The Intergovernmental Panel on Climate Change (IPCC) has released its third and final report of the sixth assessment which focusses on the Mitigation of Climate Change. The report depicts a grim picture of the climate situation with the last decade from 2010 to 2019 witnessing 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) in 2019 which is about 12% higher than in 2010 and 54% higher than in 1990. The largest growth in absolute emissions was reported by carbon dioxide (CO2) followed by methane and fluorinated gases. Although global GHG emissions dropped by 5.8% 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 their emission reduction pledges to the United Nations Framework Convention on Climate Change (UNFCCC), the world is most likely to overshoot the goal of limiting global warming to 1.50C or 20C 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 and 3.50C 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, heatwaves, and wildfires will aggravate further. Countries will need to accelerate emission reductions after 2030 to limit global warming to 1.50C or 20C and avert catastrophic events.
GHG emissions have increased in all sectors since 2010. In 2019 the energy sector contributed 34% 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 year, and a reduction in the carbon intensity of energy supply by 0.3% per year during 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% share of the global population, reported per capita GHG emissions of 19 tCO2-eq in 2019 whereas for southern Asia with 24% of global population it was 2.6 tCO2-eq. While 35% of the global population lived in countries with per capita emissions above 9 tCO2-eq., 41% lived in countries with these emissions below 3 tCO2-eq. The least developed countries contributed just 3.3% of global GHG emissions in 2019 as against around 57% by developed countries. While 10% of households with higher per capita emissions were responsible for 34-45% of global consumption-based GHG emissions, the bottom 50% contributed a mere 13-15%. North America and Europe together accounted for about 39% of cumulative CO2 emissions from 1850 to 2019 whereas southern Asia’s share was a mere 4%.
Increased investment in low-carbon technologies and infrastructure along with expanded financial flows 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 have fallen by 55 to 85% since 2010. In 2019 solar and wind energy provided 8% of the global electricity supply and accounted for two-thirds of new electricity capacity installed. Annual financial flows for climate action averaged over $632 billion in 2020. Apart from being largely focused on mitigation, the least developed countries received only a fraction of these funds. Although the Paris Climate agreement had set a goal of $100 billion per year from 2020 to assist developing countries to adapt to climate change this goal is yet to be reached.
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, improved 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. Of this potential, about 30-50% is available at costs below $20 tCO2-eq. Ecosystem-based adaptation, including nature-based solutions and other land-based mitigation measures, offers substantial co-benefits such as protection and restoration of natural ecosystems, reforestation, and carbon sequestration on agricultural soils. Mitigation measures such as bioenergy crops may be detrimental to biodiversity, food and water security, and livelihoods. Demand-side measures include reducing food wastage and shifting to healthier diets. AFOLU mitigation measures will cost around $400 billion per year by 2050 which is less than current subsidies for the sector. Shifting to more efficient and low carbon transportation such as electric vehicles, using advanced battery technologies, biofuels and hydrogen can enable deep emission cuts in the transport sector.
Urban areas contributed a major share of combined global CO2 and methane emissions in 2020 fuelled by the growing population, infrastructure and demand for goods and services. Reducing urban energy consumption, electrification and switching to low carbon energy sources and transportation, investing in green and blue infrastructure offer multiple benefits and help establish compact and low carbon cities.
Without mitigation, global GDP will likely decrease by 1.3 to 2.7% in 2050 and jeopardise the achievement of the sustainable development goals. The economic benefits of limiting global warming exceed the mitigation costs under most scenarios.
(The writer is the Lead Author, Sixth
Assessment Report, IPCC, Geneva,
Switzerland)