Time for artificial planet coolers? A cooling “sunshade” for the planet could reduce harmful coral bleaching and the number of hurricanes, which damage reefs.

With the effects of climate change becoming increasingly apparent, the idea of squirting a cloud of sulphate aerosols into the upper atmosphere is being investigated by several groups of scientists. This would scatter some of the sun’s rays back into space, reducing the rate at which the Earth is warming.

Now a study by at the University of Bedfordshire, UK, and his colleagues examines what this form of geoengineering would do to the Caribbean region and its fragile reefs. “Corals are the rainforests of the sea, and if you lose them the impacts on ecosystems and people would be complex and far-reaching,” says Crabbe.

The team used computer models to simulate both the changing climate and rising seas between 2020 and 2069. They then modelled what would happen if solar radiation was artificially reduced. “We show very convincingly that, by injecting sulphur dioxide in the atmosphere, sea surface temperatures would decrease significantly by 2069,” says Crabbe.

Hold back the hurricanes

When the sea is too warm, corals expel the tiny algae living in their tissues, which feed their hosts through photosynthesis. The corals turn white or “bleached”. After severe bleaching, most corals starve to death. Keeping temperatures down prevented this in the model.

But bleaching is not the only threat. According to Crabbe, solar radiation management would also reduce the frequency of hurricanes. These intense storms “destroy coral reefs, not only by smashing them, but also by limiting their reproduction and recruitment”: drifting larvae cannot attach themselves to a new reef in choppy waters. Crabbe says hurricanes would still occur, but not as frequently, giving the reefs some time to recover.

“One of the main concerns with solar radiation management is not necessarily its effectiveness, but its side effects,” says at the University of Oxford. For example, “it could disrupt regional weather patterns and monsoons”, which would be a problem because many people rely on predictable seasonal cycles for tasks like farming.

Back to normal

There is also the risk that geoengineering systems could be suddenly turned off. “What if the system was stopped through a terrorist attack?” asks Bellamy. “Global temperatures would jump back to where they would have been without geoengineering.” If greenhouse gas emissions had not been cut in the meantime, “that could be a very sharp rise”.

Crabbe admits that “we don’t know
 what would happen to the marine environment” in that scenario. “But the situation is currently so extreme that we have to make provisions.”

at Harvard University has suggested an alternative, less aggressive way to cool the seas: increasing the reflectivity of the oceans with tiny air bubbles that could be delivered cheaply by ships or oil rigs. “Microbubble lifetimesÌęare measured in minutes, as opposed to the months needed to turn stratospheric aerosols on and off, so brightening the water may afford better local control than dimming the sun,” he says.

But this would be a local solution, not a global one.

Other researchers have proposed brightening the clouds over coral reefs, which would cool only that area, and reducing ocean acidification – another threat to corals caused by greenhouse gas emissions – by adding minerals to the ocean to neutralise the acid.

A tiny ancient shrimp found only in a single small lake tucked away in the mountains of central Italy could soon disappear, as a combined result of climate change and an earthquake that hit the area last year.

The fairy shrimp (Chirocephalus marchesonii) has evolved from a species native to the Himalayan region. Its ancestors are thought to have reached the Appennine range during the last ice age, after their eggs latched onto the feet of migratory birds.

“Over the millennia, the shrimp has adapted to the specific environment of Lake Pilato, and its reproductive cycle is in sync with the seasonal hydrologic balance of the basin,” says Maria Gaetana Barelli of the Sibillini Park authority. The species is unique among freshwater shrimps in the area for its Asian origins, offering clues on the movement of animal species in prehistoric times.

Barelli says that to hatch, the shrimp’s eggs need such a complex combination of environmental parameters that her five-year-long research project wasn’t enough to make them hatch in captivity. This is why she is concerned that the crustacean may go extinct if the small lake it inhabits undergoes significant environmental changes.

Big shock

“The major earthquake that struck the region last summer has certainly caused deep shocks in the water system of these mountains,” says Alessandro Rossetti, a biologist with the Sibillini Park authority. “The water levels in the basin are abnormally low this year, and we still don’t know if this is due to a disruption of the aquifer. If that was the case, the lake would permanently dry out and this unique shrimp would disappear.”

A group of scientists flew drones over the lake and analysed its biochemistry, looking at factors such as temperature and acidity to gain insight into the underground water system that feeds the basin. However, more research is needed to establish whether the earthquake has fatally damaged it.

The shrimp can survive long dry spells because it buries its eggs under the lake bed, where they can remain alive and intact for more than a year until conditions are right to hatch. Hikers are the most immediate threat to the eggs, because they kill most of them by walking on dry areas of the lake bed.

However, the scientists’ main concern is climate change. “From 1990 onwards, we recorded an increasing number of hot years with abnormally low water levels,” says Rossetti.

Uncertain future

“I am very worried about the shrimp’s fate – it’s a precious animal,” says Barelli. “My concern is that this year, because the water is already so low, the individuals present in the lake might not have the time to mature sexually and lay their eggs before the basin dries out.”

But this shrimp is not the only species here that sees its survival threatened.

In a valley not far from Lake Pilato, another endemic shrimp (C. sibyllae) depends on the regular seasonal cycle of the pond where it reproduces and goes idle for a few months every year. Like C. marchesonii, this crustacean’s survival is tied to the availability of water when it matures and lays eggs.

Barelli says the risk of extinction would turn into a certainty should the basin fail to replenish for more than a year.

Paolo Guarino, a geologist at the Italian National Institute for Environmental Protection and Research, says there is a need for more historical data to “verify whether the water balance is being tipped – namely, if more water leaves the area and its basins than enters them”.

Wary of strangers

Building a network of artificial, cool retreats in the forest may be the last resort for China’s vulnerable giant pandas, as climate change threatens the iconic mammal with extinction.

New data about habitat temperature and panda distribution, collected across six mountains along the Chinese edge of the Tibetan plateau, confirm what climate models have been suggesting for a while: the animal is struggling to survive as its natural habitat gets hotter.

Researchers found that areas within the pandas’ habitat, that were exposed to a potential heat stress of up to 30 °C had increased from 332 to 4482 square kilometres over the past 40 years.

Guozhen Shen of the Chinese Academy of Sciences in Beijing, says previous studies showed that 25°C is the threshold for giant pandas to suffer heat stress, since they are adapted to cool mountain climes.

A consistently warm environment can cause dehydration and metabolic problems in giant pandas, also affecting their reproduction abilities and their cubs’ health. To escape the heat, they have to move to cooler mountainous areas where foraging becomes more difficult.

Bamboo boom or bust?

Their specific bamboo diet could be affected too, although scientists are not sure how this will pan out. While there is a risk that the bamboo might mass-bloom and die, there is also a chance that it will simply grow stronger and more abundant, says Shen.

Artificial microhabitats could shield pandas, at least in the short term, from these and other heat related impacts. According to the researchers, they could look like a patchwork of retreats and maternity dens built close to streams.

The constructions would take advantage of the natural features of each forest patch to protect the animals from the sun and enhance the number and comfort of cool spaces. For example, they could have narrow entrances to keep the heat out and interior chambers offering respite to adults and cubs, which are particularly prone to illness under extreme heat.

The researchers added that planting more trees and bamboo in selected areas could also provide additional food and canopy cover. Building a significant number of such oases around the pandas’ distribution area would also allow them move more easily across vast areas.

Facilitating migration is especially important, says Calum Brown of Karlsruhe Institute of Technology in Germany.

Fragmented habitat

“This species has been restricted to a fragmented series of habitat patches, and numbers are so low that they are at obvious risk of loss of genetic diversity and ability to withstand change,” he says. “The existing isolated and partially unsuitable islands of giant panda habitat need to be expanded and connected if the species is to survive.”

However, according to giant panda expert Kati Loeffler, climate change is only one threat to the bear’s survival. “The main challenges remain related to human activity, legal or illegal, throughout the purportedly protected areas,” she says.

This includes the impact of dams, roads mines and even of domestic animals from nearby settlements. “The addition of new reserve areas, which are effectively just a few more small islands for a few pandas, will not address the key factors that are compromising survival of wild panda populations,” Loeffler says.

Read more: Giant pandas’ secret social life revealed

Under threat

The endangered Egyptian vulture, which is disappearing in Europe and globally at an alarming rate, could bounce back thanks to the presence of landfills.

The Egyptian vulture population has declined in places such as the Iberian peninsula, where it has fallen by 25 per cent over the last two decades because of multiple threats such as poisoning, illegal persecution and collision with power lines.

Regulations that prevent farmers from leaving animal carcasses in the open have also deprived the scavengers of their natural source of food.

But in central Catalonia in Spain, the Egyptian vulture is defying gloomy predictions. “The birds have been multiplying and even expanding their reach, colonising areas where they were historically absent,” says Joan Real at the University of Barcelona.

Real and his team monitored the birds from 1988 to 2014 in an area covering 10.5 square kilometres. They mapped inhabited nesting sites and identified potential areas for new nests. They then regularly visited the sites in the March-to-August breeding season to determine any changes in numbers.

The team found that between these years, the population leaped from one to 25 breeding pairs, which mostly dwelled and reproduced close to landfills.

Large dump sites are among the food resources that human activities unintentionally provide to animals, but conservation programmes sometimes involve the creation of sites where food is dispensed intentionally, known as “restaurants”.

“We studied the distribution of the nests in relation to landfills and to vulture restaurants,” says Real. “We were surprised to discover that the vultures seem to prefer landfills to restaurants”.

Why there?

“Vultures are very sensitive to various toxins,” says Chris Bowden of the vulture specialist group at the International Union for Conservation of Nature. “In a landfill, you would find all sorts of nasty things. It makes you wonder what really makes them so attractive to these birds.”

The team observed that the vultures tend to choose less busy waste dumps where they are not disturbed by people and can nest in the surrounding rocky areas.

However, more research is needed to get to the bottom of this. “We know where the birds live, but we still need to investigate their foraging habits and how they use the land,” says Real.

But landfills are disappearing and the European Commission has been trying to halt the building of new open-air ones. “Carcasses become less available in this more sanitary world, and scavengers increasingly rely on anthropogenic food sources,” says Louis Phipps of the WILD Foundation in Oxford, UK. “Regulators should look for ways to replace what the Egyptian vultures are getting from the landfills with a more natural food supply.”

Given that in most European countries, Spain included, regulations restrict the distribution of carcasses, he believes that “authorities should look at adapting the legislation within certain areas for the benefit of the species”.

Journal reference: Ibis, DOI: