I have been fascinated with charts and graphs ever since beginning to study math in grade school. I was asking questions such as why in nature are there spikes on charts with, more often than not, subsequent downturns in association with statistical graphs? Take this chart depicting December arctic sea ice from the National Snow and Ice Data Center, for example:
What can we say about this chart? Right away, and alarmingly, we can clearly see the trend is down since measurements were started in 1978. Notice though, that there are a lot of wiggles on the chart. Almost in a regular pattern there are peaks and valleys on the chart. Upon closer scrutiny, notice that there are no more than three years in a row in which a downward or upward trend continues. What can that tell us about short term, future arctic ice extent?
Notice that there was a two-year uptick in December arctic sea ice extent from 2013-2014 then a two-year slide from 2015-2016. After there was an overall record low ice extent for the month of December in 2010 ice extinct recovered some through 2014. I remember that many contrarians were saying in 2013 and 2014 see, there is no problem. Extensions of the polar vortex brought cold air masses into the United States those years reinforcing arguments that global warming was not occurring. Yes, there was a slight recovery, as well, with arctic sea ice extent in 2013 and 2014 perhaps in association with a strengthened polar vortex. Subsequently the warmth of 2015 and 2016 blew contrarian arguments out of the water….or in this case off the ice😊. Looking at the chart what can we expect to see in 2017?
The mathematics behind statistics is interesting but can get complicated for the average reader. What I will emphasize here is that we are looking at trends and making educated guesses. There are no guarantees that a graph or chart will behave the way we expect it to. So, if 2017 continues the trend from 2015 and 2016 that would be the third year in a row of a downward trend for ice extent, perfectly within the realm of what has been observed on the chart. Usually after a couple of years of a downward turn there is a year of recovery, so my forecast for 2017 would be for at least a slight uptick in arctic sea ice extent. If not, and there were troubling signs of a new, more rapid melting trend in 2016, then global warming in the short term will be more rapid the next couple of decades. There are no signs that the overall downward trend for arctic sea ice extent will change and that there will be a full recovery in the polar region in future decades.
Let’s take another chart, this time global temperatures from NASA, which already has a forecast for 2017:
Figure 1. (Credit Bob Henson and Jeff Masters from their Weather Underground blog) Quoting their blog, “The U.K. Met Office predicts that the 2017 global temperature (forecast range shown in green at right) will likely fall below the record value expected to be set in 2016. The dark line shows global temperature since 1850 as calculated by an average of analyses by the Met Office/Hadley Centre, NASA, and NOAA. Each of the three agencies uses slightly different techniques to account for sparsely populated regions, such as the poles. These differences have very little effect on the year-to-year trends, which are in very close agreement for all three analyses. The shaded band shows the 95% uncertainty range for each annual data point. Image credit: U.K. Met Office.”
For the first time since global temperature averages have been kept there have been three years in a row of record warmth. The forecast for 2017 is to be slightly below that of 2016 but why? If 2017 were to see another record it would be the fourth year in a row of an upward spike for this graph. Going back to my last post I noted that the planet is coming off a “strong” El Nino. The strong El Nino is the main culprit for the spike on the chart in figure 1 in 2016. It usually takes the warming effects of El Nino a few months to wane after the event has ended for global averages to cool as indicated by the following NASA GISS land and sea temperature average data shown here (sorry that this chart is a little skewed):
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J-D D-N DJF MAM JJA SON Year
2001 44 46 58 52 59 55 61 49 56 52 70 55 55 53 40 56 55 59 2001
2002 75 76 91 58 65 54 62 55 65 57 59 43 63 64 69 71 57 61 2002
2003 73 55 57 55 62 49 55 66 66 75 55 75 62 59 57 58 57 65 2003
2004 59 71 64 62 42 43 26 45 53 66 72 52 55 56 68 56 38 64 2004
2005 72 58 69 69 65 67 66 63 78 80 76 68 69 68 61 68 65 78 2005
2006 57 70 63 50 47 64 54 72 64 69 72 77 63 62 65 53 63 68 2006
2007 96 70 70 76 67 58 62 60 64 60 57 50 66 68 81 71 60 60 2007
2008 24 36 73 53 51 48 60 44 65 67 66 54 54 53 37 59 51 66 2008
2009 62 53 53 61 65 65 72 66 70 64 77 65 64 63 56 59 68 70 2009
2010 73 78 92 87 75 64 62 65 61 71 79 49 71 73 72 85 64 71 2010
2011 51 53 64 65 53 59 73 73 56 66 56 54 60 60 51 61 68 59 2011
2012 46 49 58 69 76 62 57 63 76 78 75 53 63 63 50 68 60 76 2012
2013 68 55 66 52 61 65 59 66 78 69 81 67 65 64 58 60 64 76 2013
2014 73 51 77 78 87 66 57 82 90 85 67 79 74 73 64 81 68 81 2014
2015 81 86 90 74 78 78 71 78 81 106 104 111 87 84 82 81 76 97 2015
2016 117 135 130 109 93 76 83 98 87 89 93 81 99 102 121 111 85 90 2016
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J-D D-N DJF MAM JJA SON Year
Divide by 100 to get changes in degrees Celsius (deg-C).
Multiply that result by 1.8(=9/5) to get changes in degrees Fahrenheit (deg-F).
Example — Table Value : 40
change : 0.40 deg-C or 0.72 deg-F
Notice that the GISS numbers for the first time got into the triple digits starting in October 2015 and ending in May 2016. Due to mainly the cooling in the ENSO region of the Pacific, there has been a slight cooling of average planetary temperatures, but notice that the values for the later half of 2016 have remained above those of the first part of 2015.
Why is this important? Because contrarians will leap at any sign that the global warming trend has stopped. Also, those trying to ascertain or predict how fast damage to the environment is occurring need to see overall trends.
We will look at simple pictograms on my next post.
The Climate Guy