Climate Muscle Memory - August 2020

Whilst global temperatures over the last three months retreated from the peaks seen from Dec 2019 to May 2020, it seems unlikely the rising trend of the last 10 years has been deflected in any significant way. The evidence is clearer from the satellite readings of the lower troposphere than from the surface temperature and/or ocean results. So whilst August's surface temperature anomaly is the lowest since August 2018, it is still only 0.4SDs below the (rising) trend. The retreat in the troposphere temperature over the last few months, meanwhile, is negligible, and no challenge to the trend.

The collapse in economic activity and output demanded by Covid-19 related lockdowns has made no statistically discernible difference to atmospheric concentrations of greenhouse gases. This alone should alert us to the political impossibility of reducing CO2 emissions by long-term restrictions on economic activity. A few months in economic lockdown has been not only economically damaging and fiscally disastrous, it has also become politically toxic. At this stage it is quite impossible to imagine any politician anywhere in the world could argue for this as an acceptable 'new normal'. It follows that the approach to climate change will have to be one of a) mitigation and b) development of Circular Economy structures.

In August, CO2 concentrations were up 0.6% yoy, just as they have been on a 12m basis for months now - the 6m twitch against trend is just 0.05SDs below. In the short/medium term methane has 86x the greenhouse impact of CO2, which means that although CO2 concentrations are 412.6pp million whilst methane is 1875pp billion, methane still has 39% of the greenhouse impact of CO2. And methane concentrations continue to accelerate, up 0.7% yoy in May, and up 0.5% yoy. The 6m deflection above (accelerating) trend is 0.15SDs.

The other two greenhouse gases tracked are N2O (nitrous oxide - 'laughing gas', 'hippy crack') and sulphur hexaflouride (massively potent as a greenhouse gas, used in the electrical industry). The good news is that for both of them, the long term trend is one of slowing growth. Not that this is showing up just now: in May N2O concentrations were up 0.4% yoy, and the 6m deflection against trend was +0.55SDs; for sulphur hexaflouride, concentrations were up 3.3% yoy, but the deflection against trend was minus 0.27SDs.