A team of researchers headed by Prof Guy Claireaux at the University of Brest in France looked for the first time at the effects of chemically dispersed oil on the performance of European seabass to subsequent environmental challenges.

The researchers designed swimming challenge tests in an ‘aquatic treadmill’, similar to the tests used in human medicine for health diagnosis. They analysed European seabass’ maximum swimming performance, hypoxia tolerance and thermal sensitivity as markers for their capabilities to face natural contingencies. They then exposed the fish to untreated oil, chemically dispersed oil or dispersant alone for 48 hours. During the following 6 weeks they measured individual growth and then once again analysed the seabass’ performance in the swimming challenge tests.

Oil exposure impacted the ability of fish to face increased temperature, reduced oxygen availability or to swim against a current and these effects were further aggravated with the addition of the dispersant. The dispersant alone had no effect on the ability of fish to face the challenge tests.

Prof Claireaux said “An oil slick reaching the shore is not good for tourism and organisms living on the coast line. Treating the slick at sea will avoid or reduce these problems affecting surface animals (birds and marine mammals). On the other hand, oil dispersion will increase the contamination of the water column and the organisms that occupy it.”

Though applying dispersants at sea may reduce the environmental and economic impacts of an oil spill reaching the shoreline, these results show that the choice of response deployed to deal with a spill involves a trade-off between the effects at the surface and in the water column.

This is demonstrated by a study published in Nature that has been carried out at the University of Bern.

The ultimate objective of international climate policy is to prevent dangerous anthropogenic interference with the climate system. To do this, greenhouse gases are to be stabilised at a level that is acceptable for humans and for the environment.

This climate goal is commonly expressed as an increase in the global mean temperature by a maximum of two degrees since pre-industrial times. This general direction is recognised by the majority of the world’s governments.

But now, a study carried out by climate researchers based in Bern shows that the focus on the temperature increase alone is by no means enough to meet the ultimate, overarching objective – to protect the climate system from dangerous anthropogenic interference.

This is because, according to the United Nations Framework Convention on Climate Change from 1992, the climate system comprises the “totality of the atmosphere, hydrosphere, biosphere, geosphere and their interactions.” The Framework Convention also calls for the sustainability of ecosystems and food production. All of this can scarcely be realised by the two-degree target alone.

Six targets proposed

This is why Dr. Marco Steinacher, Prof. Fortunat Joos and Prof. Thomas Stocker are proposing a combination of six different specific global and regional climate targets in their work, which has just been published in the «Nature» journal.

They say that a global temperature target is «neither sufficient nor suitable» to avoid further damage that is relevant for communities and ecosystem services. These include in particular: rising sea levels, ocean acidification – which threatens coral reefs – and production on agricultural land.

Realistic development paths

The main culprit in relation to these environmental changes is the emission of the greenhouse gas CO₂, which is produced when fossil fuels are burned. The researchers have now used extensive model calculations to show which levels of CO₂ emissions would still be allowable in order to meet the proposed combined targets.

The basis for the calculations is provided by a wide range of greenhouse gas scenarios that are based on realistic economic trajectories. “We can now show which total CO₂ emissions would be tolerable in the coming decades in order to meet each and every one of the additional climate targets – for example stable production on agricultural land and limitation of ocean acidification,” says Marco Steinacher, the leading author of the study.

And the researchers ask the crucial question of what would be required in order for all of the climate targets to be met. Their unambiguous answer is that CO₂ emissions have to be lowered even more radically than provided for by the two-degree target. “When we consider all targets jointly, CO₂ emissions have to be cut by twice as much than if we only want to meet the two-degree target,” explains Steinacher.

The objective of limiting ocean acidification proved particularly challenging and is achievable only through a massive reduction in the emissions of CO₂.

Important basis for informing policy

The three researchers, all of whom are members of the Oeschger Centre for Climate Change Research at the University of Bern, recommend that further studies of this type be carried out. However, further relevant climate targets need to be set out by policy makers and by society, they say.

“Ultimately, the magnitude of environmental changes we are able to cope with and the amount of risks we are prepared to take is a social and political question. But the constant rise in CO₂ emissions is increasingly limiting our options to act,” says Fortunat Joos.

The climate physicists emphasise the fact that it is important for political decision-makers to link different climate targets to anthropogenic greenhouse gas emissions in a quantitative manner.

According to the study, in the future more detailed simulations will have to be carried out which inform about local and regional consequences of climate change. For example, these include extreme occurrences such as flooding and heatwaves. However, we do not yet have sufficient computing power to operate the complex Earth System Models needed for such probabilistic simulations.

Laborious computing work

The study was made possible by using the Bern3D-LPJ Earth System Model developed at the University of Bern. The model is able to simulate a large number of important physical and biogeochemical processes and their interactions on a regional scale.This information is needed to formulate many additional climate targets – for example to prevent the acidification of the oceans in the Tropics.

The Bern Model is so efficient that it only took a few weeks to calculate the roughly 65,000 simulations needed for the study. From this rich set of simulations, the researchers have estimated probabilities of meeting specific climate targets. This is not possible with most of the other Earth System Models currently in existence.

Researchers from Royal Holloway University, The Australian National University and Geoscience Australia, have helped clear up previous uncertainties on how the plates evolved and where they should be positioned when drawing up a picture of the past.

Dr Lloyd White from the Department of Earth Sciences at Royal Holloway University said: “The Earth’s tectonic plates move around through time. As these movements occur over many millions of years, it has previously been difficult to produce accurate maps of where the continents were in the past.

“We used a computer program to move geological maps of Australia, India and Antarctica back through time and built a ‘jigsaw puzzle’ of the supercontinent Gondwana. During the process, we found that many existing studies had positioned the plates in the wrong place because the geological units did not align on each plate.”

The researchers adopted an old technique used by people who discovered the theories of continental drift and plate tectonics, but which had largely been ignored by many modern scientists.

“It was a simple technique, matching the geological boundaries on each plate. The geological units formed before the continents broke apart, so we used their position to put this ancient jigsaw puzzle back together again,” Dr White added.

“It is important that we know where the plates existed many millions of years ago, and how they broke apart, as the regions where plates break are often where we find major oil and gas deposits, such as those that are found along Australia’s southern margin.”

A video demonstrating the ancient jigsaw puzzle can be viewed here: http://vimeo.com/68311221

The goal of sustainable intensification is to increase food production from existing farmland says the article in the journal’s Policy Forum by lead authors Dr Tara Garnett and Professor Charles Godfray from the University of Oxford. They say this would minimise the pressure on the environment in a world in which land, water, and energy are in short supply, highlighting that the environment is often overexploited and used unsustainably.

The authors, university researchers and policy-makers from NGOs and the UN, outline a new, more sophisticated account of how ‘sustainable intensification’ should work. They recognise that this policy has attracted criticism in some quarters as being either too narrowly focused on food production or as representing a contradiction in terms.

The article stresses that while farmers in many regions of the world need to produce more food, it is equally urgent that policy makers act on diets, waste and how the food system is governed. The authors emphasise that there is a need to produce more food on existing rather than new farmland because converting uncultivated land would lead to major emissions of greenhouse gases and cause significant losses of biodiversity.

Sustainable intensification is the only policy on the table that could create a sustainable way of producing enough food globally, argues the paper; but, importantly, this should be only one part of the policy portfolio. ‘It is necessary, but not sufficient,’ said Professor Charles Godfray of the Oxford Martin Programme on the Future of Food. ‘Achieving a sustainable food system will require changes in agricultural production, changes in diet so people eat less meat and waste less food, and regulatory changes to improve the efficiency and resilience of the food system. Producing more food is important but it is only one of a number of policies that we must pursue together.’

Increasing productivity does not always mean using more fertilisers and agrochemicals as these technologies frequently carry unacceptable environmental costs, argue the authors. They say that a range of techniques, both old and new, should be employed to develop ways of farming that keep environmental damage to a minimum.

The authors of the paper accept that the intensification of agriculture will have some implications for other important policy goals, such as preserving biodiversity, animal welfare, human nutrition, protecting rural economies and sustainable development. Policy makers will need to find a way to navigate through the conflicting priorities on occasion.

Lead author Dr Tara Garnett, from the Food Climate Research Network at the Oxford Martin School, said: ‘Improving nutrition is a key part of food security as food security is about more than just calories. Around two billion people worldwide are thought to be deficient in micronutrients. We need to intensify the quality of the food we produce in ways that improve the nutritional value of people’s diets, preferably through diversifying the range of foods produced and available but also, in the short term, by improving the nutrient content of commonly produced crops.’

‘Sustainability requires consideration of economic, environmental and social priorities,’ added Dr Michael Appleby of the World Society for the Protection of Animals. ‘Attention to livestock welfare is both necessary and beneficial for sustainability. Policies to achieve the right balance between animal and crop production will benefit animals, people and the planet.’

Agriculture is a potent sector for economic growth and rural development in many countries across Africa, Asia and South America. Co-author Sonja Vermeulen, from the CGIAR Program on Climate Change, Agriculture and Food Security (CCAFS), said: ‘It is sustainable intensification that can provide the best rewards for small-scale farmers and their heritage of natural resources. What policy-makers can provide is strategic finance and institutions that support sustainable and equitable pathways, rather than quick profits gained through depletion.’

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