Have The CO2 Natural Sinks & Sources Become A Problem?
The United Nations International Panel on Climate Change (UN IPCC) reports assume that the human-driven increases in global average surface temperatures will not trigger significant changes in the natural carbon cycle that will add to atmospheric levels of carbon dioxide (CO2) and other gases – at least within the current century. The overwhelming driver of atmospheric concentrations is assumed to be anthropogenic emissions, from the activities of human societies. If this were true, we would expect atmospheric concentrations to somewhat parallel changes in anthropogenic emissions, taking into account any natural cycles that create “noise” in the trend – mainly the El Nino / La Nina cycle (known as the ENSO, El Nino Southern Oscillation, cycle).
Do atmospheric CO2 concentrations track anthropogenic emissions? Thankfully the people at the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Laboratory consolidate measurements of CO2 concentrations from around the world and publish monthly and yearly averages. For emissions, I use the from fossil fuel numbers as the numbers for land use, land use change and forestry (LULUCF) which measure such things as the emissions from burning down rain forests are extremely unreliable; LULUCF changes are estimated to be responsible for about 25% of total emissions, and have seemingly fallen over the past two decades (from 4.16 GtCO2 in 2001 to 3.21 GtCO2 in 2020). For the CO2 emissions data, I have colour coded the numbers green for increases and red for decreases, for ENSO green for positive (which should temporarily boost natural CO2 emissions) and red for negative (which should temporarily reduce natural CO2 emissions).
The first thing we see (see table below) is that CO2 atmospheric concentrations have been increasing faster, at an average rate of 1.474 ppm per year in the last decade of the twentieth century (yearly data not in the table), 2.014 ppm per year in the first decade for this century and 2.38 ppm per year in the second decade. But, when we look at anthropogenic CO2 emission increases, we see a very different pattern; 0.22 GtCO2 per year in the 1990s, 0.81 GtCO2 per year in the 2000s, and only 0.15 GtCO2 per year in the 2010s. The yearly increases in anthropogenic CO2 emissions were less in the past decade than in the 1990s, and much, much less than in the 2000s! In the past decade the link between atmospheric concentrations of CO2 and anthropogenic emissions has been broken, the former keep increasing at a faster rate while the latter have hardly changed. From the ENSO status we can see that there was one high positive year in the 2010s, but there were also more negative years in the 2010s than in the 2000s; the ENSO can be removed as a causal factor.
What is causing the acceleration in the increase in atmospheric CO2 levels if it is not anthropogenic emissions from fossil fuel use? Either the LULUCF numbers are misrepresented on a massive scale and/or the natural carbon cycle is starting to become affected by increased temperatures and placing more carbon into the atmosphere. Although the LULUCF numbers are open to manipulation, the scale of the manipulations would have to be absolutely massive in relation to current emissions. Given recent improvements in international monitoring via satellite etc., and the reduction in the transference of rain forests into agricultural land (unfortunately somewhat reversed under the current Brazilian regime), LULUCF does not provide a very likely candidate. This leaves us with the natural carbon cycle.
Table 1: CO2 Trends and ENSO
CO2 data from NOAA GML at https://gml.noaa.gov/ccgg/trends/gl_gr.html; Emissions Growth data from Our World In Data at https://ourworldindata.org/co2-emissions; ENSO data from NOAA Climate Prediction Center at https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
The natural carbon cycle consists of sinks (oceans, growing plant matter, rock weathering) and sources (decaying plant matter, permafrost melt). The sinks have played a huge role by storing away the majority of the CO2 emitted through the use of fossil fuels. In the past decades this may have been enhanced by the higher levels of CO2 that facilitated increased plant growth rates. Such increases have natural limitations though, as heat stress starts to reduce plant growth and the limits of other plant growth resources (water, nitrogen) are reached. An end to these enhanced plant growth rates would in itself reduce the ability of sinks to store anthropogenic CO2 emissions, leading to more of those emissions ending up in the atmosphere.
In recent years we have also seen an increasing number of stories across the world about forest and other plant fires, with an increasing number taking place in areas of permafrost. The former release CO2 through the burning of plant matter, the latter do that and warm and expose the permafrost that then starts to melt and degrade – releasing CO2 from the plant matter that had been frozen in the permafrost. The UN IPCC assumes that such processes will not kick into a large scale for many decades. The above numbers point to them possibly being wrong.
Whatever is causing the accelerating increases in atmospheric CO2, the certainty is that it makes the job of keeping global average surface temperatures below 20C even harder, as cuts in emissions will have to offset this other factor, or factors. Such reductions, which are already very steep in all the 20C scenarios (1.50C is already an impossible pipe dream) will have to be even steeper; as in maybe 10% per year. That would require WW2-like planning and control of the world economy, with every industry being transformed and/or removed. The level of trust and cooperation required between the great powers (US, China, Russia) to do this precludes any of the antagonisms currently seen.
The above table represents just one of the climate change monsters lurking beneath the global consciousness. In future posts I will cover the rapidly increasing atmospheric methane (with a climate warming potential of up to 100 times that of CO2 over a 20-year period) levels, and the darkening of the Earth’s surface (which means less heat is reflected away). I consider that within ten years we will be experiencing a climate change policy emergency, given the above processes and the continuing government policy inaction and belief in the magic of ecomodernism. This will combine with a period of great power transition to create an incredibly difficult and dangerous period.