Some Historic Temperature Graphs




How to read this graph:

This graph compares each month separately to the 20th Century average (for months of the same name only) and ranks them separately. For example: The warmest March, June and October are all colored red. The second warmest January, May and December are all colored orange. The Februaries colored dark blue (2011, 2014) are both between the 16th and 20th warmest Februaries inclusive. The December colored yellow (2016) is the third warmest December and is 0.8° C. warmer than the average of all Decembers in the 20th Century. Etc.

Some points to note:

1. The data for this graph comes from the National Oceanic and Atmospheric Administration (NOAA)'s climate at a glance section.

2. Every month on the graph since Feb. 2008 has an anomaly (distance from the 20th Century average) above 0.4° C. The last month with a negative anomaly was Dec. 1984. The highest anomaly was 1.24° C. in March 2016.

3. This graph shows a short term rising trend from mid-2007 to the present with a bump during the 2015-2016
El Niño event. It also shows wide variation from month to month; but the rising trend is still discernible at a glance. 2005 (not shown) was the warmest year to date before this graph. It has since been surpassed by 2010, 2014, 2015 and 2016 respectively.

4. All 12 highest ranking months lie together between Sept. 2015 and August 2016, during a monster El Niño event. Nine of the 12 second highest ranking months lie between May 2015 and May 2017. The other three are Nov. 2013, Oct. 2014 and Dec. 2014. Eight of the 12 third highest ranking months lie between June 2014 and May 2017.

5. March 2017 is one of six months with an anomaly greater than 1.0° C. The other five (Dec. 2015 through April 2016) lie within the monster 2015-2016 El Niño event. March 2017 is the only non-El Niño month on record with anomaly greater than 1.0° C.

6. The average monthly anomaly so far for 2017 is 0.92° C. The average monthly anomaly for 2016 was 0.94° C. The average monthly anomaly for 2015 was 0.90° C. Temperatures appear to have risen about 0.3° C. over the 10 year period covered by this graph.

Why is this graph important?

1. This is a "you can't see the forest for the trees" graph. Forests are important; but so are individual trees. Indeed, there is no forest without trees.

2. This graph allows you to see the present in detail. (present here meaning the latest 120 months or 10 years of global climate data).

3. You can get a similar graph from NOAA's Climate at a Glance section; but I like the way this graph presents the data. I think the white spaces and the color coding increase readability.

4. Why ten year? Why not some other period like 7 or 12 years? No particular reason. With a longer period the lines get squished together and are harder to read. Shorter periods show less data.

5. I intend to update this graph every month (between the 15th and 20th) when NOAA come out with a new month of global climate data. Deleting lines from the left may lag behind adding lines to the right.

6. How did I get into this? In 2016 my favorite website for news, Common Dreams, used to report the NOAA data month after month as it set new records. They stopped when September 2016 fell to second place. Being curious, I went to the NOAA site and wondered why it wasn't reported as news that the three warmest Septembers on record were in 2015, 2016 and 2014 respectively. After a few months of silence, I decided to start reporting this data myself.

A longer term temperature graph


1. This graph (also from NOAA data) of 36 month overlapping averages (each 36 month period ending in month with same name as latest month for which data is available) from 1880 to the present shows a longer term rising trend, with an increasing rate of warming in recent years.

2. I like 36 month overlapping graphs. I think they smooth the data, but not too much. You can view 12 or 60 month overlapping graphs at NOAA's Climate at a Glance section.

3. Data previous to the 1960s is land based and not as accurate as the satellite measurements in later years.

___________________

Unlike the two graphs above, the graphs below are based on "proxy data." That is: global temperatures are inferred from things like tree rings, ice cores, the makeup of the shells of sea critters, type of flora and fauna in the fossil record, etc.

Needless to say the graphs below may not be all that accurate; and the further back in time we go, the less accurate they are likely to be. Nevertheless they seem to be the best we have; so let's go with them.


Graph from NOAA article on global warming and climate change.

This graph is derived from research by Michael Mann published in 2008.

The baseline, 1961 to 1990 average, is approximately 0.12° C. higher than the Twentieth Century average used in the first two graphs above. The scale is Fahrenheit instead of Centigrade (1.8° F. = 1.0° C.)



Graph from Temperature for the past 11,300 years, Marcott et al.

This graph is from research by Shaun Marcott published in 2013 and represents a probable reconstruction of temperatures over the last 11,300 years (Holocene).

The baseline, 1961 to 1990 average, is the same as previous graph and is approximately 0.12° C. higher than the Twentieth Century average used in the first two graphs above.

The gray squiggly lines at the right represent the previous graph superimposed on Marcott's findings.

The wide band represents probable uncertainty.

If we haven't already surpassed the highest Holocene temperatures, we must be getting pretty darn close.

It appear from this graph and the first graph presented that we have already surpassed 1.0° C. above pre-industrial times, which makes it very unlikely that we could make the Paris Accord target (no more than 2.0° C. but striving for 1.5° C.) even if we were trying hard (which we are not).



Graph from NOAA article on global warming and climate change.

This graph represents a probable reconstruction of temperatures during the ice ages and the interglacial periods. (Pleistocene)

The scale is Fahrenheit instead of Centigrade (1.8° F. = 1.0° C.) and the baseline is the average over the past millenium (possibly around 0.2° C. below the 1961 to 1990 average).

The Pleistocene was a succession of wide swings in temperature between ice ages and interglacials, possibly as much as 16° C.

If we haven't already surpassed the highest interglacial temperatures, we must be getting pretty darn close.



global temperatures, 65 million years.

I don't know where this graph comes from originally. It is all over the internet.

65 million years ago marks the probable demise of the dinosaurs.

Temperatures 50 million years ago were likely 20° C. higher than today.



global temperatures, 542 million years.

I don't know where this graph comes from either. It is also all over the internet.

542 million years, back to the Cambrian is a long time. Planet Earth has weathered a lot of changes. May it also weather this one.


More discussion of these temperature graphs to be added later

###