labs_title

Reduced North American terrestrial primary productivity linked to anomalous Arctic warming

J. Kim, J. Kug, S. Jeong, D.N. Huntzinger, A.M. Michalak, C.R. Schwalm, Y. Wei and K. Schaefer

This paper leverages the MsTMIP multi-model ensemble to examine the links between Arctic temperature anomalies and carbon uptake in North America. Warmer Arctic temperatures are found to coincide with decreased carbon uptake in North America, and this correlation is linked to anomalously cold conditions in northern North America and lower precipitation in the South Central US. Impacts on crop yields are also observed.


Figure: Atmospheric teleconnections related to Arctic warming. a–d, Regression coefficients of the March–May mean sea-level pressure (SLP), 850-hPa wind (a), 300-hPa geopotential height (GPH) and wind (b), surface temperature (c) and precipitation (d) with respect to the ART index for the period 1979–2015. Wind vectors and hatching are displayed only in significant regions at the 95% confidence level (calculated using a Student’s t-test).

Abstract

Warming temperatures in the Northern Hemisphere have enhanced terrestrial productivity. Despite the warming trend, North America has experienced more frequent and more intense cold weather events during winters and springs. These events have been linked to anomalous Arctic warming since 1990, and may affect terrestrial processes. Here we analyse multiple observation data sets and numerical model simulations to evaluate links between Arctic temperatures and primary productivity in North America. We find that positive springtime temperature anomalies in the Arctic have led to negative anomalies in gross primary productivity over most of North America during the last three decades, which amount to a net productivity decline of 0.31 PgC yr−1 across the continent. This decline is mainly explained by two factors: severe cold conditions in northern North America and lower precipitation in the South Central United States. In addition, United States crop-yield data reveal that during years experiencing anomalous warming in the Arctic, yields declined by approximately 1 to 4% on average, with individual states experiencing declines of up to 20%. We conclude that the strengthening of Arctic warming anomalies in the past decades has remotely reduced productivity over North America.

Kim, J., J. Kug, S. Jeong, D.N. Huntzinger, A.M. Michalak, C.R. Schwalm, Y. Wei, K. Schaefer (2017) "Reduced North American terrestrial primary productivity linked to anomalous Arctic warming", Nature Geoscience, doi:10.1038/ngeo2986.