In more than one sense, global warming is a hot topic here in Australia. This summer’s record temperatures have necessitated an extension of the temperature scale on weather maps, and exacerbated the occurrence of bushfires which we have seen rage throughout the southeast of the nation. In the mean time the international community appears to commit to further increases in average global temperatures as if the degree of warming over the past century hasn’t taught us a thing. But just say we could get some affirmative collective action, how do we know where to begin? As it happens, the question is not where, but when?
In a recent article in Nature, researchers quantified the influence of various factors on capping global warming to a further 2 °C and the associated cost of climate mitigation. Rogelj et al., looked at the impact of:
“the responsiveness of the physical climate system to cumulative emissions; the deployment of energy- and land-based emission-reduction technologies; the global demand for energy (which includes combined uncertainties about population, income growth and energy efficiency); the global carbon price that the international community is willing to impose; and the timing of substantive action to limit emissions”(Hatfield-Dodds summary).
From 500 model variations the authors conclude that the timing of international action has by far the highest impact on the probability of success.
What I find most noteworthy is that this impact is highly non-linear. In other words, we just can not just peddle faster to reduce emmissions when we do decide to act. The article highlights that global action on emissions in 2015 equates to 60% probability of success. This drops to 56% if we delay until 2020 and plummets to 34% if we choose to delay collective action until 2025. Bushfire anyone? The authors also contend that an INCREASE in the carbon price is more likely to drive the necessary development of low emissions technology. Blindingly obvious if you ask me, however unfortunately there are still voices that claim a carbon tax is unnecessary. (Which I might add irks me in the same manner as complaints over the price of organic meat. This is the cost of rearing an animal. To purchase really cheap meat often means the animal must suffer enormously as a consequence. Same goes for climate, except that we all suffer).
I believe the authors do a great service by bridging the gap between science and policy. They are able to clarify what is important, and what needs to be addressed with out a need to understand the principles of thermodynamic equilibrium or vector calculus. The approach connects the disciplines, and all the associated uncertainties through the economics, providing a roadmap for decision makers and yet more impetus for rapid emissions reductions.