Climate Change: Impacts and Responses Topic 6: Impacts of Climate Change topic 6 – Impacts of climate change

 Why be concerned about climate change impacts?  What impacts have been observed to date?  What impacts are likely in the future?  Summary Topic outline UN image, Logan Abassi

Learning outcomes for this topic  Demonstrate an understanding of the major risks arising from climate change  Discuss observed climate impacts to date  Name projected impacts for a range of environments and sectors  Demonstrate an understanding of why attribution of observed impacts can be problematic  Demonstrate and understanding of why uncertainty exists over impact projections  Discuss possible regional impacts for Africa

Section 1: Why be concerned about climate change impacts?

 Risks to unique and threatened systems  Risks from extreme climate events  Unfair distribution of climate impacts  Increasingly negative impacts with higher mean temperatures  Risks from large-scale discontinuities Outline: Why be concerned about climate impacts?

Risk  The potential for consequences where something of human value (including humans themselves) is at stake and where the outcome is uncertain. Risk is often represented as probability of occurrence of hazardous events or trends multiplied by the consequences if these events occur. Definition of risk IPCC AR5 WGII, Glossary

Risks to unique and threatened systems e.g. Reptiles and amphibians are moving upslope in Tsaratanana Massif (Madagascar) Calumma tsaratananensis,. credit: American Museum of Natural History Raxworthy et al., 2008

Risks from extreme climate events Woman in the Sahel terracing the soil to control for erosion. UN Photo/John Isaac e.g. in Africa - reduced crop productivity associated with heat and drought stress

Unfair distribution of impacts Image: FAO e.g. productivity losses will occur in areas already at temperature maximum

As temperatures rise further, aggregate impacts become increasingly negative everywhere Image: NRC

Risks from future large scale discontinuities Image: NASA

Risks of climate related impacts IPCC AR5 WGII, 2014, FigTS-1

Section 2: Observed impacts

 Observed global impacts  Snow, ice and frozen ground  Hydrological systems  Terrestrial biological systems  Marine and freshwater systems  Human systems Outline: Observed impacts

1 Observed global impacts IPCC 2014 SPM2 WGII

Snow, ice and frozen ground All images : NASA Columbia Glacier, Alaska Muir Glacier, Alaska Iceberg separating from Pine Island Glacier, Antarctica  Shrinking mountain glaciers  Declining Arctic sea ice cover  Declining areas of frozen ground in summer  Reduced snow cover in NH winter  Increasing freshwater release to ocean

 Trends in rainfall are complicated  Temperature trends are impacting large lakes Hydrological systems Image: NASA Image: IPCC 2007 Lake Tanganyika from space Historical and recent measurements from Lake Tanganyika

Plant and animal species are likely to respond to climate change in various ways. Responses may include changes to: Timing of life cycle events Boundaries of inhabited ranges Population density Morphology Local or global extinction. Terrestrial biological systems Creative commons Image: A. Barra

13 Marine and freshwater biological systems IPCC 2014 WGII Fig 6.8

Human and managed systems IPCC WGII 2014 (adapted from Fig 7-2)

Section 3: Future climate impacts

 Future climate-related risks  Future sectorial risks: Freshwater resources Marine systems Food production systems and food security Terrestrial ecosystems Coastal and low-lying areas Global economic impacts Human health Human security  Regional impacts: Africa Outline: Future climate impacts

Risks of climate change IPCC AR5 WG II 2014; Box TS5, Fig1

Freshwater resources IPCC WGII 2014,Fig 3.4

Marine systems IPCC AR5 WGII 2014, Fig6-14

Summary of projected changes in crop yields, due to climate change over the 21st century. The figure includes projections for different emission scenarios, for tropical and temperate regions, and for adaptation and no-adaptation cases combined. Food production system and food security PERCENTAGE OF YIELD PROJECTIONS – -5% -5 – -10% -10 – -25% -25 – -50% -50 – -100% 50 – 100% 25 – 50% 10 – 25% 5 – 10% 0 – 5% Range of Yield Change Increase in Yield Decrease in Yield IPCC AR5, 2014 WGII, Fig 7.-5

Terrestrial ecosystems Soil erosion and deforestation – Guatemala; UN Photo/John Olsson

Coastal and low-lying areas UN Photo/Logan Abassi

Global economic impact UN Photo/Kibae Park

Human health UN Photo/John Isaac

Human security IPCC AR WGII, Fig 12-3

 Far-reaching impacts in human and natural systems  Predominantly negative impacts, especially if global mean temperature increase exceeds 2°C  Impacts likely to alter ecosystems  Floods and droughts likely to increase, with increasing risks of water pollution and incidence of water-related diseases  Coastal areas likely to suffer erosion, flooding, salt-water intrusion  Negative health impacts could occur, especially heat-related deaths, malnutrition and transmission of some diseases Summary of projected impacts

Africa: key risks from climate change IPCC AR5 2014, WGII, Chapter 22

 Observed warming trend higher than the global average  Rainfall highly variable across Africa: West Africa has seen a decline Increase along Guinean coast No long term trends in precipitation in the rest of Africa  Increased rainfall inter-annual variability Africa observed impacts

 Mean temperature increase will exceed 2°C by mid to end of this century.  Precipitation projections more uncertain  Shifts in ecosystems  Water stress  Food security Africa projected impacts

 Reasons for concern about impacts include: damage to ecosystems, extreme weather events, unfair impacts distribution, sudden abrupt climate change.  Observed impacts to date include changes to glaciers, crops and ecosystems on land, in freshwater and oceans.  Future impacts are potentially far-reaching. Impacts are likely but projections are inevitably uncertain. Summary

IPCC (2007). Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment. Report of the Intergovernmental Panel on Climate Change, [M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, C.E.Hanson, (eds)]. Cambridge University Press, Cambridge, UK, 976pp IPCC (2014). Climate Change 2014: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fifth Assessment. Report of the Intergovernmental Panel on Climate Change, [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA Raxworthy et al., (2008). Extinction vulnerability of tropical montane endemism from warming and upslope displacement: a preliminary appraisal for the highest massif in Madagascar. Global Change Biology (2008) 14, 1703–1720. OnlineOpen: This article is available free online at synergy.com References

End of Topic 6: Impacts of Climate Change Next Topic: Adaptation