The Intergovernmental Panel on Climate Change (IPCC) has released a report with stark warnings on the current and future state of the oceans and cryosphere - the ice that covers planet Earth.
Glaciers are melting, sea levels are rising, and oceans are warming, making them more acidic and less productive, the report warns. Extreme coastal weather events are becoming more severe.
But the IPCC, a UN body, has a number of proposals for policymakers around the world, which it says will build resilience, help adaptation to changes that can no longer be avoided, and provide benefits for sustainable development.
Urgent and ambitious emissions reductions
Cutting emissions of greenhouse gasses and fossil fuels is key to enabling resilience and sustainable development, the report says.
“Cutting greenhouse gas emissions will limit impacts on ocean ecosystems that provide us with food, support our health and shape our cultures,” said Hans-Otto Pörtner, co-chair of the IPCC Working Group II.
“Reducing other pressures such as pollution will further help marine life deal with changes in their environment while enabling a more resilient ocean.”
Cutting emissions to limit global warming is also crucial for many of the solutions outlined. For example, coral reef restoration options may be ineffective if global warming exceeds 1.5°C, because corals are already at high risk at current levels of warming.
Networks of protected areas
This would help to maintain ecosystems "services", such as the absorption and storage of carbon dioxide, and protecting the movement of species, populations and ecosystems that will occur in response to ocean warming and sea level rises.
However geographic barriers, ecosystem degradation, habitat fragmentation and barriers to regional cooperation limit the potential for these networks.
Terrestrial and marine habitat restoration
This can enhance ecosystem-based adaptation, the report says. It also advocates for ecosystem management tools such as assisted species relocation and coral gardening.
It highlights the importance of using local and indigenous knowledge, alongside a science-based and community-supported, longterm plan.
Strengthening precautionary approaches
These include rebuilding overexploited or depleted fisheries. This brings benefits for regional economies and livelihoods. Fisheries management that regularly assesses and updates measures over time, informed by assessments of future ecosystem trends, reduces risks for fisheries but has limited ability to address ecosystem change.
Restoration of vegetated coastal ecosystems
These are ecosystems such as mangroves, tidal marshes and seagrass meadows. They provide climate change mitigation through increased carbon uptake and storage of around 0.5% of current global emissions annually.
Improved protection and management can also reduce carbon emissions from these ecosystems. There are also other benefits, such as providing storm protection, improving water quality, and benefiting biodiversity and fisheries.
Ocean renewable energy
There is a wealth of energy to be extracted from offshore winds, tides, waves, and biofuels. The uptick in demand for alternative energy sources could provide economic opportunities in the renewable energy sector.
Integrated water management approaches
This refers to changes in the cryosphere in high mountain areas. The report advocates the development and optimization of multi-purpose storage and release of water from reservoirs, with consideration of potentially negative impacts to ecosystems and communities.
“We will only be able to keep global warming to well below 2°C above pre-industrial levels if we effect unprecedented transitions in all aspects of society, including energy, land and ecosystems, urban and infrastructure as well as industry. The ambitious climate policies and emissions reductions required to deliver the Paris Agreement will also protect the ocean and cryosphere – and ultimately sustain all life on Earth,” said Debra Roberts, co-chair of IPCC Working Group II.
The 'Special Report on the Ocean and Cryosphere in a Changing Climate' was put together by more than 100 authors from 36 countries, referencing around 7,000 scientific publications.