It’s three months since ‘world leaders’ agreed during the climate summit in Paris that climatic warming must be limited to no more than 1.5 degrees Celsius.
Yesterday’s news came from Hawaii, where the world’s best annual measurements show that the rise of the atmospheric CO2 concentration is not slowing down, but accelerating instead. Just one year after we breached 400 ppm, we breached 403 – and in February the CO2 concentration at Mauna Loa stood at 404.02 ppm where 12 months earlier it was at 400.26.
That rise is faster than ever before:
Structural measurements of the rising CO2 concentration in Earth’s atmosphere started in 1958, on Hawaii. Recent measurements show the rise in CO2 is not slowing down, but accelerating. To place this in paleoclimatological perspective, the fastest and one of the most disruptive CO2 rises in Earth’s history that we know of, the Paleocene Eocene Thermal Maximum (PETM), occurred at only a tenth of the speed of the current rise. The PETM led to a ‘geological sudden’ temperature rise of over 5 degrees in 10,000 years – possibly the fastest we know from Earth’s history – and a subsequent marine extinction event.
You have three big graphs in climate science: the first is emissions, the third is temperature – and to link these two up the second and perhaps most confronting: atmospheric CO2 concentration – the one that our regulars call the ‘Keeling Curve’, named after Charles Keeling – one of our big heros. Here’s the latest update:
CO2 is cumulative, because nature cannot compensate for our emissions. Therefore this graph can only go up – as long as we don’t quit coal, oil and gas. But what’s really worrying, is that the rise of CO2 is not even declining, it is accelerating – to a new annual record last year.
In 1958 Keeling, a chemist, decided to start structural measurements of the atmospheric CO2 concentration to test the statements of 19th century scientists like Svanthe Arrhenius (our biggest hero – we have a poster of him on our wall!), and see if indeed his Swedish colleague was right when he predicted (in 1896) that our burning of fossil fuels (coal at the time) would lead to a rise in CO2 – a known greenhouse gas, since Irish physicist John Tyndall first discovered its heat absorbing properties in 1863 – and therefore the average global temperature would go up. (In effect, ‘The Science‘ was pretty much settled, in the 19th century already! — see the appendix at the bottom of this article: ‘a chronology of CO2‘)
Indeed, science builds on science – and we owe much to the masterminds of the previous centuries.
Keeling chose Hawaii – the peak of the 4170 meter high volcano Mauna Loa to be precise – as the base for his CO2 measurements, as there, in the middle of the vast Pacific Ocean, far away from continents and industry, the air offers the best view of the actual trend in that concentration.
It took Keeling only a couple of years to realise Arrhenius was indeed right – a structural rise in the concentration could indeed be observed – one that has been ‘relentless’ ever since, to quote NASA.
In 1958 the concentration lay around 315 ppm – having risen already by some 35 ppm since pre-industrial Holocene, we can, thanks to our own generation of climate scientists, deduce from ice core measurements.
That rise of 35 ppm took us some 150 years of industrialisation to create. Since 1958 the concentration has started to rise much faster – adding another 85 ppm until last year, when we posted this update of the Keeling curve, showing we had breached 400 ppm.
Some quick calculation shows between 1958 and 2015 the CO2 concentration on average rose by 1.27 ppm per year.
Over the latest four years the CO2 rise was much faster, more than 2 ppm per year, see NOAA’s overview – and 2015 broke the record for the fastest rise, of 3-4 ppm – as preliminary data show.
Not all CO2 is equal – understanding the Keeling Curve means understanding CO2 is cumulative, therefore the necessity of negative emissions
It would be a good thing if all of humanity received a basic course in climate science. That would help remove the mistaken believe that ‘nature’ can somehow compensate for our CO2 emissions.
Chemically all CO2 is equal, but there is a real difference between ‘fossil CO2’ – CO2 we emit because we dig up and burn enormous quantities of multi-million-years old fossilised carbon from Earth’s crust – and ‘biosphere CO2’.
Plants, as we all know, sequester CO2 when they photosynthesize carbon biomass (the ‘O2’ is waste to them, and oxygen to us). But this is not a one-way process. It is not like plants are conquering the Earth, eating away atmospheric carbon and producing ever more biomass.
It’s sad – but we should face it: Plants die too. In autumn it’s just the leaves falling of trees, after a storm it might be a branch – but after its entire lifespan each plants dies. The biomass then does not stay biomass – it degrades. This can happen very quickly, for instance a forest fire – or plants that are eaten, or used as fuel, or rather more slowly, the process of rotting (– or extremely slowly, for that tiny portion of dead biomass that becomes stored in oxygen-deprived environments, and over many millions of years are first stored in, and then eroded away from the geological carbon cycle – the one mankind is disturbing at an unwise rate.)
On all accounts all the CO2 plants sequester will turn into CO2 again at some point
We go this length to explain that the ‘natural carbon cycle’ of the biosphere is more or less in balance. In breaths in what it grows, and it exhales what dies off and oxidizes. It happens on a seasonal scale as well – in winter litter rots, whereas in summer leaves grow. As most of Earth’s land masses lie on the northen hemisphere (and almost all decideous forests – the ones that drop leaves in autumn, regenerate in spring) – this seasonal effects follows the boreal winter and summer.
This explains the sinus wave that you see running through the trendline of the above Keeling curve. At the end of winter CO2 is highest, at the end of summer it is lowest – relatively.
Understanding that the natural (more or less balanced) carbon cycle and the fossil (due to our energy system heavily unbalanced) carbon cycle are projected on top of each other, also leads to another important realisation: That nature cannot compensate for our emissions. Plants are no net carbon sink – plants are carbon neutral.
What’s worse: climate change is disturbing ecosystems and this may even lead to disruption of the natural carbon cycle too – where it might also become a net emitter, for instance when forests and soils dry out, and the net quantity of living biomass declines (also a consequence of deforestation).
Such positive carbon feedbacks are our gravest climate concern – the scenario of runaway warming, whereby carbon emissions lead to warming that leads to further carbon emissions, further amplifying the warming.
When we look at the early 2016 atmospheric CO2 concentration we see that that is exactly what has happened. Our fossil fuels use has not declined – therefore our fossil CO2 emissions are still dangerously high. The warming this has caused, uncorcked by the 2015 Super El Niño has led to a large-scale manifestation of carbon climate feedbacks in tropical forests – not only in Indonesia, but also in the Amazon.
That is in turn what has led to the most dramatic spike in Earth’s CO2 rise – and it happened right under the political noses of the folks that gathered in Paris to agree on the 1.5 degree climate target, but failed to agree on any meaningful policy…
They say something will happen in May. Break Free 2016. Let’s support that – and show we can break that relentless graph, with bare hands if needed.
© Rolf Schuttenhelm | www.bitsofscience.org