The global average temperature of our planet is not a direct measurement.
It is a very rough average of:
(1) Actual measurements,
(2) "Adjusted" data, and
(3) Missing measurements, that are either wild guessed or ignored.
The Earth does not have a constant temperature, because it is not in thermodynamic equilibrium.
One minute after you calculate the average temperature of our planet, it becomes old news.
I believe there's little or no benefit from calculating an average global temperature for our planet every month.
One very important reason is no one has any idea what a "normal" average temperature is.
Is it good news if the planet is getting warmer, or bad news?
Based on anecdotal evidence from past centuries, people liked warm centuries a lot more than cool centuries.
A degree C. in either direction would probably never be noticed.
We know from ice core studies that Earth has had hundreds of irregular cycles of mild warming/mild cooling, that typically last about 500 to 1,500 years, in the past one million years.
There's nothing we can do about these mild cycles, and no one knows what causes them, although the Sun should be the first suspect.
All the real time surface temperature measurements since 1900 (1800s data are inaccurate) were made DURING a warming trend.
Calculating average temperature during a warming trend only tells us we are in a warming trend.
We already knew Earth has been warming since peak ice age glaciation about 15,000 years ago -- so why spend any money to prove what's already obvious?
When a cooling trend starts, we would eventually notice it without any measurements at all.
Maybe it would take a few decades.
And if no one noticed the cooling -- so what?
We have no idea when the 1850 Modern Warming trend will end, or how much warming there will be in the future.
Its possible the 1850 warming trend has already ended, and we don't realize it yet -- the average temperature does not go up every year -- in fact, there was a flat trend from 2000 to 2015.
Climate proxy studies, supplemented by some surface thermometer records from Great Britain, tell us the centuries from 1300 to 1800 were unusually cool.
The temperature trough was probably in the late 1600s or early 1700s, during a period of unusually low solar activity (The Maunder Minimum) -- it may have been 2 degrees C. cooler than today.
The approximately +2 degrees C. warming since that cold Maunder Minimum period was certainly good news for humans!
Our planet is always warming or cooling -- and some large areas of our planet may be in a warming trend, while other large areas are in cooling trend.
In the past 40 years, for one example, there has been warming around the North Pole, and cooling around the South Pole -- not what the "warmunists" predicted.
In the whole 1900 to 2015 period there were only two warming trends -- from 1920 to 1940, and again from 1975 to 2000.
The UNs IPCC blames the 1975 to 2000 warming on manmade CO2, but says the similar 1920 to 1940 warming had natural causes?
The IPCC claim that the causes for the two similar warming trends were different, is a bizarre, unproven claim.
There were no other warming trends in that 115-year period from 1900 to 2015 -- CO2 levels went up every year, but average temperature did not -- you probably wouldn't know that if you only read about the climate in the mainstream press.
The average temperature statistic is a sampling of a relatively small number of continuously fluctuating local temperatures (a very small number of thermometers compared with the total surface area of our planet).
An average of local temperatures is not actually a temperature itself.
The global temperature statistic is called an average, but over one hundred different temperature averages have been used in meteorology and climate studies.
No one knows which average is the best.
Even the international standards organization ISO could not choose one as the best.
Whether our planet is ‘‘warming’’ or ‘‘cooling’’ can depend on which average is chosen.
Whether our planet is "warming" or "cooling" is mainly determined by the starting and ending points of the measurements/estimates -- our planet has existed for 4.5 billion years, yet people usually focus on a mere 135 years of average temperature (1880 to 2015) !
Proponents of calculating the average global temperature every month have not explained how their statistic is related to local weather conditions, which people so want to know.
Weather dynamics are actually driven by differences in temperatures across our planet, not the average temperature.
Averaging data can mask useful details.
Averages of the Earth’s surface temperature mask northern/southern hemisphere differences.
In addition, the total average temperature change from 1900 to 2015 of about + 1 degree C. (+/- 1 degree C., in my opinion), may be smaller than the change in your local temperature as the Sun rises every day !
Temperature measurements of the surface of our planet are so rough its possible the average temperature today is actually about the same as it was 150 years ago, or maybe it's +2 degrees C. warmer, rather than the claimed +1 degree C. warmer.
Average temperature statistics are nearly worthless, in my opinion.
The statistics are not a replacement for what we really need: A climate physics model that correctly explains the causes of climate change.
The popular claim that manmade carbon dioxide controls the climate is nonsense -- in the past 4.5 billion years the climate has always been changing … but there was only one very brief period when man made carbon dioxide and average temperature were positively correlated: 1975 to 2000.
That's it.
If a scientist ever develops a good climate physics model, and we finally know what causes climate change, that still doesn't mean predicting the climate would be possible … or that humans could change the climate.
Future climate predictions with a good climate physics model might not be any more accurate than predictions made in the past 40 years -- 97% of past predictions ("simulations") using the obviously incorrect 'man made CO2 controls the climate' model.
We've had 40 years of climate model simulations (predictions) that overestimate global warming 97% of the time, often by a huge amount.
Very few things in life can be predicted -- there's no reason to assume the future climate will ever be predictable.
Calculating the average temperature of our planet is a waste of taxpayers' money.
It has also been a waste of taxpayers' money to develop and use global climate models -- with every decade the gap between actual global temperatures and computer model predicted global temperatures widens.
Additional reading:
http://www.uoguelph.ca/~rmckitri/research/globaltemp/GlobTemp.JNET.pdf