Coastal flooding along with huge losses of ice and snow are becoming more extreme as oceans warm and acidify while frozen parts of the planet melt faster, the Nobel Prize-winning U.N. climate panel reported on Wednesday.
The United Nations’ Intergovernmental Panel on Climate Change, or IPCC, concluded in its first major report to focus on water that huge changes already are occurring around the 71% of the planet covered by oceans and 10% covered in ice and snow, known as the cryosphere.
The IPCC said the changes in oceans — damaged from absorbing at least 90% of the excess heat in air from carbon emissions — and in the cryosphere will lead to major ecological problems for the natural world and people around the globe, and wreak havoc on the world economy.
"There is overwhelming evidence that this is resulting in profound consequences for ecosystems and people. The ocean is warmer, more acidic and less productive. Melting glaciers and ice sheets are causing sea level rise, and coastal extreme events are becoming more severe," the IPCC said.
Written by 104 authors from 36 nations, the report found the current pace of global warming will cause almost 1 meter of sea level rise and the collapse of the West Antarctic Ice Sheet by the end of the century. Fish populations will thin, it said, ocean currents will weaken and hurricanes will strengthen.
The report was unanimously approved by 195 IPCC member nations at a meeting in Monaco this week. Its projections cover a range of scenarios for emissions of carbon dioxide, methane and other heat-trapping greenhouse gases.
Average global temperatures have already reached 1 degree Celsius above pre-industrial levels, which is halfway to the upper 2 degree C. limit that nations agreed to as part of the 2015 Paris Agreement on climate change, and two-thirds of the way to nations' preferred 1.5 degrees C. limit under the accord.
Scientists agreed the world is closest to the worst-case scenario of doing little to nothing to prevent global warming. Alarmingly, the IPCC said for the first time that "some island nations are likely to become uninhabitable due to climate-related ocean and cryosphere change," but levels of habitability remain extremely difficult to assess.
Impacts are 'sweeping and severe'
A total of 670 million people in high mountain regions and 680 million people in low-lying coastal zones depend directly on these heat-impacted areas, according to the IPCC. Four million people live permanently in the Arctic region, and small island developing nations are home to 65 million people.
“The open sea, the Arctic, the Antarctic and the high mountains may seem far away to many people,” said Hoesung Lee, a South Korean climate change economist who chairs 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.”
Sea level rise is occurring at 3.66 millimeters a year, which is two and a half times faster than the rate from 1900 to 1990, the report found. Oceans lost 1-3% of the oxygen in their upper levels since 1970, and will lose more as the warming continues.
The ice melting from Antarctica, Greenland and mountain glaciers worldwide accelerated between 2006 and 2015 to some 653 billion metric tons of ice a year. Meantime, Arctic snow cover in June shrank by more than half since 1967, a loss of 2.5 million square kilometers.
“The world’s oceans and cryosphere have been taking the heat for climate change for decades. The consequences for nature and humanity are sweeping and severe,” said Ko Barrett, an IPCC vice chair and deputy assistant administrator for the U.S. National Oceanic and Atmospheric Administration.
“The rapid changes to the ocean and the frozen parts of our planet are forcing people from coastal cities to remote Arctic communities to fundamentally alter their ways of life,” she said in a statement.