Guest essay by Eric Worrall
According to a new PLOS One study, efforts to mitigate global warming will not yield a net economic benefit until the next century.
The abstract of the study;
Approximate calculations of the net economic impact of global warming mitigation targets under heightened damage estimates
Efforts to mitigate global warming are often justified through calculations of the economic damages that may occur absent mitigation. The earliest such damage estimates were speculative mathematical representations, but some more recent studies provide empirical estimates of damages on economic growth that accumulate over time and result in larger damages than those estimated previously. These heightened damage estimates have been used to suggest that limiting global warming this century to 1.5 °C avoids tens of trillions of 2010 US$ in damage to gross world product relative to limiting global warming to 2.0 °C. However, in order to estimate the net effect on gross world product, mitigation costs associated with decarbonizing the world’s energy systems must be subtracted from the benefits of avoided damages. Here, we follow previous work to parameterize the aforementioned heightened damage estimates into a schematic global climate-economy model (DICE) so that they can be weighed against mainstream estimates of mitigation costs in a unified framework. We investigate the net effect of mitigation on gross world product through finite time horizons under a spectrum of exogenously defined levels of mitigation stringency. We find that even under heightened damage estimates, the additional mitigation costs of limiting global warming to 1.5 °C (relative to 2.0 °C) are higher than the additional avoided damages this century under most parameter combinations considered. Specifically, using our central parameter values, limiting global warming to 1.5 °C results in a net loss of gross world product of roughly forty trillion US$ relative to 2 °C and achieving either 1.5 °C or 2.0 °C require a net sacrifice of gross world product, relative to a no-mitigation case, though 2100 with a 3%/year discount rate. However, the benefits of more stringent mitigation accumulate over time and our calculations indicate that stabilizing warming at 1.5 °C or 2.0 °C by 2100 would eventually confer net benefits of thousands of trillions of US$ in gross world product by 2300. The results emphasize the temporal asymmetry between the costs of mitigation and benefits of avoided damages from climate change and thus the long timeframe for which climate change mitigation investment pays off.Read more: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239520
The authors used a discount factor of 3%, which IMO is reasonable; 3% compares favourably with yardstick rates such as long term US treasury yields, and neatly sidesteps a common criticism of climate action cost benefit projections.
The main takeaway is, even using fairly extreme climate damage projections, the sums just don’t add up – the cost of climate action exceeds any reasonable projected benefit this century.
What about the next century? Frankly they can take care of their own problems. The infamous great horse manure crisis of 1894 demonstrates how pointless it is to worry about the problems of the distant future.
Our ancestors in the late 1800s produced economic models which demonstrated that by the mid 20th century, the major cities of the world would be buried under mountains of horse manure. Their models were mathematically consistent; what they overlooked was the rise of the automobile.