Tim Radford

Rising Global Temperatures Threaten Survival of Birds and Reptiles

The gloriously-coloured forest birds of Hawaii may lose at least half their living space because of climate change, according to new research.

And soaring global temperatures mean that many of the world’s lizards could be in trouble by 2100, and could seriously compromise the loggerhead turtle, whose sex is decided by the heat of the day at the time of incubation.

The plight of lizards is highlighted by Elvire Bestion, an ecologist at the University of Exeter Environment and Sustainability Institute, U.K., and the Experimental Ecology Research Station at Moulis in France and colleagues in a report in the Public Library of Science journal PLOS Biology.

Greenhouse gases

They describe how they used a “Metatron” — a series of semi-natural enclosures in which temperatures could be turned up or down — to create two climates: one much like the present, the other 2°C warmer, the level at which the world’s nations wish to contain global warming by 2100, by limiting the combustion of fossil fuels that release greenhouse gases into the atmosphere.

In the course of two years, they tested 18 populations of the common European lizard (Zootaca vivipara), and observed each for one year to see what a temperature change did to growth rate, reproduction and survival.

Lizards are cold-blooded reptiles, and only active in the warmth of the sun, so they might be expected to benefit from an average rise in global temperatures. But, once again, researchers have found otherwise.

“It leads to faster growth of juvenile lizards and earlier access to reproduction,” Dr. Bestion says. “It also leads to lower survival in adult individuals, which should endanger population survival.”

In fact, the prediction is that lizards at the southern end of their range will certainly feel the heat, and may have to leave life’s kitchen. Depending on how humans continue increasing carbon dioxide emissions and heating the atmosphere, this might threaten between 14-30 percent of Europe’s lizards.

Lizards are common and occupy a huge range, so there is no danger of wholesale extinction. There will be somewhere they can go, and northernmost species may even benefit.

The rarest birds of Hawaii’s forested mountains, on the other hand, are already at the limits of their range. And as the world warms, forest habitat is affected, and insect-borne pathogens gain in altitude, birds that already survive in dwindling numbers could disappear altogether.

Lucas Fortini, an ecologist with the U.S. Geological Survey, and colleagues report in PLOS One that they looked into the future by matching sightings of the 20 rarest birds with climate projections and species distribution models. They report that 10 species may lose 50 percent of their range this century, and six of these may lose 90 percent of their range.

“As dire as these findings are, they do not mean that these bird species are doomed,” Dr Fortini says. “Instead, our findings indicate what may happen if nothing is done to address the primary drivers of decline: disease spreading uphill into the few remaining refuges.”

Most of the North Atlantic’s loggerhead turtles (Caretta caretta) start their life in one place: the beaches of Florida. Although the turtles have been around for 60 million years, they could also be about to feel the heat, as the sex of a turtle is determined not by inheritance but by nest temperature during incubation.

Mother turtles dig holes in the sand, deposit around 100 eggs, and then retreat. Sand temperatures — affected by rainfall as well as depth — determine whether the babies become Arthur or Martha. Males emerge from cooler locations, females from warmer. But survival is precarious, and at most only one in 2,500 reaches adulthood.

Nest temperatures

Biological scientists Alexandra Lolavar and Jeanette Wyneken, of Florida Atlantic University, report in the Endangered Species Research journal that they monitored the species for four seasons and found that, for most of each season, nest temperatures were not sufficiently cool to produce males.

“If climatic changes continue to force the sex ratio bias of loggerheads to even greater extremes, we are going to lose the diversity of sea turtles, as well as their overall ability to reproduce effectively,” Professor Wyneken says.

“Sex ratios are already strongly female biased. That’s why it’s critical to understand how environmental factors — specifically temperature and rainfall — influence hatchling sex ratios.”

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Floods Will Add to California’s Drought Woes

Drought in California could become more frequent and more extreme — but punctuated more frequently by extreme floods, according to new research.

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Hi-Tech Mirrored Glass Can Help Keep Cities Cool

A new material – and a new science called nanophotonics – could offer a revolutionary way to cool down the baking cities of tomorrow.

Climate scientists have repeatedly warned that greater extremes of heat will become the norm, and also that as temperatures rise to potentially dangerous levels, the energy costs of new air conditioning investment will significantly feed back into yet more global warming.

But Aaswath Raman, research associate in the Ginzton Laboratory at Stanford University, California, reports with colleagues in Nature journal that seven layers of hafnium oxide and silicon dioxide on a roof could do something very surprising.

Release warmth

They could directly reflect 97% of the sunlight away from the building, and at the same time release warmth in exactly the right infrared frequency to pass through the Earth’s atmosphere as if it wasn’t there.

In outdoor daytime tests that lasted for five hours, the temperatures in the structure below the new material fell to 4.9°C below the temperatures outside. And this effect was achieved without any use of electricity.

This new technique, which the scientists call photonic radiative cooling, could offer new ways of preserving food, chilling vaccines and saving lives in impoverished tropical regions far from any electrical supply.

Carbon dioxide and other greenhouse gases absorb infrared light, and thus store heat from fossil fuels − but not at the wavelengths of between 8 and 13 micrometres.

Since this “transparency window” in the atmosphere can be exploited to radiate the heat directly into space, the authors say: “The cold darkness of the universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day.”

The relatively new science of new materials – and the unexpected properties of old materials when made in layers only a few atoms thick – continues to surprise.

The science has already delivered photovoltaic cells that turn light directly into current, smart metals that can detect their own fractures, and also water-repelling fabrics that stay permanently clean.

The Stanford researchers started with layers of hafnium oxide – an inert material already used in semiconductors and optical coatings – and silicon dioxide, a compound also known as silica or quartz, and widely used both in microelectronics and as a food additive.

Unexpected properties

From these, they were able to fashion, on a thin silver base, an ultrathin film that carried with it two unexpected properties: it was a near-perfect reflector of visible light, and an efficient emitter for infrared light. The fabric is just 1.8 microns thick – a micron is a millionth of a metre – and could be sprayed onto structures.

There are problems yet to be solved. The first practical one is how to get the heat from inside the building into its new, super-efficient exterior coating. The second is to find ways to make the stuff in industrial quantities, and then work out how to use it most effectively. But it offers a new way of thinking about energy efficiency.

“Every object that produces heat has to dump that heat into a heat sink,” said Professor Shanhui Fan, Stanford scientist and one of the report’s authors. “What we’ve done is create a way that should allow us to use the coldness of the universe as a heat sink during the day.”

Global Warming Could Create a 50% Increase in Lightning Strikes

LONDON — Climate scientists foresee a brighter future for America − but no one will thank them for it, as global warming is expected to increase the total number of lightning strikes across the US this century by 50%.

David Romps, assistant professor in the Department of Earth and Planetary Science at theUniversity of California, Berkeley, and colleagues report in Science journal that they looked at predictions of rainfall, snow, hail and cloud buoyancy in 11 different climate models. They concluded that the outcome could only be more atmospheric electrical action.

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NASA to Launch CO2-Tracking Satellite

The US space agency Nasa is about to send up a satellite that will provide vital data for predicting future effects of CO2 by taking the measure of the planetary carbon budget.

OCO-2, more formally known as Orbiting Carbon Observatory-2, is planned for launch on July 1 and will circle the globe, taking an inventory of those places on the planet that absorb carbon from the atmosphere (the sinks) and those places that release it into the atmosphere (the sources).

Although the satellite’s acronymic name pleasingly evokes CO2, the carbon dioxide greenhouse gas that is now at higher levels in the atmosphere than at any time in the last 800,000 years, this is pure accident. The first attempt to launch an orbiting carbon observatory came to grief when the satellite failed to separate from the launch rocket. OCO-2 is the second attempt.

“Knowing what parts of Earth are helping to remove carbon from our atmosphere will help us understand whether they can keep on doing so in future,” said the project scientist Michael Gunson, of Nasa's Jet Propulsion Laboratory. “Quantifying these sinks now will help us predict how fast CO2 will build up in the future.”

Carbon dioxide exists in the atmosphere only in trace amounts: 400 parts per million. But humans are adding 40 billion tons of the gas a year by burning fossil fuel, destroying forests and quarrying lime for cement.

Less than half of this total stays there: the rest is taken up by forests on land and by algae in the oceans. But quite how much, for how long, and how predictably, remains a puzzle.

Climate scientists need to know more about sinks and sources to make more accurate predictions. And governments, planners and foresters need to know more about the ways the forest world absorbs and emits carbon dioxide.

The new satellite will use onboard spectrometers to take hundreds of thousands of measurements every day to answer these complex questions of supply and demand. Researchers are also likely to match the data with other studies of the planet’s changing forests.

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Air Conditioning Raising Nighttime Temperatures in the U.S.

Researchers in the US have identified a way in which city-dwellers are inadvertently stoking up the heat of the night – by installing air conditioners.

Because the cities are getting hotter as the climate changes, residents are increasingly investing in air conditioning systems − which discharge heat from offices and apartment blocks straight into the city air. And the vicious circle effect is that cities get still warmer, making air conditioning all the more attractive to residents.

According to scientists at Arizona State University, the air conditioning system is now having a measurable effect. During the days, the systems emit waste heat, but because the days are hot anyway, the difference is negligible. At night, heat from air conditioning systems now raises some urban temperatures by more than 1C, they report in the Journal of Geophysical Research Atmospheres.

The team focused on the role of air conditioning systems in the metropolitan area of the city of Phoenix, which is in the Sonora desert in Arizona, and conditions in the summertime are harsh there anyway.

But, worldwide, normally warm countries are experiencing increasing extremes of heat, and conditions in cities have on occasion become lethal.

To cap this, cities are inevitably hotspots – and it’s not just because of global warming. The concentration of traffic, commuter systems, street and indoor lighting, central heating, light industry, tarmac, tiles, bricks, building activity and millions of people can raise temperatures as much as 5C above the surrounding countryside.

At present, 87% of US households have air conditioning, and the US – which is not one of the warmer nations – uses more electricity to keep cool than all the other countries of the world combined. To keep the people of Phoenix cool during periods of extreme heat, air conditioning systems can consume more than half of total electricity needs, which puts a strain on power grids.

The Arizona scientists simulated a 10-day period of unusually hot weather between 10 July and 19 July, 2009, and used computer models and detailed readings from weather records to analyze the effect of air conditioning systems on local temperatures. Even though the biggest demand for air conditioning was in the daytime, they found the biggest difference was always at night.

“Our work demonstrates 1C degree local heating of urban atmospheres in hot and dry cities due to air conditioning use at night time,” said Francisco Salamanca, the report’s lead author. “This increase in outside air temperature in turn results in additional demands for air conditioning.

“Sustainable development and optimization of electricity consumption would require turning wasted heat from air conditioning into useful energy, which can be used inside houses for various purposes − including, for example, water heaters.”

Such actions would reduce local air temperatures: in Phoenix alone, they could directly save more than 1200 Megawatt hours of electricity per day.

In 2012, the US experienced a set of record-breaking temperatures, and the US Department of Energy has warned that days of extreme heat are expected to become more frequent and more intense because of climate change.

But this seems already to be a pattern worldwide, according to recent analyses of climate patterns. And the demand for air conditioning is expected to accelerate in India, China and other emerging economies.

As Global Temperatures Rise, the Malaria Pandemic Will Spread Upland

Things are looking up for the little parasite that infects 200 million people a year, and kills more than 600,000 of them.

As global temperatures rise, so will the altitude at which the Anopheles mosquito and its plasmodium parasite can survive, and so will the numbers at risk from malaria.

The global war against malaria has always been an uphill struggle, but populations in highland regions have usually been safe, because the parasite cannot replicate at low temperatures.

Disease spread
But Amir Siraj of the University of Denver in Colorado in the US and colleagues in the UK and Ethiopia report in the journal Science that they’ve started to consider the effect of climate change on the spread of the disease.

Projections of hazards such as these are difficult: the likelihood of infection can depend on steps civil, national and international health authorities may take, the preparedness of communities depends on spraying programs and the availability of drugs, and the numbers at risk alter as populations grow and economies develop.

All malaria needs is somewhere warm and wet, and a steady supply of potential hosts. The disease was once endemic in mild, low-lying or marshy areas of Europe (the name comes from the Italian mal aria, or bad air).

It can be controlled by spraying, and by public education. But it remains an enduring hazard in Africa, parts of Asia and South America. Upland communities, however, have tended to be safe.

Data search
But the Denver team decided to forget about all the complex possibilities and just look at some very precise data from 124 municipalities in Antioquia in western Colombia between 1990 and 2005, and 159 administrative units in the Debre Zeit region of Ethiopia from 1993 to 2005.

They reasoned that a match of seasonal temperatures and reported cases would tell them what to expect.

Sure enough, they found that during warmer years, there were more reported cases of malaria in both countries. The “median altitude” at which cases were registered shifted accordingly with annual temperatures. That gave them enough information to consider some alarming possibilities.

In a previous study, scientists predicted that a 1°C rise in global average temperatures could bring an additional three million cases a year in Ethiopia among children under 15. As average temperatures rise, so will the numbers of potential victims soar, and so will the need for investment in mitigation and insect control.

“With progressive global warming, malaria will creep up the mountains and spread to new high altitude areas,” said Menno Bouma of the London School of Hygiene and Tropical Medicine, one of the authors.

“And because these populations lack protective immunity, they will be particularly vulnerable.”

Why Messing With the Earth's Climate to Reverse Greenhouse Gas Emissions Could Make Everything Worse

Global warming will be bad. Geoengineering could make it worse. A research team has considered all the benefits of climate technofix — that is, deliberate steps to neutralize the consequences of unrestrained greenhouse gas emissions — and come to a grim conclusion.

At best, any attempt to geoengineer the changing climate back to its starting point would be relatively ineffective. At worst, it would have “severe climatic side effects.”

David Keller and colleagues from the Helmholtz Center for Ocean Research in Kiel, Germany report in Nature Communications that they used an earth system model to simulate five different strategies to cut the rate of global warming and keep the climate from dramatic change.

Geoengineering is a catchall phrase for some very different approaches. One favored and much-examined technique is to counter global warming by reducing the levels of sunlight that hit the planet’s surface, a technique called solar radiation management.

This approach has already been comprehensively dismissed by other studies, which have demonstrated that such an approach could change rainfall patterns or make conditions worse in arid zones such as the Sahel or just make things worse once the technology ceased.

The Helmholtz team decided to look at the bigger picture: although climate scientists have repeatedly warned that the only safe answer is to cut fossil fuel emissions, and although governments have acknowledged the urgency of the problem, very few really effective steps have been taken.

Varied Options

So the technofix remains an option. How effective could it be? What could climate engineers do? There are plenty of powerful ideas. One is to exploit the appetite of green things for carbon dioxide: for instance, to irrigate the Australian and Sahara deserts and grow forests that will soak up more carbon.

Another is to nourish the ocean surface waters by pumping nutrient-rich bottom water up to the surface to give algae a chance to bloom across the oceans.

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Hotter extremes belie warming 'pause'

LONDON, 1 March - If global warming has paused, nobody told the thermometer. Although global average temperature rises have not kept pace with greenhouse gas emissions in the last decade, the mercury has been higher than ever for longer than ever over increasingly larger areas of land, according to a new study in Nature Climate Change.

Sonia Seneviratne from the Swiss Federal Institute of Technology in Zurich and colleagues in Australia and Canada chose not to look at averages but at extremes of temperature. The scientists examined daytime extremes from 1979 onwards, and compared the temperatures of any particular day anywhere to an average of daily temperatures between 1979 and 2012, to identify the hottest 10%. Any region might normally expect 36.5 hottest days in a year; that is, hotter than the average.

Then they looked more closely at temperatures from 1997 to 2012. Regions that experienced 10, 30 or 50 extremely hot days above this average saw the greatest upward trends in extreme hot days over time – and over area. That is, not only were people experiencing greater heat extremes, but they were experiencing them over more days and over more extended regions.

And this consistent upward trend persisted right through the so-called “hiatus” of 1998 to 2012. The year 1998, at the time the hottest ever, coincided with a major El NiÃ±o event, the peak of a natural cycle of warmth and cooling in the Pacific.

Extreme extremes change most

Thereafter, although 13 of the 14 warmest-ever years have occurred this century, the rate of increase in warming as a global average has fallen. Climate sceptics used the trend to argue that global warming was an illusion, or part of a natural cycle. Dr Seneviratne and her colleagues do not see it that way.

“It quickly became clear the so-called ‘hiatus’ in global average temperatures did not stop the rise in the number, intensity and area of extremely hot days,” said Lisa Alexander of Australia’s Centre of Excellence for Climate System Science.

“Our research has found a steep upward tendency in the temperatures and number of extremely hot days over land and the area they impact, despite the complete absence of a strong El NiÃ±o.”

And her colleague Markus Donat added: “There has been no pause in the increase of warmest daily extremes over the land and the most extreme of the extreme conditions are showing the largest change.

"Another interesting aspect of our research was that those regions that normally saw 50 or more excessive hot days in a year saw the greatest increases in land area impact and the frequency of hot days. In short, the hottest extremes got hotter and the events happened more often.”

'Illusory' pause

However, perhaps because the world is mostly ocean, and the extremes have been measured over land, the average, year-on-year rises in temperatures have been lower in the last decade than in previous decades. There have been a number of inconclusive explanations for this phenomenon.

Cyclic changes in trade winds are one explanation; another is that the heat is there, but has been stored in the deep ocean, where measurements are not systematically taken. It’s there somewhere, waiting to be found.

And US scientists argue in the latest issue of the journal Science that the oceans may have an even bigger influence on climate than anybody foresaw, and that persistent cool conditions in the tropical Pacific may be behind what they call the “pause in global warming since 2000.”

But the latest Nature Climate Change paper puts the case that this pause or hiatus is illusory with – for a scientific paper – unusual clarity. “Based on existing observational evidence,” the authors say, “we highlight that the term pause, as applied to the recent evolution of global annual mean temperatures, is ill-chosen and even misleading in the context of climate change.

"Indeed, an apparently static global mean temperature can mask large trends in temperatures at both regional and seasonal scales.”

Energy Game Changer? Scientists Turn Algae into Crude Oil in Less Than an Hour

LONDON, 23 December - US scientists believe they may have cracked one of the great biofuel conundrums. They have turned a thick soup of algae into a mix of crude oil, gas, water and plant nutrients in less than an hour. That is, they have taken 60 minutes to do what Nature does – at great pressures and temperatures – over millions of years.

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What Happens if We Don't Prevent Average Global Temperatures from Rising?

London, 3 December - Governments have set the wrong target to limit climate change. The goal at present - to limit global warming to a maximum of 2°C higher than the average for most of human history - “would have consequences that can be described as disastrous”, say 18 scientists in a review paper in the journal PLOS One.

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