Terrestrial carbon cycle affected by non-uniform climate warming

173 Temperature regulates almost all biogeochemical processes. Future climate warming will therefore have a profound effect on ecosystem functions and services such as carbon storage1. For example, climate warming influences terrestrial primary production directly by changing the leaf process intensity , but also indirectly by increasing soil nutrient mineralization2–4, changing soil water availability5, prolonging the growing season6,7, shifting community structure8 and altering disturbance regimes9. However, the rate of climate warming varies in magnitude between seasons and between day and night. Some regions, such as the west coast of subtropical South America10, even experience cooling at certain points of the year. Temperatures have risen more quickly in winter than in summer at latitudes above 50° N, leading to a reduction in inter-seasonal differences in temperature at these high latitudes11,12. In contrast, summers have warmed more quickly than winters in some hot deserts, leading to an amplification of temperature seasonality in these regions13. Furthermore, the night has been shown to warm more quickly than the day in most areas of the world, leading to a reduction in the diurnal temperature range14, although the opposite trend has been observed14 and simulated15 in some regions, such as the Mediterranean. This non-uniform rate of climate warming between seasons, regions and time of day may underpin regional differences in the response of ecosystem carbon cycling to warming, and thereby pose a great challenge to the prediction of future feedbacks between the climate and the carbon cycle. To better understand how warming varies in space and time, we analysed global changes in seasonal mean and daily maximum and minimum temperatures using a long-term globally gridded database of air temperatures measured between 1948 and 201016. The database was constructed by combining five global observation-based temperature data sets, and includes 3-hour near-surface Terrestrial carbon cycle affected by non-uniform climate warming