The RSS Data has been released. I thought I’d take this opportunity to not only look at the global value, but also the northernmost satellite data (Arctic), the equatorial regions (Tropics), and the southern-most readings (near Antarctic – the satellite coverage doesn’t reach all the way to the pole).
Since I’m hitting all the regions, I won’t get present all the backup charts, but I will provide a numerical update on the trends. For each, I’ll simply show the overall trend using all RSS data, and the furthest line back where we can draw a flat or negative trend line.
The anomaly for the month of May was 0.090 (will be heretofore presented in 0.01 degrees Celsius, or 9.0). This is 11.2 lower than the previous month, April 2009 and 16.8 higher than May 2008.
Ranking: 16th largest anomaly out of 31 May readings (48th percentile) and 177th of 365 total anomalies (51st percentile).
12-month average = 18.2. This increased over last month due to last year’s very low anomaly dropping from the average. Thus, it is the highest average since March 2008.
May was the sixth consecutive month for which the monthly anomaly exceeded the previous year’s anomaly, despite the drop from previous month.
Global Overall Trend Line since 1979:
RSS Global Overall Trend
The overall trend dropped from 0.12904 to 0.12802. This represents the units, in 0.01 degrees Celsius, of trending per month. It corresponds to an overall temperature trend of 1.54 degrees per Century.
Flat/Cooling Trend Line:
RSS Global Flat/Cooling Trend
The length has now increased another month on the back end, and also on the front end. The flat line now extends back to February 1997, making its length 12 years and 4 months.
There is no other period in the RSS data set where cooling occurred over a 12-year, 4-month period. The data set, however, only extends back to 1979.
As an aside, I like to take a look at some posts on boards where my information is posted. Last month, someone posted the link where I pointed out that we have now gone past 12 years without a warming trend. A responder glibly replied something along the lines of “How embarrassing for that author. RSS and UAH post the decadal trends in their data.” He pointed out the positive decadal trends.
What is embarrassing is the complete lack of comprehension in the difference in what is being presented. It would have taken that person all of 10 seconds to see my longer-term trends where I state the per-century trend in temperature according to the slope. The fact that I presented a recent, isolated period of no trending doesn’t in any way conflict with a longer-term decadal trend. I never cease to be amazed at the lack of understanding people have – or at least seem to have – on such basic statistical presentations.
What’s Happening with the various trend lines?
60-month: -0.307510 (-3.69 degrees per Century). Looks to decline to the steepest negative value since the mid-80’s soon.
120-month: +0.058601 (0.70 degrees warming per Century). Now back to the level seen in June 2008, and expected to go negative by year end.
180-month: 0.077408 (0.93/C). Lowest slope since the period ending September 1995. This could go as low as 0.05 by the end of the year.
240-month: 0.151595 (1.82/C). This is a steeper slope, but is now at its lowest point since July 2001.
300-month: 0.163786 (1.97/C). This is the lowest since August 2003. The 25-year slope is the steepest of the measures.
360-month: 0.126892 (1.52/C). Lowest of the 6 observed data points.
What does it all mean? Well, we have cooled recently. But those things can happen. The 12+ falt period is getting long enough to become statistically relevant, but looking at the RSS data set just doesn’t give us a large enough data set to compare likelihood. Longer term periods definitely show that we have warmed over a lengthier period of time – that’s not really in dispute. However, any claims of acceleration in warming are simply false, as can be shown by the fact that ALL trend line measures are declining. If warming were accelerating, we would see slopes increasing.
RSS Near-Antarctic Overall Trend
Only one chart is provided, since the overall data set is also the longest cooling period. The chart, however, pretty much shows a flat line. And even though we have this lengthy cooling trend, it jumps back and forth depending on your starting point whether the trend is warming or cooling – which pretty much means it’s a flat line.
Starting at the beginning with January 1979, it’s a negative trend. Here are all the reversals that take place (starting points to current): April 1981 (+); October 1982 (-); November 1982 (+), May 1989 (-), February 1990 (+), April 1990 (-), June 1990 (+), July 1990 (-), August 1990 (+), October 1990 (-), January 1991 (+), June 1996 (-), August 1996 (+), January 2000 (-). All starting points since then show a negative slope.
The May anomaly was 30.9, which was 86.8 higher than last month, but 7.5 lower than last year.
Rank: 10th of 31 Mays (67th percentile) and 87th of 365 total, 76th percentile.
No major streaks. 9 of the last 12 anomalies have been less than prior year.
The 60-month trend is quite steeply negative (-0.297491). All the other trend measures are either slightly negative or slightly positive (from -0.0113 to + 0.0343). The 300 month value of 0.0269, however, represents a peak value in the data set for any 25-year period of time. In its history, the low was -0.042.
RSS Arctic Overall Trend
The May anomaly was 44.6. This is lower than last month by 14.3 and lower than last year by 87.1 (hundredths of a degree Celsius, remember).
The May anomaly ranked 14th of 31 Mays (54th percentile) and 126th of 365 total (65th percentile).
The 12-month average anomaly is 47.3. It’s still high, but coming down. This is the lowest 12-month average since the period ending January 2005.
The Arctic has most certainly trended up fairly high over time (overall slope is 0.27081, or 3.25 degrees warming per Century), but the recent trend has been downward:
RSS Arctic Flat/Cooling Trend
Currently, we can fit a flat/negative trend line back to May 2001.
The current 60-month trend line is very negative (-0.42606, -5.11/C). Obviously, this fluctuates a lot, but it is currently the lowest since January 2000.
120-month: The 10-year trend is still very positive (+0.25886, 3.11/C), but is at its lowest level since the period ending December 2004 and is trending down.
180-month: the 15 year trend is even higher (0.30129, 3.62/C) but has also trended down, and is at its lowest value since August 1998.
240-month: The 20-year slope is the steepest positive slope (0.43829, 5.26/C). Despite its high slope, it’s actually trending down and is at its lowest value since the period ending October 2005.
300-month: The 25 year slope (0.386403, 4.64/C) is a slight tick up from last month, which had otherwise been its lowest slope value since the period ending January 2007.
360-month: The 30-year vlaue of 0.262441 is a data set low (6 observations).
RSS Tropics Overall Trend
May anomaly = 8.4. This is down 9.6 from last month and up 42.9 from last year.
It ransk 13th of 31 Mays (58th percentile) and 163rd of 365 total (55th percentile).
The 12-month average of 7.9 is the highest since February 2008.
It is the eight consecutive month with current anomalis greater than previous year.
RSS Tropics Flat/Cooling Trend
The tropics show a flat/cooling trend back to March 1996.
60-month: The short-term trend line is very negative (-0.719114, -8.63/C). The steepest negative trend line occurred the period ending September 2008 (-0.814854) and had been the steepest negative trend line since the period ending June 2002.
120-month: +0.076548 (+0.92/C) is the lowest value since the period ending December 2007.
180-month: +0.029744 (+0.36/C) is the lowest value since the period ending September 1994.
240-month: +0.127287 (1.53/C) is the lowest value in the data set, the first data point being December 1998.
300-month: +0.158974 (1.91/C) is the lowest slope value since the period ending January 2005.
360-month: +0.117065 (1.40/C) is the lowest of the 6 observed data points.