Feature Report: Climate, Land, Oceans: The IPCC Special Reports

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The IPCC Report on the Ocean and the Cryosphere

About the report: 104 IPCC scientists from 36 countries reviewed 6,981 publications and studies. The drafts of the report received 30,000 comments from outside experts. The result was an 800-page assessment, with summaries for policymakers and journalists1 .

Le rapport du GIEC sur l’océan et la cryosphère
The warming of the oceans threatens the living conditions of many populations and marine biodiversity. Here, the thaw of a glacier in the north of Patagonia (Chile) ©Martin BERNETTI / AFP

Oceans and the Cryosphere 

Oceans cover 70% of the Earth’s surface and the cryosphere covers between 7% and 17%, depending on the season. The cryosphere, from the Greek word “kryos”, meaning cold, refers to the frozen parts of the planet, including glaciers, ice caps (the Arctic and Antarctic), icebergs, sea ice, permafrost (permanently frozen ground), frozen lakes and rivers, snow and seasonal ice cover. The total volume exceeds 1.5 billion cubic kilometers of water.

The Effects of Global Warming

The increase in the Earth’s average temperature has impacts on both the ocean and the cryosphere. As oceans warm, they become more acidic and damage biodiversityRefers to the natural diversity of living organisms. It can be measured through the study of species, genes and ecosystems. in marine ecosystems. Glaciers and ice caps are melting, causing sea levels to rise. In addition, extreme coastal events are becoming more widespread and severe. However, if urgent action is taken to stem the growth of greenhouse gas (ghg) Gas with physical properties that cause the Earth's atmosphere to warm up. There are a number of naturally occurring greenhouse gases... emissions, it is still possible to limit the magnitude of these changes. 

Melting Glaciers 

If emissions continue to remain at a high level, small glaciers in Europe, East Africa, the Andes and Indonesia are likely to lose 80% of their current ice mass by 2100. This phenomenon would have consequences on a multitude of activities, from water supply and agriculture to hydropower and tourism.

Did You Know?
The sea level is expected to rise between 30 and 60 cm by 2100
(15 cm in the 20th century).

Rising Sea Levels

The average global sea level is rising due to the expansion of warming sea water and the melting of glaciers and polar ice caps. After increasing about 15 cm in the 20th century, the sea level is currently rising at a rate of 3.6 mm/year, or more than twice as fast. Even if global warmingGlobal warming, also called planetary warming or climate change... is kept well below 2°C, the rise could reach between 30 and 60 cm by 2100. Above 2°C, it could increase to between 60 and 110 cm. 

A Threat to Islands and Low-Lying Environments

Extreme sea level events along the coast, during high tides or fierce storms, for example, will happen more frequently due to the average rise in sea levels. As a result, small island nations (65 million people) and heavily populated low-lying regions (680 million people), particularly in Asia, will be exposed to greater risks. Some island states may even become uninhabitable, but the intergovernmental panel on climate change (ipcc)Body established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988... has not offered any precise figures.

Oceans Absorb Heat and CO2

Oceans provide two major benefits: 

Ocean Acidification

These two benefits have their disadvantages, however: the absorbed heat causes the sea level to rise and oxygen levels to drop, and the capture of carbon dioxide (co₂)Along with water vapor, carbon dioxide is the primary greenhouse gas (GHG) in the Earth's atmosphere... makes the water more acidic. Ocean acidification is extremely harmful to marine organisms, especially coral, plankton and shellfish. The impacts of acidification travel through the food chain, affecting the distribution of fish populations. Global warming is also prompting some fish species to move north in search of cooler water, thereby reducing the catch potential in developing countries. Establishing fishery management policies and protected areas are possible solutions mentioned in the report for minimizing risks.

 

Key Figure
80 % : The loss of glacier ice mass if CO2 emissions continue to increase rapidly.

Thawing Permafrost

Permafrost areas that are hundreds of years old are warming and thawing. Even if global warming is kept at less than 2°C, almost 25% of the near-surface (between 3 and 4 meters deep) permafrost will thaw by 2100. And if greenhouse gas emissions continue to grow rapidly, around 70% of near-surface permafrost will disappear. Permafrost in the northern hemisphere contains a vast quantity of carbon, almost twice the amount of carbon in the atmosphere. If it were to melt, it would significantly raise the amount of greenhouse gas emissions in the atmosphere, particularly methane (ch4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills... . Expanding the plant coverage in areas where the permafrost has melted would not offset the thaw-induced emissions.

 

 

Sources:
1See the press release – https://www.ipcc.ch/site/assets/uploads/2019/09/srocc-P51-press-release.pdf