Rising concentrations of heat-trapping greenhouse gases in the atmosphere are reshaping the world from the top down, according to a special report on the world’s oceans and frozen regions from the United Nations climate panel.

Melting glacial ice, driven by man-made temperature changes, is disrupting the supply of water, food, and energy downstream while raising the risk of landslides, floods, and other natural hazards in the Alps, Andes, Caucasus, Himalayas, and other major mountain ranges. Along with the collapse of ice sheets on Antarctica and Greenland, the meltwaters also contribute to an accelerating rise in sea levels. In the Arctic, permafrost is weakening, causing land to slump and destabilizing roads and structures.

“Taken together, these changes show that the world’s ocean and cryosphere have been taking the heat from climate change for decades,” said Ko Barrett, vice chair of the Intergovernmental Panel on Climate Change, the scientific panel that produced the report. “The consequences for nature and humanity are sweeping and severe.”

The report was released just as Italian authorities were evacuating residents in the Alps who live beneath a portion of the Mount Blanc glacier that mountain observers in the area claim is nearing collapse.

The shrinking of glaciers and breakdown of ice sheets, which combined cover 10 percent of the Earth’s land area, are some of the most visible symbols of a fevered planet.

“For glaciers, the climate signal is so, so clear,” Aditi Mukherji of the International Water Management Institute, told Circle of Blue. Mukherji was a review editor for the report, which looked at observed changes, future projections, and actions for mitigation and adaptation. “Mountains regulate the climate,” she added. “And they provide water, food, and energy. The report is very timely.”

Mountain ice is important locally, regionally, and globally, said Ben Orlove of Columbia University, a lead author on the chapter on high mountain regions.

Locally, glaciers provide water to sustain small-scale farming and for drinking. Glaciated peaks often hold special religious or cultural meaning for the 680 million people, or 10 percent of the world’s population, who live in high mountain zones.

Melting of glaciers is also remaking local ecosystems. Plant and animal species are migrating upwards as high-elevation regions warm. At the same time, species that depend on cold environments run the risk of sharp declines in abundance, or even extinction, the report states.

“Indigenous and local populations who depend on these resources, their lives are in disarray,” said Mukherji, who works primarily in southern Asia.

Orlove pointed to a number of studies of Himalayan villages that showed that a loss of water availability in the high mountains resulted in people leaving their homes. “As agriculture declines, people move out,” he told Circle of Blue. Some may find employment elsewhere and send back money. But loss of young workers in Pakistani villages caused the local irrigation infrastructure to fall into disrepair.

Regionally, meltwater from snow and ice is the raw force that drives the turbines at hydropower dams, irrigates rice paddies and wheat fields, and provides drinking water downstream. Rivers like the Ganges, Indus, and Mekong, which rely on glaciers for a portion of their flow, support hundreds of millions of people in China, India, Pakistan, Vietnam, and other countries.

And globally, glacial melt contributes a substantial fraction of sea level rise, about one-sixth of the observed annual change between 2006 and 2015, according to the report.

Melting ice in the Arctic and in mountain areas has had “predominantly negative impacts” for food security, water quality, infrastructure, health, and cultural resources, the report states.

A Call for Responses

IPCC reports do not contribute new research. They are compilations and distillations of existing studies. More than 6,900 were considered in this edition.

A significant portion of the report centered on policies for responding to climate change. Mukherji, who is the water chapter coordinating lead author for the next IPCC report, said that the report authors are being asked by government leaders “to be more solution-focused.”

The report authors answered that call by drawing on a range of adaptation examples, from monitoring systems that warn communities when glacial lakes are a flood risk to conflict mediation that builds trust between those who share a resource.

“There’s a lot of local innovation,” Orlove said, mentioning the ice stupas built by communities in the Ladakh region of northern India. The stupas, whose tower shape mimics the design of a Buddhist monument, are sprayed with water in the autumn and winter months, in essence banking the water for the next growing season. When the ice melts in the spring, the water is used for irrigation as a supplement to declining glaciers and snowpack. These changes are likely to become more common. As the planet warms, mountain regions will see a shift in the timing of river flows: runoff will increase in the winter and decline in the summer, creating a mismatch between when water arrives and when it is needed for irrigation.

The stupas and other local resilience projects are bearing fruit. But much more is needed, often because those who are most vulnerable to the tumult of a changing climate are least financially capable of responding. “We also see that local efforts would be stronger with better financing and government support,” Orlove said.

Mukherji praised these sorts of local innovation. But she questioned the ability of local communities to shoulder the burden of resilience on their own. Her preference is for national governments to step in with adequate financing so that solutions can be scaled up to meet the magnitude of the challenge.

The report authors argue for these sorts of coordinated actions, not only to respond to growing hazards but also, by agreeing to reduce carbon emissions, to avoid them in the first place.

“If greenhouse gases continue to increase, global warming will drastically alter the ocean and the cryosphere,” said Hoesung Lee, chair of the IPCC. “However, if we reduce emissions sharply, consequences for people and their livelihoods will still be challenging but they will be potentially more manageable for those who are most vulnerable.”