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