Go beyond GHGs to clean air faster

Climate change stands as the defining crisis of our time, posing imminent threats to our environment, economy, and lives. In the extraordinary story of climate change, Greenhouse Gases (GHGs), known culprits in the global warming saga, have frequently taken centre stage with their persistent presence in the atmosphere. Their role in rising temperatures, sea levels, and climate change is well-established, leading to continuous efforts to lower GHG emissions, epitomised by international agreements such as the Paris Agreement (2015), which aims to limit global temperature rise below 2 degrees Celsius. However, a comprehensive understanding of climate change must go beyond GHGs. A significant subplot in this narrative that demands equal consideration is the role of Short-Lived Climate Pollutants (SLCPs). 

SLCPs, also known as Climate Forcers or Super Pollutants, have a relatively short lifespan in the atmosphere, typically ranging from days to a few decades. They include methane, hydrofluorocarbons (HFCs), tropospheric ozone, and black carbon (soot). For example, the atmospheric lifetime of methane and hydrofluorocarbons (HFCs) is about 12 years and 15 years, respectively. Tropospheric ozone remains in the atmosphere for only hours to weeks, while black carbon lasts a few days to a few weeks.

Among SLCPs, methane is primarily released during coal, oil, and natural gas production and transport. It is also emitted by livestock and other agricultural practices. HFCs are commonly used as substitutes for ozone-depleting substances in refrigeration, air conditioning, and insulation. While HFCs do not harm the ozone layer, they have a high global warming potential. Tropospheric ozone is a critical component of smog that damages human health and contributes to global warming. On the other hand, black carbon is a byproduct of incomplete combustion of fossil fuels and biomass. 

Despite their relatively short lifetimes, these pollutants severely impact human health and significantly contribute to climate change. For instance, methane is about 25 times more effective at trapping heat than carbon dioxide. It can displace oxygen in confined spaces and potentially cause respiratory issues. Black carbon accelerates melting by reducing snow and ice's reflectivity when deposited on them. When inhaled, particulates containing black carbon can harm cardiovascular and respiratory health. SLCPs accelerate global warming in areas like the Arctic, exacerbate air pollution, and deteriorate air quality and public health in countries like India.

Therefore, India and the rest of the world must mitigate SLCPs for several reasons. First, due to their short-lived nature, curbing SLCP emissions can yield almost immediate climate benefits. It may provide a buffer and temporary relief by preventing near-term temperature rises while long-term GHG mitigation strategies and efforts are undertaken to switch to cleaner energy sources and lower CO2 emissions. SLCPs are responsible for up to 45 per cent of current anthropogenic global warming. Second, countries can address air pollution and the health issues SLCPs cause by reducing methane and black carbon emissions. Furthermore, these measures can help manage the region's water resources by slowing the glaciers' rapid melting.

Mitigation strategies for GHGs and SLCPs are complementary, not mutually exclusive. By reducing both emissions, we can tackle the dual challenge of global climate change and local air pollution. In this context, the Global Methane Pledge (GMP), a joint agreement by the European Union and the US, aims to cut global methane emissions by 30% by 2030. The pledge was launched in Glasgow during COP26 in 2021. At COP28 in Dubai in 2023, GMP partners announced over $1 billion in new grant funding for methane action. These efforts signify a crucial step towards mitigating methane emissions and addressing climate change. It is believed that if globally implemented, some of the control measures can significantly reduce emissions from SLCPs. Reducing methane, one of the primary precursors, is the principal strategy. However, methane emissions from agricultural practices are a prominent concern where farming is a significant livelihood. 

India's rapid urbanisation and vast population are significant emitters of GHGs and SLCPs. Being a nation with diverse climates and ecosystems, it can play a vital role in GHG and SLCP mitigation. While the country has made strides in GHG mitigation through its adoption of renewable energy, there is an equal and urgent need to tackle SLCPs. Implementing measures to reduce SLCP emissions, such as improving waste management practices, banning open burning of municipal waste, promoting cleaner cookstoves, improving livestock management, and investing in sustainable agriculture, can significantly contribute to the fight against climate change. A greater emphasis on lowering SLCPs, such as methane and black carbon, is highly anticipated now. The most effective approach to reducing SLCP emissions is to gradually reduce their production and use and switch to more environmentally friendly alternatives.

(Anand Madhukar is assistant professor and programme coordinator (Climate Science & Policy), and Jahnavi Shah is a Master's student at TERI School of Advanced Studies, New Delhi)