Cascading impacts and tipping points for the Earth’s oceans and cryosphere are outlined in a report released by the Intergovernmental Panel on Climate Change (IPCC), a body of the United Nations.

The report comes a little over a month after a prior IPCC report on climate change and its effects on land (desertification, food security, greenhouse gas fluctuations in ecosystems, etc). It also comes days after a global climate strike organized by activists throughout the world.

“A total of 670 million people in high mountain regions and 680 million people in low-lying coastal zones depend directly” on systems in and around the ocean or cryosphere, which are the frozen parts of the planet.

“Four million people live permanently in the Arctic region, and small island developing states are home to 65 million people,” the IPCC notes.

The international body warns of marine heatwaves that will increase in “frequency, duration, spatial extent, and intensity under future global warming, pushing some marine organisms, fisheries, and ecosystems beyond the limits of their resilience.”

Marine heatwaves that were once one-in-hundred-day events at pre-industrial levels are projected to become one-in-four-day events by 2031-2050 and one-in-two-day events by 2081-2100, according to the report.

The duration of such marine heatwaves is expected to last from 126-152 days, an increase from 8-10 days during 1850-1900.

Most of the severe marine heatwaves will likely occur in the western tropical Pacific Ocean and Arctic Ocean.

It will intensify the bleaching of coral reefs. Under “high emission scenarios,” the Earth is expected to lose nearly all coral cover by 2100.

“Smaller countries and especially small islands face the challenge of being unable to ‘hedge’ the risk through geographical redistribution,” the report acknowledges.

The IPCC points out the global ocean has warmed “unabated since 1970 and has taken up more than 90 percent of the excess heat in the climate system.” Meanwhile, marine heatwaves have very likely “doubled in frequency since 1982,” and their intensity increases every year.

A collapse of the western Antarctic ice sheet is highlighted as one of the tipping points that will have a huge impact on the climate. The report says such an event would occur when the ice shelves broke and ice flowed toward the ocean.

Some Arctic regions may have already reached tipping points. The loss of Arctic sea ice, ocean acidification, methane release from permafrost, Greenland ice sheet decay, disappearance of individual glaciers, and landslides related to glaciers and permafrost are listed as abrupt events that could transpire.

When it comes to ocean acidification or the loss of the Greenland ice sheet, it may be centuries to millennia before the effects are reversed if certain thresholds are crossed.

To address these impacts and decrease the potential for intensifying severe effects of climate disruption, the authors of the report recommend “strongly reducing greenhouse gas emissions, protecting and restoring ecosystems, and carefully managing the use of natural resources.” They call for measures to improve the ability of communities to adapt to changes so risks to livelihoods are minimized.

It encourages scientists to work with local and indigenous communities to develop options for managing risks.

Three case studies are featured in the report—the extreme climate events in Tasmania during 2015-2016; the threats of warming, ocean acidification, temperature, and sea level rises in the Coral Triangle; and the severe Atlantic Ocean hurricanes of 2017.

Hurricanes Harvey, Irma, and Maria resulted in $265 billion in damage. It made 2017 the “costliest hurricane season on record.” The warming of “surface waters” in the Gulf of Mexico, as well as in the world’s oceans, fueled the destructive power of the storms that left unprecedented rainfall in Texas and resulted in the deaths of 68 people in Houston.

“The Houston metropolitan area was devastated [by Harvey] with the release of about 4.6 million pounds of contaminants from petrochemical plants and refineries,” the report recalls.

“Irma caused 44 direct deaths and wiped out housing, schools, fisheries, and livestock in Barbuda, Antigua, St. Martin, and the British Virgin Island,” according to the report. “Maria caused 31 direct deaths in Dominica and two in Guadeloupe and around 65 in Puerto Rico, and completely vacated Barbuda. Maria destroyed almost all power lines, buildings, and 80 percent of crops in Puerto Rico and damaged pharmaceutical industries that provided 33 percent of Puerto Rico’s GDP causing shortages of some medical supplies in the [United States].”

The report adds, “The effects of Maria are expected to increase the poverty rate by 14% because of unemployment in tourism and agriculture sectors for more than a year in Dominica and resulted in outmigration to neighboring countries or the U.S.”

The Coral Trianlge is a four million square-mile section of the ocean and coastal waters in southeast Asia and the Paific. The area surrounds Indonesia, Malaysia, Papua New Guinea, Philippines, Timor Leste, and the Solomon Islands.

It is the “center of the highest coastal marine biodiversity in the world,” and that’s “due to its geological setting, physical environment, and an array of ecological and evolutionary processes which makes it a conservation priority,” the report states. Over 100 million people from “diverse and rich cultures” benefit from food, building materials, and coastal protection.

Yet, it faces severe threats of warming, ocean acidification, sea level rises, as well as coastal development and overfishing.

“Coastal deforestation, coastal reclamation, destructive fishing methods and over-exploitation of marine life” already create immense pressures. Forty percent of the coral reefs and mangroves in the area have been lost over the past 40 years.

Back in 2015-2016, Tasmania in southeast Australia endured “the driest warm season on record (October to April), together with the warmest summer on record.”

It resulted in droughts. “Thousands of lighting strikes during the first two months of the year led to more than 165 separate vegetation fires.” Damage to more than 296,400 acres of land including in protected areas resulted in costs that exceeded 50 million in Australian dollars.

Late January gave way to heavy rainfall and floods. That put further strain on emergency services. This period became the wettest season on record for Tasmania. “Meanwhile, an intense marine heatwave off the east coast persisted for 251 days from spring 2015 through to autumn 2016.”

Water levels for hydroelectric dams became drastically low. The dry period further reduced the ability of people to generate power. Emergency diesel generators were needed for power.

“The marine heatwave caused disease outbreaks in farmed shellfish, mortality in wild shellfish and species found further south than previously recorded,” according to the report. It had cascading impacts on all sectors of the Tasmanian economy.

IPCC details several of significant marine heatwaves that occurred in the past decade.

In 2016, the Alaskan Sea was plagued by algal blooms that poisoned the shellfish and resulted in the deaths of seabirds. It reduced the size of pollock, Pacific cod, and Chinook salmon.

The Northeast Pacific went through a heatwave from 2013-2015. The warming caused the “largest ever recorded outbreak of demoic acid along the North American west coast. Demoic acid was detected in many marine mammals, such as whales, dolphins, porpoises, seals, and sea lions.”

This toxin forced the “extensive closure razor clam and crab fisheries” in the area.

In 2012, the northeast Atlantic had a heatwave that disrupted the U.S. lobster industry. Lobsters moved from deep offshore waters to more shallow coastal waters. Catch rates skyrocketed, but this created a supply chain bottleneck. A collapse in lobster prices occurred, threatening the viability of many U.S. and Canadian fisheries.

The IPCC’s work renews a sense of urgency for decisive action from leaders, particularly those in countries most responsible for carbon emissions and environmental degradation.

“The more decisively and the earlier we act, the more able we will be to address unavoidable changes, manage risks, improve our lives and achieve sustainability for ecosystems and people around the world—today and in the future,” Debra Roberts, the co-chair of the IPCC’s working group declared.