Climate change: The science and the risks
Prof Guy F MidgleyNational Biodiversity Institute
University KwaZulu Natal LTAS project lead, IPCC lead author
NATIONAL CLIMATE CHANGE RESPONSEADAPTATION IMPLEMENTATION
• Phenomenal increase in wealth and human well-being, esp. wealthiest
• Urbanisation, often coastal• Green revolution, and deforestation• Globalisation, trade, information • Democratisation, environmentalism• Population ~9 billion peak
• Highest CO2 level in 5 million years,projected higher than 20 million years by end of century
• Associated pollution• Ocean acidification• “Greening”, esp. arid and semi-arid
ecosystems
• Highest temps in > 2000 years• Warmer oceans• Rising sea level, melting ice and permafrost• Increasing rainfall intensity• Increasing high temperature and rainfall
extremes• Changes in ecology
Anthropogenic C Emissions: Fossil Fuel
Raupach et al. 2007, PNAS; Canadell et al 2007, PNAS
1990 - 1999: 1.3% y-1
2000 - 2006: 3.3% y-1
0
1
2
3
4
5
6
7
8
9
1850 1870 1890 1910 1930 1950 1970 1990 2010
Fo
ssil
Fu
el E
mis
sio
n (
GtC
/y) Emissions
280
300
320
340
360
380
400
1850 1870 1890 1910 1930 1950 1970 1990 2010
1850 1870 1890 1910 1930 1950 1970 1990 2010
2006 Fossil Fuel: 8.4 Pg C[2006-Total Anthrop. Emissions:8.4+1.5 = 9.9 Pg]
Greenhouse effect observed from space
Harries, 2001
www.mtholyoke.edu
Arctic sea ice
Permafrost
Local impacts of permafrost melt
Sea level rise
More CO2
More heat
More evaporation
More water vapour
11Trenberth et al 2004 Climate Dynamics
More evaporation, more rain
12Held & Soden 2006; J Climate
http://www.earth-policy.org/indicators/C54
Sheffield et al 2012 naturev491
Drought trends 1950-2010
Trend in Sea
Surface Temp 1982-2005
Rouault 2007
South African land based measurements show warming (1960 to 2003)
Trend in Max. TemperatureTrend in TemperatureTrend in Min. Temperature
Significant Positive trendNon-significant Positive trend
Significant Negative trendNon-significant Negative trend
No trend
Trend in Max. TemperatureTrend in TemperatureTrend in Min. Temperature
Significant Positive trendNon-significant Positive trend
Significant Negative trendNon-significant Negative trend
No trend
Adapted from Kruger and Shongwe (2004)
Limpopo, annual rainfall trends
Total rainfall # raindays
1955 Eastern Cape Courtesy Timm Hoffman (U Cape Town)
2010 Eastern Cape. Courtesy Timm Hoffman ( U Cape Town)
LGM 180 ppm
Pre-industrial260 ppm
Ambient375 ppm
Above-ambient450 ppm
Acacia sieberiana
Arid regions where vegetation cover has increased ~10% since 1980’s
Donahue et al in press
Linking mitigation to impacts/adaptation
Mitigation impact on temperature change
IGSM Scenarios(Sokolov et al., 2009, and Webster et al., 2009)
Zone 4
Zone 3
Zone 1
Zone 6
Zone 5
Zone 2
Zones used
• Changes average for the period 2045-2050
-8 -6 -4 -2 0 2 4 60
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Change in Precipitation
UCE
L1s
Zone 1 - Annual
-10 -5 0 5 100
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Change in Precipitation
UCE
L1s
Zone 2 - Annual
-10 -5 0 5 100
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Change in Precipitation
UCE
L1s
Zone 3 - Annual
-8 -6 -4 -2 0 2 4 60
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Change in Precipitation
UCE
L1s
Zone 4 - Annual
-10 -5 0 5 10 150
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Change in Precipitation
UCE
L1s
Zone 5 - Annual
-8 -6 -4 -2 0 2 4 60
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Change in Precipitation
UCE
L1s
Zone 6 - Annual
Mitigation impact on rainfall change, ~2050
Mitigation impact on temperature change~2050
0.5 1 1.5 2 2.5 3 3.5 40
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Change in Temperature
UCE
L1s
Zone 1 - Annual
0.5 1 1.5 2 2.5 3 3.50
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Change in Temperature
UCE
L1s
Zone 2 - Annual
0.5 1 1.5 2 2.5 3 3.5 40
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Change in Temperature
UCE
L1s
Zone 3 - Annual
0.5 1 1.5 2 2.5 3 3.50
0.5
1
1.5
2
Change in Temperature
UCE
L1s
Zone 4 - Annual
0.5 1 1.5 2 2.5 3 3.50
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Change in Temperature
UCE
L1s
Zone 5 - Annual
0.5 1 1.5 2 2.5 3 3.50
0.5
1
1.5
2
Change in Temperature
UCE
L1s
Zone 6 - Annual
Integrated Analytical Framework
Agriculture (food, exports)
Local economy (growth, jobs,
welfare, inequality)
Global change (temperature, rainfall,
fossil fuel prices)
Rivers (runoff, streamflow)
Flooding (frequency, severity)
Sea level rise (land loss, salination)
Energy (hydropower)
Infrastructure (roads, ports, houses)
Mozambique Effects of Global/Local Mitigation Policy
Change in total value-added (GDP)
30
20
10
0
40
50
60 Unconstrained Emissions
-15% -10% -5% 0%Average deviation from baseline, 2046-
2050
5%
Den
sity
L1 Stablization (with UE prices)
L1 Stabilization (with L1S prices)
Main risks for South Africa?• Observations
– increasing mean and maximum temperatures (high confidence)– fewer rain days, no change in total rainfall (medium confidence)– increasing wildfire risk (high confidence)– plant cover increasing due to CO2 fertilization (medium confidence)– costs of extreme events 2000-2009 at least ~R1 billion per annum (high
confidence), trends not known• Future risks and opportunities
– Extreme climate events – low-lying, flood plain, coastal settlements– Water – drought and flood risk, allocations – Land cover change – vegetation thickening – Human health and discomfort – labour, aged, infants, informal housing,
vector-borne diseases– Agriculture and food supply – intensive (livestock, grains, vegetables and
fruit), extensive, small scale subsistence– Transport infrastructure – vulnerability, increased specification– Opportunities – using ecosystems/biodiversity to reduce risks
Can ecosystems be managed for climate change adaptation?
Can this be incentivised?
Wetland intact Wetland degrading Wetland degraded
~1940 ~1960 ~2000
+109589
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