Guest essay by Eric Worrall
According to the Potsdam Institute, globalisation will worsen the impact of climate change, because greater global trade flows make us more dependent on regions which are likely to suffer climate related heat stress. But some of their assumptions are a little questionable.
The abstract of the study;
Assessing global impacts of unexpected meteorological events in an increasingly connected world economy is important for estimating the costs of climate change. We show that since the beginning of the 21st century, the structural evolution of the global supply network has been such as to foster an increase of climate-related production losses. We compute first- and higher-order losses from heat stress–induced reductions in productivity under changing economic and climatic conditions between 1991 and 2011. Since 2001, the economic connectivity has augmented in such a way as to facilitate the cascading of production loss. The influence of this structural change has dominated over the effect of the comparably weak climate warming during this decade. Thus, particularly under future warming, the intensification of international trade has the potential to amplify climate losses if no adaptation measures are taken.
So what assumptions does the study make? Aside from the rather questionable assumption that a larger network of potential suppliers increases vulnerability to supply shock, the following caught my eye;
Although physiological heat stress is influenced by a number of meteorological factors (14), it has been shown that labor productivity declines quasilinearly with temperature above a threshold that is estimated to be ≥25°C (15–22). Reductions in labor supply associated with temperature shocks are observed mainly but not exclusively (23, 24) in industries exposed to outdoor temperature, such as forestry, mining, and construction (25).
Following a recent econometric study (16), the effect of temperature on labor supply is computed proportional to the daily temperature above 27°C. As suggested by the data, the production of the sectors of construction, agriculture and fishing, and mining and quarrying is reduced by a factor of 0.6, 0.8, and 4.2%, respectively, for each degree above this threshold (table S1). Exemplary time series for the South Korean construction and the Ecuadorian agriculture sector (fig. S1) show the shock-like daily heat stress forcing on the production.
Read more: Same link as above
The authors seem to be suggesting that every degree above 25C (77F), or is it 27C, there is a substantial drop in productivity.
My personal view is this assumption is nonsense. As noted in a previous post, I used to work in a factory in Melbourne. In Summer the internal temperature of the factory frequently exceeded 50C (120F). The work was manual, but not physically demanding – it involved operating a heated press once every few minutes, shifting pressed rubber components which weighed a few kilos, then loading the press with fresh raw material. New employees had difficulty with the heat and polluted air, but after a week or two your body adapts, and you just get on with it.
As long as your labour is mechanised, the human body functions well at temperatures far in excess of anything likely to be encountered in a warmer world.
What about physically demanding work in tropical heat? Fortunately there is an adaptive solution for this contingency. Its called working at night. In cities in the far tropics, activities like construction are sometimes performed at night, when the temperature drops to around 20C (68F), using a blaze of high intensity artificial lights to turn night into day.
Of course you need access to cheap energy and good lighting equipment, to work at night.