El cambio climático: ¿un bulo científico?

[Isocrates]

Ya que parece que Manel está disfrutando de sus vacaciones, puedo proporciona, para su alegría y esparcimiento a su regreso, un enlace directo al artículo que Svensmark escribió para la "Royal Astronomical Society".

Aquí está...

http://www.blackwell-synergy.com/doi/pdf...07.48118.x


Y, al hilo de los bellos comentarios que Manel me ha dedicado al comentar este tema , no puedo resistir la tentación de copiar aquí un pequeño apartado del artículo... sí, del puño y letra del propio Svensmark, para que no sea solo Manel -que ya nos dijo que tuvo el privilegio de leer su libro antes de que se publicara- quien tenga acceso a la palabras del gran hombre . Me he permitido marcar un par de párrafos en negrita... porque me aburría.

Do clouds really drive climate change?
Low-level clouds cover more than a quarter of the Earth and exert a strong cooling effect at the surface. (For clouds at higher altitudes there is a complicated trade-off between cooling and warming.) The 2% change in low cloud during a solar cycle, as seen in figure 3, will vary the input of heat to the Earth’s surface by an average of about 1.2 W m–2, which is not trivial. It can be compared, for example, with 1.4 W m–2
attributed by the Intergovernmental Panel on Climate Change for the greenhouse effect of all of the additional carbon dioxide in the air since the Industrial Revolution (Houghton et al. 2001). If cosmic-ray counts merely went up and down with the 11-year cycle of solar activity, there would be no trend in the climate. Systematic records of influx to the Earth’s surface go back to 1937. Cosmic-ray changes before then can be seen in the rate of formation of radioactive isotopes such as beryllium-10, or inferred from the Sun’s open coronal magnetic field. As seen in figure 5, the various methods agree that there was a pronounced reduction in cosmic rays in the 20th century, such that the maximal fluxes towards the end of the century were similar to the minima seen around 1900. This was in keeping with the discovery that the Sun’s coronal magnetic field doubled in strength during the 20th century (Lockwood et al. 1999). Here is prima facie evidence for suspecting that much of the warming of the world during the 20th century was due to a reduction in cosmic rays and in low-cloud cover. But distinguishing between coincidence and causal action has always been a problem in climate science. The case for anthropogenic climate change during the 20th century rests primarily on the fact that concentrations of carbon dioxide and other greenhouse gases increased and so did global temperatures. Attempts to show that certain details in the climatic record confirm the greenhouse forcing (e.g. Mitchell et al. 2001) have been less than conclusive. By contrast, the hypothesis that changes in cloudiness obedient to cosmic rays help to force climate change predicts a distinctive signal that is in fact very easily observed, as an exception that proves the rule. Cloud tops have a high albedo and exert their cooling effect by scattering back into the cosmos much of the sunlight that could otherwise warm the surface. But the snows on the Antarctic ice sheets are dazzlingly white, with a higher albedo than the cloud tops. There, extra cloud cover warms the surface, and less cloudiness cools it. Satellite measurements show the warming effect of clouds on Antarctica, and meteorologists at far southern latitudes confirm it by observation . Greenland too has an ice sheet, but it is smaller and not so white. And while conditions in Greenland are coupled to the general climate of the northern hemisphere, Antarctica is largely isolated by vortices in the ocean and the air. The cosmic-ray and cloud-forcing hypothesis therefore predicts that temperature changes in Antarctica should be opposite in sign to changes in temperature in the rest of the world. This is exactly what is observed, in a well-known phenomenon that some geophysicists have called the polar see-saw, but for which “the Antarctic climate anomaly” seems a better name (Svensmark 2007). To account for evidence spanning many thousands of years from drilling sites in Antarctica and Greenland, which show many episodes of climate change going in opposite directions, ad hoc hypotheses on offer involve major reorganization of ocean currents. While they might be possible explanations for low-resolution climate records, with error-bars of centuries, they cannot begin to explain the rapid operation of the Antarctic climate anomaly from decade to decade as seen in the 20th century (figure 6). Cloud forcing is by far the most economical explanation of the anomaly on all timescales. Indeed, absence of the anomaly would have been a decisive argument against cloud forcing – which introduces a much-needed element of refutability into climate science.

Así pues, si alguien aún albergaba alguna duda, creo que está claramente demostrado que Svensmark mantiene la existencia de un calentamiento global a lo largo del SXX, y que el enfriamiento de la Antártida no es, en su modelo, sino un hecho específico del continente helado (precisamente por el alto Albedo de su "blanca nieve" -ahí oyó campanas Manel sin saber muy bien de dónde venía-) que se produce cuando el resto del mundo se está calentando.


Así que, lo que es casi tan importante, también queda probado, Manel, que no sabías de qué estabas hablando y que te arrojaste a lanzar acusaciones con la alegre despreocupación que otorga la ignorancia, sin haber comprendido el trabajo de Svensmark y presumiendo de haber tenido el privilegio de leer su libro antes de que se publicara. Este no es buen foro para hacer esas cosas