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The Greening Earth Prof. Ranga B. Myneni Department of Earth & Environment Boston University USA [email protected] http://cliveg.bu.edu/ Probing Vegetation Conference From Past to Future July 45, 2013 Antwerp, Belgium 1/12

Ranga Myneni

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Page 1: Ranga Myneni

The  Greening  Earth  

Prof.  Ranga  B.  Myneni    

Department  of  Earth  &  Environment  Boston  University  

USA    

[email protected]  http://cliveg.bu.edu/  

Probing  Vegetation  Conference  From  Past  to  Future  

July  4-­‐5,  2013  Antwerp,  Belgium  

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“La  Belle  Saison”  René  Magritte  

What  Happens  When  Radiation  from  the  Sun  Strikes  a  Green  Leaf?  

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Monitoring  Vegetation  From  Space  

Image  Credit:  Satellite  Imaging  Corp.  

Pigments  in  green  leaves  (notably  chlorophyll)  absorb  strongly  at  red  and  blue  wavelengths  (approximately  less  than  0.7  microns).      Lack  of  such  absorption  at  near-­‐infrared  wavelengths  results  in  strong  scatter  from  leaves  (approximately  greater  than  0.8  to  1.2  microns).      The  “greenness”  of  the  ground  is  simply  the  difference  between  these  two  measurable  quantities  (appropriately  normalized).      NDVI  =  (NIR-­‐RED)  /  (NIR+RED)      NDVI  =  Normalized  Difference  Vegetation  Index    

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Average  Greenness  Of  Our  Planet  

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“Wooded  Landscape”  Sir  Anthony  Van  Dyck  

How  Did  The  Greenness  of  Our  Planet  Change?  

•  Satellite  Vegetation  Greenness  Data  (AVHRR)  •  July  1982  to  December  2012  (30+  years)  •  8x8  kilometer  pixels  •  2  Views  a  month  

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The  Greening  Earth  

Annual  Gross  Productivity  =  Growing  Season  Total  Vegetation  Greenness  Statistically  signihicant  (p<0.1)  based  on  Vogelsang’s  t-­‐PS_T  test  

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By  How  Much  did  the  Earth  Green  over  the  Past  30  years?  

•  31%  of  the  global  vegetated  area  greened    •  This  greening  translates  to  a  14%  increase  in  gross  productivity    •  The  greening  is  seen  in  all  vegetation  types  

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“L’Eveil  de  la  Foret”  Paul  Delvaux  

Why  did  Our  Planet  Green?  

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•  42%  can  be  attributed  to  relaxation  of  climatic  constrains  to  plant  growth  

•  57%  to  “other”  anthropogenic  factors    •  1%  unknown  

Why  did  Our  Planet  Green?  

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Is  this  a  Good  or  Bad  Development?  

Ice  core  record  from  Vostok,  Antarctica:  Antarctic  temperature  and  CO2  levels    Credit:  Siegenthalter  et  al.  (2005)  

Credit:  CLS/Cnes/Legos    

Global  Mean  Sea  Level  Rise  

Credit:  NASA  GISS  

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“Winterlandschap  met  Schaatsers  en  een  Vogelval”  Pieter  Bruegel  de  Oude  

Elfstedentocht?  We  Can  Forget  it!  

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The  Arctic  could  be  ice-­‐free    in  about  30-­‐50  years!  

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“Peasants  Merry-­‐Making”  David  Teniers  de  Jonge  

What  Can  We  Do?  •  Monitor  Changes:  Cost-­‐effectively  and  accurately  with  Satellite  Sensors  •  Action:  Inform  the  Public  &  Policy  Makers    •  Hope:  We  can  be  as  happy  as  these  David  Teniers  II’s  “Peasants”  

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