1.5°C scenarios – Ecorealities

A line graph titled Temperature Change from the En-ROADS Simulator, superimposed over a faded background image of three industrial smokestacks emitting thick smoke. The vertical axis measures Degrees Celsius from 0.0 to 3.5 in increments of 0.5. The horizontal axis measures years from 2000 to 2100 in twenty-year increments. Horizontal dotted lines mark the 1.5 and 2.0 degrees Celsius thresholds. A legend centred at the bottom defines two colour-coded scenarios: Baseline in a black box and Current Scenario in a bright blue box. The black Baseline line rises steadily from approximately 0.8 degrees Celsius in the year 2000 to reach 3.3 degrees Celsius by 2100. The thick blue Current Scenario line tracks the baseline initially, peaks at approximately 1.8 degrees Celsius near 2050, and gradually declines to roughly 1.6 degrees Celsius by 2100. Source: background image Adobe Stock 95437745, foreground image Climate Interactive & MIT Sloan (2026) En-ROADS Simulator (Version 26.6.0).

Transformative climate action vs delayed and insufficient action

Key ideas In theory, we can stabilise and reduce the global mean temperature in the 21st century via rapid decarbonisation and wise policies to avoid a dangerous escalation of human-caused climate change. Climate Interactive & MIT Sloan’s En-ROADS Climate Solutions Simulator gives a simplified picture of some key aspects of […]

A two-panel line and area graph, comparing global carbon dioxide emissions from 2010 to 2100 across two different pathways: the Low Energy Demand, or LED, scenario on the left and a scenario labelled SSP2-2.6 on the right. A legend at the top explains the visual elements. A thick black line tracks the total amount of CO2 produced in the economy, a dashed purple line indicates gross CO2 emissions emitted into the atmosphere, and a solid light blue line tracks net CO2 emissions emitted into the atmosphere. Shaded areas represent specific sources and sinks: solid grey for gross fossil fuel and industry emissions, a hatched pattern for fossil fuel and industry emissions captured with carbon capture and storage (CCS), brown for net CO2 emissions from agriculture, forestry and other land use (AFOLU), and yellow for gross CO2 removal by bioenergy combined with CCS (BECCS). Both panels share a vertical axis measuring annual global CO2 emissions in gigatonnes per year, scaling from negative 20 to 50. The left panel for the LED scenario shows the thick black line for total CO2 produced dropping rapidly and steeply towards near zero, closely matched by the purple dashed line. It contains no hatched or yellow areas, relying solely on rapid fossil fuel emissions reduction and a small brown land-use sink to push the light blue net emissions line below zero around 2050. In contrast, the right panel for the SSP2-2.6 scenario shows the black total emissions line remaining much higher throughout the century. To achieve net-zero emissions, this scenario requires a massive hatched area emerging after 2030, representing extreme deployment of carbon capture to offset the delayed fossil fuel phase-out, alongside a deep yellow area appearing below the zero line representing heavy reliance on BECCS technologies. Consequently, the light blue net emissions line takes decades longer to reach zero, finally crossing the threshold around 2070. Source: a presentation by Arnulf Grubler on a Low Energy Demand scenario (downloaded in 2019).

Climate change

Decarbonisation scenarios

“Scenarios with very low or low GHG emissions (SSP1-1.9 and SSP1-2.6) lead within years to discernible effects on greenhouse gas and aerosol concentrations and air quality, relative to high and very high GHG emissions scenarios (SSP3-7.0 or SSP5-8.5). Under these contrasting scenarios, discernible differences in trends of global surface temperature would begin to emerge from natural variability within around 20 years, and over longer time periods for many other climatic impact-drivers (high confidence).” [IPCC (2021) AR6 WGI Summary for Policymakers, D.2, pg. 30]