TOKYO (Kyodo) -- A United Nations panel has warned in a draft report on climate change that sea levels could rise by up to 1.3 meters by 2100 due to global warming, calling the figure "significantly greater" than earlier assessments.
Ocean heatwaves, in which the sea surface of a given area gets unusually warm, are also likely to become more frequent and "push marine organisms and ecosystems to the limits of their resilience," said the draft of a special report by the Intergovernmental Panel on Climate Change, to be officially released in September.
With the IPCC stepping up its warnings on the impact of global warming on the ocean and frozen regions, calls to cut greenhouse gas emissions globally are likely to increase ahead of the implementation of the Paris climate accord that covers a period from 2020.
"Climate change related impacts on the ocean and cryosphere are expected to compound the environmental risks already faced by many humans and natural systems," the report obtained by Kyodo News said. The contents will be finalized after discussions among experts and governments.
The report said ice in Antarctica and Greenland has also been lost at accelerated rates, such as due to glacier flows, and that there is increasing evidence that the observed changes are "irreversible on centennial timescales."
The loss of ice-sheet mass is one of the reasons behind the sea-level changes, which the draft estimates will be higher by up to 1.33 meters in 2100, compared to the average during 1986 to 2005.
An IPCC climate change assessment report in 2013 projected that mean sea levels would be higher by up to 0.98 meter.
Warmer marine surface and sea water could also contribute to rains, strong winds and high waves caused by cyclones, the draft said.
The report also warned that sea areas where oxygen levels have dropped extremely low for living things to survive have expanded, because global oxygen concentrations have decreased by 1 to 2 percent since the 1970s on the back of rising marine surface temperatures.
The increased carbon dioxide concentration in the air has also acidified the oceans, it said.
The IPCC is the international body for the assessment of climate change established by the U.N. Environment Program and the World Meteorological Organization.