POPULATION AND ENERGY DEMAND GROWTH WILL DRIVE THE 2ºC CLIMATE GOAL TOWARDS ADAPTATION

Over 86% of the 546 EJ of energy consumed currently by the world’s 7.2 billion population is derived from non-renewable fossil fuels, resulting in the annual emission of 36 gigatonnes of carbon-dioxide equivalent (GtCO₂). IPCC estimates that between 1870 and 2010, 1,890 GtCO₂ were emitted globally, and suggest that in order to avoid negative climate effects associated with >2^oC warming, this number should not exceed 2,900 GtCO₂. Yet, the world of 2100 will demand twice as much energy as currently produced, largely resulting from: 1) world population increasing to 11 billion by 2100; 2) bringing the one-fifth of the world’s population currently living without access to electricity onto the energy grid, as proposed by the World Bank and United Nation’s Sustainable Energy for All Initiative; and 3) expansion of energy use to foster continued economic development in the low per capita energy use countries , especially South Asia and Sub-Saharan Africa. Here we examine the world’s known non-renewable energy reserves and quantify the changes in the global energy mix necessary to address the 21^st century population, economic expansion, and climate change issues under two energy-use scenarios. In order to maintain <2^oC warming we find that renewable energy (9% today) must comprise 50% of total energy use by 2028 and 94% by 2100. Alternatively, if availability of the non-renewable fuels is the constraint, we find that renewable energy must expand to comprise 50% of total energy use by 2054 and 87% by 2100. In either scenario, renewable energy availability must expand dramatically by the end of the 21^st century. However, under the <2^oC scenario renewable energy will need to expand by 36-fold in the next 13 years (2015 to 2028), a rate and magnitude that is unprecedented in the history of development and expansion of any energy source. Due to ongoing economic and political debates, we see the <2^oC mitigation scenario as untenable. Rather, we see cumulative carbon emissions approaching 4,700 GtCO₂ by 2100. Given the required rate and magnitude of the transition to renewable energy to meet the <2˚C warming goal, focus should instead be placed on implementing climate adaptation measures and expanding renewable energy availability as quickly as possible in order to limit warming to 2.5-3˚C.