Climate change

Reviews | Climate change is melting the ice of Greenland and Antarctica. It’s time to act.

As abnormally high temperatures this month caused an unprecedented melting of the Greenland ice sheet, experts delivered a chilling message: get used to it. Huge reserves of ice lie on land in Greenland and Antarctica, and if even a small fraction melted in the oceans, sea levels would rise dramatically. Scientists are still determining how quickly this might happen. But the new research leaves little room for optimism.

During this century, countless millions of people will have to reckon with rising seas. There are few easy answers, but humanity must – urgently – prepare now.

in a new paper in the journal Nature Climate Change, researchers estimated that the “zombie ice cream“- huge chunks destined to melt from the changes that have already occurred – will raise sea levels by almost a foot. Scientists calculate that about 3.3% of the island’s ice sheet will disappear from the oceans, much of it this century, equivalent to 110 trillion tons of ice.These estimates, based on direct observations from Greenland, are more pessimistic than previous projections, which were based on the computer modeling.According to the researchers, their new estimates represent the minimum that could occur if global warming were to continue.

These estimates do not take into account the melting that is happening in other regions, especially Antarctica – and the news from scientists on this end of the world, announced this month, was not good. A study published in Nature Geoscience has revealed harrowing new details about Antarctica’s gigantic Thwaites Glacier – a frozen expanse the size of Florida, also known as the “doomsday glacier” because its collapse could raise the level of the sea ​​3 to 10 feet. Scientists are still trying to determine how the glacier will react to global warming. The researchers therefore used an underwater robotic vehicle to map the behavior of the ice when it encountered different sorts of circumstances in the past, particularly when it interacted with the seafloor on which it is anchored. They found evidence that ice reacts quickly to adverse conditions, suggesting that “rapid withdrawal pulses are likely to occur in the near future”. “Thwaites is really holding today by his fingernails,” said Robert D. Larter of the British Antarctic Survey, one of the co-authors.

What is fast in geologic time seems slow on human timescales. The most serious consequences of melting ice caps may not occur for decades or more. Given how little experts know about the dynamics of these giant ice formations, their predictions could still be wrong. But the world is already feeling the effects of relatively modest sea-level rise. One example is the catastrophic flooding in New York City during Super-Hurricane Sandy in 2012. Melting land ice is one of the impacts the most predictable of global warming. As a result, the earlier communities prepare, the more likely they are to minimize damage from future disasters. Moreover, preparing early will cost less than reacting too late.

Expensive engineering efforts will be justifiable for critical areas. Hampton Roads, for example, is home to extensive naval facilities and will require substantial investment in water management projects. Manhattan, which Hurricane Sandy flooded, provoking some $19 billion in damage, is even more vital to the US economy. Construction has already started on a $20 billion project to build elevated parks, plazas and gates along Lower Manhattan. Local and federal authorities are discussing other options, such as massive sea gates that would close New York Harbor during major storms.

Even this grandiose plan may not make sense for Manhattan, as it contemplates various ways to keep water out. Proposals of this kind would be less justifiable for other places. A 2019 report by the Center for Climate Integrity found the country could spend $400 billion to build seawalls to protect coastal communities. As hard as it sounds, there are some places where it just doesn’t make sense to spend a lot of money trying to hold back the tides. Some will have to be dropped.

Smart planning is essential. State and local governments should enforce building codes that take into account the ever-increasing risk of flooding, like Houston did after Hurricane Harvey inundated the city in 2017. Meanwhile, government at all levels should refuse to subsidize risky waterfront development, such as offering favorable flood insurance rates for areas prone to flooding.

A recent reform of the Federal Emergency Management Agency’s National Flood Insurance Program brought premiums into line with the risks homeowners face, dramatically increased monthly costs for some owners and sparking howls of opposition. FEMA predicts that many more coastal areas will face high flood risk by 2100, the high-risk area 55% expansionit will therefore be a perpetual challenge for landlords and the government to correctly assess the exposure of different locations.

Leaders need to be tougher. At some point, localities will have to refuse to maintain roads, sewers and other services in areas where people should not live. States and localities such as New Jersey, in the aftermath of Hurricane Sandy, are buying up real estate in high-risk areas and turning them into floodplains and wetlands, natural barriers against flooding. Buyouts can be expensive for cash-strapped towns. But there are promising public-private models. Norfolk has explored ways to condition new construction in safer areas to developers helping to buy up properties in riskier areas. The federal government should also invest more in buyout efforts, allowing the National Flood Insurance Program to buy out homeowners rather than continually paying them to rebuild.

Yet even if buyout programs are well funded, some people will refuse to move, regardless of the risk. This will cause political problems, as residents of battered communities seek government assistance to rebuild in better derelict areas. This will also be true in other areas that climate change is making more perilous, such as the edges of forests that are increasingly susceptible to fire. The more the government insulates people from the real and growing cost of the choices they face in the face of global warming, the higher the final bill for society as a whole will be.

The world has been amply warned. Scientists have sounded the alarm: sea level rise is not a matter of “if”, but a matter of “when and how much”. The country’s leaders must not wait for floodwaters to inundate their communities — or for worsening wildfires or worsening droughts — to plan for the new reality.