Tropical Forests in a 4oC+ World Yadvinder Malhi Environmental Change Institute School of Geography and the Environment Oxford University, UK

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1 9/29/29 Tropical Forests in a 4oC+ World Yadvinder Malhi Environmental Change Institute School of Geography and the Environment Oxford University, UK 1

2 Projected temperature change under A2 emissions scenario IPCC 27 2

3 Rate of warming of land regions, N Temperate Tropical S Temperate o C decade -1 2 Temperature Change (oc) Latitude ( o ) Projected warming in land regions by late 21 st century under A2 emissions scenario Mean of 15 IPCC Global Climate Models Temperature anomaly o C) Latitude ( o )

4 Modelled and observed rates of change Rate of change ( o C/decade) Mean rate of warming of Amazonia at end of last ice age.1 o C decade -1 Bush et al. 24, Science Latitude ( o ) Modelled rates: late 2 th to late 21 st century, A2 emissions scenario Observed rates: The warmest parts of the planet are warming and will continue to warm fast How will tropical organisms and ecosystems respond to this warming? 4

5 Tropical species have narrower current thermal tolerances Insects Lizards Deutsch C. A. et.al. PNAS 28 Tewksbury et.al. Science 28 Predicted impact of warming on the thermal performance of ectotherms in 21 Deutsch C. A. et.al. PNAS 28;15:

6 9/29/29 All these changes in fitness will be imposed with varying intensity on nodes of the tangled web Phillips et al. 22, Nature 6

7 Responses to potential decline in performance Responses of organisms, species and ecosystems will be complex do not simply map onto decline in performance. Plasticity of physiological thresholds and acclimation of physiology Rapid evolutionary adaptation Behavioural change timing and spatial distribution of activities Migration and dispersal In all cases the RATEof change is probably the greatest challenge Latitudinal Temperature Gradient ( o C/ o ) Spatial gradients in temperature are shallow in the tropics N Temperate Tropical S Temperate km o C Latitude ( o ) 7

8 Horizontal temperature gradient ~ 38 km o C -1 Vertical temperature gradient ~.18 km o C -1 On current rates of warming, the required rates of migration to remain in the same temperature regime are Horizontal migration rate ~ 116 km decade -1 (32 m day -1 ) Vertical migration distance ~ 55 m decade -1 Observed tree migration rate in Andes ~ m decade -1 Feeley et al., submitted to Global Change Biology Species responses to climatic warming Mountains may be refugia (2, 4) 5 traps (3, 5) or a chance (6) Ch Körner 8

9 Soares et al. 26. Nature The greatest threat climate change and deforestation 9

10 25 Business-as-Usual Scenario: Deforested 2.7 million km 2 Forest 3.3 million km 2 Non-forest 1.5 million km 2 32 Pg C Soares et al. 26 Nature 25 Governance Scenario: Deforested 1.7 million km 2 Forest 4.4 million km 2 Non-forest 1.5 million km 2 17 Pg C Soares et al. 26 Nature 1

11 Precipitation IPCC Fourth Assessment Report 11

12 A simple rainfall biogeography of Amazonia Seasonal Forest Rainforest Savanna Malhiet al., 29 Exploring the likelihood and mechanism of a climate-change induced dieback of the Amazon rainforest, Proceedings of the National Academy of Sciences. Adjusted climate model predictions for Amazonia (A2 Scenario) Seasonal Forest Rainforest Savanna Malhi et al. 29, Exploring the likelihood and mechanism of a climate-change induced dieback of the Amazon rainforest, Proceedings of the National Academy of Sciences, 12

13 Effects of temperature and CO 2 on water use by forests 6 Evapotranspiration (mm day -1 ) Low T Low CO2 Low T High CO2 High T Low CO2 High T High CO2 UK MOSES-TRIFFID Model Low CO 2 = 28 ppm, High CO 2 = 85 ppm Change in T = +4.5 o C Malhi et al. 29, Exploring the likelihood and mechanism of a climate-change induced dieback of the Amazon rainforest, Proceedings of the National Academy of Sciences, 6 Evapotranspiration (mm day -1 ) Savanna? Seasonal Forest Rainforest Savanna Low T Low CO2 Low T High CO2 High T Low CO2 High T High CO2 13

14 The role of fire Forest fires in eastern Acre State (Brazil) during the 25 Amazonian drought Aragão et al, Spatial patterns and fire response of recent Amazonian droughts, Geophysical Research Letters. (27) 14

15 No burn First burn Barlow J & Peres CA (28) Fire-mediated dieback and compositional cascade in an Amazonian forest. Philos Trans R Soc London Second or third burn 6 Evapotranspiration (mm day -1 ) Fire-prone forests Seasonal Forest Rainforest Savanna Low T Low CO2 Low T High CO2 High T Low CO2 High T High CO2 15

16 Interactions between potential deforestation and climate change Business as usual deforestation by 25 High governance deforestation by 25 Malhi et al. (28) Climate change, deforestation, and the fate of the Amazon, Science. Modelled effect of conversion to soybean on rainfall in Eastern Amazonia Relative Precipitation (p/p ) Amazonia - SOYBEAN Area: East/Northeast DJF MAM JJA SON.6 % 2% 4% 6% 8% 1% Deforestation Area (%) Sampaio et al. 28 Journal of Geophysical Research 16

17 Eastern Amazonia 21 Deforestation warming: + 5 o C Greenhouse warming: o C Eastern Amazonia 21 Deforestation warming: + 1 o C Greenhouse warming: o C 17

18 Maintaining tropical forest area is a strategy for adapting to climate change Minimise contact points between forest fragments and fire zones Lower surface temperatures because of evaporative cooling of near-surface area Maintenance of shade habitats Maintenance of dry season rainfall Maintain connectivity for species migration to cooler or wetter refugia Forest protection is also a component strategy for mitigation of global climate change. This presents an opportunity Reduced Emissions from Deforestation and Forest Degradation (REDD) 18

19 Conclusions Rapid change is coming to tropical forests climate change and deforestation present a dangerous synergy. We are only beginning to comprehend the impacts of this change Rapid climate change is reweaving the web of life. We do not yet know what this implies for risk of extinction or ecosystem shift New opportunities for tropical forest conservation are emerging through recognition of their value in climate change mitigation and adaptation we are only beginning to grasp the challenge that these opportunities will bring. 19