The IPCC recently released its third and final report of the sixth assessment cycle, which focuses on Mitigation of Climate Change. The report depicts a very grim picture of the climate situation and notes that the last decade from 2010 to 2019 witnessed the highest decadal absolute increase in greenhouse gas (GHG) emissions since 1850.
Global net anthropogenic GHG emissions were around 59 GtCO2-eq. (gigatonnes of carbon dioxide equivalent), which is about 12 per cent higher than in 2010 and 54 per cent higher than in 1990. The largest growth in absolute emissions was reported by carbon dioxide (CO2), followed by methane (CH4) and fluorinated gases (F-gases). Although global GHG emissions dropped by 5.8 per cent in 2020 as compared to in 2019 due to the Covid-19 pandemic, they rebounded again by the end of 2020 as economic growth picked up.
If these trends continue and countries stick to the emission reduction targets as reflected in their nationally determined contributions (NDCs) pledged to the United Nations Framework Convention on Climate Change (UNFCCC), the world is most likely to overshoot the goal of limiting global warming to 1.5°C or 2°C above pre-industrial levels as agreed at the Paris Climate Summit in December 2015.
Based on current policies and trends, the report warns that global temperature is likely to reach a median of between 2.2 to 3.5°C by the year 2100. If this happens, it will have disastrous consequences for human and natural systems as well as lives and livelihoods. The frequency and intensity of extreme weather events and disasters such as prolonged droughts, floods, heat waves, wildfires, sea level rise and pandemics are set to aggravate further. Countries will need to abruptly accelerate emission reductions after 2030 to limit global warming to 1.5°Cor 2°C and avert catastrophic events.
GHG emissions have increased in all sectors since 2010. In 2019, the energy sector contributed about 34 per cent of global GHG emissions, followed by industry (23 %), agriculture, forestry and other land uses (22 %), transport (15 %) and buildings (6 %). Although there has been an improvement in global energy efficiency by 2 per cent per year, and a reduction in carbon intensity of energy supply by 0.3 per cent per year from 2010 to 2019 due to fuel switching from coal to gas, reduced expansion of coal capacity and increased use of renewables, owing to increased activities in the industrial, energy, transport, buildings, agriculture and urban sectors, overall GHG emissions continued to rise.
There are gross inequalities in emissions between regions and households. North America, with 4.8 per cent share of the global population, reported per capita GHG emissions of 19 tCO2-eq. in 2019, whereas for southern Asia, with 24 per cent of the global population, this figure was 2.6 tCO2-eq. While 35 per cent of the global population lived in countries with per capita emissions above 9 tCO2-eq., 41 per cent lived in countries that reported per capita emissions below 3 tCO2-eq. Least developed countries contributed just 3.3 per cent of global GHG emissions (excluding net CO2 emissions from land use, land cover change and forestry) in 2019 as against about 57 per cent by developed countries.
While 10 per cent of households with higher per capita emissions were responsible for 34 to 45 per cent of global consumption-based GHG emissions, the bottom 50 per cent contributed a mere 13 to 15 per cent. The global wealthiest 10 per cent contributed about 36-45 per cent of global GHG emissions. North America and Europe together accounted for about 39 per cent of cumulative CO2 emissions from 1850 to 2019, whereas southern Asia’s share was a mere 4 per cent. However, the Asia and Developing Pacific regions accounted for 77 per cent of the net 21 GtCO2-eq. increase in GHG emissions since 2010.
Along with expanded financial flows, increased investment in low-carbon technologies and infrastructure has helped strengthen global climate policies. However, these benefits are unevenly distributed across regions and sectors. The unit cost of low emission technologies such as solar and wind energy, and lithium-ion batteries has fallen by between 55 and 85 per cent since 2010.
In 2019, solar and wind energy provided 8 per cent of global electricity supply and accounted for two-thirds of new electricity capacity installed. Annual financial flows for climate adaptation and mitigation averaged about USD 632 billion in 2019/2020. Apart from being largely focused on mitigation (90-95 %), least developed countries received only a fraction (<5 %) of these funds. Public and private financial flows for fossil fuels were greater than those for climate mitigation and adaptation. Although the Paris Climate agreement had set a volume of USD 100 billion per year from 2020 to assist developing countries to adapt to climate change, this goal remains a pipe dream.
To limit global warming to 1.5°C or 2°C above pre-industrial levels, the report assesses various policy options to mitigate and adapt to climate change. It calls for a major systemic transformation in the energy sector involving reduced fossil fuel use, deployment of low carbon energy sources, and improving energy conservation and efficiency. Low carbon technologies are envisaged to supply a major share of global electricity by 2050.
The agriculture, forestry, and other land uses (AFOLU) sector emits about a quarter of global GHG emissions. The sector is a carbon sink and source of renewable resources with an estimated mitigation potential of 8 to 10 GtCO2 eq. per year between 2020 and 2050 at costs below USD 100 tCO2 eq., with the largest share coming from forests and other natural systems. Of this potential, 30-50 per cent could even be implemented at costs below USD20 tCO2-eq.
Ecosystem-based adaptation including nature-based solutions and other land-based mitigation measures offer substantial co-benefits such as protection and restoration of forests and other natural ecosystems, enhancement of biodiversity and ecosystem services, and carbon sequestration in agricultural soils. Other measures include reducing deforestation in bio-rich tropical regions, improved and sustainable crop and livestock management. Demand-side measures comprise lowering the level of food wastage and shifting to healthier diets. The net costs of delivering 5 to 6 GtCO2 per year of forest-related carbon sequestration and emission reduction are estimated at around USD 400 billion per year by 2050, which is less than current subsidies provided to agriculture and forestry. Even if all mitigation measures are successfully implemented in the AFOLU sector, this cannot compensate for the adverse consequences due to lack of climate action in other sectors.
Shifting to more efficient and low carbon transportation such as electric vehicles and using advanced battery technologies, sustainable biofuels and low emission hydrogen can enable deep emission cuts in the land, sea and aviation-based transport sectors.
Urban areas contributed between 67 to 72 per cent of combined global CO2 and methane emissions in 2020 due to growing population, infrastructure and demand for goods and services. Reducing urban energy consumption, electrification and switching to low carbon energy sources and transportation including encouraging people to use non-motorised transport (e.g. walking and bicycles) and public transport, investing in green and blue infrastructure (e.g. green roofs, conserving urban lakes and water bodies, more park areas) offer multiple benefits and can help in making our cities compact, low carbon and environment friendly.
Barriers to the implementation of mitigation measures comprise technological constraints, costs, risks, trade-offs, governance, institutional weaknesses and socio-cultural factors. For instance, while some mitigation measures such as reforestation and conservation of forests and other ecosystems may enhance biodiversity and ecosystem services, others, like large-scale deployment of bioenergy crops, may be detrimental to biodiversity, food and water security, livelihoods, including rights of indigenous and local communities and of small farmers, especially in regions where land is a limiting factor and there is competition for land used for food production and other livelihood activities. Shifting to electric vehicles and non-motorised forms of transportation in cities and investing in green and blue infrastructure will have co-benefits such as improving air quality and health outcomes.
Without mitigation, global GDP is expected to decrease by 1.3 to 2.7 per cent in 2050 in pathways likely to limit warming to 2oC and between 2.6 to 4.2 per cent by 2050 in pathways likely to limit warming to 1.5oC. It will also jeopardise achievement of the sustainable development goals. The global economic benefits of likely limiting warming to 2oC exceed the mitigation costs under most scenarios.
K. N. Ninan is Lead Author of Working Group III, Sixth Assessment Report, Intergovernmental Panel on Climate Change, Geneva, Switzerland and Senior Fellow at the World Resources Institute – India, New Delhi.