Fact check: How much has the average temprature of the world changed in the past 100 years?

1. Summary of the results

Based on the analyses provided, the global average temperature has increased significantly over the past 100 years. The most consistent finding across sources indicates that global temperatures have risen by approximately 1.1-1.4°C (1.9-2.5°F) since the late 1800s ^{[1] [2] [3]}.

Key findings include:

• NASA data shows at least 1.1°C (1.9°F) warming since 1880, with most warming occurring since 1975 at a rate of 0.15-0.20°C per decade ^[1]
• 2024 global temperature was 2.32°F (1.29°C) above the 20th-century average and 2.63°F (1.46°C) above pre-industrial levels ^[3]
• The warming rate has accelerated dramatically: while the overall rate since 1850 averaged 0.11°F (0.06°C) per decade, the rate since 1982 has been more than three times faster at 0.36°F (0.20°C) per decade ^[4]
• All ten warmest years on record have occurred in the last decade (2015-2024), demonstrating the acceleration of warming ^[3]

2. Missing context/alternative viewpoints

The original question lacks several crucial contextual elements:

• The warming has not been uniform over time - scientific data shows the rate has dramatically accelerated, with yearly temperature increases of 0.0155°C since 1951 and 0.0198°C since 1971, compared to 0.0067°C over the entire 172-year period since 1850 ^[5]
• Future projections are alarming - one analysis projects a global temperature anomaly of 1.5556°C for 2050, which would exceed the maximum allowable increase set by the UNFCCC ^[5]
• The warming rate has increased since 1990 specifically, with global mean surface temperature warming at 0.19°C/decade over the past 50 years, and observations sitting "well outside the CMIP6 model ensemble in terms of warming rate and rate increase" ^[6]
• Different baseline periods yield different numbers - temperatures are measured against various reference periods (20th-century average, 1850-1900 average, pre-industrial average), which can create confusion about the exact magnitude of change

3. Potential misinformation/bias in the original statement

The original question itself appears neutral and factual, seeking specific temperature data over a defined timeframe. However, the framing could potentially minimize the urgency of climate change by:

• Focusing only on the past 100 years rather than highlighting that the most dramatic warming has occurred in recent decades
• Not acknowledging the acceleration of warming - the question implies a steady rate of change when the data clearly shows exponential acceleration
• Lacking context about climate targets - the question doesn't reference that current warming levels already approach or exceed international climate agreement thresholds

The question is straightforward but could benefit from additional context about the non-linear nature of recent warming trends and the unprecedented rate of current temperature increases compared to historical patterns.