This is The ChangeUnderground for the 27th of March 2023.
I’m your host, Jon Moore
Decarbonise the Air, Recarbonise the Soil!
The 6th IPCC Report, link in the show notes, was released last Monday. A day after I’d published the last episode, of course, so I’ve had a week to get my head around it and hopefully, distil it down to a more manageable yet still accurate summary. Also today as I was setting up the chook run for winter, expanding the run area and calling in the semi-feral chooklings who are between 10 and 16 weeks old, I noticed and remember we’re at the end of the second month of Autumn in the southern hemisphere, I noticed one of the pear trees had a spray of open blossom. Actually what I first noticed was the sound of bees then the flowers but what is going on???
So I’ve gone deeply into the 6th IPCC Report and here’s my summary, in the same neutral tone as it was written, I hope, if I can keep the disquiet out of my voice.
Current Status and Trends
Global surface temperature has increased by 1.09°C [0.95°C–1.20°C] higher in 2011–2020 than 1850–1900, with larger increases over land (1.59°C [1.34°C–1.83°C]) than over the ocean (0.88°C [0.68°C–1.01°C]). The likely range of total human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8°C–1.3°C, with a best estimate of 1.07°C.
Well-mixed greenhouse gases (GHGs) contributed a warming of 1.0°C–2.0°C and other human drivers (principally aerosols) contributed a cooling of 0.0°C–0.8°C, natural (solar and volcanic) drivers changed global surface temperature by –0.1°C to +0.1°C and internal variability changed it by –0.2°C to +0.2°C. The observed increases in well-mixed GHG concentrations since around 1750 are unequivocally caused by GHG emissions from human activities over this period. The historical cumulative net CO2 emissions from 1850 to 2019 were 2400±240 GtCO2 of which more than half (58%) occurred between 1850 and 1989.
Global net anthropogenic GHG emissions have been estimated to be 59±6.6 GtCO2-eq in 2019, about 12% (6.5 GtCO2-eq) higher than in 2010 and 54% (21 GtCO2-eq) higher than in 1990, with the largest share and growth in gross GHG emissions occurring in CO2 from fossil fuels combustion and industrial processes (CO2-FFI) followed by methane, whereas the highest relative growth occurred in fluorinated gases (F-gases), starting from low levels in 1990. Average annual GHG emissions during 2010-2019 were higher than in any previous decade on record, while the rate of growth between 2010 and 2019 (1.3% year-1) was lower than that between 2000 and 2009 (2.1% year-1).
In 2019, approximately 79% of global GHG emissions came from the sectors of energy, industry, transport and buildings together and 22% from agriculture, forestry and other land use (AFOLU). Emissions reductions in CO2-FFI due to improvements in energy efficiency have been less than emissions increases from rising global activity levels in industry, energy supply, transport, agriculture and buildings.
Greenhouse gas emissions are continuing to rise, with average annual GHG emissions in the past decade higher than in any previous decade on record. The report calls for immediate and ambitious actions to reduce greenhouse gas emissions and limit the impacts of climate change.
Observed Changes and Trends
Human influence has warmed the atmosphere, ocean and land and this has resulted in a rise in the global mean sea level by 20 cm between 1901 and 2018, with the average rate of sea level rise increasing significantly since 1971. The increasing frequency of extreme weather events, such as heatwaves, heavy precipitation, droughts and tropical cyclones, can be attributed to human influence since at least 1950. Climate change has caused substantial damages, reduced food security and affected water security, hindering efforts to meet UN Sustainable Development Goals (SDGs).
Furthermore, climate change has caused widespread adverse impacts and related losses and damages to nature and people which are unequally distributed across systems, regions and sectors. Approximately 3 and half billion people are highly vulnerable to climate change. Increasing weather and climate extreme events have exposed millions of people to acute food insecurity and reduced water security. Human mortality from floods, droughts and storms was 15 times higher in highly vulnerable regions compared to regions with very low vulnerability between 2010 and 2020.
Although overall agricultural productivity has increased, climate change has slowed this growth over the past 50 years globally, with related negative impacts mainly in mid- and low-latitude regions but positive impacts in some high-latitude regions. Ocean warming and ocean acidification have adversely affected food production from fisheries and shellfish aquaculture in some oceanic regions. Roughly half of the world’s population currently experiences severe water scarcity for at least part of the year due to a combination of climatic and non-climatic drivers. (Podcast footnote: non-climate drivers include wars and repressive governments. End Footnote.)
Climate change has caused adverse impacts on human health, such as increasing the incidence of vector-borne diseases, i.e. malaria and climate-related food-borne and water-borne diseases. Mental health challenges are associated with increasing temperatures, trauma from extreme events and loss of livelihoods and culture. Climate and weather extremes are increasingly driving displacement, particularly in Africa, Asia, North America and Central and South America, with small island states in the Caribbean and South Pacific being disproportionately affected relative to their small population sizes.
Progress and Adaptation
Progress that has been made in adapting to climate change across all sectors and regions of the world. Growing public and political awareness of climate impacts and risks has led to at least 170 countries and many cities including adaptation in their climate policies and planning processes. This is a positive development as it indicates that governments and communities are taking action to mitigate and adapt to the impacts of climate change.
The effectiveness of adaptation in reducing climate risks has been documented for specific contexts, sectors and regions. For example, cultivar improvements, on-farm water management and storage, soil moisture conservation, irrigation, agroforestry and community-based adaptation have been effective in reducing the impact of climate change on agriculture. Sustainable land management approaches, use of agroecological principles and practices and other approaches that work with natural processes have also been effective. Ecosystem-based adaptation approaches such as urban greening, restoration of wetlands and upstream forest ecosystems have been effective in reducing flood risks and urban heat. Combinations of non-structural measures like early warning systems and structural measures like levees have reduced the loss of lives in case of inland flooding.
However most observed adaptation responses are fragmented, incremental, sector-specific and unequally distributed across regions. Despite progress, adaptation gaps exist across sectors and regions and will continue to grow under current levels of implementation, with the largest adaptation gaps among lower income groups. There is also increased evidence of maladaptation in various sectors and regions which especially affects marginalised and vulnerable groups adversely.
There are soft limits to adaptation which are currently being experienced by small-scale farmers and households along some low-lying coastal areas, resulting from financial, governance, institutional and policy constraints. Some tropical, coastal, polar and mountain ecosystems have reached hard adaptation limits, indicating that even with effective adaptation, losses and damages cannot be entirely prevented.
The key barriers to adaptation include limited resources, lack of private sector and citizen engagement, insufficient mobilisation of finance (including for research), low climate literacy, lack of political commitment, limited research and slow and low uptake of adaptation science and low sense of urgency. There are widening disparities between the estimated costs of adaptation and the finance allocated to adaptation. Although global tracked climate finance has shown an upward trend since the previous assessment report, current global financial flows for adaptation, including from public and private finance sources, are insufficient and constrain implementation of adaptation options, especially in developing countries. Adverse climate impacts can reduce the availability of financial resources by incurring losses and damages and through impeding national economic growth, thereby further increasing financial constraints for adaptation, particularly for developing and least developed countries.
On the upside, Progress has been made in adapting to climate change. There are still significant challenges that need to be addressed to reduce the impact of climate change on vulnerable communities and ecosystems. It is essential that governments, communities and the private sector work together to overcome the barriers to adaptation and increase investment in adaptation options to ensure that we can effectively manage the risks associated with climate change.
Progress, Gaps and Challenges
Policies and laws addressing mitigation have consistently expanded since the last report (AR5) which is a positive development. Many regulatory and economic instruments have been successfully deployed, resulting in several gigatons of avoided global emissions. However, there are still gaps between projected emissions from implemented policies and those from nationally determined contributions (NDCs) which make it likely that warming will exceed 1.5°C during the 21st century and make it harder to limit warming below 2°C.
Several mitigation options are technically viable and becoming increasingly cost-effective, such as solar energy, wind energy, electrification of urban systems, urban green infrastructure, energy efficiency, demand-side management, improved forest- and crop/grassland management and reduced food waste and loss. The costs of solar energy, wind energy and lithium-ion batteries have decreased significantly and their deployment has increased, varying widely across regions. However projected emissions far out pace climate goals set by governments.
So progress has been made in mitigating global warming but there are still significant gaps and challenges that need to be addressed. Immediate action is needed to limit warming to 1.5°C to 2°C and a strengthening of policies is required to bridge the implementation gap and achieve the goals set by the Paris Agreement.
Future Climate Change
If greenhouse gas (GHG) emissions continue, global warming will increase in the near future, with the best estimate of reaching 1.5°C even under very low GHG emissions scenarios. This would intensify multiple and concurrent hazards and changes in extremes will continue to become larger. However deep, rapid and sustained reductions in GHG emissions can lead to a discernible slowdown in global warming within around two decades and also lead to discernible changes in atmospheric composition within a few years.
Under different GHG emissions scenarios, discernible differences in trends of global surface temperature would begin to emerge from natural variability within around 20 years. Moreover, targeted reductions of air pollutant emissions lead to more rapid improvements in air quality within years compared to reductions in GHG emissions only. In the long term, further improvements are projected in scenarios that combine efforts to reduce air pollutants as well as GHG emissions.
Continued emissions will further affect all major climate system components leading to projected changes such as intensified global water cycles, very wet and very dry weather and climate events and seasons and reduced extents and/or volumes of almost all glaciers in the world. Natural land and ocean carbon sinks are projected to take up a decreasing proportion of these emissions and the Arctic will be practically ice-free in September at least once before mid-century under all scenarios considered.
To mitigate these risks, the importance of deep reductions in GHG emissions in all sectors and regions, along with the implementation of measures to reduce air pollutant emissions is essential. This includes policies such as carbon pricing, fossil fuel subsidy reform, regulations and investments in low-carbon technologies. Moreover, the need for international cooperation, especially in the transfer of low-carbon technologies, capacity-building and financial support to developing countries is critical. These long-term responses would require transformative changes in the economy, society and governance systems.
Global efforts to limit warming to 1.5°C (>50%) with no or limited overshoot and those that limit warming to 2°C (>67%), require immediate and rapid greenhouse gas emissions reductions in all sectors this decade. All global modelled pathways that fit these criteria require global net zero CO2 emissions by the early 2050s or around the early 2070s, respectively.
These global modelled pathways include significant reductions in CO2 and non-CO2 greenhouse gas emissions. Specifically, global methane emissions are expected to be reduced by 34% by 2030 relative to 2019 in pathways that limit warming to 1.5°C. However, some hard-to-abate residual GHG emissions remain which are emitted from sources like agriculture, aviation, shipping and industrial processes. These emissions would need to be counterbalanced by deploying carbon dioxide removal (CDR) methods to achieve net zero CO2 or GHG emissions. There are different choices among global databases about which emissions and removals occurring on land are considered anthropogenic and most countries report their anthropogenic land CO2 fluxes including fluxes due to human-caused environmental change (e.g., CO2 fertilisation) on ‘managed’ land in their national GHG inventories.
To reach net zero CO2 or GHG emissions significant reductions in gross emissions of CO2 are needed as well as substantial reductions of non-CO2 GHG emissions. While there are some hard-to-abate residual GHG emissions that remain, the deployment of CDR methods can help to achieve net zero CO2 or GHG emissions. Additionally transitioning from fossil fuels without carbon capture is also included in global modelled mitigation pathways reaching net zero CO2 and GHG emissions.
Urgency and Benefits of Near Term Action
Climate change is a major threat to the well-being of humans and the planet. It is urgent to take integrated climate action to secure a sustainable future for all which involves adapting to the changes already happening and reducing greenhouse gas emissions to limit future changes. The choices and actions implemented in the current decade will have long-lasting impacts for thousands of years. Climate resilient development which integrates adaptation and mitigation, is necessary and enabled by increased international cooperation, inclusive governance and coordinated policies. Continued emissions will lead to irreversible changes on a millennial timescale, threatening ecosystems, biodiversity and human well-being.
The benefits of taking near-term action are significant. Deep, rapid and sustained mitigation and accelerated implementation of adaptation actions in this decade would reduce projected losses and damages for humans and ecosystems and deliver many co-benefits such as improved health, air and water quality and energy access. The benefits of taking action outweigh the costs and the longer emissions reductions are delayed, the fewer effective adaptation options there will be. Governments, civil society and the private sector play a crucial role in enabling and accelerating the shift towards sustainability and climate resilient development. This involves making inclusive development choices that prioritise risk reduction, equity and justice and integrating decision-making processes, finance and actions across governance levels, sectors and timeframes. Enabling conditions for climate resilient development vary by national, regional and local circumstances and include political commitment, coordinated policies, social and international cooperation, ecosystem stewardship, knowledge diversity, technological innovation and improved access to adequate financial resources, especially for vulnerable regions, sectors and communities.
In summary of the summary, things are crook, we can do other things to make them less crook and if we don’t, things will turn crooker quickly. And still that out of season pear blossom was quite beautiful.
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Decarbonise the air, recarbonise the soil!
Thank you all for listening and I’ll be back, all things being equal, next week.
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SYNTHESIS REPORT OF THE IPCC SIXTH ASSESSMENT REPORT (AR6)