Will the world pass 2 degrees Celsius over pre-industrial levels before 2050?

The International Energy Agency (IEA) defines an 'emissions gap' between implemented policies and formal pledges. This gap represents the difference in emissions if governments adhere to current policies versus fully meeting their climate pledges ^{[^]}. The IEA's Stated Policies Scenario (STEPS), reflecting current implemented policies, projects a global average temperature increase of approximately 2.7 °C by 2100 ^{[^]}. In contrast, the Announced Pledges Scenario (APS), which assumes the full implementation of all national climate pledges, projects a more limited global average temperature increase of about 1.7 °C by 2100 ^{[^]}.

Current policies align with a substantial global warming pathway. The emissions trajectory under the IEA's STEPS is largely consistent with the IPCC's SSP2-4.5 pathway ^{[^]}. This 'middle of the road' IPCC scenario also leads to approximately 2.7 °C of global warming by 2100, indicating that present policies are set on a course for significant temperature increases ^{[^]}. For comparison, the more pessimistic IPCC SSP3-7.0 pathway projects a substantially higher warming of around 3.6 °C by 2100 ^{[^]}.

Bridging the emissions gap requires substantial reductions from major economies. The divergence between the IEA's STEPS and APS scenarios critically highlights the additional emissions reductions necessary to fulfill countries' formal climate pledges ^{[^]}. Achieving the emissions levels outlined in the APS would imply a significant decrease in emissions, moving the world closer to a trajectory aligned with the 1.5 °C global warming goal. Fulfilling these commitments is therefore crucial to avoid the higher temperature increases projected under current policies or more pessimistic IPCC pathways ^{[^]}.

Global warming by 0.23 °C is projected from aerosol reductions. The global mean surface temperature increase unmasked by 2045, attributable to the phase-out of SO2 emissions from global shipping and industrial air quality policies in Asia, is centrally estimated at approximately 0.23 °C. This projection integrates an estimated 0.05 °C from shipping regulations by 2050 ^{[^]} and approximately 0.18 °C from East Asian aerosol declines by 2040–2049 ^{[^]}.

Shipping regulations and East Asian policies drive this temperature increase. The full implementation of the IMO 2020 low-sulfur fuel regulation in global shipping is estimated to contribute an additional warming of about 0.05 °C to the global mean surface temperature between 2020 and 2050 ^{[^]}. Concurrently, rapid declines in anthropogenic aerosol emissions from East Asia have significantly contributed to recent global warming, with this effect projected to reach approximately 0.18 °C by the 2040–2049 period ^{[^]}.

Past aerosol reductions also unmasked significant global warming. The IPCC AR6 further notes that global warming has been partly unmasked by large reductions in anthropogenic aerosol emissions globally, including in Asia since 2010, contributing 0.1 to 0.2 °C over the period 1970–2019 ^{[^]}.

Permafrost carbon feedback will significantly contribute to future global warming. Leading cryosphere research bodies estimate that the permafrost carbon feedback (PCF) could add an additional 0.13–0.27 °C to global warming by 2100, relative to a baseline without permafrost carbon emissions ^{[^]}. The Intergovernmental Panel on Climate Change (IPCC) synthesizes these findings, noting a potential 0.04–0.17 °C warming by 2100 under high emissions scenarios ^{[^]}. For the shorter term, by 2050, cumulative net permafrost carbon emissions are projected to be between 10 and 50 petagrams of carbon (Pg C), with some studies projecting up to 100 Pg C under high emissions scenarios ^{[^]}.

Current climate models often underestimate permafrost carbon feedback. Many CMIP6 Earth system models (ESMs) include simplified representations of permafrost processes or lack explicit permafrost carbon modules, which leads to an underestimation of the PCF's contribution to global warming ^{[^]}. Median CMIP6 ESMs project a cumulative net permafrost carbon release of 30–60 Pg C by 2100 under a very high emissions scenario (SSP5-8.5) and 10–30 Pg C by 2100 under a low emissions scenario (SSP1-2.6) ^{[^]}. These projections are notably lower than estimates from dedicated permafrost process-based models, which project cumulative emissions up to 400 Pg C by 2100, indicating a significant discrepancy in the representation of this critical feedback loop ^{[^]}.

By 2027, solar-plus-storage will outcompete coal operationally. Specifically, the levelized cost of energy (LCOE) for solar PV combined with 4-hour battery storage is projected to fall below the marginal cost of operating existing coal-fired power plants in India and Indonesia. This economic milestone, identified by BloombergNEF's analysis, indicates a potential acceleration in the retirement of coal infrastructure in these nations ^{[^]}.

Falling renewable and battery costs drive this energy transition. These projections are supported by the ongoing decline in the costs of renewable energy technology and battery storage. Battery storage costs have reached record lows ^{[^]}, and solar LCOE is anticipated to maintain its downward trajectory ^{[^]}. This continuous reduction in costs is a pivotal element in the broader energy transition, making new clean energy solutions more economically viable than legacy fossil fuel assets ^{[^]}.

Decadal forecasts do not provide specific 'super' El Niño probabilities. Decadal forecasts from organizations like the UK Met Office and NOAA generally focus on global and regional temperature and precipitation anomalies over 5- to 10-year periods, accounting for natural variability and anthropogenic forcing ^{[^]}. However, the available sources do not offer a specific modeled probability for a 'super' El Niño event, defined as an Oceanic Niño Index (ONI) anomaly exceeding 2.0°C, occurring between 2025 and 2035 ^{[^]}. NOAA's Climate Prediction Center (CPC), for example, typically provides shorter-term ENSO outlooks rather than decadal probabilities for extreme ONI thresholds ^{[^]}.

'Super' El Niño events significantly increase global average temperatures temporarily. Strong El Niño events are known to temporarily increase global average temperatures by 0.1 to 0.2 degrees Celsius in their peak year ^{[^]}. A 'super' El Niño specifically indicates an event where sea surface temperatures in the Niño 3.4 region are more than 2.0 degrees Celsius above average ^{[^]}. These events cause an additional temporary warming spike by releasing heat from the Pacific Ocean into the atmosphere, contributing to global temperatures on top of the long-term warming trend driven by climate change ^{[^]}. The strong 2023-24 El Niño notably contributed to record global mean surface temperatures, pushing them closer to the 1.5°C threshold above pre-industrial levels ^{[^]}.

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