Plataforma Wilkins

Elemental, querido Watson!!

Leí hace 2 días, en El País y en el ABC, (por segunda vez en lo que va de año(!)) que la plataforma Wilkins se había desgajado completamente de la Antártida y que su desintegración es inminente. Tratándose de dos de los medios de información más importantes de España, por supuesto, no le di ninguna credibilidad (hasta este punto hemos / han llegado). Y llevo un par de días esperando que se publique algo al respecto en donde de verdad hay que ir hoy en día a buscar la información, esto es, a páginas y blogs especializados, en este caso, en todo lo relacionado con el cambio climático.

Nada hay aquí, ni en WUWT ni en CA. En RealClimate no dijeron nada hasta ayer, y lo que dijeron es que se está separando, no que se haya separado. Joe Romm, en su híper-alarmista y mega censurado blog "Climate Progress", ¡tampoco ha dicho nada aún! Y esto sí que me sorprende sobremanera.

¿Qué carajo está pasando con la plataforma Wilkins? ¿De dónde sacaron su información El País y el ABC para publicar lo que publicaron el día 5? ¿Está pasando o no está pasando, y de pasar qué es lo que pasa? ¿Y por qué este atronador silencio en todos los lugares que deberían estar comentándolo, independientemente del corte ideológico de cada uno? Estoy en ascuas...

Saludos.

Nunca pensé que esto fuera posible, pero Gavin, de Real Climate, me ha venido a dar la razón con respecto al tema de la plataforma Wilkins. Ha ocurrido con un par de intervenciones y sus respectivas respuestas:

1) Nylo:

Today The Independent (UK) informs that a piece of ice the size of New York has collapsed. However it also informs that (I copy literally) “The loss of ice shelves does not raise sea levels significantly because the ice is floating and already mostly submerged by the ocean”. Is this true? I never heard of it before. It also warns that there is a risk of sea-level rise anyway because “their loss will allow ice sheets on land to move faster, adding extra water to the seas”. However the Wilkins is not a glacier-fed ice shelf. How much and how fast would that effect be felt?

2) Gavin responde:

The almost negligible impact of floating ice shelf collapse on sea level is well known (the only reason it is not zero is because of the fact that the ice is fresh and the sea water it displaces is salty). However, the acceleration of the upstream glaciers after a collapse has only recently been observed and happens relatively quickly. After Larsen-B collapsed, the feeding glaciers sped up by about 400% (see here). But why do you think the Wilkins ice shelf doesn’t come from a land based glacier? It definitely does - you just don’t get that thickness of ice from in-situ formation.

3) Nylo responde a Gavin:

Gavin, about what leads me to think that it is not glacier-fed, look at this paragraph from http://earthobservatory.nasa.gov/Features/WilkinsIceSheet (NASA site):

“The Larsen Ice Shelf is “typical” in that it is primarily fed by a land-based glacier. The Wilkins Ice Shelf is somewhat unusual in that only the southern end of the shelf appears to be fed by land-based ice; the rest of the shelf may have formed from accumulation of sea ice that held fast to the coastline through many seasons, as well as snow cover. Glaciologists estimate that the part of the Wilkins Ice Shelf that formed from sea ice may be 300 to 400 years old, and the part that is fed by glacier flow is older, perhaps up to 1,500 years old. Because the Wilkins Ice Shelf is only marginally fed by glacier flow, however, its collapse was not expected to have the same impact on sea level rise as the collapse of the Larsen B potentially could”.

As you see, it does claim that you can get “that thickness of ice from in-situ formation”. Actually, it says that you can get it in only 400 years (this means, I suppose, that it would have started to happen more or less at the Little Ice Age). And appart from that, do the parts of the Wilkins Ice Shelf that are disintegrating belong to the Southern, glacier-fed part of the shelf? Because if they happen to belong to the Northern part, it seems to me like there would be nothing to worry about at all, with no glacier ice accelerating anywhere.

4) Gavin concede:

Ok, in the absence of any more detailed info, this seems to be correct. I am nonetheless surprised that you can get 300m thick landfast sea ice, maybe someone who knows more about the details can comment.

La verdad es que lo que le sorprende a Gavin también me sorprende a mí. 300 metros de espesor son muchos como para haberse formado en 400 años a base de precipitaciones. Pero la clave aquí es que la fuente es de la NASA, y Gavin trabaja para la NASA. Seguramente no se atreve a desacreditar todavía a quien quiera que escribiese eso sobre la plataforma Wilkins. Volverá :)

Por cierto, nótese en el primer comentario de Gavin eso de que "el prácticamente nulo impacto sobre el nivel del mar del colapso de una plataforma de hielo es bien conocido". Caramba, pues no me habré hartado yo de leer apocalípticas predicciones de subidas del nivel del mar por culpa de éstas, sin que ninguno de aquellos para los que es "bien conocido" abriera la boca para protestar...