Defusing the climate time bomb for a liveable future

While releasing the synthesis report of the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC) recently, United Nations Secretary General Antonio Guterres warned nations that the climate time bomb is ticking. He noted that humans are responsible for all global warming in the past 200 years; the rate of temperature rise is the highest in the last 200 years; and carbon dioxide concentrations are the highest in at least two million years.

According to the UN Secretary General, the synthesis report is a guide for defusing the climate time bomb and a survival guide for humanity. He gave a clarion call for fast-tracking climate action by all countries so that the Paris climate goal of limiting temperature rise to 1.5 degrees Celsius is achievable.

The IPCC report calls for rapid and far-reaching transitions across all sectors to achieve deep and sustained emission reductions in order to secure a liveable and sustainable future for all.

This involves the deployment of low- or zero-emission technologies, reducing and changing demand through infrastructure design and access, socio-cultural and behavioural changes, increased technological efficiency and adoption, social protection (climate or other services) and protecting and restoring ecosystems.

The report suggests a package of mitigation and adaptation measures to reduce emissions in different sectors and activities. In the energy sector, it calls for supply- and demand-side measures to reduce the carbon footprint of the energy sector, which contributed 34% of global greenhouse gas (GHG) emissions in 2019.

This includes drastically reducing dependence on fossil fuels, carbon capture and storage of remaining fuel systems, shifting to renewable energy sources (wind, solar and small-scale hydropower), fostering energy security and diversification by relying on low-emission electricity and improving storage and energy efficiency.

The industrial and transport sectors accounted for 38% of global GHG emissions in 2019. The report calls for coordinated action throughout value chains to promote all mitigation options, including demand management, energy and material efficiency, circular material flows, abatement technologies and transformational changes in production processes.

For the transport sector, the report suggests that sustainable biofuels, low-emission hydrogen and derivatives (including ammonia and synthetic fuels) can support mitigation of CO2 emissions from shipping, aviation, and heavy-duty land transport but they require production process improvements and cost reductions. Electric vehicles powered by low-GHG emission electricity have large potential to reduce land-based transport GHG emissions.

Advances in battery technologies could facilitate the electrification of heavy-duty trucks and complement conventional electric rail systems. The environmental footprint of battery production and growing concerns about critical minerals can be addressed by material and supply diversification strategies, energy and material efficiency improvements and circular material flows.

World population projections by UN agencies suggest that by 2050, about 68% of the population will reside in urban areas. Urban systems are therefore critical for achieving deep emission reductions and advancing climate-resilient development.

Key adaptation and mitigation elements in cities include considering climate change impacts and risks (e.g., climate services) in the design and planning of settlements and infrastructure; land use planning to achieve compact urban form, co-location of jobs and housing; supporting public transport and other modes such as walking and cycling; efficient design, construction, retrofit, and use of buildings; reducing and changing energy and material consumption; sufficiency; material substitution; and electrification in combination with low emissions sources.

Urban transitions that offer benefits for mitigation, adaptation, human health and well-being, ecosystem services and vulnerability reduction for low-income communities are fostered by an inclusive long-term planning that takes an integrated approach to physical, natural and social infrastructure.

Green/natural and blue infrastructure supports carbon uptake and storage, and either singly or when combined with grey (buildings, roads, stormwater) infrastructure, can reduce energy use and risk from extreme events such as heatwaves, flooding, heavy precipitation and droughts, while generating co-benefits for health, human well-being and livelihoods.

The agriculture, forestry and other land uses (AFOLU) sector, which accounts for 22% of global GHG emissions, provides several low-cost climate mitigation options at less than $20 per tonne of carbon dioxide equivalent (tCO2-eq).

Conservation, improved management and restoration of forests and other natural ecosystems offer the largest share of economic mitigation potential, with reduced deforestation in tropical regions having the highest total mitigation potential.

Ecosystem restoration, reforestation and afforestation can lead to trade-offs due to competing demands on land. Minimising trade-offs requires integrated approaches to meet multiple objectives, including
food security.

Demand-side measures such as shifting to sustainable healthy diets and reducing food loss/waste and sustainable agricultural intensification can reduce ecosystem conversion and methane and nitrous oxide emissions and free up land for reforestation and ecosystem restoration.

Sustainably sourced agricultural and forest products, including long-lived wood products, can be used instead of more GHG-intensive products in other sectors. Effective adaptation options include cultivar improvements, agroforestry, community-based adaptation, farm and landscape diversification and urban agriculture.

These AFOLU response options require integration of biophysical, socio-economic and other enabling factors. Some options, such as conservation of high-carbon ecosystems (e.g., peatlands, wetlands, rangelands, mangroves and forests), deliver immediate benefits, while others, such as restoration of high-carbon ecosystems, take decades to deliver measurable results.

The UN Secretary General proposed a Climate Solidarity Pact to G20 under which all big emitters, including India and China, make extra efforts to cut emissions, while wealthier countries mobilise financial and technical resources to support emerging economies in a common effort to keep the Paris climate goal of 1.5 degrees Celsius alive.

It is disappointing that while billions of dollars have been mobilised by wealthy countries at a short notice to give military aid to Ukraine, they have failed to mobilise $100 billion per annum for assisting developing countries to transit to a climate-resilient development path as envisaged under the Paris Climate Accord.

(The writer is lead author,
Sixth Assessment Report, IPCC, Geneva, Switzerland)