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Lesley Batty Symposium Organiser

Recent research may require adjusted thinking on the topic of greenhouse gases and climate change

Climate change and the continual rise in greenhouse gas (GHG) emissions are well established in the environmental policy agenda. However, although the general scientific evidence for climate change is now rarely refuted, the issue continues to be a very large, complex and wide-reaching challenge and there is still significant ongoing research in the field. These studies often produce novel findings with implications for the policy response to climate change.

The importance of nitrogen
In the current climate change forum, discussion of GHG emissions more often becomes a discussion of carbon emissions and the carbon cycle. However, the European Nitrogen Assessment produced last year by a team of scientists led by Mark Sutton and Clare Howard, stresses that human disruption of the nitrogen cycle has been just as severe and could have consequences just as serious as those related to carbon.

In its natural state, nitrogen exists mainly in the form of stable nitrogen gas. However, over the past century, intensive fertiliser production and burning of fossil fuels have led to a doubling of the rate at which more reactive nitrogen is formed. This has resulted in increased formation of the GHG nitrous oxide as well as other gases and particulate matter harmful to human health. Deposition is also leading to a change in soil fertility, altering plant growth rates and community composition.

Nitrogen presents a unique challenge to policy as the cycle is very complex meaning that a response will require cooperation between actors from a wide range of disciplines. However, within Europe, progress in addressing this challenge has already been made with the establishment of NitroEurope which brings together 64 institutions to collaborate on understanding and addressing the impact of nitrogen on the GHG balance. The result of this work is the European Nitrogen Assessment which has now been adopted as an activity under the international Convention on Long-range Transboundary Air Pollution.

Critically, the ENA estimates the economic cost of nitrogen damage – increasingly seen as the most effective way to communicate environmental issues to policy makers and industry – which it puts at €70-320 billion/year in the EU, making a compelling argument for urgent attention. Recommended actions for policymakers to pursue include improving the efficiency of agriculture, improving fossil fuel combustion methods, and reducing consumption of energy and animal products.

Link between emissions, ocean temperatures and ‘extreme’ weather
The link between industrial emissions and climate change is now widely accepted, but a study published in Nature this month is the first to clearly show a link between industrial air pollution and recorded variations in ocean temperature.

Findings of the study, which used a state-of-the-art Met Office climate model to simulate physical processes in the Earth’s atmosphere, show a link between aerosol pollution in the atmosphere and changes in the pattern of temperature shifts in the Atlantic Ocean. These shifts, known as the Atlantic Multidecadal Oscillation, see warm and cold fluctuations in the ocean’s temperature over several decades and are widely believed to result in changes to hurricane activity in the North Atlantic and rainfall patterns in Africa, South America and India, often leading to humanitarian disasters.

The new study is significant as, until now, these fluctuations were thought to be due to natural variability but, according to Ben Booth, a Met Office climate processes scientist and lead author of the research, the findings now suggest that ‘natural disasters…such as persistent African drought…may not be so natural after all’.

The model shows a clear correlation between Atlantic variations and industrial pollution levels; peaks in emissions coincide with cooler ocean temperatures whilst the introduction of clean air policy in the 90s resulted in warming of the seas. This has significant implications for climate change and emission policy of the future as it shows a clear link between air pollution, regional climate variability and natural disasters.

Warning that biomass may increase rather than reduce EU carbon emissions
A call was made to policymakers at the European Parliament at the end of March for Brussels to rethink its carbon accounting rules for biomass energy, stating that the current EU definition of wood biomass as a ‘carbon neutral’ fuel is inaccurate.

Currently, wood makes up the bulk of the EU’s biomass energy – alongside agricultural crops and residues, and vegetation waste – and is awarded subsidies, feed-in tariffs and electricity premiums in order to encourage its adoption as one of the EU’s main sources of renewable energy.

However, groups including the European Environment Agency’s independent Scientific Committee, have warned that the time lag between the carbon debt created when a tree is felled, transported and combusted as fuel, and the carbon credit gained when a new tree has grown to absorb carbon in place of the old one (‘bio-recovery time’), will result in a rise in CO2 concentrations in the interim. More critically, the carbon balance will depend on what is grown to replace felled forests – under the current accounting rules of the EU, energy crops can be grown on the footprint of previous woodland, even though these tend to absorb and store less CO2 with the result that net carbon emissions may in fact increase.

The Intergovernmental Panel on Climate Change (IPCC) states that biomass can only be classified as carbon neutral if all land use impacts have been considered, something which the EU has acknowledged with proposals for binding criteria designed to identify truly carbon-neutral biomass sources.

These proposals are due to be released later this year but have been repeatedly postponed due to opposition from countries including forest-rich Finland and Sweden. According to sources quoted by EurActiv, there is an apparent lack of enthusiasm amongst the EU’s energy directorate to pursue these criteria, and it is possible their release could be put back yet again.

Implications for environmental policy
Such advances in climate change and emissions research can reveal current environmental policy to be ineffective in tackling the issues they are designed to address, or – such as in the case of biomass energy – even unintentionally damaging. Ensuring ongoing research and effective communication across the science-policy interface within the field of climate change is therefore critical.

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