Increased concentrations of greenhouse gases (GHGs) in the atmosphere due to both natural and anthropogenic activities have resulted in severe environmental consequences threatening the biosphere of the Earth due to global warming and sea level rise. Therefore, strategies to reduce GHG emissions in both global and local contexts is mandatory. In this lecture, the terms ecological footprint (EFP), carbon footprint (CFP), global warming potential (GWP), and climate footprint will be defined and factors contributing to these terms discussed. The different strategies to reduce CFP include improving and promoting energy conservation and efficiency, using fuels with low carbon output such as nuclear and hydrogen fuels, changing to renewable energy (solar, hydropower, wind, and bioenergy), promoting carbon capture and storage, and using and promoting geoengineering approaches (reforestation, afforestation).

The global GHG emissions by sector include energy, direct industrial processes, waste, and agriculture, forestry, and land use. The energy sector includes electricity, heat and transport which accounts for 73.2% and direct industrial processes, waste, and agriculture, forestry and land use contribute to 5.2%, 3.2% and 18.4%, respectively, as per 2016 data [1]. The countries contributing to GHG in 2020 are in the order China > USA > India > EU27 > Indonesia > Russian Federation > Brazil and the international transportation coming to next place. However, as per capita GHG emissions, the order is USA > Russian Federation > China > Brazil > Indonesia > EU27 > World > India. In EU countries, in 2020, the fuel combustion in energy industries, transportation including international aviation, households, commercial and other institutions, and manufacturing and construction industries account for 23.3%, 23.2%, 15.4%, and 12.1% GHG emissions thus totalling to 74.0%. In EU countries, there is a considerable reduction in GHG emissions from 1990 to 2020 in most sectors except fuel combustion in transport, including international aviation. The fuel combustion in transportation has a significant increase in by 50 million tonnes of CO2-equivalents [2].

According to the World Resources Institute Climate Analysis Indicators Tool (WRI CAIT), the contributions to Sri Lanka’s GHG emissions, in 2011, are from energy sector (40%), waste (28%), land use change and forestry (LUCF) (15%), agriculture (14%) and industrial processes (3%). Energy sector emissions include transportation (39%), electricity and heat (28%), other fuel combustion (27%), and manufacturing and construction (5%). However, the energy sector which includes power generation and transport dominates over all other sectors [3]. The R&D activities currently in action in Sri Lanka such as developing carbon capture methods, conversion of carbon dioxide to useful chemicals, green energy technologies (hydropower, wind power, solar energy conversion and storage, hydrogen generation, fuel cells and supercapacitors), floating solar panels fixed under NORPART programme, development of all electric sport car “VEGA” and electric three wheeler vehicles and carbon negative vehicle body parts, alternative to cement in concrete production, carbon-negative construction materials, waste management and conversion of sludges to organic fertilizer will be discussed.