These regions are: north-western North America, the Siberian Plateau in northeast Asia, and the Antarctic Peninsula and Bellingshausen Sea. American Geophysical Union, Antarctic Research Series, Volume 79: Washington, D.
These areas warmed by more than 1.5°C between 19 AD (compared with a global mean of 0.5°C).
Climate data is therefore very noisy, and climate scientists must determine patterns in this data using complex statistical techniques. Climate change varies seasonally, on decadal timescales, and is geographically patchy.
More populated regions have atmospheric sulphate aerosols, that may mask warming.
Urban meteorological stations may also record anomalous warming due to urban heat island effects.
“Climate” encompasses data such as temperature, humidity, pressure, wind, precipitation (snow or rain), and other meteorological measurements.
This page is intended to be a short introduction, and by no means covers all of the vast topic of climate change.
For more information, see: New Scientist; IPCC; Met Office.