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IPCC special report finds oceans and cryosphere changing rapidly due to global warming

  • As a massive expanse of unusually warm water spreads across the northeastern Pacific Ocean for the second time in the past five years, the latest special report from the Intergovernmental Panel on Climate Change (IPCC), released today, finds that marine heatwaves have “very likely” become twice as frequent and increasingly intense over the past four decades.
  • The report focuses on the benefits of taking action to limit global warming — and the costs of delaying that action — for the world’s oceans and cryosphere (the parts of Earth’s surface that are frozen, such as ice sheets and frozen ground). It is the work of more than 100 authors from 36 countries who assessed 7,000 scientific publications to assemble the latest scientific findings on the current and future impacts of global climate change.
  • Conservationists characterized the report as a dire wake-up call for world leaders. “With today’s release of the Special Report… international leaders are confronted by the stark and immediate consequences of failing to adequately address greenhouse gas emissions, as they impact the oceans,” Jason Patlis, executive director of the Marine Conservation Program at WCS (Wildlife Conservation Society), said in a statement.

As a massive expanse of unusually warm water spreads across the northeastern Pacific Ocean for the second time in the past five years, the latest special report from the Intergovernmental Panel on Climate Change (IPCC), released today, finds that marine heatwaves have “very likely” become twice as frequent and increasingly intense over the past four decades.

The report focuses on the benefits of taking action to limit global warming — and the costs of delaying that action — for the world’s oceans and cryosphere (the parts of Earth’s surface that are frozen, such as ice sheets and frozen ground). It is the work of more than 100 authors from 36 countries who assessed 7,000 scientific publications to assemble the latest scientific findings on the current and future impacts of global climate change.

“The world’s ocean and cryosphere have been ‘taking the heat’ from climate change for decades, and consequences for nature and humanity are sweeping and severe,” Ko Barrett, Vice-Chair of the IPCC, said in a statement. “The rapid changes to the ocean and the frozen parts of our planet are forcing people from coastal cities to remote Arctic communities to fundamentally alter their ways of life.”

For instance, as glaciers, snow, ice, and permafrost melt they are increasing the risks to the 670 million humans who live in mountainous regions from avalanches, floods, landslides, and rockfalls. According to the report, if we don’t rein in our greenhouse gas emissions, small glaciers in eastern Africa, the tropical Andes, Europe, and Indonesia could lose as much as 80 percent or more of their current ice mass by 2100. As these mountain glaciers disappear, availability and quality of water downstream is adversely impacted.

“Changes in water availability will not just affect people in these high mountain regions, but also communities much further downstream,” Panmao Zhai, Co-Chair of IPCC Working Group I, said in a statement. “Limiting warming would help them adapt to changes in water supplies in mountain regions and beyond, and limit risks related to mountain hazards. Integrated water management and transboundary cooperation provides opportunities to address impacts of these changes in water resources.”

Of course, as glaciers and ice sheets lose mass, the rate of sea level rise increases, with potentially severe consequences for the 680 million people in low-lying coastal zones. The report finds that Earth’s sea level rose by about 15 centimeters in the 20th century, and is currently rising at a rate more than twice as fast, 3.6 millimeters per year — a rate that is still accelerating. The seas could rise as much as 30 to 60 centimeters by 2100 even if greenhouse gas emissions are reduced quickly enough to limit global warming to well below 2°Celsius, the report finds. If we don’t sharply reduce emissions, sea level rise could reach 60 to 110 centimeters within that timeframe.

“In recent decades the rate of sea level rise has accelerated, due to growing water inputs from ice sheets in Greenland and Antarctica, in addition to the contribution of meltwater from glaciers and the expansion of warmer sea waters,” Valérie Masson-Delmotte, Co-Chair of IPCC Working Group I, said in a statement. “This new assessment has also 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. 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.”

Sea level rise, in turn, leads to an increase in the frequency of extreme sea level events, per the report. Earth is already 1°Celsius warmer than pre-industrial averages, and any additional amount of global warming could mean that, by 2050, floods that occurred once per century in the past will occur every year in many low-lying coastal cities and small islands. Some small island nations, which are home to 65 million people around the world, might become uninhabitable altogether, especially as increases in tropical cyclone winds, rainfall, and storm surges driven by climate change exacerbate extreme sea level events.

Wildlife populations are already feeling the impacts, as well. Oceans have absorbed more than 90 percent of the excess heat in Earth’s climate system produced by human activities and 20 to 30 percent of manmade carbon dioxide emissions since the 1980s. Warmer ocean waters means less oxygen and nutrients for marine life, and carbon uptake by oceans causes ocean acidification. All of these impacts of the changing climate have already affected the distribution and abundance of marine life from coastal areas to the open ocean and the sea floor, according to the report.

“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. We increase our ability to build resilience and there will be more benefits for sustainable development.”

Dr. Elizabeth McLeod, a contributor to the IPCC special report and Global Reef Systems Lead at The Nature Conservancy, said in a statement: “The release of today’s report reinforces the urgency of the climate crisis. We have a clear choice: continue to imperil our most vulnerable communities and stand by as our food and water security are threatened; or take ambitious action now to boost the health of our ocean and cryosphere, and protect both people and nature.”

Conservationists characterized the report as a dire wake-up call for world leaders. “With today’s release of the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) by the Intergovernmental Panel on Climate Change (IPCC), international leaders are confronted by the stark and immediate consequences of failing to adequately address greenhouse gas emissions, as they impact the oceans,” Jason Patlis, executive director of the Marine Conservation Program at WCS (Wildlife Conservation Society), said in a statement.

“This report’s findings are staggering,” Andrew Norton, director of the International Institute for Environment and Development, said in a statement. “The rate and magnitude of change to the ocean, glaciers and ice sheets are happening much faster than previously predicted. The climate emergency must be met with equally accelerated action.”

He added: “Rich countries must step up their response to tackling climate change. The countries most able and historically responsible urgently need to make bigger cuts in emissions, transfer appropriate technologies and provide the money they committed to help developing countries cope with the climate crisis.”

Researchers collecting supplies for the NASA-funded ICESCAPE mission—Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment—which examined melt ponds, the ice around them, and the waters below. Photo Credit: NASA Goddard Space Flight Center.

This story is part of Covering Climate Now, a global collaboration of more than 300 outlets worldwide to strengthen coverage of the climate story.

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