Any possibility of near-term regional warming due to the implementation of emission standards should be offset by aggressively cutting back short-lived warming pollutants
The recent Working Group 1 report of the Intergovernmental Panel on Climate Change finds that particulate matter (PM or simply, fine particles) have ‘masked’ the impact of greenhouse gas emissions generated over the last century by about a third. As air quality levels in India and elsewhere improve, this ‘net-cooling’ effect will be lost making warming worse in the near term. Given that air pollution and climate change often get conflated, this may seem surprising and confusing. If air pollution mitigation ‘worsens’ global warming, must we rethink pollution controls at all? Not quite.
Combustion of fossil fuels (especially coal and diesel) and biomass (like firewood or crop residue) emit pollutants that contribute to both air pollution and climate change. These emitted pollutants interact with each other in complicated ways. Air pollution is the single largest risk factor to public health in India, driven primarily by fine particles and ground level ozone. Together, they account for nearly one-fifth of all premature deaths in the country and according to the World Bank at least 8.5% of GDP. Air pollution has a much faster impact on our environment and health, whereas climate change will have long-term implications to not only our environment and health, but also to our economic and social well-being. One recent example is the reduction in air pollution across India during the COVID-19 pandemic lockdown in 2020 because of reduced industrial and transport activities and benefits ranging from blue skies to clean air. In spite of these reductions in 2020, 9 out of the top 10 and 35 out of the top 50 most polluted cities were from India.
Whether the goal is better air quality in the near-term or reduction of climate change related losses in the long-term, the mitigation efforts required are at the same sources. So, it is only beneficial for all stakeholders if treatment of these entities is combined. Where possible, governments must seize opportunities that are able to tackle both simultaneously, with special attention on sources where the benefits will be immediate for public health through better air quality. Where actions reducing health-harming air pollution may result in a net-increase in warming, governments should similarly prioritise health gains, and look for opportunities to compensate for the “climate penalties” with other measures that reduce warming pollutants.
Mitigating air pollution and climate change in an integrated way
Interventions improving energy efficiency or replacing polluting fuels with cleaner alternatives tend to mitigate both climate change and air pollution. In particular, sources emitting black carbon — soot from incomplete combustion, a substantial component of fine particle emissions in India — are especially attractive candidates for mitigation. In addition to absorbing radiation in the atmosphere, black carbon also gets deposited on the snow, like in the Himalayas, and adds to warming by reducing the amount of solar radiation reflected from otherwise bright surfaces. It has also played a significant role in the drying up of the monsoons, especially in the Indo-Gangetic Plains (IGP). Perhaps the most important intervention for mitigating black carbon emissions is to enable households to transition from solid fuels to rely exclusively on liquified petroleum gas (LPG), providing both climate and public health benefits. According to the Global Burden of Disease studies, fuels used for household cooking and heating contribute up to 30% of India’s air pollution related health burden. These health impacts are disproportionately borne by women and infants. With LPG subsidies now eliminated, we risk households returning to traditional biomass, and losing the gains from the Ujjwala programme. Reducing crop residue burning, and cleaning up brick manufacturing process with efficient kilns and/or electrification also offer substantial co-benefits.
Some components of fine particles like sulphates and nitrates, formed by chemical conversion of sulphur dioxide (SO2) and nitrogen oxides (NOx) emissions, only scatter solar radiation. Mitigating these would have the effect of “increasing” warming in the near term, but the benefits of controlling these emissions are substantial for air quality and human health. In 2019, India was the estimated largest producer of SO2 emissions, followed by Russia and China. Coal power plants account for 50% of India’s SO2 emissions, and 30-40% of the fine particles attributable to power plants are sulphates. The fine particles from power plants have been estimated to lead to 80,000- 115,000 premature deaths a year.
In India, road transport (a key source of NOx) plays a central role for mobility and commerce, and there is an exponential increase in interest to clean the sector with the introduction of electric vehicles. Decarbonisation of the transport and electricity sectors mitigates both greenhouse gases and air pollution. However, given its impact on livelihoods in coal-dependent regions there is an ongoing debate on how India can achieve a just transition.
Meanwhile, India is expected to continue to rely on coal. Despite the Environment Ministry laying down emission standards for SO2 and NOx in 2015, coal power plants have dragged their feet on compliance. There is a floating suggestion from the Central Electrical Authority on further delaying retrofits and phaseout of old power plants to 2034, with barely any acknowledgment of their continued health impacts through fine particles. This is unacceptable. The government must enforce the standards immediately. It should also be cognisant of the possibility of near-term warming at a regional scale due to any resultant reduction in sulphates, and simultaneously accelerate efforts to reduce short lived warming pollutants like black carbon, ozone and methane.
The IPCC WG1 report warns, in unusually strong language, about the near-inevitability of a 1.5 degree C increase in global temperatures, and its consequences on the frequency of extreme events. Conversely, the report is also clear that the actions required to counter this trend have to start now, and go beyond net-zero pledges. Developing a synergy between air pollution and climate change actions, with priority given to reducing near term human health impacts, is critical.
Views expressed in the above article are personal.