The new Special Report on the Ocean and Cryosphere from the IPCC, recently unveiled in Monaco, paints a worrying picture of how the world may look at the end of the century.
If carbon emissions aren’t cut, sea levels will be 60-100 centimetres higher in 2100 than at the end of the 20th century. Small glaciers in Europe and East Africa will lose 80% of their ice, placing water supplies for hundreds of millions of people at risk. The global ocean will absorb more carbon dioxide and acidify, 15% of ocean life will die off and coral will be almost extinct.
China’s glaciers are crucial “water towers” both for its own people and the nations downstream so climate change will have a huge impact in the region. Given these challenges, experts say that despite international disagreements, a combination of global mitigation and regional adaptation is needed.
The disappearing Third Pole
After evaluating almost 7,000 academic papers, 104 experts from 34 countries have produced this report on the future of the earth’s ice and ocean. It predicts glacial melting will cause rivers to shrink and make extreme weather events both more frequent and more intense, and agricultural yields unpredictable. If global warming continues at the current pace, Asia’s mountain glaciers will shrink by 64% by the end of the century – resulting in a severe water crisis.
China has more low-latitude glaciers than any other country, and the Third Pole of the Qinghai-Tibetan plateau is the most important glacial region outside of the Arctic and Antarctic. It is also the source of the Yangtze and Yellow Rivers, and many other important international rivers, including the Brahmaputra, the Ganges, the Mekong and the Salween. Glacial melting will therefore affect other Asian nations downstream as well as China.
Glaciers help regulate the amount of water flowing through rivers. As they melt or even disappear in the future, that function will be lost and seasonal and annual fluctuations will increase, meaning more frequent droughts and floods along the rivers.
Liu Qiao, an associate researcher with the Chinese Academy of Sciences’ Institute of Mountain Hazards and Environment, says that while melting will increase river flows in the short term, a peak melting point will be reached as the glaciers shrink. Glacial water resources in some arid regions will shrink – in particular, in China’s north-west.
Shrinking glaciers will also increase the risk of natural disasters and threaten nearby infrastructure. In the Himalayas and the mountains of south-east Tibet, glacial lakes are expanding, which increases the risk of flooding due to their collapse. Liu Qiao gave the example of the temperate glaciers in south-east Tibet, where shrinking is most apparent and large quantities of loose material has been exposed. That material could cause landslides during heavy summer rains, threatening local residents and infrastructure. One of the authors of the IPCC report, Golam Rasul, chief economist at the International Centre for Integrated Mountain Development, said that some areas may no longer be suitable for habitation and residents will need to be relocated.
Away from the Third Pole, other glaciers across China’s west are also facing melting, shrinkage and thinning. In the arid north-west, the melting of glaciers in the Tianshan and Qilianshan ranges will directly impact on water use downstream. Given this, Wang Feiteng, a researcher with the Chinese Academy of Sciences’ Northwest Institute of Eco-environment and Resources, thinks a strategy of adaptation, with more efficient use of water resources and appropriate siting of economic activities, is necessary.
The ocean in peril
Rising sea levels are one of the main dangers of climate change. According to the IPCC, if greenhouse gas emissions continue, sea levels will rise a further 60-110 centimetres over and above the 15-centimetre rise seen in the 20thcentury. That would see large expanses of land lost in low-lying regions, forcing coastal communities from their homes and causing huge economic losses. Some island nations may be lost.
Major cities threatened by rising sea levels include Mumbai, Shanghai, New York, Miami, Bangkok and Tokyo. A rise in sea levels of 50 centimetres would see assets worth 26.9 trillion dollars inundated in the world’s 20 worst-affected port cities.
China’s coastline stretches 18,000 kilometres, and 144 million people live in low-lying coastal areas. The Yangtze delta is extremely vulnerable to sea level rise. Research has found that a rise of 50 centimetres would affect 30.2 million people in 15 of China’s port cities, along with assets worth 10.8 trillion dollars.
Climate change is also expected to result in shocking changes to the marine ecosystem. According to the report, if carbon emissions do not decrease, the warmer ocean will dissolve more carbon dioxide, making the seawater more acidic. By the end of the century ocean biomass will have reduced by 17%, with coral under particular threat – even if the global temperature rise is limited to 1.5C, almost all warm-water coral reefs are expected to suffer regional or partial destruction.
Coral reefs are the “rainforests of the sea”, providing habitats for fish and many other marine organisms. The lives of 500 million people worldwide depend on coral ecosystems.
The outlook for China’s coral reefs is similarly bleak. Huang Hui, a researcher with the Chinese Academy of Sciences’ South China Sea Institute of Oceanology, has visited almost every part of China where coral grows. She offered two statistics: coral abundance has declined by at least 80% over the past 30 years on coastal fringing reefs along the Chinese mainland and adjoining Hainan Island; and on offshore atolls and archipelagos in the South China Sea, coral cover has declined from an average of 60% to around 20% within the past 10-15 years. Huang said that “the main threat to China’s coral currently is human destruction. In comparison, the damage caused by climate change is miniscule.”
Lian Jiansheng, associate researcher with the Pacific Society of China’s Coral Reef Committee, agrees, saying that coastal development, over-fishing and increasing numbers of the crown-of-thorns star fish, which eats coral, are all harming China’s coral reefs far more than climate change.
But he pointed out that climate change, and primarily rising sea levels, has been affecting China’s coral reefs since 2010, and particularly in 2010, 2014-2017 and 2019, when coral bleaching associated with sea level rises was recorded. There has been a clear change since 2010.
Facing up to climate risks
Given these severe climate risks, some say it is time to concentrate on adaptation. Shen Yongping of the Chinese Academy of Sciences’ Northwest Institute of Eco-environment and Resources is among them. He says China’s funding and research is focused on mitigation – but adaptation is more pressing. “The need for adaptation is more real and more urgent than mitigation by reducing emissions. And our adaptation efforts could act as models to be followed elsewhere.”
He thinks a principle of maximising benefits and minimising harm should be applied. For example, advantage can be taken of warmer temperatures and fewer frosts to benefit agriculture by increasing crop yields, while the impact of other agricultural, environmental and economic problems caused by climate change will need to be minimised. “This will require more work and more funding,” he said.
Report author Golam Rasul says that limited finances and technical capacities mean a balance between adaptation and mitigation is crucial. Communities in the Third Pole have already made efforts to adapt to cryosphere changes, but in the long term there are uncertainties over future changes and the sustainability and effectiveness of adaptation. More importantly, if current emissions levels continue, climate change may go beyond the ability of poor Third Pole communities to cope. Regional and international cooperation and policy innovation are needed to cut global greenhouse gas emissions and avoid catastrophic impacts.
Another of the report authors is Kang Shichang, director of the State Key Laboratory of Cryospheric Science. He thinks mitigation is the top priority, as reducing emissions of pollutants, particularly of short-lived climate forcers such as black carbon, both mitigates climate change and improves health. “Of course, we need to build on that to prepare for the future, and infrastructure should be built in line with availability of water resources.”
