The "Reduction in GDP vs. Temperature" graph under Graphs > Population & GDP compares the four climate damage function options in En-ROADS. This graph is different from the other graphs in En-ROADS, because it has the temperature change on the x-axis, not time. On the y-axis is the percent reduction in GDP due to climate impacts. The colored lines show the four estimates from the literature, and the blue line shows the Current Scenario. For example, if the damage function assumption is changed to Dietz & Stern (2015), the Current Scenario changes to follow the orange line that shows the Dietz and Stern (2015) function. This graph shows the relation between temperature and economic impact, hence the temperature values on the x-axis go up to 5 °C even though most scenarios never go that high.
Learn more: Overview of the damage function in En-ROADS