The Intergovernmental Panel on Climate Change (IPCC) is urging ambitious, coordinated and "unprecedented" action to address the crisis facing the Earth's oceans and cryosphere - the areas of frozen water on the planet.
In its latest report, the UN body looked at two future scenarios. One where there are low greenhouse gas emissions, with a rise of global temperature by 2100 of between 0.5 and 2.4 C. And the other with high emissions, and a catastrophic temperature rise of 3.2 - 5.4C by 2100.
In either case, the oceans, their ecosystems, and consequently humanity, face a range of threats.
The dangers facing those in mountainous regions due to melting ice and declining water reserves, rising sea levels and rising ocean temperatures, and the prospect of more extreme coastal weather events.
The report also presents a number of proposed solutions, to mitigate the adverse effects, adapt to them, and in some cases reverse them.
Watch the presentation of the report in the player above.
The challenges facing our ice and oceans
Melting ice and snow in high mountainous regions are presenting dangers to people living in those communities, the report warns. The loss of water will contribute to dangers such as landslides, avalanches, rockfalls and floods. Smaller glaciers around the world are projected to lose more than 80% of their current ice mass by 2100, if emissions aren’t cut. This will affect tourism, regional culture, and even cause issues further downstream for sectors such as agriculture.
Melting ice, for example like that seen at record levels at Greenland’s ice sheet, is contributing to rising sea levels. While sea level has risen globally by around 15 cm during the 20th century, it is currently rising more than twice as fast -and accelerating - the report showed.
Extreme coastal weather events could be exacerbated by rising sea levels as well, putting low-lying coastal cities and small island communities at risk.
Warming and changing ocean chemistry is already impacting ecosystems, and the communities that rely on them.
The authors outline a number of ways policy-makers should address these issues. It advocates the protection, restoration and the management of renewable resource use, alongside the overarching need to limit the global temperature rise, by drastically cutting down on emissions.
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.
“The open sea, the Arctic, the Antarctic and the high mountains may seem far away to many people,” said Hoesung Lee, Chair of the IPCC. “But we depend on them and are influenced by them directly and indirectly in many ways – for weather and climate, for food and water, for energy, trade, transport, recreation and tourism, for health and wellbeing, for culture and identity.”
“If we reduce emissions sharply, consequences for people and their livelihoods will still be challenging, but potentially more manageable for those who are most vulnerable,” Lee said.
“We increase our ability to build resilience and there will be more benefits for sustainable development.”