The World's oceans are in danger

Sophie Carreau
03 October 2019
The 51st session of the IPCC took place from 20 to 23 September in the Principality of Monaco. During the meeting, the IPCC released its latest report on oceans and cryosphere. Find out the headline statements.

The report observes how climate change is affecting the population and what adaptation efforts should be considered.

 

The highlights

Over the past 40 years, oceans have absorbed at least a quarter of the human-produced greenhouse gas emissions. As a result, their acidity levels and temperature increased but their salinity was reduced.

Oxygen concentration has actually decreased by 2 % in 50 years and could be further reduced if greenhouse gas emissions increase at the same rate. This risk will obviously have an impact on global food security, as it will lead to a 40 % decrease in food reserves in shallow tropical waters.

Corals are also drastically affected, as we see with the Great Barrier Reef of Australian corals, which is dying. Corals are also severely affected. In addition, heat waves are the main cause of phenomena such as “El Niño”, which contribute to forest fires and influence cyclones.

Depending on the intensity of global warming until 2100, up to 90 % of wetlands could be flooded due to rising sea levels. It would result in an increase of climate refugees number. The number of climate refugees will grow considerably. The report also highlights that an increase in disasters, such as cyclones and floods, is to be expected, impacting not only coastal cities but also small island states.

The world's 4 biggest polluters - China, United States, Europe and India - are extremely exposed to the impacts of climate change. Shanghai, China's largest city, is threatened by rising waters, as are the coastal cities of the United States. After 2030, if the situation remains the same, New York will be facing floods every 5 years.

Les glaciers de montagne sont tout autant menacés. Ceux-ci pourraient perdre jusqu’à 80% de leur volume d’ici 2100.

A glacier in Iceland
© Shutterstock

The report also points to the worrying meltdown of the polar ice by an average of about 430 billion tonnes per year over the past 12 years. This is the major cause of global sea level rise. Mountain icebergs are equally threatened. Their volume could be reduced by up to 80 % by 2100. Two billion people depend on these icebergs for their drinking water supply, the situation is therefore particularly worrying.

The most alarming point in the report remains the melting of permafrost, the permanently frozen ground that covers almost a fifth of the Earth's surface. The melting of permafrost will trigger a vicious cycle, since it will release more greenhouse gases - as well as toxic substances such as mercury - into the air, which will accelerate global warming. At least a third of the permafrost could disappear by 2100 in the best of scenarios, or even all of it.

The word “cryosphere” comes from the Greek “kryos”, which means “cold” or “ice”. It refers to areas on Earth where water is present in solid form. This includes ice floes, frozen lakes and rivers, snow-covered areas, icebergs, but also ice sheets and frozen ground, temporarily or permanently.

In October 2018, the IPCC had already published a first report on the impact of global warming of 1.5°C. In August 2019, a special report on land degradation and food security was published. This latest report on oceans and cryosphere (see box) is the last chapter in this series.

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