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How do temperature records show that Earth has warmed since the 19th century?
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Global warming
A series of photographs of the Grinnell Glacier taken from the summit of Mount Gould in Glacier National Park, Montana, in (from left) 1938, 1981, 1998, and 2006. In 1938 the Grinnell Glacier filled the entire area at the bottom of the image. By 2006 it had largely disappeared from this view.
Instrumental records provide the most reliable evidence of Earth's warming since the mid-19th century, as they are based on precisely dated measurements from well-understood instruments. While records were sparse in the 19th century, systematic global data collection has allowed scientists to document significant climate trends.12
Key findings from these instrumental records include:
- Surface Temperature Rise: Global surface temperatures rose by approximately 0.9 °C (1.5 °F) between 1880 and 2012. More recent data from the World Meteorological Organization and NASA confirm that the years 2015–2024 were the warmest since record-keeping began, with 2024 identified as the warmest year on record.1
- Decadal Trends: Since 1980, each successive decade has been warmer than any preceding decade in the instrumental record.3
- Supporting Indicators: Warming is further evidenced by a global sea level rise of 19–21 cm (7.5–8.3 inches) between 1901 and 2010, as well as a significant decrease in Northern Hemisphere snow cover.1
These trends are consistent with the Intergovernmental Panel on Climate Change's assessment that human activities have had an unequivocal influence on the climate system.3