Between 2010 and 2019, average annual global greenhouse gas emissions were at their highest levels in human history, but the rate of growth has slowed. Without immediate and deep emissions reductions across all sectors, limiting global warming to 1.5°C is beyond reach. However, there is increasing evidence of the success of climate action, said scientists in the latest Intergovernmental Panel on Climate Change (IPCC) report out April 4.
Since 2010, there have been sustained decreases of up to 85% in the costs of solar and wind energy, and batteries. An increasing range of policies and laws have enhanced energy efficiency, reduced rates of deforestation, and accelerated the deployment of renewable energy.
“We are at a crossroads. The decisions we make now can secure a livable future. We have the tools and know-how required to limit warming,” said IPCC Chair Hoesung Lee. “I am encouraged by climate action being taken in many countries. There are policies, regulations, and market instruments that are proving effective. If these are scaled up and applied more widely and equitably, they can support deep emissions reductions and stimulate innovation.”
The Working Group III report provides an updated global assessment of climate change mitigation progress and pledges, and examines the sources of global emissions. It explains developments in emission reduction and mitigation efforts, assessing the impact of national climate pledges in relation to long-term emissions goals.
We have options in all sectors to at least halve emissions by 2030
According to the authors, limiting global warming will require major transitions in the energy sector. This will involve a substantial reduction in fossil fuel use, widespread electrification, improved energy efficiency, and use of alternative fuels (such as hydrogen).
Having the right policies, infrastructure, and technology in place to enable changes to our lifestyles and behavior can result in a 40-70% reduction in greenhouse gas emissions by 2050. The evidence also shows that these lifestyle changes can improve health and wellbeing.
Cities and other urban areas also offer significant opportunities for emissions reductions. These can be achieved through lower energy consumption (such as by creating compact, walkable cities), electrification of transport in combination with low-emission energy sources, and enhanced carbon uptake and storage using nature. There are options for established, rapidly growing, and new cities.
Reducing emissions in industry will involve using materials more efficiently, reusing and recycling products and minimizing waste. For basic materials, including steel, building materials, and chemicals, low- to zero-greenhouse gas production processes are at their pilot to near-commercial stage.
This sector accounts for about a quarter of global emissions. Achieving net zero will be challenging and will require new production processes, low and zero emissions electricity, hydrogen, and, where necessary, carbon capture and storage.
Agriculture, forestry, and other land use can provide large-scale emissions reductions and also remove and store carbon dioxide at scale. However, land cannot compensate for delayed emissions reductions in other sectors. Response options can benefit biodiversity, help us adapt to climate change, and secure livelihoods, food and water, and wood supplies.
A major new component of the Working Group III report is a new chapter on the social aspects of mitigation, which explores the ‘demand side’, in other words, what drives consumption and greenhouse gas emissions.
Significant changes across transport, industry, buildings and land-use will make it easier for people to lead low-carbon lifestyles and, at the same time, improve wellbeing. By 2050, a combination of effective policies, improved infrastructure and technologies leading to behavioral change has the potential to enable reductions in greenhouse gas emissions by between 40 and 70%.
“Action in the coming decade is critical to keep the 1.5°C goal within reach. At the same time, it is important to recognize that even if we fail to limit global warming to 1.5°C, it is essential to keep moving forward with mitigation efforts. Less climate change is clearly better from a risk management perspective,” says IIASA Integrated Assessment and Climate Change Research Group Leader, Volker Krey, who was one of the lead authors of the report.
Closing investment gaps, bridging inequities, and achieving the Sustainable Development Goals
The report looks beyond technologies and demonstrates that while financial flows are a factor of three to six times lower than levels needed by 2030 to limit warming to below 2°C, there is sufficient global capital and liquidity to close investment gaps. However, it relies on clear signaling from governments and the international community, including a stronger alignment of public sector finance and policy.
“The assessment highlights the wide differences in the contribution of different regions, nations, and households to global greenhouse gas emissions. Least Developed Countries (LDCs) and Small Island Developing States (SIDS), for instance, have historically not contributed significantly to global greenhouse gas emissions, nor are they doing so now,” notes chapter lead author Shonali Pachauri, who leads the Transformative Institutional and Social Solutions Research Group at IIASA.
“For populations in low-emitting countries that lack access to modern energy services and decent standards of living, providing universal access to these services has no significant implications for global emissions growth.”
Accelerated and equitable climate action in mitigating and adapting to climate change impacts is critical to sustainable development. Some response options can absorb and store carbon and simultaneously help communities limit the impacts associated with climate change. For example, in cities, networks of parks and open spaces, wetlands, and urban agriculture can reduce flood risk and reduce heat-island effects.
Mitigation in industry can reduce environmental impacts and increase employment and business opportunities. Electrification with renewables and shifts in public transport can enhance health, employment, and equity.
The next few years are critical
The scenarios assessed by working group III show that limiting warming to around 1.5°C requires global greenhouse gas emissions to peak before 2025 at the latest, and be reduced by 43% by 2030. At the same time, methane would also need to be reduced by about a third. Even if this is done, it is almost inevitable that we will temporarily exceed this temperature threshold but could return to below it by the end of the century.
The global temperature will stabilize when carbon dioxide emissions reach net zero. For 1.5°C, this means achieving net zero carbon dioxide emissions globally in the early 2050s; for 2°C, it is in the early 2070s. The assessment shows that limiting warming to around 2°C still requires global greenhouse gas emissions to peak before 2025 at the latest, and be reduced by a quarter by 2030.
“The report shows the importance of the next couple of years up to 2030 in terms of whether we will be able to reach the warming goals of the Paris Agreement. We have shown the options and investment that are needed. The ball is now in the policy court to accelerate implementation,” concludes Coordinating Lead Author and IIASA Energy, Climate, and Environment Program Director, Keywan Riahi.
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