Greenhouse gas emissions from human activity are destabilising oceans, leading to more intense superstorms, increased deadly heatwaves and record losses of polar sea ice, according to a United Nations report.
Future warming will lead to a host of catastrophic impacts and turn extreme floods that have inundated some coastal cities and island nations every 100 years into an annual occurrence, the UN Intergovernmental Panel on Climate Change concluded in a report issued in Monaco on Wednesday.
These effects are likely to happen whether climate heating emissions are curbed or not in coming decades, while many millions more of people living in coastal communities - including Ireland face more extreme flooding and sustained sea level rise.
But far worse impacts will hit without urgent action to cut fossil fuel emissions, including an eventual sea level rise of more than four metres this century in the worst case, they conclude, noting this outcome would redraw the map of the world and harm billions of people.
The assessment of the climate crisis in the world’s oceans and ice caps concludes melting permafrost and dwindling marine life are inevitable as oceans are crumbling under an onslaught of needless stressors from overfishing to pollution, compounded by climate breakdown.
In contrast it outlines how marine environments in a healthy state could help reduce the worst effects of global heating.
This report is the first to specifically address the impacts of a warming world on the Earth’s oceans and “cryosphere” the parts of the planet that are covered in ice, such as glaciers, permafrost and sea ice.
Data in the report represents the work of 104 scientists from 36 countries, and it references nearly 7,000 publications.
It confirms what is happening to oceans and ice caps “is already unprecedented - and the escalating changes will depend on how much we increase emissions and how quickly we act to scale back”.
The combined effects will mean water quality will suffer, while there will also be increasing landslides, avalanches and tsunamis. With the effects of rising levels of acidity and dropping oxygen levels in the oceans, marine animal and plant life will continue to deteriorate, most notably coral reefs - and ultimately human populations across the planet will be directly impacted by the consequences, the IPCC finds.
The report details a deadly cycle whereby the world’s oceans absorb much of the extra heat being generated by global heating and take in a proportion of the emissions of carbon dioxide, making the seas more acidic which damages sea creatures and coral in particular.
All people on Earth depend directly or indirectly on the ocean, and ice caps and glaciers to regulate the climate and provide water and oxygen. But the scientists show “unprecedented and dangerous changes” are being driven by global heating.
Sea level rise is accelerating as losses from Greenland and Antarctica increase, and the ocean is getting hotter, more acidic and less oxygenated trends that will continue to the end of the century without radical action,
It also predicts an increase in extreme El Ninos; a weather phenomenon in the Pacific, which pushes up global temperatures and can cause an increase in wildfires.
Threat to humanity
The landmark report shows oceans "are poised to turn into a huge threat to humanity "unless we massively scale up emission cuts in line with the goal to keep temperature rise to 1.5 degrees", said Wendel Trio, director of Climate Action Network Europe.
“Without much deeper cuts to emissions, the growing threat of superstorms, rising seas, melting glaciers and permafrost will imperil hundreds of millions of people. The destruction will be far worse if governments don’t adopt more ambitious goals for reducing carbon pollution,” he added.
So far the responses from European leaders to the climate crisis have been maddeningly slow, he said. “After underwhelming commitments made at the UN climate action summit, the EU needs to speed up its work towards adopting a more ambitious climate target by early next year. Bringing it in line with the Paris Agreement’s target to limit temperature increase to 1.5 degrees will require emissions to be reduced by 65 per cent by 2030.”
The IPCC reports outlines a range of measure to alleviate the problems by protecting the oceans and its restoring habitats, which absorb and store carbon through, for instance, sea grass beds in shallow waters.
Half the world’s megacities, and almost two billion people, live on coasts. Even if heating is restricted to just two degrees, scientists expect the impact of sea level rise to cause several trillion dollars of damage a year, and result in many millions of migrants.
"The future for low-lying coastal communities looks extremely bleak," said Prof Jonathan Bamber at Bristol University in the UK, who is not one of the report's authors. "But the consequences will be felt by all of us. There is plenty to be concerned about for the future of humanity and social order from the headlines in this report." - Additional reporting: Guardian Services