A Warm July in the Antarctic
Posted by The Diatribe Guy on August 31, 2009
After seeing the July RSS anomaly that showed a warm July, I was perturbed that – once again – I was languishing in cool weather in Wisconsin while someplace else apparently “suffered” from warmer temperatures. Looking at the territorial data, one of the culprits for that nasty warm weather was the extreme south. It was rightly pointed out to me a while back that I must be careful in presenting the RSS data as “Antarctic,” since it only goes to the latitudinal line of -70 degrees. So, please know that when I reference the Antarctic region here, it simply means the -60 to -70 region, which is as far dwon as RSS goes.
The July anomaly in this region was 1.0490 (a full degree Celsius and then some), which was a pretty warm one. It is the 5th highest anomaly in the 367 data points and is the 2nd warmest July in the 31 data points. It is nearly 7 tenths of a degree warmer than a year ago and the anomaly if 0.56 units higher than last month.
Keep in mind that it’s winter down there right now. I point that out because I guess I’m just not sure how much of a difference a degree makes in July with regard to melting ice. I know that when it’s winter here, -19 doesn’t seem to do much more than -20. But what do I know? I’m just an actuary. And a Packer fan. Are you watching these guys? The offense is looking phenomenal! Preseason or not, I’m getting pumped for the season to start.
But I digress.
Anyway, the last 13 12-month average anomalies had been negative, but thanks to the most recent one, the current 12-month average is at 0.45 (0.0045 in degrees Celsius). That’s not even a hundredth of a degree, so it’s essentially flat.
There’s no real streak of warming or cooling to consider. This is the second straight year-over-year increase, after 2 decreases. In fact, there really have been no real streaks to speak of for years. You have to go back to 2003 just to find the last time there was 6 months of consecutive anything. And that one was a consecutive cooling stretch.
Despite the current large anomaly, it is evident that there is no particular long-term trend. There are fluctuations both positive and negative about an almost perfectly flat zero line. Also, there doesn’t seem to be any particular indication that things are fluctuating wildly about any more than they have in the past. In fact, the last 10 years saw no anomalies above an absolute value of 1.000 until this one, which is the largest gap in the data. We often hear about how climate change is producing more extremes, but we don’t see that in this data.
This graph isn’t all that different from the overall one. The overall graph has an ever-so-slight positive slope, and this one is ever-so-slightly negative, but the difference in time is ony 2 months. So, there’s really not much more to say. Even though slightly negative, just like above, the trend is generally flat for the last 30+ years.
Since 2003, the 60-month slope values have declined over time. The current slope value is negative, though it is above the trend line.
This is kind of an interesting chart. Since this is only over a 30-year span, it’s pretty tough to make a case for long-term cycles, but it’s interesting to look at the dip on the left-hand side of the chart, and then a period of time around and above the zero anomaly lasting 9 years or so. Then there is a four year plunge and subsequent increase until another period of stagnation – this time a little bit above the zero line – that has lasted about 7 years. Who’s to say the pattern will repeat, but if it does, we may see the beginning of another plunge in Antarctic temperatures starting in a couple years.
The 15-year trend line has a small positive slope. It had been declining, but thanks to a couple higher anomalies in the last couple months it’s increased. The current slope value suggests warming at a pace of about 0.78 degrees Celsius per Century.
The last couple slope values have had a decent increase, but you can see that the overall trend over the last couple years has been a declining value in the slope calculation.
There has been an overall increase in the 300-month slope values, though this data only goes back about 5 years. There isn’t enough data to observe any long-term cycles.
There are only eight data points showing a full 30-years of slopes, so there isn’t much to say here except that in that short period of time the slope values have declined from slightly negative to a little more negative. The current 30-year slope suggests cooling at a rate of 0.13 degrees Celsius per Century.
So, there you go. One of the contributors to July’s larger anomaly is a region where we observe flat temperatures over the long haul. The spike is not unusual historically in isolation, and looks to be an aberration. As always, we’ll see what happens.