The 2015 Paris Agreement calls for countries to pursue efforts to limit global-mean temperature rise to 1.5 °C. The transition pathways that can meet such a target have not, however, been extensively explored. Here we describe scenarios that limit end-of-century radiative forcing to 1.9 W m −2 , and consequently restrict median warming in the year 2100 to below 1.5 °C. We use six integrated assessment models and a simple climate model, under different socioeconomic , technological and resource assumptions from five Shared Socioeconomic Pathways (SSPs). Some, but not all, SSPs are amenable to pathways to 1.5 °C. Successful 1.9 W m −2 scenarios are characterized by a rapid shift away from traditional fossil-fuel use towards large-scale lowcarbon energy supplies, reduced energy use, and carbon-dioxide removal. However, 1.9 W m −2 scenarios could not be achieved in several models under SSPs with strong inequalities, high baseline fossil-fuel use, or scattered short-term climate policy. Further research can help policy-makers to understand the real-world implications of these scenarios.

To put the Paris Agreement in context, we reviewed available 1.5 °C scenarios to assess viable emissions pathways and required mitigation across all sectors. Recently released 1.5 °C (1.9 W m −2

Food insecurity can be directly exacerbated by climate change due to crop production-related impacts of warmer and drier conditions expected in important agricultural regions 1, 2, 3. However, efforts to mitigate climate change through comprehensive, economy-wide greenhouse gas emission reductions may also negatively affect food security, due to indirect impacts on prices and supplies of key agricultural commodities 4, 5, 6. Here we conduct a multiple model assessment on the combined effects of climate change and climate mitigation efforts on agricultural commodity prices, dietary energy availability, and the population at risk of hunger. A robust finding is that by 2050, stringent climate mitigation policy, if implemented evenly across all sectors and regions, would have a greater negative impact on global hunger and food consumption than the direct impacts of climate change. The negative impacts would be most prevalent in vulnerable low-income regions such as Sub-Saharan Africa and South Asia, where food security problems are already acute.