What does it mean for South Africa and the region?

Pedro M. S. MonteiroSouthern Ocean Carbon – Climate Observatory (SOCCO)

CSIR-CHPCCape Town

Why Oceans and Cryosphere?

SROCC Headline

• Climate regulation: (heat, CO2, water)• Ecosystems and services

• Food • Water• Renewable energy• Health and well being• Tourism• Trade and transport• Cultural

Assessment of the Present and the Future

• State of the Ocean and Cryosphere

• Physical Changes

• Impacts on Ecosystems

• Impacts on People and Ecosystem Services

• What could be done?

Synthesis of Physical and Ecosystem Impacts

Some initial considerations

• Coupled ocean - atmosphere continuum

Ocean in numbers: • 71% area, • 97% water, • > 95% of CO2,

25% of anthropogenic CO2 and > 90% excess heat

• Not just Climate Change but also Rate of Change• SROCC CC Scenarios RCP2.6 and RCP8.5• Assessment of CMIP5 not CMIP6 (AR6)

• Here Focus is on the Ocean – less so on Cryosphere

Cryosphere Projected Physical Changes: (High Confidence)

• Sensitive to emissions scenarios & committed trends

• Glacier loss: 18% RCP2.6 and 36% RCP8.5 – 2100 (Mont Blanc)

• Ice sheets: Antarctica > Greenland – more so 2100+

• River runoff – reduced by 10% by 2100

• Probability of ice free September 1% (1.5oC) and 10-35% for 2oC

Contemporary Ocean Physical Processes and Change

• Warming (heat uptake > 90% excess heat – 2x rate pre 1993• Marine heat waves: 2x frequency and 80% attributable to anthropogenic

• Stratification (warming and freshwater)• Separates the surface and deep ocean: nutrients and storage)• Ocean de-oxygenation (stratification)

• Sea level rise (trend and extreme events)• Acceleration – ice cap melting• Amplification of extreme events (storms)

• CO2 (uptake and release – 25% total emissions)• Ocean acidification – (carbonate chemistry – feedback)

Contemporary and future trends in ocean heat content and its impact on stratification

Most heat uptake is in the Southern Ocean

Northern Hemisphere ocean stratification sensitivity

RCP8.5

RCP2.6

The Contemporary Uptake of CO2 by the Ocean

Gregor et al., 2019

Anthropogenic CO2 storage in the ocean basins

Flux of CO2 between the ocean and the atmosphere. Net ~2.2PgCyr-1

Projected Changes: Ocean (High Confidence)

• Warming: • Heat Content: 2-4x RCP2.6 and 5-7x RCP8.5

• Heat waves

• CO2 uptake: CO2 flux feedback – accelerate atmospheric CO2

• Ocean Acidification: impact v sensitive to emission scenario

• Oxygen decline: 3 – 4% globally – regionally (59 – 80%) >> NB:

• AMOC: overturning circulation – slow down

• Benguela Upwelling

The collateral damage of ocean CO2

uptake is Ocean Acidification:

Rates are very regional depending on the carbonate content of the ocean

Very sensitive to the emission scenario: end of the century carbonate undersaturation

Contrast of the extent of undersaturation at end of the century (2081-2100) between RCP8.5 and RCP2.6

RCP8.5

RCP2.6

Projected trends to 2100 and regional character of those trends:

Ocean productivity and biogeochemical processes

pH

Oxygen %

Nitrate %

Primary Production %

Global and Regional Sea Level Rise• SLR doubled between 20th and 21st Centuries and ice sheet and

glaciers > thermal expansion –

• Greenland 2x and Antarctica 3 x (2007-2016 vs 1997-2006)

• Regional expression – land subsidence + SLR

• Extreme events: • extreme wave heights – Atlantic 1cm yr-1

• Storm surges (tropical and mid-latitude cyclones )

• Higher frequency of cat 4 and 5 hurricanes

Historical Sea level rise Long term projected sea level rise

Frequency of extreme event: human settlement, coastal infrastructure and ecosystem services

Has there been a national risk assessment for short term variability and long term sea level rise on coastal groundwater aquifers?

Some of the most important aquifers in South Africa are in the low lying coastal systems

Ecosystem Change

• Primary Production

• Food web ecology

• Fisheries

• Benthic ecology

• Very sensitive to emission scenarios

Poleward migration (±50km/decade)

Contemporary (1986-2005) and projected (2080-2100) changes in ocean primary and higher level production:

Coastal Ecosystems

• All coastal ecosystems – moderate to high risk (RCP2.6 v. high risk RCP8.5)• Multiple stressors – heat-OA-O2 – very high confidence• Benguela (SA) - Benguela (Namibia)

• Seagrass beds and Mangroves, Salt marshes:

• Blue Carbon – project losses 20 – 90% loss – SLR, warming, OA

• Salinization of estuaries: - local extinctions: aquifers

• Warm water corals – major losses even < 1.5oC (migration)

Projected Risks: People & Ecosystem Services

• Cryosphere:• Hydro-power, irrigation, • Floods, avalanches, subsidence, landslides, - infrastructure, cultural, tourism, recreation• Sea level rise

• Ocean – Ecosystems and Fisheries• Poleward geographic shifts (eg: west south coast fisheries in SA)• Multi-stressors – slows or prevents natural recovery• Krill – sea ice loss• Resources conflicts (high seas vs EEZ)• Seafood safety – health• Aquaculture and tourism

• Ocean Corals• Biodiversity, food provision, coastal protection

Possible Responses: Governance & Opportunities

• Adaptation – 1.5oC to 2oC (committed)

• Mitigation: critical to limit the long term damage and costs of adaptation –global policy (UNFCCC) – national economic transformation

• Governance: shift from resource centered to large ecosystem centered –CC exposing governance weaknesses (CT) - Stronger capacity to adapt

• Integrated Earth Systems and Development

Risk Assessment Models

Key Messages: Governance and Skillsand Partnerships

• Short Term: 1 – 5 Years• Strong global position on emissions reduction – 1.5oC – Paris 2.0

• Strengthen the capacity to adapt: HCD and Technological skills

• Strengthen the science – from resources science to systems science

• Observations and Predictions [major opportunities]

• Open integrated Data and data analytics

• Build on OCIMS, SARVA, Greenbook

• Medium – Long Term: 5 – 10 years• Strategic and innovative national policy [DEFF, DSI, Treasury]

• Strategic and innovative international ocean policy [High seas + EEZ]

What are science gaps that could influence the effectiveness of policy and its implementation?

• What do we know about the rates our different coastal / shelf regions will • Warm• Take up CO2 and develop ocean acidification• De-oxygenate• Do we understand the integrated / cumulative impact of these 3 climate drivers

• Ecosystem thresholds of abrupt change; tipping points • Are our MPAs suitable for the expected changes?• How will coastal aquifers be influenced by a 1 – 5m sea level rise• What does a 1 – 5m rise in sea level mean for the long term integrity of blue carbon• Do we have an effective short term – long term risk model?

DSI Climate Change Research NetworkContribution to Outcome 10 & to Bi-annual Cabinet Report on the state of climate change RDI

Purpose is to:

• convene national to regional scale strategic planning for the biophysical aspects of Climate Change research

• provide a platform for exchange of knowledge generated via CC related research

• ensure that CC knowledge generated is captured and communicated effectively

• convene expert opinion and communicate on specific climate events (e.g. El Nino, Western Cape Drought)

• execute tasks such as interpretation and assessment of global reports

• facilitate contributions to national climate change related events and communications or policy development processes(e.g. Global Change Conference, National Communications, Draft Policy (DEFF CCNAS))

DSI will mandate the ACCESS programme to further develop and execute this function

Thank youFB: Southern Ocean Carbon – Climate Observatory