The instrumental temperature record shows the fluctuations of the temperature of the atmosphere and the oceans as measured by temperature sensors. Currently, the longest-running temperature record is the Central England temperature data series, that starts in 1659. The longest-running quasi-global record starts in 1850.
The time period for which reasonably reliable near-surface temperature records exist from actual observations from thermometers with quasi-global coverage is generally considered to start in about 1850 - earlier records exist, but coverage and instrument standardization are less. The instrumental temperature record is viewed with considerable skepticism for the early years.
There are concerns about possible uncertainties in the instrumental temperature record including the fraction of the globe covered, the effects of changing thermometer designs and observing practices, and the effects of changing land-use around the observing stations. The ocean temperature record too suffers from changing practices (such as the switch from collecting water in canvas buckets to measuring the temperature from engine intakes) but they are immune to the urban heat island effect or to changes in local land use/land cover (LULC) at the land surface station.
The global temperature changes are not uniform over the globe, nor would they be expected to be, whether the changes were naturally or humanly forced. Certain places, such as the north shore of Alaska, show dramatic rises in temperature, far above the average for the globe as a whole. The Antarctic peninsula has warmed by 2.5 °C (4.5 °F) in the past five decades in certain places; meanwhile East Antarctic has not significantly warmed.
