The Carbon Cycle in the Tropics

Dunkeld, November 23rd 2010

John Grace School of GeoSciences, The University of Edinburgh, Crew Building, The Kings Buildings,

Edinburgh EH9 3JN, UK

What is the carbon cycle?

Global Carbon Project 2009

8.6 in 2008

Disturbance of the Cycle

Fossil Fuel CO2 Emissions

Friedlingstein et al. 2010, Nature Geoscience; Gregg Marland, Thomas Boden-CDIAC 2010

CO2 e

miss

ions

(Pg

C y-1

) CO2 em

issions (Pg CO2 y

-1)2009: Emissions:8.4±0.5 PgCGrowth rate: -1.3%1990 level: +37%

2000-2008Growth rate: +3.2%

2010 (projected):Growth rate: >3%

0.9 Gt carbon per year

biodiversity Pharmaceutical productsIndigenous people

water

8-9 Gt carbon per year

Fossil fuel emissions

Tro

pic

al

def

ore

stat

ion

The Undisturbed Forest may be:

•Stock of Carbon

•Sink of Carbon

Houghton et al (2001) Global Change Biology

Uncertainty in the storage of carbon in forest biomass

Grace et al (1995) Science 270, 778-80

Many rain forests are not only ‘stocks’ of carbon, but also remove carbon from the atmosphere at significant rates

Large Scale Biosphere Atmosphere Experiment in Amazonia

And

reae

et

al (

2002

) J

Geo

phys

Res

. 10

7

Evidence for a forest sink: eddy covariance, biomass inventory, flask analysis

All three sites appeared to be C- sinks

Grace & Malhi (2002) Nature

Lateral flows to the river, and then what?

Phillips et al (1998) Science 282, 439.

• Recent paper by phillips et al

2009 Update, from large inventory

Million ha ∆ tree carbon Gt

C&S America 786 0.62

Africa 632 0.44

Asia 358 0.25

Total 1777 1.31

Non-industrial ‘Sinks’ and ‘sources’ of carbon dioxide- 20 years of data

Roedenbeck et al 2003 Units: gC/m2/year

Fuxnet, to measure CO2 fluxes

Models +

Land cover,

Atmospheric concs Land

sink

466 flux towers