Von Frank Bosse und Fritz Vahrenholt
(Translated and condensed [due to time constraints] by P. Gosselin)
The star at the center of our solar system was also very inactive last month. The determined sunspot number SSN of 26.1 was only 50% of what is normal.
Fig. 1: Mean solar activity (blue) compared to the activity of the current cycle (red) and the very similar solar cycle 5 (black).
A comparison of all the cycles:
Fig. 2: The activity of all cycles 1 to 24. Depicted is the deviation from the mean. The current cycle began in December 2008 and is the 3rd quietest since systematic observations began in 1755.
The behavior of the solar polar fields also indicate that the upcoming solar cycle 25 could be as weak as SC 6. According to the current conditions, we could experience a solar minimum that is similar to that experienced during the Dalton Minimum (SC 5, 6 and 7) of 1790 – 1830. The strongly decoupled polar fields is a phenomenon that has yet to be observed since systematic observations began in the 1970s – a time when the solar activity was stronger than at any time ever observed.
Antarctica: So little ice as never observed before!
Last month we saw plenty of headlines about this. The German ARD remained rather factual, but others were dramatic and even employed photo-shopped images suggesting climate alarm. First the facts: This year’s ice extent is at a record low, as is referenced by the NSIDC in its report. Here’s the chart:
Fig. 3: Sea ice extent around Antarctica in February compared to 1979 (in %). Source.
The dashed line depicts the overall trend, and it remains strongly upward. The long-term trend is what counts when it comes to climate. Yearly fluctuations are related to weather. A look at the GISS temperatures across Antarctica shows no relevant trend.
Fig. 4: Antarctic surface temperature as to GISS.
What follows are the sea surface temperatures (SST). Here we see where the sea ice loss is coming from:
Fig. 5: Temperature anomaly of the ocean surrounding Antarctica.
Here we recognize the downward trend since the 1990s, followed by a sharp upward spike at the end. Certainly much of this has to do with the weather at the end of 2016, more precisely since September. There is no real information on what is behind the spike.
One suspicion is the very powerful El Nino of 2015/16, but such a spike did not follow the El Nino 1997/98. It must be kept in mind that there were some real global differences between the last powerful El Nino and the one from the late 1990s, see study here. One suspects that a chain of events may have unfolded which led to a warming of the water around Antarctica. Next year will likely tell us if this is only a temporary powerful warming spike, or if it is the start of a trend reversal.
Media reports that global warming is now catastrophically reducing sea ice around Antarctica are however, wild speculation. In a recent study here on the AMOC, it is determined that a powerful heat transport towards the North causes a special pattern: The sea surface temperature (SST) cools and the depths get warmer. The deeper water at the edge of the continent down to 700 meters shows a warming trend. Here’s a look at the lower depths there:
Fig. 6: Ocean temperature anomalies down to 700 meters deep around Antarctica.
The divergence between the lower layers and its surface can be clearly seen. In Fig. 5 we see the sudden positive spike in SST, but the ocean down to 700 meters cannot of course follow along due to its high thermal inertia.
In the North Atlantic we do see, however, a retreat in heat transport since about 2012:
Figure. 7: The surface temperature anomalies in the sub-polar North Atlantic since 1980.
It may very well be that the El Nino is in part causing the “see-saw” effect: A stronger northward directed heat transport (strong AMOC) cools the water at the sea surface of the ocean (the sea ice grows) around Antarctica while it gets warmer in the water depths. A weaker AMOC (Fig. 7 favors a diminishment compared to the years after 1998) reverses the condition in the south: it gets warmer on the sea surface (sea ice melts) and the depths get colder.
We await with suspense the measurements around Antarctica to see whether this is the case. These are all natural processes, and whether man-made warming plays a role — if yes, how much of a factor it really plays — is completely unclear.
It is far too early to start blaring out that man is melting the Antarctic. Propaganda and science do not go well together. The internal variability of the currently cooling North Atlantic is simply “nature at work”.