The Scripps or NOAA Mauana Loa CO2 reporting are generally used to represent the global CO2 equivalent. Since both measures have been used for years, they are helpful for long term tracking of atmospheric carbon dioxide. However they only represent the CO2 at one point on the planet and not the global variation in CO2 readings.
The CO2 ppm on April 8, 2014 for Scripps at Mauna Loa was 401.58 ppm.
The NOAA/ERSL/GMD Mauna Loa reading was 401.32, according to the 5 day CO2 average reporting.
The latest NOAA/ERSL graphic reveals the following trend, each dot representing the daily CO2 ppm average for that date.
However another way of determining global CO2 is by use of satellite imagery. The METOP IASI instrument captures daily CO2 readings globally. A mean of those readings provide another way of measuring the global daily mean - and also the CO2 variations at various altitudes or millibar equivalents.
For example, the April 8, 2013, 12-24 hr IASI image reveals a global mean CO2 of 395 ppm at 945 mb. This was lower than the readings reported at Mauna Loa, which were around 397-398 ppm. Also note the range of global readings.
This variance between MLO and the IASI global mean is not occurring this year. In fact the MLO reading is lower than many areas in the Northern hemisphere. At 945 mb, the global mean CO2 for April 8 is 402 ppm, an increase of 7 ppm compared to last year - a very troubling development!
It will be interesting to see if this increase of 7 ppm over last year remains constant through April and May.