Recent carbon trends and the fate of the natural sink Biosphere between sink & source 22.01.2008 Johannes Enssle GCM 2007 Student presentation Physical Fundamentals of Global Change
Content 1. Recent global carbon trends (2000-2006) 2. Global carbon budget from 1850 2006 3. Biosphere: between sink & source 4. Vulnerability and saturation of the terrestrial sink 5. Summary & Conclusions
Trajectory of Global Fossil Fuel Emissions CO 2 Emissions (GtC y -1 ) 10 9 8 7 6 Actual emissions: CDIAC Actual emissions: EIA 450ppm stabilisation 650ppm stabilisation A1FI A1B A1T A2 B1 B2 2005 2006 Observed growth rates 2000-2006 3.3% 5 1990 1995 2000 2005 2010 Raupach et al. 2007, PNAS, as in presentation of the GCP by Canadell 2007
Drivers of Anthropogenic Emissions Factor (relative to 1990) 1.5 1.4 World 1.5 1.4 1.3 1.3 1.2 1.2 1.1 1.1 1 1 0.9 0.9 0.8 F Emissions (emissions) 0.8 0.7 P Population (population) 0.7 0.6 g Wealth = G/P= per capita GDP 0.6 h Carbon = F/Gintensity of GDP 0.5 0.5 1980 1985 1990 1995 2000 2005 1980 Raupach et al 2007, PNAS, as adapted by Global Carbon Project (Canadell 2007)
Anthropogenic C Emissions: Land Use Change Carbon Emissions from Tropical Deforestation 1.80 1.60 1.40 Africa Latin America 2000-2006 1.5 Pg C y -1 (16% total emissions) Pg C yr -1 1.20 1.00 0.80 0.60 S. & SE Asia SUM 0.40 0.20 0.00 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Houghton, unpublished, Canadell 2007
2. The Global Carbon Budget (1850 2006)
Perturbation of Global Carbon Budget (1850-2006) 2000-2006 GtC/yr CO 2 flux (Pg C y -1 ) Sink Source extra-tropics deforestation tropics 1.5 Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS
Perturbation of Global Carbon Budget (1850-2006) CO 2 flux (Pg C y -1 ) Sink Source fossil fuel emissions deforestation 2000-2006 7.6 1.5 GtC/yr Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS
Perturbation of Global Carbon Budget (1850-2006) CO 2 flux (Pg C y -1 ) Sink Source fossil fuel emissions deforestation 2000-2006 7.6 1.5 GtC/yr Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS
Perturbation of Global Carbon Budget (1850-2006) CO 2 flux (Pg C y -1 ) Sink Source fossil fuel emissions deforestation atmospheric CO 2 2000-2006 7.6 1.5 GtC/yr 4.1 (45%) Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS
Perturbation of Global Carbon Budget (1850-2006) CO 2 flux (Pg C y -1 ) Sink Source fossil fuel emissions deforestation atmospheric CO 2 2000-2006 7.6 1.5 GtC/yr 4.1 (45%) ocean 2.2 (24%) Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS
Perturbation of Global Carbon Budget (1850-2006) CO 2 flux (Pg C y -1 ) Sink Source fossil fuel emissions deforestation atmospheric CO 2 land ocean 2000-2006 7.6 1.5 GtC/yr 4.1 (45%) 2.8 (30%) 2.2 (24%) Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS
The land cycle (1980s) 120 GPP - 60 AR - 55 HR - 4 Fires +1 GtC/yr NBP = 1GtC/y Source: IPCC 2001, TAR, Chapter 3.1 as estimated for the 1980s
3. Biosphere: between sink & source
Factors that Influence the Carbon Fluxes 1. The rate of CO 2 emissions. 2. The rate of CO 2 uptake and ultimately the total amount of C that can be stored by land and oceans: Land: CO 2 fertilization effect, soil respiration, N deposition fertilization, forest regrowth, woody encroachment, fire suppression Oceans: CO 2 solubility (temperature, salinity), ocean currents, stratification, winds, biological activity, acidification, Canadell et al. 2007, Springer; Gruber et al. 2004, Island Press
The Efficiency of Natural Sinks: Land and Ocean Fractions Land High variability No clear trend Vulnerable to climate change. Ocean Clear trend downwards Canadell et al. 2007, PNAS
4. Vulnerability and saturation of the terrestrial sink
Causes of the Declined in the Efficiency of the Ocean Sink Part of the decline is attributed to up to a 30% decrease in the efficiency of the Southern Ocean sink over the last 20 years. This sink removes annually 0.7 Pg of anthropogenic carbon. Credit: N.Metzl, August 2000, oceanographic cruise OISO-5 Le Quéré et al. 2007, Science The decline is attributed to the strengthening of the winds around Antarctica which enhances ventilation of natural carbon-rich deep waters. The strengthening of the winds is attributed to global warming and the ozone hole.
2003 Heat Wave in Europe The largest productivity crash of the past 100 years CO 2 Anomaly 30% Reduction of GPP 0.5PgC Net source of CO 2 4 years Equivalent C sink Ciais et al. 2005, Peylin et al., unpublished
Carbon Sinks from Forest Regrowth Years Source: Canadell 2007
Fertilization Effect of 550 ppm of CO 2 on Forest Productivity Source: Canadell 2007
Vulnerability of the Carbon Cycle in the 21 st Century Hot Spots of the Carbon-Climate System Land Permafrost HL Peatlands T Peatlands Veg.-Fire/LUC Oceans CH 4 Hydrates Biological Pump Solubility Pump Many Pools and Processes not included in Earth System models Field and Raupach 2004 Canadell et al. 2006
Vulnerability of the Carbon Cycle in the 21 st Century Hot Spots of the Carbon-Climate System 400 Pg C - frozen soils vulnerable to warming >400 Pg C - frozen sediments vulnerable to warming Land Permafrost HL Peatlands T Peatlands Veg.-Fire/LUC Oceans CH 4 Hydrates Biological Pump Solubility Pump Many Pools and Processes not in included in Earth System models Field and Raupach 2004 Canadell et al. 2006
Vulnerability of the Carbon Cycle in the 21 st Century Hot Spots of the Carbon-Climate System Photo: : Erkki Oksanen 400 Pg C cold peatlands vulnerable to climate change Land Permafrost HL Peatlands T Peatlands Veg.-Fire/LUC Oceans 100 Pg CHC 4 Hydrates tropical peatlands Biological Pump vulnerable to land use and Solubility Pump climate change Many Pools and Processes not in included in Earth System models Field and Raupach 2004 Canadell et al. 2006
Vulnerability of the Carbon Cycle in the 21 st Century Hot Spots of the Carbon-Climate System >500 Pg C vegetation and soils vulnerable to drought x land use x fire Land Permafrost HL Peatlands T Peatlands Veg.-Fire/LUC Oceans CH 4 Hydrates Biological Pump Solubility Pump Many Pools and Processes not in included in Earth System models Field and Raupach 2004 Canadell et al. 2006
Since 2000: Summary & Conclusions (i) The growth of carbon emissions from fossil fuels has tripled compared to the 1990s and is exceeding the predictions of the highest IPCC emission scenarios. The carbon intensity of the world s economy has stopped decreasing (after 100 years of doing so). The efficiency of natural sinks has decreased by 10% over the last 50 years (and will continue to do so in the future).
Summary & Conclusions (ii) All of these changes characterize a carbon cycle that is generating stronger climate forcing and sooner than expected. Protect current carbon pools, avoid deforestation! Be worried, be very worried! Use wood!
Sources Special Thanks to Joseph Canadell and the Team from the Global Carbon Project www.globalcarbonproject.org info@globalcarbonproject.org
The Global Carbon Balance (1990s) 1990s + 3.2 GtC/yr -1.7 GtC/yr Source: http://www.climatescience.gov/library/stratplan2
During the last two decades, biosphere was subsidizing our fossil-fuel emissions: 1980s 1990s 2000-2006 Fossil fuel + cement +deforest. 5.4 GtC/yr 6.4 GtC/yr 9.1 GtC/yr Annual atmospheric increase 3.3 GtC/yr 3.2 GtC/yr 4.1 GtC/yr Oceanic biosphere net sink -1.9 (35 %) -1.7 (27 %) -2.2 (24 %) Terrestrial biosphere net sink -0.2 ( 4 %) -1.4 (22 %) -2.8 (30 %) Total biosphere sink ~39 % ~49 % ~54% How come these big changes? How may the terrestrial sink change in future? Sources: adapted from IPCC 2001, TAR, Chapter 3.2 and Canadell 2007
Future Dynamics of C Sink Mechanisms 1. Are the sink mechanisms permanent features? Sink Strength time 3. Will they saturate? time 4. Will they disappear? Sink Strength Sink Strength time 2. Will they increase in strength? Increased Precipitation (depending on timing of warming) Sink Strength None Woody Encroachment Forest Regrowth CO2 fertilization Cropland Soils N deposition time
Summary & Conclusions (ii) Window of Opportunity becomes smaller and smaller. The current net C sink is not a permanent feature of the terrestrial biosphere but the result of an imbalance driven by past and present human activities. Some regions might turn into net-sources. Several tipping-points are possible.
Some key definitions Source: IPCC 2001, TAR