Ill effects of nitrogen overdose
Excessive use of nitrogen is causing problems ranging from coastal dead zones to fish kills and global warming.
NITROGEN continues to be used inefficiently as a plant nutrient in agriculture, according to the United Nations Environment Programme (UNEP) Year Book 2014.
The amount of usable nitrogen produced by humans is now about 190 million tonnes per year, greater than the 112 million tonnes created through natural processes. As nitrogen moves through the environment, the same nitrogen atom can contribute to multiple negative effects in the air, on land, in freshwater and marine systems, and on human health. This sequence continues over a long period and is referred to as the “nitrogen cascade”.
Excess nitrogen in the environment contributes to many problems, including:
> Coastal dead zones and fish kills due to severe eutrophication (a high concentration of nutrients, which leads to excessive plant growth and oxygen deprivation). There are currently over 500 known coastal dead zones in well-studied areas of the world, whereas in 2003 only around 150 such oxygen-depleted areas were reported. Once other regions start reporting, it is estimated that 1,000 coastal and marine areas will be identified as experiencing the effects of eutrophication.
> Nitrogen emissions to the air, notably those of nitrous oxide (N2O), contribute to climate change. Sometimes referred to as the “forgotten greenhouse gas”, N2O is over 300 times more effective at trapping heat in the atmosphere than carbon dioxide over a 100-year period. Human activities such as agriculture, deforestation and fossil fuel combustion are increasing the amount in the atmosphere.
Better management practices are essential to reduce nitrogen losses to the environment from agricultural sources.
According to the UNEP-commissioned report, Our Nutrient World, a 20% improvement in global nutrient use efficiency by 2020 will reduce annual use of nitrogen by an estimated 20 million tonnes.
The report also highlights the hazards of fish farming. Aquaculture A GLOBAL carbon price of at least US$32 (RM104) per tonne is needed by 2015 to apply an effective brake on global warming – almost five times today’s European market rate.
A study co-authored by British economist Nicholas Stern, an authority on the costs of climate change, reviewed a widely-used model for assessing risk and found it led to a “gross under-assessment” of danger.
This beefs up the case for strong cuts in greenhouse gas emissions, helped by a carbon price “in the range of US$32 to US$103 per tonne of CO2 in 2015,” said the study carried by The Economic
Planting rice in nangarhar province, afghanistan. Wide application of fertiliser in agriculture has left huge amounts of nitrogen in the environment, and consequently, various adverse impacts. — aFP production has increased since the 1950s from 650 thousand tonnes to almost 67 million tonnes, and today provides half of all fish for human consumption. Marine aquaculture production by volume grew by 35% during the last decade, while production in fresh and brackish water grew by 70% and 83%, respectively.
While progress has been made towards making marine aquaculture more sustainable, environmental concerns remain. Fish farms can release nutrients, undigested feed and veterinary drugs to the environment. They can also increase risks of diseases, parasites and harmful algal blooms. In some countries, certain forms of shrimp farming have destroyed large areas of coastal habitats, such as mangrove forests.
Healthy marine ecosystems are fundamental to securing food and providing jobs. Environmentally sound development of the marine aquaculture sector is needed to avoid the loss of important ecosystem services. Technical innovations, the growing skills of aquaculture producers, and improved knowledge of environmental impacts provide hope for a sustainable marine aquaculture sector.
The report also says that air quality is deteriorating in most cities. The World Health Organisation (WHO) estimates that in 2012, air pollution led to around seven million premature deaths (one out of eight total global deaths), more than double previous estimates. It is the leading cause of environmentally related deaths. The WHO guideline for average annual fine particulate matter is 25 microgrammes per cubic metre. Cities in low- and middle-income countries far exceed this level. For example, in Kathmandu, Nepal, particulate matter (PM2.5) levels of over 500 microgrammes per cubic metre have been measured.
The cost of air pollution to the listed a global carbon price as one option for tackling the challenge. It warned temperatures could rise by up to 4.8°C this century and sea levels by 26cm to 82cm on present emissions trends.
The International Monetary Fund and World Bank have also this year called for the introduction of a universal price on carbon – the most common greenhouse gas blamed for climate change.
For the moment, carbon prices are determined by national or regional systems – either as a tax on emissions or as a cap-andtrade scheme that allows companies to sell unused allotments.
The European Union Emissions world’s most advanced economies, plus India and China, is estimated at US$3.5tril (RM11.3tril) per year in lives lost and ill health. In Organisation for Economic Co-operation and Development countries, the monetary impact of death and illness due to outdoor air pollution is estimated to have been US$1.7tril in 2010. Research suggests that motorised on-road transport accounts for about 50% of that amount.
In light of the high costs related to the health and environmental effects of air pollution, all countries should invest in clean air policies, the report says. — UNEP Trading Scheme (ETS), the most ambitious cap-and-trade system in the world, has seen prices drop drastically from a peak of about 30 euros (RM133) per tonne eight years ago to 5.7 euros (RM25) today – partly due to countries issuing too many allowances.
The Stern-Dietz report said the standard model used to calculate economic risks from climate change, also by studies included in the IPCC’s latest report, used unrealistic values and under-estimated the potential damage.
The updated model, “strengthens the case for strong cuts in emissions of greenhouse gases,” Dietz said in a statement. – AFP