Climate change is causing human emissions of heat-trapping gases warming the climate by nearly 2 degrees Fahrenheit since 1850-1900.

1. Measured warming: what the numbers say

Global surface temperatures have risen by about 1.1°C relative to 1850–1900 in the 2011–2020 period, with datasets and reports quoting a likely human‑caused range roughly from 0.8°C to 1.3°C and best estimates near 1.07°C (≈2.01°F) since that pre‑industrial baseline ^{[1] [7]}. Different analyses give slightly different point values — some reports place recent decade averages at ~1.1°C ^{[1] [3]}, Berkeley Earth’s recent analysis estimated 2023 at ~1.54°C above 1850–1900 though that single‑year frame differs from decadal averages used elsewhere ^[8].

2. Why scientists attribute it to human emissions

Multiple lines of evidence point to greenhouse gases from human activities — burning fossil fuels, industrial processes, agriculture — as the primary cause: observed warming matches model simulations only when anthropogenic forcings are included, atmospheric CO2 and other GHG concentrations have climbed sharply since ~1850, and natural drivers (solar, volcanic) and internal variability cannot explain the magnitude and pattern of change alone ^{[9] [4] [5]}. Longstanding syntheses by the IPCC and national agencies conclude that human emissions are responsible for approximately 1.1°C of the warming since 1850–1900 ^{[2] [5]}.

3. The apparent small number conceals large energy changes

A global mean rise of about 1–1.3°C may sound modest, but that increment represents a large increase in heat energy stored across the climate system — especially oceans and cryosphere — and drives shifts in weather extremes, sea level, and ecosystems ^{[1] [3]}. Scientific reports emphasize that even seemingly small global averages translate into substantial regional disruptions and accelerating impacts if warming continues ^{[6] [3]}.

4. Uncertainties, ranges and why datasets vary

Different datasets and time windows produce slightly different warming estimates because of choices about baselines (1850–1900), inclusion or smoothing of internal variability, and the span used to calculate averages; the IPCC gives a human‑caused warming estimate with uncertainty bounds (e.g., 0.87°C ±0.12°C for 2006–2015) and NOAA notes a likely range 0.8–1.3°C for human‑caused total warming ^{[5] [1]}. Single‑year records such as Berkeley Earth’s 2023 analysis highlight short‑term peaks influenced by El Niño and other factors, which is why multi‑decadal averages are the preferred metric for global warming trends ^{[8] [1]}.

5. Complicating factors and alternative perspectives

Aerosols from industrial activity historically offset some warming by reflecting sunlight, which explains slower warming in some periods; the balance of warming and cooling anthropogenic drivers is quantified in attribution studies but remains a source of nuance ^{[1] [10]}. A minority of commentators seize on differences between datasets or on short‑term variability to downplay the human role, but mainstream scientific assessments from NOAA, IPCC, Royal Society and NASA converge on anthropogenic greenhouse gases as the main driver ^{[1] [2] [6] [4]}.

6. What this implies for the near future

Scientific projections and policy assessments warn that without rapid, sustained reductions in greenhouse‑gas emissions, global average temperatures will likely pass higher thresholds: the IPCC and other groups project chances of exceeding 1.5°C within decades and substantially larger warming by 2100 under high‑emission pathways ^{[2] [5] [6]}. Agencies stress that measurable impacts persist for centuries because CO2 and other GHGs remain in the system long after emission reductions ^[3].