How Do Scientists Measure Global Temperature?

17th January  2017
How Do Scientists Measure Global Temperature?

Ever wondered how scientists know the planet is heating up? And how they measure global temperature levels?  Yes, look out the window is one way or check your mobile phone.  Better than that, every year usually towards the second or third week in January, scientists all over the world begin a phase of activity, anticipation and an expectation of colossal concern.  The reason?  It’s when the mean global temperature readings are observed from the previous year.

It was particularly interesting when the readings for 2016 come out, because that’s when we saw the temperature record smashed in 2014 (released January 2015 and read at + 0.27c), smashed again in 2015 (+0.42c) and then again in 2016 where it looks likely to read around +0.46c.

The first group of scientists to release its data will be the JMA (Japan Meteorological Agency), NASA (National Aeronautics and Space Administration) followed closely by the NOAA (United States National and Oceanic Atmospheric Administration) and finally the UK Met Office (Meteorological Office)

Taking these readings is challenging in every sense, the places where these readings are taken from can be some of the most inhospitable places on the planet.  The readings are taken, monitored by ships out in the roughest seas and oceans, or by using water-based weather buoys and even satellites.  Temperatures can also taken up in the air, above our land and the readings are measured against, what is considered to be normal or average for that location.

Any reading, which shows a positive (warmer than average) is given a “+” sign in front of its reading.  Any reading showing a negative a “-“(minus) and these readings are known as “anomalies”.  Daily readings are averaged out over the entire month.  Which allows scientists, to calculate temperature anomalies from year to year or season to season.

The four agencies within their published data have all revealed a warming trend.  NASA, has the most comprehensive readings of all the agencies, whereas the JMA covers only 85 per cent of the planet and is particularly absent from both Polar Regions.

The Challenges of the Poles

As regards, the Polar regions these do need to be covered when commissioning data, because the planet is not warming up at the same rate all over.  Both NASA and NOAA, use the missing data by filling in a statistical method, which takes readings from geographically close points.  Scientists then divide the globe up into small grids, thereafter listing the expected normal temperature, calculating any anomalous read outs, which in turn allows the poles to be calculated with as much accuracy as it can hope for.