The Special Report on Global Warming of 1.5°C:
Impacts on ocean ecosystems and dependent societies
Dr Carol Turley OBE, Plymouth Marine Laboratory

IPCC SR1.5 side event , 4th December 11:30-13:00, COP24

The ocean has taken up 27% of carbon dioxide emissions:…. reducing atmospheric warming but causing ocean acidification

27% of CO2

Ocean acidification

The ocean is absorbing nearly all the heat energy fromglobal warming causing it to warm:
Ocean warming affects:• Ocean deoxygenation

93% of heat

• Sea level rise
• Ocean circulation and mixing hence
weather and extreme events (egstrength of hurricanes)

Ocean warming

The ocean receives all the water from melting ice:…. along with thermal expansion, resulting in sea level rise

100% of water

Sea level rise

Image credit: UKOA, Sea Surface ConsortiumWhere are we now?
Since pre-industrial times, human activities
have caused approximately:• 0.83°C of ocean warming• 30cm rise in sea level• 30% increase in ocean acidity• 2% loss of ocean oxygen (since 1960)• Increased frequency and duration of marine
heatwavesCredit: Seb Hennige

Where could we be by 2100?
With current rates of emissions human activities could
cause approximately:• 3.17°C of ocean warming• 86cm rise in sea level• 150% increase in ocean acidity• 3.5% loss of ocean oxygen (since 1960)• Even more intense and more frequentmarine heat waves
Credit: PML• Stronger storms/hurricanes

IPCC SR1.5: Risk level assessed between 1.5 and 2℃
Level of additional risk due toclimate changeRisk level assessed between 1.5 and 2℃

Image: Clara Manno

Image: Seb Hennige

Risk level assessed between 1.5 and 2℃?

Image: Dan Exton

What are the benefits to coral reefs of avoiding 2℃?

• 70-90% of the warmer watercoral reefs that exist today will
disappear when global
warming exceeds 1.5°C (veryhigh confidence)

Conclusions: What are the benefits of avoiding 2℃?
Limiting global warming to 1.5°C compared too2 C is projected to:•Reduce increases in ocean temperature aswell as associated increases in ocean acidityand decreases in ocean oxygen levels (highconfidence)•Reduce risks to marine biodiversity,fisheries, and ecosystems, and theirfunctions and services to humans (highconfidence)•

Expose 10.4 million fewer people to theimpacts of sea level globally in 2100

Societal Impacts• Impacts will be strongest in coastal
communities relying on marine
productivity and coastal protection• Many of these are highly vulnerable
and less able to adapt

The ocean is at the frontline of climate change… multiple stressors often occurring at the same time and place

Directly relevant to CO2 emissions and the UNFCCC [Article 2, UNFCCC]

Acidification+Warming+

Oxygen loss+

Sea Level Rise+

Marine heat waves+•

There are large benefits for ocean ecosystems and dependent societies ofavoiding 2℃•Impacts to the ocean brings clear, undisputable additional rationale forcountries to reduce CO2 emissions urgently and avoid 2℃

StormsoCan we stop global warming exceeding 1.5 C?
Multiple pathways modelled•The answer is yes but only with
unprecedented action on greenhouse gas
emissions over next 10 years•The report concludes that remaining at
1.5oC will require reducing CO2 emissions
by at least 45% by 2030, and net-zero by2050•By 2050, 70-85% of electricity globally willneed to be supplied by renewables

2050

Net ZeroYear•All scenarios require some direct captureof CO2 (i.e. needing innovation), as well aschanging patterns of production,consumption and lifestyleSR1.5 IPCC 2018

Thank you
ct@pml.ac.uk

More information see: www.oceansofimpact.global