SciDev.Net

This report, written by a team of international scientists and published by the UN Environment Programme (UNEP), explores the effects of 'atmospheric brown clouds'(ABCs) on regional climate, agriculture and human health.

ABCs are large plumes of pollutant gases that result from burning fossil fuels and biomass. The authors of the UNEP report examine the spread of ABCs — particularly in Asia — and discuss their likely impacts, including decreases in the Indian summer monsoon rainfall, accelerated glacial retreat and increases in surface ozone.

They suggest that ABCs threaten water and food security in Asia, impact human health and may mask the warming effects of climate change by 20 – 80 per cent. The authors recommend an international response to tackle the twin effects of ABCs and greenhouse gases, and the unsustainable development that underpins them.

Concerns over climate change may soon force drastic reductions in carbon dioxide emissions. In response to this challenge, it may prove necessary to render fossil fuels environmentally acceptable by capturing and sequestering carbon dioxide until other inexpensive, clean and plentiful technologies are available. In this Science review article, Klaus S. Lackner gives a detailed overview of the various options available for carbon sequestration, highlighting the pros and cons of each.

Several factors influence the costs of greenhouse gas mitigation. This report illustrates the importance of one such factor — international emissions trading — in reducing the costs of carbon control. The authors argue that an international greenhouse gas emissions trading regime will significantly lower global mitigation costs.

Worldwide, greenhouse gas emissions are rising faster in transportation than in any other sector. Rapid motorisation — more cars and trucks — is the principal cause. This report focuses on the challenges faced by developing countries in accommodating and managing motorisation and the demand for improved transportation.

The report provides a broad characterisation of transportation in developing countries, identifying common challenges and opportunities for policymakers, and suggesting policy options that aim to slow the growth of greenhouse gas emissions from the transportation sector.

The most important observations are:

• Rapid motorisation — and rapid growth in transport-related greenhouse gas emissions — are unavoidable in most developing nations.
• The relationship between car ownership and income is not fixed.
• Once people have personal vehicles, they use them even if alternative transportation modes are available.
• There are many sensible policies and strategies that would slow the growth of transportation sector greenhouse gas emissions. Key strategies include increasing the cost of using conventional private cars and enhancing the quality and choices of alternative transportation.
• Many of the strategies for slowing and eventually reducing greenhouse gas emissions from transportation have local as well as global benefits.