The little things matter

6th August 2014


Particulate emissions

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The National Trust

Julian Jackson provides a reminder that much can be achieved by tackling emissions of small particle climate pollutants

The effects of carbon dioxide as the main greenhouse gas (GHG) are well known. However, GHGs as a whole include other pollutants that have significant effects on the atmosphere and the process of climate change. Small particle climate pollutants (SPCPs) – methane, hydrocarbons, chlorofluorocarbons, tropospheric ozone and dirty particulates – are expected to contribute 0.6ºC of global warming by 2050, and have been given less attention as GHGs than CO2.

The good news is that they are the “low hanging fruit” of ameliorating climate change. An aggressive programme of SPCP emissions reduction could make a significant difference to climate targets.

A complex picture

The effects of SPCPs are complex. For example, circulation of black or dark particulate matter reduces the effects of atmospheric heating by reducing the amount of sunlight reaching the lower levels, but when it lands on snow or ice it contributes to melting.

The latest IPCC report, assessment 5 (AR5), is careful to distinguish between the positive and negative effects of radiative forcing – that is, the cumulative effects of multiple actors on the climate. The report states: “Concentrations of CO2, methane and nitrous oxide now substantially exceed the highest concentrations recorded in ice cores during the past 800,000 years. The mean rates of increase in atmospheric concentrations over the past century are, with very high confidence, unprecedented in the last 22,000 years.” The report notes that the net cooling effect of aerosols (chlorofluorocarbons) is less than earlier thought due to improved methods of estimation.

There is also a moral aspect to SPCPs. Among the contributors to SPCP emissions are wood fires, kerosene stoves and lamps, and diesel emissions. All of these cause massive health problems, particularly in developing countries. According to the World Health Organisation, kerosene alone is estimated to cause one million deaths a year. Other malign contributors to indoor air pollution include coal, charcoal, dung and crop wastes. The main sufferers are women and children because they spend more time around the domestic hearth. Increased ozone also contributes to health problems and reduced crop yields.These pollutants then circulate in the atmosphere, contributing to climate change in numerous ways.

The cryosphere

The area most susceptible to climate change is the cryosphere – a term for the regions that are covered in ice and snow either seasonally or year-round. Climate change is happening in the cryosphere faster and more dramatically than anywhere. It is a leading indicator for what may well happen elsewhere and it is not encouraging. For example, there is a tiny island called Shishmaref in the Chukchi sea between Alaska and Russia. Only a mile wide, it is home to a hunter-gatherer population of 600 Inupiats, a people who have lived there for thousands of years.

Some scientists think that the island has endured the most dramatic effects of climate change: rising temperatures have resulted in a reduction in the sea ice that serves to buffer Shishmaref from storm surges. At the same time, the permafrost on which the island’s dwellings are built has also started to melt, leaving the shore more vulnerable to erosion. In recent years the shore has been receding by up to 3.3 metres a year and the sea is undermining roads and other infrastructure, including water and sewage pipes. Coast defences have offered little protection and there is now talk of moving the population.

As the cryosphere melts, darker materials replace the highly reflective white surface of ice and snow, so less heat is reflected back into space. This results in more ice melting – a classic feedback effect. The Arctic council estimates that the global sea level is now estimated to rise by 0.9–1.6 metres over the next 90 years, more than three times the IPCC’s estimates in 2007.

Ozone levels and emissions of black carbon also play their part in this mechanism, although there is still uncertainty in AR5 about the cumulative global impact. The overall effect is complex because the anti-climate change effects of aerosols on clouds and the absorption of solar radiation by black particulates complicate the issue. The AR5 report suggests that this has offset a substantial portion of the overall radiative forcing – that is to say, it would have been much worse without this effect.

The Himalayas are also a major region susceptible to pollution effects. The mountain ranges, which extend 2,400km through six countries – India, Pakistan, Afghanistan, China, Bhutan, and Nepal – make up the largest cryosphere region and fresh water source outside the polar areas. Rapid climate-induced changes in the region directly affect the water resources of more than 1.3 billion people, as well as services such as electricity and the food supplies of three billion inhabitants.

Impacts include disruption of the annual monsoons, changes in runoff from river basins, and an increased risk of flooding and landslides. This area has undergone an average 1.5ºC surface temperature increase compared with pre-industrial levels.

Because these polar and alpine areas have reacted more strongly in general to global warming, showing an increase in temperature twice that of the global mean, they are also at greater risk. The 2ºC global limit set by the Copenhagen accord translates into a 4ºC or even higher rise in most snowy regions. This has serious implications for humanity.

“Implementing air quality measures to cut small particulates as soon as possible will improve the health and quality of life for many millions of people each year, while at the same time decreasing risks from sea-level rise, loss of water resources and other impacts of rapid cryosphere change in the first half of this century,” says Pam Pearson, director at the International Cryosphere Climate Initiative. “Yet it cannot be over-emphasised that ambitious actions on CO2 must also occur within the next two decades to decrease these cryosphere risks as well.”

Tackling small particulates

The sensible method to reduce the danger is to move forward rapidly to using more sustainable methods for heating, cooking and lighting. Four cook-stove models – liquid petroleum gas (LPG), biogas, ethanol and forced-draft stoves – have proven to reduce particle pollution and black carbon.

Biogas digesters, which convert manure from cows, pigs and even human waste to cooking fuel, are commercially available in sizes ranging from a single household to a small village; so are larger installations that gather such waste and distribute the gas. Ethanol provides an increasingly popular alternative fuel in Africa and South America, and the health and climate benefits should equal those of LPG and biogas. The ethanol needs to be sustainably produced, however, given competing demands for land and water use for cultivation.

Because of their remoteness, many of these areas are unlikely ever to be connected to an electricity grid. They do have plenty of sunshine, however. WWF-India has been involved in a number of demonstration projects where kerosene lighting has been replaced with solar panels. The result has been a significantly improved quality of life for villagers.

One project, in the Sunderbans in the Ganges Delta, enabled a village to move to clean energy. The project has established a technically and financially sustainable, off-grid centralised renewable energy-based village power system. It is based on the highly successful Bushlight project, which, since 2002, has been providing reliable renewable energy services to remote indigenous communities in Australia. It is a scalable solution that can provide access to safe and clean energy in the form of grid-quality electricity in isolated areas.

The microsolar power station at Rajat Jubilee in the Sunderbans connects 49 households, six local businesses and three community buildings, and supplies uninterrupted grid-quality power. Residents are trained to use and operate the systems and are involved in planning their electricity use in 24-hour cycles so that everyone gets a fair share of the power generated. To avoid using wires, the batteries are charged three times a week at a central generating station.

Local women can now supplement their income by working in the evening, by mending clothes for example, and their children can do their homework without now being subject to the potentially deadly effects of kerosene fumes. The benefits of modern communications and computer systems are, of course, predicated on electricity supply.

Sustainable technologies like this can be rolled out across many areas of the developing world and reduce a wide variety of pollutants and GHGs as well as improve the lives of huge numbers of people.

Changing behaviour

It is also necessary to reduce traditional post-harvest crop burning. In many cases this practice can over time cause a net loss of soil nutrients, necessitating greater use of expensive fertilisers. The soil deteriorates, resulting in a cycle of low humus soil structures, reduced yields and declining productivity, and abandonment of the land.

Changing established agricultural methods involves education and a willingness by farmers to realise that the traditional practices they and their ancestors have employed may not be the best way to conserve the land. Although the areas affected are large – more than three billion people are estimated to use wood-stoves – the technologies to address this are available, not costly, and easy to implement. The ability of villagers in the Sunderbans to rapidly learn to use solar power shows how quickly technology will catch on when it addresses a need.

Although a vast amount of GHG emissions come generally from the developed economies, the effects of the various small-particle emissions globally are not negligible. Offsetting some or all of the 0.6ºC of warming they produce by using cleaner technology would be an enormous achievement.

Given the grim warnings of AR5, which include raised sea levels and pollutants remaining in the biosphere for thousands of years, preventing the emissions of small particles is a step in the right direction to reduce climate change. The worldwide rollout of clean energy technologies would also improve the lives of billions of people who depend on horribly polluting and dangerous methods of heating, lighting and cooking.


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