. This has been determined by ‘stellar occultation’. An occultation is where the object being studied passes in front of a more remote object (such as a star) and eclipses the light from the remote object.
As we discussed during our Sept 2019 blog, Centaurs appear to orbit, spectroscopic, and features-wise be closer in nature to short period comets rather than asteroids. However, distinct differences from both major classes (comets and asteroids) are seen in the Centaurs. For example the size of Chiron is quite exceptional for a comet; and thus they are considered to be transition, or hybrid objects between comets and asteroids.
There has been some speculation recently that observations (Ruprecht, MIT, 2011), again using occultation, suggest that the Chiron has a ring structure – a bit like a much sparser version of the rings of the planet Saturn. Our own view is that this explanation of the observations is very unlikely. The size, and thus mass, of Chiron is insufficient to sustain a ring structure.
Our interpretation of the MIT observations is that the object exhibited a gaseous/dust outgassing (i.e. like the coma – the sublimation – of a comet).
The Education of Achilles by Bénigne Gagneraux (1785)
(Achilles riding on the back of Chiron)