What is the Yearly Average Temperature Anomaly?

It is the difference between the average yearly global surface temperature and its pre-industrial baseline. The pre-industrial baseline is calculated as the average temperature from 1850 to 1900.

The average temperature anomaly is a crucial metric because the change in the Earth’s average temperature is causing major transformations to our planet. It puts the existence of many species - including humans – at risk.

Many scientific global average temperature anomalies use a 1951 to 1980 baseline, showing anomaly values roughly 0.3 °C (0.54 °F) lower. While it is scientifically valid to choose any baseline, the global community, governments and other organizations are setting targets to limit global warming at 1.5 °C (2.7 °F) with respect to the pre-industrial baseline from 1850 to 1900.

Units and measures

Degree Celsius (°C) or degree Fahrenheit (°F) per year

Insights from this chart

Since 1850

The overall increase in the average temperature anomaly since the pre-industrial baseline is driven by human emissions of several greenhouse gases, like carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O) and others, which cause an increased greenhouse effect. We, i.e. humans, are still emitting more greenhouse gases and are causing more warming.

The period from 1850-1900, with relatively small blue and orange fluctuations in the chart, sets the baseline and is widely known as the pre-industrial era baseline.

Global warming already started in the 1920s. During the 1945 to 1975 period, heavy atmospheric pollution caused by humans cooled the Earth by reflecting sunlight, a process known as global dimming. The cooling effect from global dimming was reduced significantly by several global efforts to reduce air pollution.

Since the late 1970s, there has been a steady and very rapid increase in the global average temperature anomaly, with peaks in 2016 and 2020. The highest global average temperature anomaly so far was +1.36 °C (2.45 °F) in 2016.

Last ~ 2000 Years

For a large part of the last 2000 years the global average temperature anomaly was about 0.2 °C (0.36 °F) above the 1850 to 1900 baseline. The warming of the last 100 years is very large and extremely fast compared to the long period before.

The global temperature anomaly does change over time due to natural causes, but human greenhouse gas emissions caused changes that disrupt our planet. If we, humanity, reduce our greenhouse gas emissions we can halt global warming.

About the data

For values since 1850 we primarily use Berkeley Earth and add data from NASA GISS when they have more recent values available. This data is gathered using a huge number of weather stations on land, ships, buoys and more.

For the years leading up to 1850 we use PAGES2k Consortium reconstruction data. It is based on models where temperatures are reconstructed from proxies. Proxy analysis has higher uncertainty, and we display the smoothed set to highlight the longer-term fluctuations.

The value for the current year is actually the average for the last 12 months; for example, in March we include values since the previous April. This approach allows us to include the latest data for a full year and avoids showing possibly misleading values when using shorter time periods.

Data sources

Temperature Data Berkeley Earth
Credits: Rohde, R. A. and Hausfather, Z.: The Berkeley Earth Land/Ocean Temperature Record, Earth Syst. Sci. Data, 12, 3469–3479, https://doi.org/10.5194/essd-12-3469-2020, 2020.Update cycle: monthlyDelay: ~ 1 month

Global mean temperature data NASA GISS
Credits: GISTEMP Team, 2022: GISS Surface Temperature Analysis (GISTEMP), version 4. NASA Goddard Institute for Space Studies. Dataset accessed 20YY-MM-DD at https://data.giss.nasa.gov/gistemp/. Lenssen, N., G. Schmidt, J. Hansen, M. Menne, A. Persin, R. Ruedy, and D. Zyss, 2019: Improvements in the GISTEMP uncertainty model. J. Geophys. Res. Atmos., 124, no. 12, 6307-6326, doi:10.1029/2018JD029522Update cycle: monthlyDelay: ~ 1 weeks

PAGES2k Common Era Surface Temperature Reconstructions NCEI NOAA
Credits: PAGES2k Consortium: Raphael Neukom, Luis A. Barboza, Michael P. Erb, Feng Shi, Julien Emile-Geay, Michael N. Evans, Jörg Franke, Darrell S. Kaufman, Lucie Lücke, Kira Rehfeld, Andrew Schurer,Feng Zhu,Stefan Brönnimann, Gregory J. Hakim, Benjamin J. Henley, Fredrik Charpentier Ljungqvist, Nicholas McKay, Veronika Valler, Lucien von Gunten. 2019. Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nature Geoscience, 12. doi: 10.1038/s41561-019-0400-0. Data accessed on May 4. 2022