Satellites reveal contrasting responses of regional climate to the widespread greening of Earth

Forzieri, Giovanni; Alkama, Ramdane; Miralles, Diego G.; Cescatti, Alessandro

doi:10.1126/science.aal1727

Cited by 323 publications

(257 citation statements)

References 52 publications

Supporting

Mentioning

239

Contrasting

Unclassified

Order By: Relevance

“…While semi-arid ecosystems of eastern Africa might play a smaller role than Australian ones (simply due to the difference in the area they cover), it would still influence the magnitude and trend of the global carbon sink by terrestrial ecosystems. Furthermore, Forzieri et al (2017) report the importance of the interplay between vegetation cover (in terms of leaf area index, LAI) and surface biophysics, finding an amplification of their relationship under extreme warm-dry and cold-wet years. Here we found that the ENSO contribution impacts the temporal LAI variability in eastern Africa considerably (Fig.…”

Section: Present-day Simulationsmentioning

confidence: 99%

“…A5), presenting a good example of such temporal variations that can play significant roles in modulating key vegetation-climate interactions. According to the analysis by Forzieri et al (2017), the magnitudes of differences we found in our study due to accounting for an intensified ENSO signal are influential on the surface energy balance components such as longwave outgoing radiation, latent heat flux, and sensible heat flux. Our findings reiterate the importance of considering ENSO contribution in carbon and energy budget calculations for any region that is influenced by ENSO variability.…”

Section: Present-day Simulationsmentioning

confidence: 99%

See 1 more Smart Citation

The influence of El Niño–Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario

et al. 2017

View full text Add to dashboard Cite

Abstract. The El Niño-Southern Oscillation (ENSO) is the main driver of the interannual variability in eastern African rainfall, with a significant impact on vegetation and agriculture and dire consequences for food and social security. In this study, we identify and quantify the ENSO contribution to the eastern African rainfall variability to forecast future eastern African vegetation response to rainfall variability related to a predicted intensified ENSO. To differentiate the vegetation variability due to ENSO, we removed the ENSO signal from the climate data using empirical orthogonal teleconnection (EOT) analysis. Then, we simulated the ecosystem carbon and water fluxes under the historical climate without components related to ENSO teleconnections. We found ENSO-driven patterns in vegetation response and confirmed that EOT analysis can successfully produce coupled tropical Pacific sea surface temperature-eastern African rainfall teleconnection from observed datasets. We further simulated eastern African vegetation response under future climate change as it is projected by climate models and under future climate change combined with a predicted increased ENSO intensity. Our EOT analysis highlights that climate simulations are still not good at capturing rainfall variability due to ENSO, and as we show here the future vegetation would be different from what is simulated under these climate model outputs lacking accurate ENSO contribution. We simulated considerable differences in eastern African vegetation growth under the influence of an intensified ENSO regime which will bring further environmental stress to a region with a reduced capacity to adapt effects of global climate change and food security.

show abstract

Section: Present-day Simulationsmentioning

confidence: 99%

Section: Present-day Simulationsmentioning

confidence: 99%

The influence of El Niño–Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario

et al. 2017

View full text Add to dashboard Cite

show abstract

“…In return, changes in vegetation dynamics may affect local climate via several biophysical processes, leading to positive or negative feedback in the land-climate system [16,17]. For instance, Forzieri, G. et al [18] showed that positive trend in LAI contributed to the warming of boreal zones and to a cooling in arid regions. The impacts of climate change on the vegetation dynamics and their potential interactions have been increasingly studied, given their possible benefits in carbon sequestration [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Satellite Leaf Area Index: Global Scale Analysis of the Tendencies Per Vegetation Type Over the Last 17 Years

et al. 2018

View full text Add to dashboard Cite

Abstract:The main objective of this study is to detect and quantify changes in the vegetation dynamics of each vegetation type at the global scale over the last 17 years. With recent advances in remote sensing techniques, it is now possible to study the Leaf Area Index (LAI) seasonal and interannual variability at the global scale and in a consistent way over the last decades. However, the coarse spatial resolution of these satellite-derived products does not permit distinguishing vegetation types within mixed pixels. Considering only the dominant type per pixel has two main drawbacks: the LAI of the dominant vegetation type is contaminated by spurious signal from other vegetation types and at the global scale, significant areas of individual vegetation types are neglected. In this study, we first developed a Kalman Filtering (KF) approach to disaggregate the satellite-derived LAI from GEOV1 over nine main vegetation types, including grasslands and crops as well as evergreen, broadleaf and coniferous forests. The KF approach permits the separation of distinct LAI values for individual vegetation types that coexist within a pixel. The disaggregated LAI product, called LAI-MC (Multi-Cover), consists of world-wide LAI maps provided every 10 days for each vegetation type over the 1999-2015 period. A trend analysis of the original GEOV1 LAI product and of the disaggregated LAI time series was conducted using the Mann-Kendall test. Resulting trends of the GEOV1 LAI (which accounts for all vegetation types) compare well with previous regional or global studies, showing a greening over a large part of the globe. When considering each vegetation type individually, the largest global trend from LAI-MC is found for coniferous forests (0.0419 m 2 m −2 yr −1 ) followed by summer crops (0.0394 m 2 m −2 yr −1 ), while winter crops and grasslands show the smallest global trends (0.0261 m 2 m −2 yr −1 and 0.0279 m 2 m −2 yr −1 , respectively). The LAI-MC presents contrasting trends among the various vegetation types within the same pixel. For instance, coniferous and broadleaf forests experience a marked greening in the North-East of Europe while crops and grasslands show a browning. In addition, trends from LAI-MC can significantly differ (by up to 50%) from trends obtained with GEOV1 by considering only the dominant vegetation type over each pixel. These results demonstrate the usefulness of the disaggregation method compared to simple ones. LAI-MC may provide a new tool to monitor and quantify tendencies of LAI per vegetation type all over the globe.

show abstract

“…Forests cover more than~42 million km 2 in the Northern Hemisphere (~30% of the land surface), and affects local climate mainly through biophysical processes [1][2][3][4]. The biophysical processes (e.g., albedo, evapotranspiration rate (ET) and surface roughness) all have effects on surface energy fluxes, which causes the effects of forests on local climates to be complicated [5].…”

Section: Introductionmentioning

confidence: 99%

Local Effects of Forests on Temperatures across Europe

Tang

Zhao

2018

Remote Sensing

View full text Add to dashboard Cite

Forests affect local climate through biophysical processes in terrestrial ecosystems. Due to the spatial and temporal heterogeneity of ecosystems in Europe, climate responses to forests vary considerably with diverse geographic and seasonal patterns. Few studies have used an empirical analysis to examine the effect of forests on temperature and the role of the background climate in Europe. In this study, we aimed to quantitatively determine the effects of forest on temperature in different seasons with MODIS (MODerate-resolution Imaging Spectroradiometer) land surface temperature (LST) data and in situ air temperature measurements. First, we compared the differences in LSTs between forests and nearby open land. Then, we paired 48 flux sites with nearby weather stations to quantify the effects of forests on surface air temperature. Finally, we explored the role of background temperatures on the above forests effects. The results showed that (1) forest in Europe generally increased LST and air temperature in northeastern Europe and decreased LST and air temperature in other areas; (2) the daytime cooling effect was dominate and produced a net cooling effect from forests in the warm season. In the cold season, daytime and nighttime warming effects drove the net effect of forests; (3) the effects of forests on temperatures were mainly negatively correlated with the background temperatures in Europe. Under extreme climate conditions, the cooling effect of forests will be stronger during heatwaves or weaker during cold spring seasons; (4) the background temperature affects the spatiotemporal distribution of differences in albedo and evapotranspiration (forest minus open land), which determines the spatial, seasonal and interannual effects of forests on temperature. The extrapolation of the results could contribute not only to model validation and development but also to appropriate land use policies for future decades under the background of global warming.

show abstract

Satellites reveal contrasting responses of regional climate to the widespread greening of Earth

Cited by 323 publications

References 52 publications

The influence of El Niño–Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario

The influence of El Niño–Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario

Satellite Leaf Area Index: Global Scale Analysis of the Tendencies Per Vegetation Type Over the Last 17 Years

Local Effects of Forests on Temperatures across Europe

Contact Info

Product

Resources

About