Global temperature, and real numbers
Warmest February on record, but nowhere near warmest month ever.
As we and other news outlets have reported, last month was the warmest February on record in the U.S. database, by a substantial margin.
The global-surface temperature "anomaly" calculated by the National Centers for Environmental Information was +2.18 degrees Fahrenheit, compared with the average temperature for all Februaries of the 20th Century.
A reader has asked – and I suspect others have: What's with this "anomaly" business; why doesn't the government simply give us the absolute temperature?
The U.S. climate keepers actually have solid reasons for doing it this way. They consider the anomaly a more-precise measure than the estimated "absolute" value.
Discerning the global surface temperature is an immensely complex undertaking, and we understand the government's reasoning, which we will attempt to explain below.
But we also pledge that from here on, we will include that raw estimate in our reports on monthly temperature. We'll start by saying that for February 2016, it would be 56.08 Fahrenheit.
The 20th Century global average for February is 53.9, the second-coolest month of the year, behind January, at 53.6.
Those are the winter months in Northern Hemisphere, and summer in the Southern Hemisphere.
NCEI scientist Jessica Blunden points out the fact that the Northern Hemisphere has so much more land makes the planet colder overall in our winter months, and warmer in summer.
July is the warmest month, with an average of 60.4 Fahrenheit. The annual average for all 12 months is 57.
In case you were wondering, and even if you weren't, in terms of raw temperature value, February 2016 was No. 968 among the 1,634 months in the period of record, dating to 1880.
As one might expect, eight of the 10 hottest occurred in July; the other two in August. No. 1 would be last July, at 61.85, followed by July 1998 and July 2010, tied at 61.71.
So why does NCEI insist on using the anomaly?
The monthly averages are calculated by taking the high-low daily average temperatures at about 2,500 stations worldwide, explains Blunden's colleague, Deke Arndt.
Some uninhabited regions are poorly measured, so NCEI uses "interpolation" to fill in gaps.
The world's terrain is hardly homogenous. Temperatures in a valley and the nearest mountaintop top, say, could be 2 degrees above 20th Century averages, but they certainly would be different in raw values, perhaps 20 degrees or more.
By the NCEI reasoning, it makes more sense to log both in as being 2 degrees above average, rather than the absolute number.
For more on the reasoning, see the NCEI explanation.
As for March, based on trends, we expect this to be the warmest March in terms of anomalies, and middle of the pack in absolute values.