We know climate change is the biggest threat facing our world, which is why it is Greenpeace’s priority campaign. Today’s report by the Intergovernmental Panel on Climate Change (IPCC)’shighlights the enormous impacts and consequences climate change is having on our oceans. This must act as a wake-up call for everyone who depends on, or cares about our oceans and the vast array of life within them.

Below we’ve pulled together some of the key messages the IPCC report delivers on oceans.

Climate Change is already affecting our oceans

Climate change alters the physical, chemical, and biological features of the ocean. And as we pump CO2 into the atmosphere, its uptake in our oceans is also making them more acidic. This in turn impacts some of the species in our ocean, including plankton – the basis of ocean food webs. While the species affected may not be recognisable to all of us, they are the small creatures that many of the fish we eat, and many of the iconic ocean creatures that we treasure depend on as food.

Climate Change makes other things worse

Warming and acidifying waters and rising sea levels make other human impacts on oceans more complicated, or simply worse. They compound issues like overfishing, habitat destruction and pollution, and they make the ocean less resilient to the effects of natural cycles and fluctuations like El Nino.

Climate Change is a threat to food security

Animals tend to be limited in where they can live by basic temperatures and availability of food. Warming waters, changing ocean currents and chemistry mean that we are already seeing species move. Broadly speaking they are moving towards cooler waters – the polar regions or deeper seas. That means that tropical countries especially could see fish and crucial food sources declining dramatically from their waters. At the same time, shifting stocks of fish are likely to lead to increased conflict between fishing nations, such as we have already seen on mackerel in the North Atlantic.

Climate Change means smaller fish

One of the impacts already seen is a fundamental change to the size of sea creatures, making them smaller – an impact also seen in overfished areas. This is likely to lead to major shifts in how species interact (who eats who, mostly!) which could have profound and difficult-to-predict impacts on species we depend on.

Climate Change means fewer fish

Some predictions suggest that as well as species shifting, and becoming smaller, that the oceans’ productivity itself could drop by 9%, and that’s in a world with a growing population and increasing demand for food.

Climate Change means more oceanic dead zones

Compounding the effects of nutrient and pollution run-off from land, warming seas are predicted to have more areas starved of oxygen, and devoid of life. This especially true of coastal seas or enclosed areas, such as the Baltic Sea, and has severe consequences for local food supplies and livelihoods

Climate Change hurts most at the poles and the tropics

The impacts of a warming world are already being felt more strongly in these regions, and this will continue. That’s disastrous news for species –rich tropical coral reefs, as well as iconic Arctic and Antarctic creatures, which simply may have nowhere left to go.

Climate Change is happening, and it is already having huge impacts on our oceans and ocean life. But together we can help limit the damage.

Greenpeace’s climate and energy campaign works to accelerate cuts and eventual phase out in climate pollution. As the same time Greenpeace’s oceans campaign is working to defend and protect our seas, the amazing life to be found in them, the livelihoods that depend on them, and the future resources they can yield. The less stress oceans face from pollution, overfishing and other human activities, the better they can cope with climate change impacts.

One of the strongest, yet simplest, solutions is to give our oceans more protection by creating Ocean Sanctuaries. These are protected areas, off limits to destructive fishing and other activities, which give our oceans a chance to breathe. They need to cover a significant proportion of the ocean to make a difference, but by putting areas of ocean off-limits we can both protect species and habitats, but give the oceans a bit more chance. It’s about building resilience, and giving our seas a fighting chance, whether it’s the Great Barrier Reef, the High Arctic, or the deep sea.

Ocean creatures can’t vote or ask politicians to help – but you can, and you can help us supportocean sanctuaries.

Overfishing, and destructive fishing is having a huge impact on our oceans, fundamentally changing them in many parts of the world – that’s why Greenpeace’s work to tackle illegal fishing, overfishing, and fishing methods that destroy habitat, waste resources, and needlessly catch and kill vast amounts of other sea life is vital to fundamentally transforming how we treat our oceans. We know Climate Change makes the impacts of all of that worse, so we should do what we can to turn the tide across the fishing industry. Quite simply, we need to do less harm – but in practice that is a huge task, involving work at sea, in ports, with suppliers, markets and retailers.  We need your support to do that.

Lastly we are working with affected communities across the world. From the Arctic to the Pacific, from Europe to Australia, we have been making alliances, helping give voice to communities and local fishers and taking their concerns directly to those in power. Those alliances matter because these communities have a stake in the future of our seas, and by empowering them, and making sure their voices are heard, we have a better chance of securing more stable, sustainable and sensible solutions for an increasingly changing world.

 Willie Mackenzie is an Oceans Campaigner at Greenpeace UK.