Saturday, August 31, 2019

HIGHER TIDES.....they're coming!


From The Economist -  August 17th - 2019


Higher tide


The water is coming. The world is not ready

Imagine a huge horizontal A-frame: a recumbent, two-dimensional Eiffel Tower. Pin a pivot through its tip, so it can swivel around 90 degrees. Then add to its splayed feet something like the rocker of a rocking chair, but 210 metres long, 22 metres high and 15 metres wide. Now double it: picture, across a 360-metre-wide canal, its mirror image. Paint all their 13,500 tonnes of steel glistening white.

What you have imagined, the Dutch have built. When the Maeslant barrier (pictured on a subsequent page) is open, it allows ships as large as any ever built to pass along the canal to Rotterdam, Europe's biggest port. When closed, it protects that city—80% of which sits below sea level— from the worst storm surges the North Sea can throw at it.

In 1953 such a surge, driven by hurricane-force winds and coinciding with a spring high tide, broke through the dykes that protect much of the Netherlands from the sea in dozens of places, killing almost 2,000 people and inundating 9% of its farmland. Over the following 50 years the Dutch modernized their sea defences in one of the most ambitious infrastructure projects ever undertaken; the Maeslant barrier, inaugurated in 1997, was its crowning glory. It is to be swung shut whenever the sea surges above three metres (the 1953 surge was 4.5 metres). So far it has yet to be used in an emergency. But with the motor of a regional economy of €150bn ($167bn) at stake, better to be safe than sorry. In January the city's mayor, Ahmed Aboutaleb, told The Economist he now expects the barrier to have to close more frequently than the once-a-decade its makers planned for. It had come within 20cm just the day before. As Mr Aboutaleb makes clear, the rising threat is a result of climate change. Few places are as vulnerable as the Netherlands, 27% of which is below sea level. But many other places also face substantial risk, and almost all of them are far less able to waterproof themselves than the Dutch. It is not just a matter of being able to afford the hardware  (the Netherlands has 40,000km of dykes, levees and seawalls, plus innumerable sluices and barriers less mighty than the Maeslant). It is also a matter of social software: a culture of water governance developed over centuries of defending against the waves. The rest of the world cannot afford - the centuries it took the Dutch to build that up.

There are some 1.6m kilometres of coastline shared between the 140 countries that face the sea. Along this they have strung two-thirds of the world's large cities. A billion people now live no more than ten metres above sea level. And it is coming to get them. Global mean sea level (gmsl) ticked up by between 2.7mm and 3.5mm a year between 1993, when reliable satellite measurements began, and 2017 (see chart on next page). That may not sound like much; but to raise gsml a centimetre means melting over 3trn tonnes of ice. And though forecasts of sea-level rise are vexed with uncertainties and divergences, there is a strong consensus that the rate is accelerating as the world warms up. The Intergovernmental Panel on Climate Change (ipcc), which assesses climate change for the UN, says sea level rose by around 19cm in the 20th century. It expects it to rise by at least twice that much this century, and probably a good bit more. It is worth noting that last year the authors of a study looking at 40 years of sea-level-rise forecasts concluded that the ipcc's experts consistently "err on the side of least drama".
Sea-level rises on the order of one metre—a bit above the ipcc range for 2100— will cost the world a lot. Leaving aside fatalities owing to storms and storm surges, whose effects are worse in higher seas, one estimate made in 2014 found that by 2100 the value of property at risk from marine flooding would be worth between $20trn and $200trn. The Union of Concerned Scientists, an American ngo, estimates that by that time 2.5m existing coastal properties in America, today worth $1.1trn, could be at risk of flooding every two weeks.

A massive problem for some; an existential risk for others. Atoll nations like Kiribati—average elevation less than two metres—risk losing almost all their territory to floods like that pictured on the previous page. In 2015 the president of Micronesia, another Pacific island state, described the fate of such nations in the global greenhouse as "potential genocide". This, one hopes, goes too far; refugees could surely be resettled. Still, the extirpation of entire territorial states would be without any modern precedent.

We need to talk about calving

Some of this is unavoidable. About two-fifths of the increase so far comes not from water being added to the oceans, but from the water already in the oceans warming up and thus expanding. Scientists estimate the sea-level rise for a one-degree warming—which is what the world is currently experiencing, measured against the pre-industrial climate—at between 20cm and 60cm. They also note that, because it takes time for the oceans to warm up, that increase takes its time. This means the seas would continue rising for some time even if warming stopped tomorrow.

Not that it will. Today's mitigation measures are not enough to keep warming "well below" 2°C, the target enshrined in the Paris agreement of 2015; in the absence of more radical action, 3°C looks more likely. That would suggest a sea-level rise of between 60cm and 180cm from thermal expansion alone.

Though thermal expansion has dominated the rise to date, as things get hotter the melting of ice on land will matter much more. The shrinking of mountain glaciers, the water from which all eventually runs to the sea, is thought to have contributed a bit more than a third of the human-induced gmsl rise to date. The great ice sheets of Greenland and Antarctica have not yet done as much. But their time seems nigh.

In bathtub water-level terms, the melting of continental ice sheets is to thermal expansion as a rubber duck is to a person. When the most recent ice age ended, the melting of the ice sheets sitting atop western Eurasia and much of North America increased gmsl by around 120 metres.

Today's residual ice sheets are smaller— the equivalent of less than 70 metres of sea-level rise. And most of that is in the East Antarctic ice sheet, widely seen as very stable. The Greenland ice sheet, the second largest, is shrinking both because its glaciers are flowing more quickly to the sea and because the surface is melting at an unprecedented rate, but its loss of mass is not yet huge. It is the West Antarctic ice sheet which scares scientists most. Many think it will become unstable in a warmer world—or that it may already be unstable in this one.

The West Antarctic ice sheet looks, in profile, like a flying saucer that has landed on the sea-floor. A thin rim—an ice shelf-floats on the sea. A thicker main body sits on solid rock well below sea level. As long as the saucer is heavy enough, this arrangement is stable. If the ice thins, though—either through surface melting or through a faster flow of glaciers—buoyancy will cause the now-less-burdened saucer to start lifting itself off the rock. The boundary between the grounded ice sheet and its protruding ice shelf will retreat.

As this grounding line recedes, bits of the ice shelf break off. The presence of an ice shelf normally checks the tendency of ice at the top of the ice sheet's saucer to flow down glaciers into the sea. As the shelf fragments, those glaciers speed up. At the same time the receding grounding line allows water to undermine the ice sheet proper, turning more of the sheet into shelf and accelerating its demise (see diagram).

First suggested in the 1970s, marine-ice-sheet instability of this sort was long considered largely theoretical. In 1995, though, the Larsen A ice shelf on the Antarctic Peninsula, which is adjacent to the West Antarctic ice sheet, collapsed. Its cousin, Larsen B, suffered a similar fate in 2002. By 2017 there was a 160km crack in Larsen C. The glaciers on the peninsula are accelerating; so is the rate at which the sheet itself is melting. Marine-ice-sheet instability feels much more than theoretical. And though the West Antarctic ice sheet is a tiddler compared with its eastern neighbour, its collapse would mean a gmsl rise of about 3.5 metres. Even spread out over a few centuries, that is a lot.

Some fear that collapse could be quicker. In 2016 Robert DeConto, from the University of Massachusetts, and David Pollard, of Pennsylvania State University, noted that the ice cliffs found at the edge of ice sheets are never more than 100 metres tall. They concluded that ice cliffs taller than that topple over under their own weight. If bigger ice shelves breaking away from ice sheets—a process called calving— leave behind cliffs higher than 100 metres, those cliffs will collapse, exposing cliffs higher still that will collapse in their turn, all speeding the rate at which ice flows to the sea. The rapid retreat of the Jakobshavn glacier in Greenland offers some evidence to back this up.

Such cascades, the researchers calculated, could speed up the collapse in West Antarctica and bring one on in Greenland…… Mr DeConto and Mr Pollard point to ice-cliff instability as the reason why. When the process was included in models of today, they found that if greenhouse-gas levels continued to rise at today's reckless rates, Antarctica alone could add a metre to gmsl by 2100 and three metres by 2200.

This conclusion is not unassailable. In February Tamsin Edwards, of King's College, London, and colleagues published more sophisticated computer simulations that replicate the ancient sea levels without large-scale ice-cliff collapse, and thus suggest a slower rate of gmsl rise. Where the earlier work found a one-metre rise due to Antarctic ice this century, they found 22cm. The total rise, though, was still a disturbing 1.5 metres. And the possibility that, over further centuries, levels will rise many metres more remains real.

A lot less flat than a millpond

Efforts to pin down the extent and speed of ice-sheet collapse are themselves accelerating. When Anders Levermann led the sea-level work for the ipcc's most recent climate assessment, published in 2014, marine-ice-sheet instability was just a footnote. There were four computer models of the process back then, Mr Levermann says; today he can count 16. In January a team of British and American scientists embarked on a five-year, $25m field mission to study the Thwaites glacier in West Antarctica and its ice sheet from above and, using undersea drones, below, thus adding new data to proceedings.

However great the rise in gmsl ends up, not all seas will rise to the same extent. Peculiarly, sea levels near Antarctica and Greenland are expected to drop. At present, the mass of their ice sheets draws the seas to them in the same way the Moon's mass draws tides. As they lose weight, that attraction will wane. Other regional variations are caused by currents—which are expected to shift in response to climate change. A weakening Gulf Stream, widely expected in a warmer world, would cause sea level to rise on America's eastern seaboard even if gmsl did not change at all.

Then there is the rising and falling of terra not-quite firma. Some of this is natural; many northern land masses, long pressed down by the mass of ice-age ice sheets, have been rising up since their unburdening some 15,000 years ago. Some of it is human, and tends to be more local but also much more dramatic.

If you remove enough stuff from the sediments below you, the surface on which you stand will settle. In the first half of the 20th century Tokyo sank by four metres as Tokyoites not yet hooked up to mains water drained aquifers. Parts of Jakarta are now sinking by 25cm a year, as residents and authorities of Indonesia's capital repeat Japan's mistakes. Last year a study of the San Francisco Bay area found that maps of 100-year-flood risk—the risk posed by the worst flood expected over 100 years—based on sea-level rise alone underestimate the area under threat by as much as 90% compared with maps that accounted for land that was getting lower because of subsidence.

As land sinks, the sea erodes it away. Komla Sarkar, who lives in the village of Chandpur in Bangladesh's flood-prone south, recalls childhood days when her parents grew crops and kept goats and chickens between their hut and the water. "When we leave our houses in the morning," she now says, "we don't feel confident they will still be there when we return."

People often worsen erosion. Satellite images show that stretches of Mumbai's coast have eroded by as much as 18 metres since 2000, in part because developers and slum-dwellers have paved over protective mangroves. Other aspects of climate change will have effects, too. Heavier bursts of rainfall upstream will mean that some low-lying coastlines will see the risks posed by the sea compounded by those from rivers. In 2012 a team of Japanese researchers predicted that by 2200 the Bay of Bengal would experience 31% fewer cyclones than today, but that 46% more will roil the Arabian Sea on the other side of the subcontinent.

The biggest extra effect of human activity, though, may well be putting more property at risk as a more populous and richer world concentrates itself in cities by the sea. In the rich world, and increasingly in emerging economies too, the closer to the beach you can erect a condo or office block, the better. In New York alone 72,000 buildings sit in flood zones. Their combined worth is $129bn.

In October 2012 Hurricane Sandy jolted the city into a new awareness of the threats it faces, given that geology, gravity and the Gulf Stream are conspiring to raise the seas lapping at its shores by half as much again as the global average. Other cities are worrying, too. Rotterdam now welcomes 70 delegations a year from fact-finders seeking to apply Dutch know-how to New Jersey, Jakarta and points in between.

Barrier methods

A lot of effort is devoted to engineering a way out of the problem. New York is paying almost $800m for the Big U, a necklace of parks, walls and elevated roads to shield lower Manhattan from another Sandy. Mumbai wants to build four huge and costly seawalls. Bangladesh, a delta country ten times more populous and one-thirtieth as rich as the Netherlands, is doubling its coastal embankment system and repairing existing infrastructure. Indonesia intends a $40bn wall in the shape of a giant mythical bird to seal Jakarta off from the seas.

Such schemes take decades to plan and execute, which means the conditions they end up facing are not necessarily those they were conceived for. When the Big U was first proposed, a year after Sandy, the worst-case scenario for sea-level rise on America's east coast was one metre. When its environmental assessment report was eventually published this April, that looked closer to the best case.

London's Thames Barrier—conceived, like the Dutch delta defences, after the floods of 1953—closed just eight times between its inauguration in 1982 and 1990. Since 2000 it has shut 144 times. In Venice mose, a system of flood barriers which cost a staggering €5.5bn, will be needed every day if the seas rise by 50cm. Such near-permanence will render moot the huge effort and expense that went into keeping it unobtrusively submerged when not in use. At one metre of sea-level rise it would be basically pointless. Even the resourceful Dutch only designed Maeslant with one metre of sea-level rise in mind.

Kate Orff, a landscape architect, dismisses walls as one-dimensional attempts to solve multidimensional problems. Her project, a string of offshore breakwaters on the western tip of Staten Island to prevent coastal erosion while preserving sea life, is one of various "softer infrastructure" projects to have been funded by Rebuild by Design, a $1bn post-Sandy programme. Arunabha Ghosh of the Council on Energy, Environment and Water, an Indian think-tank, favours approaches which can be scaled up over time as the threat increases. These include anything from restoring mangroves, patch by patch, to barriers built out of interlocking blocks that can be added to as needed. "Modularity lets you shorten the time horizon," Mr Ghosh says.

As welcome as these ideas are, they remain niche. Rebuild by Design's $1bn is a drop in the bucket compared with the $60bn which Congress earmarked for post-Sandy recovery efforts. Some of that money was spent sensibly, for example on hardening power stations and hospitals. A lot was used to replace storm-lost buildings with new ones built in the same way and much the same place.

If this were paid for by the owners, or their insurers, it might be unobjectionable. But insureds and banks are only slowly beginning to capture sea-level rise in policies and mortgages. In a world awash with capital eager to build, buy or develop, prices seldom reflect the long-term threat. Some price signals are emerging where the problems are most egregious. Controlling for views and other amenities that they offer, prices of Floridan properties at risk of flooding have underperformed unexposed ones by 10-15% over the past few years, says Christopher Mayer of Columbia Business School. But they have not exactly tanked.

Instead of rebuilding as is, better to put in place appropriate defences, soft as well as hard, and rebuild in styles better suited to the conditions. Alternatively, in some cases, encourage, help or even require people to walk away. In the rich world such "managed retreat" is anathema. People see the government's job as protecting them, not moving them. Relocating a neighbourhood in New York requires the consent of the residents; holdouts can block decisions for years. "Across the country, there is no appetite for eminent domain," admits Dan Zarrilli, in charge of climate policy at New York's city hall.

In Bangladesh, though, the Ashrayan project, run directly by the prime minister's office, has relocated 160,000 families affected by cyclones, flooding and river erosion to higher ground at a total cost of $570m. Each family is housed in an army-built barracks and receives a loan of $360, plus 30kg of rice, to restart its life. It is expected to be extended for another three years, and cover another 90,000 households. Fiji has resettled a number of communities from low-lying islands, with dozens more earmarked for relocation. Meanwhile Kiribati, 2,000km away, has gained title to 20 square kilometres of Fiji as a bolthole against the day when its 117,000 citizens have to quit their homes.

Such schemes may require few civil engineers but they need plenty of social engineering. Bangladeshi officials familiar with the Ashrayan scheme have found converting fishermen into farmers far from straightforward. High ground wanted by some may also be coveted by others. When a Kiribati government delegation visited its plot in Fiji recently, it found some non-Kiribatis making themselves at home.

Permanent resettlement is not the only form of people moving that needs considering. In places where communications are good and storms frequent evacuation can be an effective life-saver. But what of places where the big storms are very rare? Drills to make people familiar with plans they have never yet had to enact are possible—but they are also massively inconvenient, and maybe worse. A few years ago Mr Aboutaleb cancelled a test evacuation of 12,000 Rotterdammers after computer models suggested a handful of elderly or infirm evacuees might die in the process.

Even if people move, they cannot take with them everything that they value. This is not just a matter of private property. Last October Lena Reimann of Kiel University published a warning that 37 of the 49 unes-co world-heritage sites located on the Mediterranean's coasts can now expect to flood at least once a century. All but seven risk being damaged by erosion in the coming decades. Sites do not need world-heritage status to matter. The headman of the first flood-prone Fijian community resettled by the government bemoans the burial grounds abandoned to the sea.

No we Canute

The inertia in the climate system means that not even the most radical cuts in emissions - nor, indeed, a dimming of sunlight brought about by means of solar geoengineering—will stop sea levels dead in their tracks. Adaptation will be necessary. But there is little appetite to pay for it. A rise that seems precipitous to Earth scientists remains well beyond the planning horizons of most businesses: even utilities rarely take a century-long perspective. Governments can always find more pressing concerns, both at home and when helping others abroad. Less than one-tenth of $70bn in annual global climate aid goes to helping poor places cope with all effects of climate change, not just sea-level rise.

The lack of action reflects a lack of drama—for almost everyone, the worst floods of the year or decade happen somewhere else. The oceans will not suddenly crush all the world's coasts like some biblical retribution or Hollywood tsunami. It will rise slowly, like a tide, its encroachment as imperceptible from moment to moment as it is inexorable. But unlike a tide, it will not turn. Once the oceans rise, they will not fall back. ■


The Economist August 17th 2019

Rising seas

A world without beaches
How to prepare for the deluge

The ocean covers 70.8% of the Earth's surface. That share is creeping up. Averaged across the globe, sea levels are 20cm higher today than they were before people began suffusing the atmosphere with greenhouse gases in the late 1800s. They are expected to rise by a further half-metre or so in the next 80 years; in some places, they could go up by twice as much—and more when amplified by storm surges like the one that Hurricane Sandy propelled into New York in 2012. 

Coastal flood plains are expected to grow by 12-20%, or 70,000-100,000 square kilometres, this century. That area, roughly the size of Austria or Maine, is home to masses of people and capital in booming sea-facing metropolises. One in seven of Earth's 7.5bn people already lives less than ten metres above sea level; by 2050, 1.4bn will. Low-lying atolls like Kiribati may be permanently submerged. Assets worth trillions of dollars—including China's vast manufacturing cluster in the Pearl river delta and innumerable military bases—have been built in places that could often find themselves underwater.

The physics of the sea level is not mysterious. Seawater expands when heated and rises more when topped up by meltwater from sweating glaciers and ice caps. True, scientists debate just how high the seas can rise and how quickly and politicians and economists are at odds over how best to deal with the consequences—flooding, erosion, the poisoning of farmland by brine. Yet argument is no excuse for inaction. The need to adapt to higher seas is now a fact of life.

Owing to the inexorable nature of sea-swelling, its effects will be felt even if carbon emissions fall. In 30 years the damage to coastal cities could reach $1trn a year. By 2100, if the Paris agreement's preferred target to keep warming below 1.5°C relative to preindustrial levels were met, sea levels would rise by 50cm from today, causing worldwide damage to property equivalent to 1.8% of global GDP a year. Failure to enact meaningful emissions reductions would push the seas up by another 30-40CM, and cause extra damage worth 2.5% of GDP.

In theory minimizing the damage should be simple: 

construct the hardware (floodwalls), install the software (governance and public awareness) and, when all else fails, retreat out of harm's way. This does not happen. The menace falls beyond most people's time horizons. For investors and the firms they finance, whose physical assets seldom last longer than 20 years, that is probably inevitable—though even businesses should acquaint themselves with their holdings' nearer-term risks (which few in fact do). For local and national governments, inaction is a dereliction of duty to future generations. When they do recognize the problem, they tend to favour multibillion-dollar structures that take years to plan, longer to erect, and often prove inadequate because the science and warming have moved on.

As with all climate-related risks, governments and businesses have little incentive to work out how susceptible they are. Some highly exposed firms are worried that, if they disclose their vulnerabilities, they will be punished by investors. Governments, notably America's, make things worse by encouraging vulnerable households to stay in harm's way by offering cheap flood insurance. More foolish still, some only reimburse rebuilding to old standards, not new flood-proof ones.

However, there are ways to hold back the deluge. Simple things include building codes that reserve ground levels of flood-prone buildings for car parks and encourage "wet-proofing" of walls and floors with tiles so as to limit the clean-up once floodwaters recede. Mains water, which is desirable in its own right, may stop people without access to it from draining aquifers, which causes land to subside; parts of Jakarta are sinking by 25cm a year, much faster than its sea is swelling. If more ambitious projects are needed to protect dense urban centres, they ought to be built not for the likeliest scenario but for the worst case, and engineered to be capable of being scaled up as needed. The New York region has funnelled $1bn out of a reconstruction budget of $60bn to such experiments in Sandy's wake.

Authorities must also stop pretending that entire coastlines can be defended. Unless you are Monaco or Singapore, they cannot. Elsewhere, people may need to move to higher ground. Bangladesh, for instance, is displacing 250,000 households.

All this requires co-ordination between different levels of government, individuals and companies, not least to prevent one man's levee from diverting water to a defenceless neighbour. Market signals need strengthening. Credit-raters, lenders and insurers are only beginning to take stock of climate risks. Making the disclosure of risks mandatory would hasten the process. And poor, vulnerable places need support. Just $70bn a year of the $100bn in pledged climate aid to help them tackle the causes and impact of global warming has materialized. Less than one-tenth of it goes to adaptation. This must change.

Open the floodgates

Actuaries calculate that governments investing $1 in climate resilience today will save $5 in losses tomorrow. That is a good return on public investment. Rich countries would be foolhardy to forgo it, but can probably afford to. Many developing countries, by contrast, cannot. All the while, the water is coming. ■


From The Economist - August 10th - 2019

Science & technology
The Economist August 10th 2019
Technologists are working out ways to lessen the likelihood that debris falling from space will kill people

Space debris and human safety

Stopping a hard rain

Every day a tonne or two of defunct satellites, rocket parts and other man-made orbiting junk hurtles into the atmosphere. Four-fifths of it burns up to become harmless dust, but that still leaves a fair number of fragments large enough to be lethal. It is testament to how much of Earth's surface is sea, and how sparsely populated the remainder remains, that the only recorded victims of this artificial hailstorm are five sailors aboard a Japanese vessel, who were injured in 1969, and a woman in Oklahoma who was grazed by a piece of falling rocket in 1997. But it is also testament to luck—and the odds of that luck holding are shortening.

Population growth means that the fraction of Earth's surface which space debris can hit harmlessly is shrinking. At the same time, more spacecraft are going up (111 in successful launches in 2018, compared with 66 a decade earlier, and with many launches carrying multiple payloads). And payloads themselves are increasingly designed so that equipment which has fulfilled its purpose falls out of orbit years or decades sooner than it otherwise would, lest it collide with functioning spacecraft. In light of all this, more attention is being paid to the safe disposal of satellites and other space junk. To do that, space agencies and private companies alike want to steer craft to the least risky impact-destinations possible, and also reduce the number of fragments that will survive re-entry and endanger people and property.

A drop in the ocean

One tried and tested solution is to plunge a re-entering craft into a zone known as the South Pacific Ocean Uninhabited Area. This is the expanse between Chile and New Zealand. It is island-free, little sailed and little overflown. Such controlled re-entries are not a completely precise science. Any ships and planes heading into the vicinity at the time will be advised to steer clear of a potential impact area that may exceed 10,000 km2—roughly the size of Lebanon. But if everyone takes these warnings seriously, then controlled re-entries are as safe as it gets, according to Holger Krag, head of the European Space Agency's Space Debris Office in Darmstadt, Germany.

Job done, you might think. Yet only a few controlled re-entries are carried out each year. The reason is cost. If a spacecraft is to be put into the steep descent needed to aim it reasonably precisely at a particular spot on Earth's surface, it will need to carry two or three times as much fuel as is required for standard orbital adjustments. It will also require larger thrusters. That fuel and those thrusters add to a mission's weight, and therefore its launch costs. Ground controllers are also necessary to supervise the re-entry. Ending a mission with a controlled re-entry can thus add more than €2om ($22m) to its cost.

A cheaper alternative is a "semi-controlled" re-entry. Instead of diving towards a pre-arranged target, a satellite is lowered gradually into the atmosphere using either what thruster-fuel remains to it or a specially designed drag-sail. This sail intercepts air molecules that have leaked into space from the atmosphere, slowing down the satellite it is attached to and thus decreasing the craft's altitude until it reaches a point where air resistance to the body itself pulls it into the atmosphere.

The trade-off is that the danger zone associated with such a de-orbiting is much larger than that of a properly controlled reentry. It is still possible to arrange for this zone to have lots of oceans and few big cities. But there is not the certainty of no casualties that the South Pacific Ocean Uninhabited Area brings with it. Also, though more economical than the fully controlled variety, semi-controlled re-entry is not free. Saving fuel for it shortens mission lengths. Adding a drag sail adds to launch weight. In practice, therefore, almost all spacecraft re-enter the atmosphere at random. But this has not prevented experts from working out the probability that the random re-entry of a given mission will cause casualties. And that is useful information, because it can be used to decide whether a mission should go ahead in the first place.

Re-entry-survivability analysis, as it is known, is done using software that crunches data on the size, shape, configuration, composition and thickness of a satellite's components. That provides an estimate of the number, weight, size and shape—and therefore potential harmful-ness—of pieces that atmospheric friction will not reduce to dust. The probability of casualties can then be calculated in light of the population density under the spacecraft's orbit.

Hyperschall Technologie Gottingen (HTG), a German firm, charges about €50,000 for such an analysis. Its clients include three European satellite manufacturers— OHB System of Germany, Elecnor of Spain and Airbus—as well as several space agencies. For their money, these organizations get a bespoke assessment of the likely fate of a particular spacecraft, based on digital files of its design, and using programs with names like "Spacecraft Entry Survival Analysis Module" and "Debris Risk Assessment and Mitigation Analysis" that have been calibrated by experiments in the plasma wind tunnels owned by Germany's space agency.

If these calculations come back showing that the risk of a satellite killing or injuring someone during re-entry is greater than one in 10,000—which roughly half do—then permission to launch will probably be denied unless the craft is redesigned or can be rigged for a semi-controlled entry at more favourable odds. The idea of setting the acceptable risk at 10,000 to one, though derided by some as arbitrary, was adopted by America's space agency, nasa, in 1995, by Japan in 1997, by France in 1998 and by a dozen or so other places in the years since.

Feeling the heat

Having to do such calculations at all, though, is suboptimal. The best solution to the problem of re-entering space debris is to build spacecraft so that nothing will reach the ground in the first place. One way to "design for demise", says Ettore Perozzi, an expert on debris at Italy's space agency, is to build a spacecraft "like a chocolate bar", so that it snaps easily into pieces. The idea is for specially positioned weak parts to fail early during re-entry, ripping the thing apart at an altitude of about 125km, rather than the standard 80km or so. This exposes the spacecraft's guts to greater destructive heat for additional seconds.

One promising means of getting a spacecraft to rip open early, according to Charlotte Bewick, head engineer for debris at OHB System, is to forge screws, nuts and other parts for couplings out of special "shape memory" alloys. When heated, these alloys return to a "remembered" shape they once held—which, in this case, will facilitate a rapid wiggling apart early in re-entry. Thales Alenia Space, a Franco-Italian firm, sees more promise in another way of accelerating a spacecraft's break-up. It has patented a "demisable" coupling that, thanks to a special washer, comes apart quickly when heated. Engineers are testing prototypes in a plasma wind tunnel and reckon the winning design will contain a low-melting-point alloy of zinc.

Another way to reduce what reaches the ground is to substitute refractory materials such as titanium and steel, used to make things like fuel tanks and fly wheels, with substances such as aluminium and graphite epoxy that vaporise more easily. According to Lilith Grassi, a debris expert at Thales Alenia, this approach is bearing fruit.

Even these measures, though, will not bring every spacecraft into compliance with the one-in-10,000 rule. So engineers have thought up additional ways to lower the likelihood of a casualty. Those at OHB System, for example, have proposed fastening together with strong cabling any components expected to survive re-entry. That will prevent them from fanning out - meaning, as Dr Bewick puts it, that the surviving debris will hit Earth like a single bullet instead of a shotgun blast, thus reducing the chance that anyone will be struck.

OHB System has yet to find a customer for a satellite fitted with such containment cabling. It would add weight, and thus cost. Moreover, some dislike the notion of increasing the amount of material that will strike Earth, even if that increase reduces the chance of a death. But a related approach is under study at Thales Alenia. This firm may begin encasing in a single package the lenses and other components of optical systems that currently often hit the ground as a spray.

Something no one seems to be asking in all this, is what an appropriate level of safety for satellite re-entries actually is. The original reason for picking 10,000 to one as an acceptable risk level has been lost in the mists of time. To a given individual in Earth's human population of 7-5bn, it translates into one chance in 75 trillion per re-entry. This is vanishingly small, even in a world where re-entries are numbered in the hundreds per year.

On the other hand, any death delivered from outer space in this way would be headline news, and might result in calls for the rules to be tightened still further. So far, the satellite business has a pretty good safety record. It would like to keep things that way. ■

Saturday, August 24, 2019


From The Economist - August 3 - 2019

Books & arts 

Killer insects

The itch of fate

The Mosquito. By Timothy Winegard. Button Books; 496 pages; $28. 
Text Publishing; £12.99

During the second world war, American troops in the Far East were said to have two foes. The first was Japanese. One propaganda poster depicted an enemy's sabre, slick with blood. The second adversary had no sword but was terrifying all the same. Malaria-carrying mosquitoes infected around 60% of Americans stationed in the Pacific at least once. Drugs such as Ata-brine could help, but nasty side-effects meant that some gis shunned their daily dose—with predictable consequences. "These Men Didn't Take Their Atabrine" warned a sign propped below a pair of human skulls in Papua New Guinea.

At least decent treatment was available. For most of human existence, says Timothy Winegard in his lively history of mosquitoes, "we did not stand a chance" against the insect and its diseases. That was partly because of ignorance. Earlier humans blamed malaria and its mosquito-borne cousins on "bad air" from swamps, even as the years passed and death kept whining at their ears. Malaria once killed over 20% of people in the Fens of eastern England. Yellow fever ravaged Memphis, Tennessee, deep into the 1800s. No wonder Mr Winegard calls the mosquito a "destroyer of worlds", which may have dispatched around half of all humans ever born.

But his book is more than a litany of vietims. Mr Winegard convincingly argues that the insect has shaped human life as well as delivering death. Mosquitoes helped save the Romans from Hannibal and Europe from the Mongols. And if malaria has changed history, so has resistance to it. Europeans believed that the relative immunity enjoyed by some Africans made them ideal slaves in the New World. Later, the tables were turned. "They will fight well at first, but soon they will fall sick and die like flies," predicted Teussaint Louverture of the Frenchmen sent to end his slave revolution in Haiti. He was right. About 85% of the 65,000 soldiers deployed to the colony died of mosquito-borne illnesses, and Haiti won its independence.

These dashes across time and distance could become exhausting, but Mr Winegard is an engaging guide, especially when he combines analysis with anecdote. One highlight relays a bizarre plot by a Confederate zealot to infect Abraham Lincoln with yellow fever; another passage explains the ancient Egyptian habit of fighting malarial fevers by bathing in urine. (A few of the witticisms fall flat. Calling the 18th-century Caribbean a "dinner-party buffet" for mosquitoes seems glib, for example; anthropo-morphising the pests as a "guerrilla force" is a metaphor too far.)

But much of Mr Winegard's narrative is thrilling—above all the concluding chapters in which he tackles the modern mosquito. Drugs and insecticides have helped slash malaria rates, but mosquitoes can quickly develop immunity themselves. In total, the insects still kill over 800,000 people every year. And though gene-editing might one day render them harmless, or even obliterate them altogether, mosquito-borne illnesses such as Zika have recently been spreading to new regions. The destroyer of worlds has not finished yet. ■


From The Economist - August 3 - 2019


Brazil has the power to save Earth's greatest rainforest— or destroy it

Although its cradle is the sparsely wooded savannah, humankind has long looked to forests for food, fuel, timber and sublime inspiration. Still a livelihood for 1.5bn people, forests maintain local and regional ecosystems and, for the other 6.2bn, provide a—fragile and creaking—buffer against climate change. Now droughts, wildfires and other human-induced changes are compounding the damage from chainsaws. In the tropics, which contain half of the world's forest biomass, tree-cover loss has accelerated by two-thirds since 2015; if it were a country, the shrinkage would make the tropical rainforest the world's third-biggest carbon-dioxide emitter, after China and America.

Nowhere are the stakes higher than in the Amazon basin— and not just because it contains 40% of Earth's rainforests and harbours 10-15% of the world's terrestrial species. South America's natural wonder may be perilously close to the tipping-point beyond which its gradual transformation into something closer to steppe cannot be stopped or reversed, even if people lay down their axes. Brazil's president, Jair Bolsonaro, is hastening the process—in the name, he claims, of development. The ecological collapse his policies may precipitate would be felt most acutely within his country's borders, which encircle 80% of the basin— but would go far beyond them, too. It must be averted.

Humans have been chipping away at the Amazon rainforest since they settled there well over ten millennia ago. Since the 1970s they have done so on an industrial scale. In the past 50 years Brazil has relinquished 17% of the forest's original extent, more than the area of France, to road- and dam-building, logging, mining, soyabean farming and cattle ranching. After a seven-year government effort to slow the destruction, it picked up in 2013 because of weakened enforcement and an amnesty for past deforestation. Recession and political crisis further pared back the government's ability to enforce the rules. Now Mr Bolsonaro has gleefully taken a buzz saw to them. Although congress and the courts have blocked some of his efforts to strip parts of the Amazon of their protected status, he has made it clear that rule-breakers have nothing to fear, despite the fact that he was elected to restore law and order. Because 70-80% of logging in the Amazon is illegal, the destruction has soared to record levels. Since he took office in January, trees have been disappearing at a rate of over two Manhattans a week.

The Amazon is unusual in that it recycles much of its own water. As the forest shrivels, less recycling takes place. At a certain threshold, that causes more of the forest to wither so that, over a matter of decades, the process feeds on itself. Climate change is bringing the threshold closer every year as the forest heats up. Mr Bolsonaro is pushing it towards the edge. Pessimists fear that the cycle of runaway degradation may kick in when another 3-8% of the forest vanishes—which, under Mr Bolsonaro, could happen soon. There are hints the pessimists may be correct (see Briefing). In the past 15 years the Amazon has suffered three severe droughts. Fires are on the rise.

Brazil's president dismisses such findings, as he does science more broadly. He accuses outsiders of hypocrisy—did rich countries not fell their own forests?—and, sometimes, of using environmental dogma as a pretext to keep Brazil poor. "The Amazon is ours," the president thundered recently. What happens in the Brazilian Amazon, he thinks, is Brazil's business.

Except it isn't. A "dieback" would directly hurt the seven other countries with which Brazil shares the river basin. It would reduce the moisture channelled along the Andes as far south as Buenos Aires. If Brazil were damming a real river, not choking off an aerial one, downstream nations could consider it an act of war. As the vast Amazoniah store of carbon burned and rotted, the world could heat up by as much as 0.1°C by 2100—not a lot, you may think, but the preferred target of the Paris climate agreement allows further warming of only 0.5°C or so.

Mr Bolsonaro's other arguments are also flawed. Yes, the rich world has razed its forests. Brazil should not copy its mistakes, but learn from them instead as, say, France has, by reforesting while it still can. Paranoia about Western scheming is just that.

The knowledge economy values the genetic information sequesered in the forest more highly than land or dead trees. Even if it did not, deforestation is not a necessary price of development.

Brazil's output of soyabeans and beef rose between 2004 and 2012, when forest-clearing slowed by 80%. In fact, aside from the Amazon itself, Brazilian agriculture may be deforestation's biggest victim. The drought of 2015 caused maize farmers in the central Brazilian state of Mato Grosso to lose a third of their harvest. 

For all these reasons, the world ought to make clear to Mr Bolsonaro that it will not tolerate his vandalism. Food companies, pressed by consumers, should spurn soyabeans and beef produced on illegally logged Amazonian land, as they did in the mid-2000s. Brazil's trading partners should make deals contingent on its good behaviour. The agreement reached in June by the eu and Mercosur, a South American trading bloc of which Brazil is the biggest member, already includes provisions to protect the rainforest. It is overwhelmingly in the parties' interest to enforce them. So too for China, which is anxious about global warming and needs Brazilian agriculture to feed its livestock. Rich signatories of the Paris agreement, who pledged to pay developing ones to plant carbon-consuming trees, ought to do so. Deforestation accounts for 8% of global greenhouse-gas emissions but attracts only 3% of the aid earmarked for combating climate change.

The wood and the trees

If there is a green shoot in Mr Bolsonaro's scorched-earth tactics towards the rainforest, it is that they have made the Amazon's plight harder to ignore—and not just for outsiders. Brazil's agriculture minister urged Mr Bolsonaro to stay in the Paris agreement. Unchecked deforestation could end up hurting Brazilian farmers if it leads to foreign boycotts of Brazilian farm goods. Ordinary Brazilians should press their president to reverse course. They have been blessed with a unique planetary patrimony, whose value is intrinsic and life-sustaining as much as it is commercial. Letting it perish would be a needless catastrophe. ■

Saturday, August 10, 2019


The Economist July 27th 2019 

Financial crime

Land of the tax-free

Will America go from hunter to hunted in cross-border tax evasion?

America has launched brutal assaults over the past decade on countries, such as Switzerland and Liechtenstein, where banks have helped American citizens hide money and thereby evade tax. Forced to clean up, these erstwhile havens have seen much tainted capital flow elsewhere—not least to America itself. Now it is the former aggressor's turn to be on the defensive. Other countries are using similar tools to those America once employed to reveal untaxed money stashed by their own citizens in the world's largest economy.

As well as fining and prosecuting the enablers of tax-dodging—Swiss banks alone coughed up at least $5.5bn—America passed a law in 2010 known as fatca that required foreign financial firms to spill the beans on American clients. Stung into action, more than 100 other countries signed up to the "Common Reporting Standard" (CRS), and now swap tax-relevant financial information with each other.

America, however, did not join the CRS. Instead it shares information on the foreign clients of American banks under fatca's reciprocal provisions. But sharing is patchy; a lot of countries get nothing. Combine that with the high level of anonymity offered by American shell companies, and it is hardly surprising that America has become the destination of choice for many tax evaders. One tax expert reckons that "over 9p% of assets avoiding the CRS have been herded into the USA”.

America does not have to worry about the sort of bludgeoning that it doled out to Switzerland—no other country has anything like the same extra-territorial financial power. But other countries are finding that there are legal tools at their disposal, all the same. One is the so-called John Doe summons. 

This American provision assists tax authorities going after "a particular person or ascertainable group or class of persons" whom they suspect of financial wrongdoing, but whose identities are unknown. If approved by a court, the summons forces banks to hand over names.

Until now the biggest user of such summonses in tax cases has been America, which, for instance, used the procedure in 2008 to prise open Swiss bank secrecy. That resulted in UBS handing over the names of around 4,500 account-holders. 

In April the tables were turned when a request from Finland prompted America's Internal Revenue Service to petition a federal court in North Carolina for leave to serve John Doe summonses on three banks in America. Heavy use at Finnish ATMs of payment cards issued by the banks, and linked to American accounts, had led the Finnish tax authority to conclude that they were being used by Finnish taxpayers who had hidden untaxed income across the Atlantic. The court has since granted approval.

Other countries suffering tax leakage will be looking more closely at this procedure. Any of the 90 with a ratified bilateral tax treaty with America can use it, though some seem unaware of the option. (By contrast, America has agreed to exchange information with only 47 countries under FATCA.) Experts say it could help to break open not only dodgy bank accounts but also trusts and insurance policies, which are also commonly used to hide capital.

There could still be obstacles, for instance if an account is owned by an entity rather than an individual. But banks issued with a summons are required to investigate who stands behind account-holding shell companies. Due-diligence rules designed to curb money-laundering and the financing of terrorism, issued by FincEN, a federal agency, already require banks to know the identity of such "beneficial" owners (though not all seem to do so). A shell-cracking bill picking up momentum as it passes through Congress would also help improve corporate transparency.

If more countries take the John Doe route, it would help balance the unequal relationship America enjoys in matters of financial transparency. For too long it has got away with demanding much while offering little in return. Taxdodgers stashing cash in America, says Mark Morris, an international tax consultant, should "prepare to be smacked open like a pinata