Dynamic changes in terrestrial net primary production and their effects on evapotranspiration

Zhi Li,Yaning Chen,Gonghuan Fang,Yang Wang

doi:10.5194/hess-20-2169-2016

Abstract

Abstract. The dramatic increase of global temperature since the year 2000 has a considerable impact on the global water cycle and vegetation dynamics. Little has been done about recent feedback of vegetation to climate in different parts of the world, and land evapotranspiration (ET) is the means of this feedback. Here we used the global 1 km MODIS net primary production (NPP) and ET data sets (2000–2014) to investigate their temporospatial changes under the context of global warming. The results showed that global NPP slightly increased in 2000–2014 at a rate of 0.06 PgC yr−2. More than 64 % of vegetated land in the Northern Hemisphere (NH) showed increased NPP (at a rate of 0.13 PgC yr−2), while 60.3 % of vegetated land in the Southern Hemisphere (SH) showed a decreasing trend (at a rate of −0.18 PgC yr−2). Vegetation greening and climate change promote rises of global ET. Specially, the increased rate of land ET in the NH (0.61 mm yr−2) is faster than that in the SH (0.41 mm yr−2). Over the same period, global warming and vegetation greening accelerate evaporation in soil moisture, thus reducing the amount of soil water storage. Continuation of these trends will likely exacerbate regional drought-induced disturbances and point to an increased risk of ecological drought, especially during regional dry climate phases.

Highlights

Organizations such as the Intergovernmental Panel on Climate Change (IPCC) and the World Meteorological Organization (WMO) have reported that the past decade was the warmest on record
We investigated the following three major points of interest: (1) whether the high variability temperature of the past decade continued to increase net primary production (NPP), or if different climate constraints were at play; (2) why NPP variations in the Northern and Southern hemispheres respond differently to climate changes; and (3) what the spatiotemporal variation of NPP is, and what its effects are on ET
While NPP in most parts of the Northern Hemisphere (NH) increased (Fig. 1a), it decreased in most parts of the Southern Hemisphere (SH) (Fig. 1b)

Summary

Introduction

Organizations such as the Intergovernmental Panel on Climate Change (IPCC) and the World Meteorological Organization (WMO) have reported that the past decade was the warmest on record. How global vegetation is responding to the changing climate is not well established. From 1982 to 1999, climatic changes enhanced plant growth globally, especially in the northern middle and high latitudes (Nemani et al, 2003); this was followed in 2000–2009 by a droughtinduced reduction in global NPP (Zhao and Running, 2010). Gang et al (2015) projected the dynamics of NPP in response to future anticipated climate changes in the 2030s, 2050s, and 2070s, and found that global NPP would show an increasing trend. NPP at high latitudes in the Northern Hemisphere (NH) would likely be more sensitive to future climate change.

Methods

Results

Discussion

Conclusion