Green with savvy? Brazil's climate pledge to the Paris Agreement and its transition to the green economy

There is a lively debate in climate policy about the fastest, least-cost and most effective way of reducing carbon emissions. Mitigation policies are basically demand-driven, since they directly address the reduction in the demand for energy-intensive goods. Conversely, by increasing the share of renewables in the energy mix, energy-efficiency policies turn to the supply side of the economy, regulating the exploration and extraction of fossil fuels, whereby emissions are indirectly reduced. Typically, mitigation involves costs of reducing (CR) emissions that have already been given off, whereas energy efficiency implies costs of controlling (CC) them before release. So, an important policy question arises as to whether and how far combine (synergy) or choose (trade-off) out of different policy options. Although assuming a growing demand for energy, the Paris Agreement (PA) highlights mitigation of emissions directly, by reducing energy intensity, whereas the Green Economy underscores potential savings of natural resources by increasing energy efficiency and hence mitigating emissions indirectly. In 2016, Brazil formally joined the Paris Agreement and became the largest developing country to set an economy-wide emissions target in its Nationally Determined Contributions (NDCs), pledging a 37% reduction (128.5 MtCO2), in 2025, in its emissions with respect to their 2005 levels (347.31 MtCO2). Additionally, the country's Plans for Decadal Energy Expansion (PDE) targeted the share of renewables in its energy matrix up to 48% by 2025. By applying directional derivatives, gradient vectors and an optimization model, the objective of this article is to evaluate whether, how fast and how far these policies can turn the country into a cleaner, greener and low-carbon economy. The results suggest that, regarding emissions mitigation, Brazil's pledges sound too ambitious. Instead, increasing renewable energy rather than directly mitigating emissions yields more economically and environmentally efficient outcomes, thereby favoring a faster and far-reaching transition to a greener economy.