Keep Factually independent
Whether you agree or disagree with our analysis, these conversations matter for democracy. We don't take money from political groups - even a $5 donation helps us keep it that way.
How confident are scientists about future climate projections and their expected impacts by 2050 and 2100?
Executive summary
Scientists are highly confident that Earth will keep warming this century, but the amount of warming and specific regional impacts by 2050 and 2100 depend strongly on future emissions and on model choices (NOAA; IPCC) [1] [2]. Recent studies have narrowed uncertainty in projected global warming ranges for the late 21st century (a 90% interval around ~1.1–3.2°C in one 2024 analysis), yet scenario differences still produce median outcomes from about ~1.9°C to ~2.7°C or higher by 2100 under different policy paths [3] [4] [2].
1. “Virtually certain” warming — the broad scientific consensus
Climate agencies and assessments state it is virtually certain the world will continue to warm; that is a central, settled conclusion used across climate communications (NOAA) [1]. The IPCC links the degree of future warming tightly to emissions pathways: ambitious mitigation that reaches net-zero CO2 around mid-century aligns with much lower end-century warming than continued high emissions [2].
2. Scenarios drive the numbers — why 2050 and 2100 look different
Projections are conditional on socioeconomic-emissions scenarios (SSPs/RCPs). Some pathways that achieve net-zero by mid-century (e.g., SSP1-1.9) produce very low additional warming by 2081–2100 (reported ‘very likely’ ranges like 0.15–0.95°C relative to 1995–2014 under that scenario), whereas higher-emission scenarios produce much larger warming by 2100 [5] [2]. Analysts therefore emphasize ranges and probabilities rather than single numbers [3] [2].
3. How confident are scientists quantitatively? Narrowing uncertainty — recent progress
A 2024 peer-reviewed analysis reported that uncertainty in projected warming for 2081–2100 has narrowed, giving a 90% confidence interval of about 1.1–3.2°C when weighting plausible scenarios equally — less than half the width of earlier assessments [3]. This shows growing confidence about the range of likely outcomes, though the interval still spans values with very different impacts [3].
4. Median projections used by policy groups — what they currently estimate for 2100
Policy-focused trackers give operational medians: for example, Climate Action Tracker’s “current policy” median for 2100 is around 2.7°C (with stated chances of being higher — e.g., 33% chance of ≥3.1°C), and other reputable syntheses show medians in roughly the 1.9–2.7°C band depending on policy assumptions [4] [6]. These mid-range estimates underline that present policy commitments leave substantial warming risk by 2100 [4].
5. Near-term (to 2050) confidence and expected impacts
By 2050 the signal of warming is strong in models: coastal and sea-level impacts are already quantifiable in the near term — global average sea level is projected to rise by roughly 0.25–0.30 meters by 2050 in many model runs, and U.S. coasts may see about 10–12 inches (2020–2050) on average, comparable to the rise seen over the previous century [7] [8]. Because 2050 is closer, uncertainties from long-term carbon-cycle feedbacks and very long-lived greenhouse gases play a smaller role than for 2100, but regional impacts (precipitation changes, extremes) still have more model spread [7] [9].
6. Impacts and confidence vary by phenomenon — not all projections are equally certain
Temperature rise and global mean sea level have the highest confidence in direction and substantial confidence in magnitude ranges; projections for event frequency (e.g., hurricane frequency) and some regional outcomes have lower confidence. For example, scientists project stronger hurricanes on average and heavier rainfall in storms but say there is less confidence in projections of hurricane frequency itself [9]. Similarly, precipitation and ecosystem responses have larger regional uncertainties [9] [2].
7. Disagreement and debate — models, sensitivity and “mild warming” claims
Some peer-reviewed analyses argue that an ensemble of models calibrated to recent observations suggests milder end-century warming (e.g., below ~2.5–3.0°C), especially if observational biases are significant; others and major synthesis bodies (IPCC, CAT) present higher median estimates under current policies [10] [4]. These differences reflect ongoing debate about equilibrium climate sensitivity, model selection and observational biases; the literature documents both viewpoints and their assumptions [10] [3].
8. What this means for decision‑makers and the public
Science provides high confidence that warming will continue and that impacts will grow with greater warming; the actionable uncertainty is about how much and where, which depends on policy choices now and over coming decades [1] [2]. Because some pathways can still limit warming substantially (net-zero CO2 around 2050 to hold close to 1.5°C), mitigation timing matters for outcomes by 2050 and especially by 2100 [2].
Limitations: available sources here do not provide a single definitive probability distribution covering all outcomes and regions; they present scenario-dependent ranges, recent narrowing of global temperature uncertainty, and competing peer-reviewed perspectives [3] [10] [4].