26 September, 2019 News stories

MONACO: Hundreds of scientists and Government representatives met in Monaco this week to finalise the new Intergovernmental Panel on Climate Change Special Report on the Ocean and Cryosphere in a Changing Climate.

Approved yesterday (on 24 September 2019) by the 195 IPCC member Governments, the report provides new evidence for the benefits of limiting global warming to the lowest possible level – in line with the goal that Governments set themselves in the 2015 Paris Agreement.

British Antarctic Survey Polar Oceanographer Professor Mike Meredith led the Polar Regions chapter of the report and is in Monaco. He says:

“The heating of our world is having a major impact on all things frozen. One of the big changes we have seen is the impact of warming on the melt of the Greenland and Antarctic ice sheets, which has risen substantially in recent decades. These frozen regions are critically important for global sea levels, which will effect flooding all over the world. This report presents the best assessment to date of the scale of change and provides Governments with the information needed to decide how to best to mitigate or adapt.”

“The open sea, the Arctic, the Antarctic and the high mountains may seem far away to many people,” said Hoesung Lee, Chair of 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.”

Knowledge assessed in the report outlines climate-related risks and challenges that people around the world are exposed to today and that future generations will face. It presents options to adapt to changes that can no longer be avoided, manage related risks and build resilience for a sustainable future. The assessment shows that adaptation depends on the capacity of individuals and communities and the resources available to them.

Valérie Masson-Delmotte, Co-Chair of IPCC Working Group I says:

“This new assessment has revised upwards the projected contribution of the Antarctic ice sheet to sea level rise by 2100 in the case of high emissions of greenhouse gases,” she said. “The wide range of sea level projections for 2100 and beyond is related to how ice sheets will react to warming, especially in Antarctica, with major uncertainties still remaining.”

More frequent extreme sea level events

Sea level rise will increase the frequency of extreme sea level events, which occur for example during high tides and intense storms. Indications are that with any degree of additional warming, events that occurred once per century in the past will occur every year by mid-century in many regions, increasing risks for many low-lying coastal cities and small islands.

Without major investments in adaptation, they would be exposed to escalating flood risks, the report shows. Some island nations are likely to become uninhabitable due to climate-related ocean and cryosphere change, the report said, but habitability thresholds remain extremely difficult to assess.

Increases in tropical cyclone winds and rainfall are exacerbating extreme sea level events and coastal hazards. Hazards will be further be intensified by an increase in the average intensity, magnitude of storm surge and precipitation rates of tropical cyclones, especially if greenhouse gas emissions remain high.

“Various adaptation approaches are already being implemented, often in response to flooding events, and the report highlights the diversity of options available for each context to develop integrated responses anticipating the full scale of future sea level rise,” said Masson-Delmotte.

Changing ocean ecosystems

Warming and changes in ocean chemistry are already disrupting species throughout the ocean food web, with impacts on marine ecosystems and people that depend on them, the report said.

To date, the ocean has taken up more than 90% of the excess heat in the climate system. By 2100, the ocean will take up 2 to 4 times more heat than between 1970 and the present if global warming is limited to 2°C, and up to 5 to 7 times more at higher emissions. Ocean warming limits mixing between water layers and, as a consequence, reduces the supply of oxygen and nutrients for marine life.

Marine heatwaves have doubled in frequency since 1982 and are increasing in intensity. They are projected to further increase in frequency, duration, extent and intensity. Their frequency will be 20 times higher at 2°C warming, compared with pre-industrial levels. They would occur 50 times more often if emissions continue to increase strongly.

The ocean has taken up between 20 to 30% of human-induced carbon dioxide emissions since the 1980s, causing ocean acidification. Continued carbon uptake by the ocean by 2100 will exacerbate ocean acidification.

Ocean warming and acidification, loss of oxygen and changes in nutrient supplies, are already affecting the distribution and abundance of marine life in coastal areas, in the open ocean and at the sea floor.

Shifts in the distribution of fish populations have reduced the global catch potential. In the future, some regions, notably tropical oceans, will see further decreases, but there will be increases in others, such as the Arctic. Communities that depend highly on seafood may face risks to nutritional health and food security.

Declining Arctic sea ice, thawing permafrost

The extent of Arctic sea ice is declining in every month of the year, and it is getting thinner. If global warming is stabilized at 1.5°C above pre-industrial levels, the Arctic ocean would only be ice-free in September – the month with the least ice – once in every hundred years. For global warming of 2°C, this would occur up to one year in three.

Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC)

The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) is the third in a series of Special Reports produced in the IPCC’s Sixth Assessment Cycle. The report was prepared under the joint scientific leadership of IPCC Working Groups I and II, with support from the Working Group II Technical Support Unit.

The word “cryosphere” – from the Greek kryos, meaning cold or ice – describes the frozen components of the Earth system, including snow, glaciers, ice sheets and ice shelves, icebergs and sea ice, ice on lakes and rivers as well as permafrost and seasonally frozen ground.

The Summary for Policymakers presents the key findings of the Special Report, based on the assessment of the available scientific, technical and socio-economic literature relevant to the ocean and cryosphere in a changing climate.The Summary for Policymakers of the Special Report on the Ocean and Cryosphere in a Changing Climate as well as additional information are available at https://www.ipcc.ch/srocc

About the IPCC

The Intergovernmental Panel on Climate Change (IPCC) is the UN body for assessing the science related to climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide policymakers with regular scientific assessments concerning climate change, its implications and potential future risks, and to put forward adaptation and mitigation strategies. It has 195 member states. In the same year the UN General Assembly endorsed the action by WMO and UNEP in jointly establishing the IPCC.

IPCC assessments provide governments, at all levels, with scientific information that they can use to develop climate policies. IPCC assessments are a key input into the international negotiations to tackle climate change. IPCC reports are drafted and reviewed in several stages, thus guaranteeing objectivity and transparency.

The IPCC assesses the thousands of scientific papers published each year to inform policymakers about the state of knowledge on climate change. The IPCC identifies where there is agreement in the scientific community, where there are differences and where further research is needed. It does not conduct its own research.

To produce its reports, the IPCC mobilizes hundreds of scientists. These scientists and officials are drawn from diverse backgrounds. Only a dozen permanent staff work in the IPCC’s Secretariat.

The IPCC has three working groups: Working Group I (the physical science basis of climate change); Working Group II (impacts, adaptation and vulnerability); and Working Group III (mitigation of climate change). It also has a Task Force on National Greenhouse Gas Inventories that develops methodologies for estimating emissions and removals. All of these are supported by Technical Support Units guiding the production of IPCC assessment reports and other products.

IPCC Assessment Reports consist of contributions from each of the three working groups and a Synthesis Report. Special Reports undertake a shorter assessment of specific cross-disciplinary issues that usually span more than one working group.

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