This is an extremely high peak. The average daily peak in 2015 until May 1 was 2371 ppb, while the highest daily mean ranged from 1807 ppb (January 10) to 1829 ppb (April 22). Daily peaks and daily highest mean levels in 2015 are shown on the image below.
These peaks are much higher than they were in previous years, as illustrated by the image below, from an earlier post and showing the average highest peak readings in 2013 and 2014 at selected altitudes..
Peak readings in above image are averages over April 2013 and April 2014. On specific days, peak readings could be much higher, e.g. on April 28, 2014, methane levels were recorded as high as 2551 ppb at 469 mb. As said, methane levels as high as 2845 ppb were recorded on April 25, 2015, while the average peak for the first four months of 2015 was 2371 ppb, and this average was calculated from peaks across altitudes.
The table below shows the altitude equivalents in mb (millibar) and feet.
|56,925 ft||44,689 ft||36,850 ft||30,569 ft||25,543 ft||19,819 ft||14,383 ft||8,367 ft||1,916 ft|
|74 mb||147 mb||218 mb||293 mb||367 mb||469 mb||586 mb||742 mb||945 mb|
Peak levels in April appear to be rising strongly each year, following higher peak readings during previous months, especially at higher altitudes, i.e. especially the Arctic Ocean. It appears that much of the additional methane originating from the higher latitudes of the Northern Hemisphere has moved closer to the equator over the past few months, and is now accumulating at higher altitudes over the continents on the Northern Hemisphere, i.e. Asia, Europe, North America and north Africa.
Further analysis of the rise in global mean methane levels appears to confirm the above. The image below shows methane levels on April 22, over three years. While there appears to be little or no rise in mean methane levels at low altitudes, the rise is quite profound at higher altitudes.
|[ click on image to enlarge ]|
As that post concluded a year ago, it appears that the rise of methane in the atmosphere is accelerating. What can we expect? As temperatures can be expected to continue to rise and as feedbacks start to kick in, this may well constitute a non-linear trend. The image below shows a polynomial trend that is contained in IPCC AR5 data from 1955 to 2011, pointing at methane reaching mean global levels higher than 3000 ppb by the year 2030. If methane starts to erupt in large quantities from clathrates underneath the seafloor of the Arctic Ocean, this may well be where we are heading.
The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.