Post 3. Climate Ebbs and Flows

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

Leave a Reply

Your email address will not be published.