{"id":8398,"date":"2023-12-28T23:53:05","date_gmt":"2023-12-28T22:53:05","guid":{"rendered":"https:\/\/klima-fakten.net\/?p=8398"},"modified":"2024-04-10T20:53:48","modified_gmt":"2024-04-10T19:53:48","slug":"the-inflection-point-of-co2-concentration","status":"publish","type":"post","link":"https:\/\/klima-fakten.net\/?p=8398&lang=en","title":{"rendered":"The inflection point of CO2 concentration"},"content":{"rendered":"
\"image_print\"<\/a><\/div>\n\n\n

And rising and rising\u2026?<\/h4>\n\n\n\n

At first glance, the atmospheric CO2<\/sub> concentration is constantly rising, as shown by the annual mean values measured at Maona Loa (ftp:\/\/aftp.cmdl.noaa.gov\/products\/trends\/co2\/co2_mm_mlo.txt):<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The central question that arises is whether the concentration is growing faster and faster, i.e. whether more is being added each year? If so, the curve would be concave, i.e. curved upwards.<\/p>\n\n\n\n

Or is the annual increase in concentration getting smaller and smaller? Then it would be convex, i.e. curved downwards.<\/p>\n\n\n\n

Or is there a transition, i.e. a turning point in the mathematical sense? This could be recognized by the fact that the annual increase initially increases and then decreases from a certain point in time.<\/p>\n\n\n\n

At first glance, the overall curve appears concave, which means that the annual increase in concentration appears to increase with each year.<\/p>\n\n\n\n

The answer to this question is crucial for the question of how urgent measures to curb CO2<\/sub> emissions are.<\/p>\n\n\n\n

Closer examination with the measured annual increase<\/h4>\n\n\n\n

To get a more accurate impression, we calculate the — raw and slightly smoothed — annual increase in CO2<\/sub> concentration:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

This confirms that until 2016 there was a clear trend towards ever higher annual concentration increases, from just under 0.75 ppm\/year in 1960 to over 2.5 ppm\/year in 2016.<\/p>\n\n\n\n

Since 2016, however, the annual increase has been declining, initially slightly, but significantly more strongly in 2020 and 2021. The corona-related decline in emissions certainly plays a role here, but this does not explain the decline that began in 2016.<\/p>\n\n\n\n

There is therefore an undisputed turning point in the concentration curve in 2016<\/strong>, i.e. a trend reversal from increasing concentration growth to decreasing concentration growth. Is there a satisfactory explanation for this? This is essential, because if we can foresee that the trend of decreasing concentration growth will continue, then it is foreseeable that the concentration will stop increasing at some point and the goal of the Paris Climate Agreement, the balance between CO2<\/sub> sources and CO2<\/sub> sinks, can be achieved in the foreseeable future.<\/p>\n\n\n\n

Explanation due to stagnating emissions<\/h4>\n\n\n\n

As part of the Global Carbon Brief project, Zeke Hausfather 2021 revised the values of global CO2<\/sub> emissions over the last 20 years <\/a>based on new findings, with the important result that global emissions have been constant for 10 years within the limits of measurement accuracy:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

To assess the implications of this important finding, one needs to know the relationship between emissions and CO2 concentration.<\/p>\n\n\n\n

From my own research on this in a publication <\/a>and in a subsequent blog post<\/a>, it follows that the increase in concentration results from the emissions and absorptions, which are proportional to the CO2<\/sub> concentration. <\/p>\n\n\n\n

This model has also been described and published in a similar form by others:<\/p>\n\n\n\n