CO2 and a quick trip to the Twilight zone

At the start of each year the Met Office announce to the world that they can reliably predict the increases of CO2 in the atmosphere during the coming year – it’s not at at all difficult to do all you need is a pen, ruler and a bit of graph paper for goodness sake – but obviously to them this is important. They’ve even found a convenient statistic to use – CO2 levels will reach 50% higher than in pre-industrial times this year – to spice up their story with. Of course all this news about their CO2 predictions is all wrapped in another sermon like pronouncement about the dangers of global warming. It’s a bit like the brainwashing advertising campaigns of the 1970’s when we were being told about the risk of cigarettes causing cancer or not forgetting to use our seat belts.

Wouldn’t be an even bigger deal, and a bit of a bugger, if and when the world finally does get its CO2 emissions into the atmosphere under control, to find that the saw tooth levels of CO2 measured on Mauna Loa still keep remorselessly increasing at the same rate, and some scientific expedition finds that unknown vast quantities of CO2 has been naturally percolating into the atmosphere from tectonic plate activity on the ocean floor for many millions of years.

Just to get back to reality after a quick detour into the Twilight zone, here is what the Met Office have to say about it all:-

Atmospheric carbon-dioxide to pass iconic threshold

Author: Grahame Madge

00:01 (UTC) on Fri 8 Jan 2021


In 2021, carbon dioxide in the atmosphere will reach levels 50% higher than before the industrial revolution, due to human-caused emissions, says a Met Office forecast. 

The Met Office predicts that annual average CO2 concentration at Mauna Loa Observatory, Hawaii, will be 2.29 ± 0.55 parts per million (ppm) higher in 2021 than in 2020. This rise is driven by emissions from fossil fuel burning and deforestation, but will be slightly smaller than usual due to a temporary strengthening of natural carbon sinks. Weather patterns linked to the current La Niña event are expected to promote a temporary burst of growth in tropical forests that soak up some of humanity’s emissions.  

Despite these La Niña-related effects, CO2 will still continue to build up in the atmosphere, and will exceed 417 ppm for several weeks from April to June. This is 50% higher than the level of 278 ppm in the late Eighteenth Century when widespread industrial activity began. 

2021 carbon-dioxide forecast

As usual, the annual peak – at new record levels in May – will be followed by a temporary fall in concentrations as ecosystems take up CO2 during the northern hemisphere growing season – but from September onwards the CO2 will continue to rise again. The annual average CO2 concentration will be 416.3 ± 0.6 ppm. 

Professor Richard Betts MBE, who leads the production of the Met Office’s annual CO2 forecast, said: “Since CO2 stays in the atmosphere for a very long time, each year’s emissions add to those from previous years and cause the amount of CO2 in the atmosphere to keep increasing. Although the Covid-19 pandemic meant that 7% less CO2 was emitted worldwide in 2020 than in previous years, that still added to the ongoing build-up in the atmosphere. Emissions have now returned almost to pre-pandemic levels, but their effect this year will be partly dampened for a while by the stronger natural sinks due to the La Niña.” 

Mauna Loa Observatory in Hawaii is the site of the longest-running continuous record of atmospheric CO2 concentrations, which were begun in 1958 by David Keeling.  

The iconic ‘Keeling Curve’ graph is a potent symbol of humanity’s accelerating impact on the global climate system. CO2 concentrations in the Keeling Curve record first reached 349 ppm, 25% above pre-industrial levels, in 1986.  

Professor Betts added: “The human-caused build-up of CO2 in the atmosphere is accelerating. It took over 200 years for levels to increase by 25%, but now just over 30 years later we are approaching a 50% increase. Reversing this trend and slowing the atmospheric CO2 rise will need global emissions to reduce, and bringing them to a halt will need global emissions to be brought down to net zero. This needs to happen within about the next 30 years if global warming is to be limited to 1.5°C.” 

The Met Office has been issuing annual forecasts of the CO2 at Mauna Loa since 2016, and has successfully predicted the influence of year-to-year changes in natural carbon sinks on the rate of CO2 rise. In 2020, once it became clear that the pandemic would cause a temporary dip in emissions, the impact of this on the CO2 rise was also successfully predicted. 

Courtesy UKMO

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