Annual temperature differences or anomalies calculated from the temperature data collected at the Abisko Scientific Research Station, Abisko, Sweden, 1913 to 2018. Temperature differences from the Arctic, Northern Hemisphere and Global perspectives are offered as a comparison. These calculations are based on a baseline (default 1961-1990). Users can adjust the baseline period to see the effects on the anomalies.
Why temperature difference or anomaly?
“The term temperature anomaly (or difference) means a departure from a reference value or long-term average. A positive anomaly indicates that the observed temperature was warmer than the reference value, while a negative anomaly indicates that the observed temperature was cooler than the reference value.” Taken from: https://www.ncdc.noaa.gov/monitoring-references/faq/anomalies.php
What is a baseline and why use it?
“With regard to climate a single year is not appropriate to use as the baseline. Climate variability means that a single year may be unusually warm or cold or dry or wet and does not therefore make a useful reference point for measuring climate change. More common in climatological applications is the use of the average climate over a 30-year period to define the reference or baseline climate. A 30-year climatic average smoothes out many of the year-to-year variations in climate, while the individual 30 years of such a period captures much of the interannual and short time-scale variability of climate that may be relevant for an impact application. For these reasons, the period 1961-90 is generally used as the baseline period. This period has generally good observed data availability (e.g. the observed climatology described by the DDC), it represents the recent climate to which many present-day human or natural systems are likely to be reasonably well adapted, and the period ends in 1990, the year adopted by many IPCC and UN FCCC applications.” Taken from https://www.ipcc-data.org/ddc/ddc_faq.html
Abisko data taken from the Abisko Scientific Research Station. Arctic, Northern Hemisphere and Global temperature data taken from the GISS Surface Temperature Analysis (GISTEMP v4) database.