World Oceans Day 3: climate change adaptation and mitigation

World Oceans Day is on the 8^th of June. Since 1992, the United Nations has taken this day to celebrate all the ways that the ocean supports our lives and livelihoods, and to highlight the significant challenges we face in ocean conservation.

To mark this event, and key international climate change talks later this year, our marine team is bringing you a series of blogs to celebrate the vast big blue that surrounds us, while learning more about its role in climate change mitigation and adaptation. 

By Irene Llabres Pohl, Technical Advisor Mountains to Sea; and Helen Kettles, Technical Advisor Marine Ecosystems

With fundamental changes being observed throughout New Zealand’s and the world’s oceans (see previous blogs), it is pressing for us to better understand and devise strategies to safeguard the health of the ocean on which human well being depends.

Climate change impacts are often tricky to disentangle from the many other pressures we put on the environment, let alone manage. But we must try! We’re working to future-proof all the work DOC does in the marine space, in line with our Climate Change Adaptation Action Plan. The ocean does provide us with some phenomenal opportunities to put us in a better position to face climate change. Here a few sure-win action:

Nature-based solutions

Unsurprisingly, nature knows best and will have the best chances to adapt if we leave it be. So called nature-based solutions involve working with nature through protection and restoration to maintain or re-establish natural resilience to cope with change. Because nature-based solutions are about working with nature to manage climate change impacts, they simultaneously provide other benefits such as biodiversity protection. In light of the ongoing biodiversity loss crisis, nature-based solutions are our best allies.

What are some of these solutions?

Marine protected areas

Marine protected areas (MPAs) can work to restore and  protect the natural functioning of marine ecosystems and with it the many ways us humans benefit from it (food, medicine, and wellbeing) by limiting extractive uses. While they cannot stop external pressures such as pollution, we manage those through other tools, they provide species, habitats and ecosystems with a safe haven from direct impacts. The thinking is that by protecting marine ecosystems they will be healthier and more resilient to climate change impacts.

Marine reserves provide the highest level of protection in New Zealand but other tools at our disposal include fisheries closures and customary management approaches. Learn more about the marine reserves DOC manages.

Restoration and protection of coastal ecosystems

Coastal ecosystems including estuaries are at major threat from climate change due to sea-level rise, marine heat waves, and extreme weather events. They are also amongst some of our most degraded ecosystems, which limits their capacity to act as floodwater protection, water filters and fish nurseries. In light of climate change, protecting and restoring coastal ecosystems such as seagrass meadows, saltmarsh (a shout out to all the community groups actively doing this), and shellfish beds (another shout out to the great people at Revive our Gulf), is key towards building coastal resilience.

Blue carbon

Blue carbon is the carbon stored naturally by coastal and marine ecosystems. Simply put, carbon taken out of the atmosphere means less green-house effect. Coastal ecosystems such as seagrass, mangroves and saltmarshes are, though relatively small in extent, true blue carbon superstars, representing about 50% of the marine carbon sink. Mangroves for example can store up to 10 times as much carbon as the same area of land-based forests. This is because they don’t stop storing carbon when they reach their full height like trees do. Most of the carbon is sucked down by these plants and locked up in the sediment and that can process can go on forever.

When these ecosystems are degraded not only do they stop taking carbon out of the atmosphere, they will also release carbon back into the atmosphere when they decompose. Protecting and restoring these natural carbon sinks are recognised as an important component of climate change mitigation.

Cushioning the effects of ocean acidification

CO₂ released from fossil fuels is being absorbed into the oceans and causes ocean acidification which impacts a variety of animals with shells (see Blog No. 2).

But nature even has some solutions for this!

As marine plants grow they are sucking the CO₂ out the water (just like trees do from the air). It’s a lesson in chemistry  – in doing this they are reducing the acidity of the water around them. So, at marine reserves like the ones at Leigh, where protection has allowed kelp forests to recover they are banking blue carbon AND reducing the acidification impacts on nearby species. Kelp and seagrass associated with mussel farms will also provide some protection to this export industry. Isn’t nature amazing…the gift that keeps giving.

Practical adaptation action

Marine species are already vulnerable to a range of threats and climate change poses an additional risk. For example, over the last couple of years DOC has recorded highest ever pup mortality of New Zealand sea lion/rāpoka/whakahao on Campbell Island, the breeding site which accounts for 30% of pups born into the population. More research into this is needed but currently we think that the changing climate might exacerbate the already harsh environment, favouring conditions such as heavy rainfall and subfreezing temperatures at a time when pups are at their most vulnerable. To help sea lion pups adapt DOC is currently trialling different designs for pup shelters at various fur seal colonies around the mainland. This is a joint project with Auckland Zoo and landowners. 

Environmental health disclaimer

The above information might raise the illusion that we can get ourselves out of severely cutting down greenhouse gas emissions because marine ecosystems (like forests on land) suck CO₂ out of the atmosphere and we have some idea about how to help nature adapt to climate change. As an unprecedented global challenge, there’s still much to learn (not that climate change is happening, we’re way past that) but one thing we are clear is that the severity of the challenge ahead is set by actions we take now. Cutting down emissions from fossil fuels and agriculture (because methane is 80 times more effective in trapping heat as CO₂) still needs to be a primary focus. But we need all the help we can get so it’s get onboard with nature too as it’s so worth it!

Find out about the government’s Carbon Neutral Government Programme.

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For more information about climate change and conservation, visit our website: http://www.doc.govt.nz/our-work/climate-change-and-conservation