A Deep Dive Into The Technical Side Of The 2023 IPCC Report

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This month, the final installment of the Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report (AR6) was issued. The 2023 IPCC Report is clear: the world is not adapting fast enough to climate change, and some climate impacts are already so severe they cannot be adapted to, leading to losses and damages. Yet low carbon technologies offer hope.

The Technical Summary  of AR6 is a document that hasn’t received much media scrutiny. Let’s look at some of its key areas, especially those of interest to the cleantech audience.

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What is the AR6? The IPCC synthesis report provides the most comprehensive, best available scientific assessment of climate change. As the world’s most authoritative scientific body on climate change, the IPCC looked to the findings of 234 scientists on the physical science of climate change; 270 scientists on impacts, adaptation, and vulnerability to climate change; and, 278 scientists on climate change mitigation.

What is the Technical Summary? The Technical Summary (TS) is designed to bridge between the comprehensive assessment of the WGI Chapters and its Summary for Policymakers (SPM). It is primarily built from the Executive Summaries of the individual chapters and Atlas and provides a synthesis of key findings based on multiple lines of evidence (e.g., analyses of observations, models, paleoclimate information and understanding of physical, chemical and biological processes, and components of the climate system).

Two calibrated approaches are used to communicate the degree of certainty in key findings, which are based on author teams’ evaluations of underlying scientific understanding:

1. Confidence is a qualitative measure of the validity of a finding, based on the type, amount, quality and consistency of evidence (e.g., data, mechanistic understanding, theory, models, expert judgment) and the degree of agreement.
2. Likelihood provides a quantified measure of confidence in a finding expressed probabilistically (e.g., based on statistical analysis of observations or model results, or both, and expert judgement by the author team or from a formal quantitative survey of expert views, or both).

What the AR6 report concluded: With 1.1 degrees C (2 degrees F) of global temperature rise, changes to the climate system that are unparalleled over centuries to millennia are now occurring in every region of the world, from rising sea levels to more extreme weather events to rapidly disappearing sea ice. Additional warming will increase the magnitude of these changes. Every 0.5 degree C (0.9 degrees F) of global temperature rise, for example, will cause clearly discernible increases in the frequency and severity of heat extremes, heavy rainfall events and regional droughts. Right now, we’ve got just under a decade left of emissions-as-usual before we’ve sailed past that goal.

Global warming levels are highly relevant as a dimension of integration across scientific disciplines and socio-economic actors and are motivated by the long-term goal in the Paris Agreement of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels.”

The bad news: The IPCC produces a report every 7 or so years that summarizes existing climate research. The 2023 IPCC synthesis report holds more forecasts of doom than its 2014 predecessor. Higher risks from climate change are now projected to come at lower levels of global warming. Each contemporary generation is being born into an ever-warmer world. And it’s clear how crucial it is to act quickly.

The good news: In the most recent IPCC report, low carbon technologies receive praise for their ability to reduce carbon emissions. Uncertainty in climate change projections results from assessing alternative socio-economic futures, the so-called “scenario uncertainty.” Low carbon solutions are available right now. If we direct resources appropriately, gains by 2030 could help to realize our current climate goals.

• In pathways that limit warming to 1.5 degrees C (2.7 degrees F), figures assume significant use of abatement technologies like CCS.
• Without them, these same pathways show much steeper declines by mid-century.

Net zero CO2 emissions are a condition that occurs when the amount of CO2 emitted into the atmosphere by human activities equals the amount of CO2 removed from the atmosphere by human activities over a specified period of time. Net negative CO2 emissions occur when anthropogenic removals exceed anthropogenic emissions.

Low carbon technology strategies: In many countries, policies have enhanced energy efficiency, reduced rates of deforestation, and accelerated technology deployment, leading to avoided and in some cases reduced or removed emissions. Multiple lines of evidence suggest that mitigation policies have led to robust levels of avoided global emissions. Here’s what the world may need to look like in 2030 if we’re going to reach net-zero emissions by 2050 (which is what we’d need to do to hit the 1.5 °C target), according to a few of the International Energy Agency’s projections:

• Power generation from renewables needs to be over 20,000 terawatt-hours, 60% of the global total.
• Richer countries need to stop running coal-fired power plants without carbon capture.
• EVs need to make up 60% of vehicle sales.

Committed change, long-term commitment: Changes in the climate system, resulting from past, present, and future human activities, which will continue long into the future (centuries to millennia) even with strong reductions in greenhouse gas emissions. Some aspects of the climate system, including the terrestrial biosphere, the deep ocean and the cryosphere, respond much more slowly than surface temperatures to changes in greenhouse gas concentrations. As a result, there are already substantial committed changes associated with past greenhouse gas emissions. For example, global mean sea level will continue to rise for thousands of years, even if future CO2 emissions are reduced to net zero and global warming halted, as excess energy due to past emissions continues to propagate into the deep ocean and as glaciers and ice sheets continue to melt.

Change in the drivers of the climate system: Since 1750, changes in the drivers of the climate system are dominated by the warming influence of increases in atmospheric GHG concentrations and a cooling influence from aerosols, both resulting from human activities. In comparison there has been negligible long-term influence from solar activity and volcanoes. Concentrations of CO2, methane (CH4), and nitrous oxide (N2O) have increased to levels unprecedented in at least 800,000 years, and there is high confidence that current CO2 concentrations have not been experienced for at least 2 million years. Global mean concentrations of anthropogenic aerosols peaked in the late 20th century and have slowly declined since in northern mid-latitudes, although they continue to increase in South Asia and East Africa.

Adaptation: AD6 says with very high confidence that there has been progress with adaptation planning and roll-out in all sectors and regions – and that accelerated adaptation will bring benefits for human well-being. Here are some examples included in the report.

• Adaptation to water-related risks make up more than 60% of all documented adaptation practices.
• Food production improvements in areas such as through planting trees on cropland, diversification in agriculture, and water management and storages, are yielding positive results.
• Urban greening and restoring wetlands and forests are ecosystem-based approaches that have been effective in reducing flood risks and urban heat.
• Non-structural measures,  such as early warning systems and structural measures such as levees have reduced deaths from flooding, the report says with medium confidence.

Most adaptation is “fragmented, incremental, sector-specific and unequally-distributed across regions,” the report says. “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.” Key barriers to adaptation include a lack of financial resources, political commitment and a “low sense of urgency.

One of the authors of the IPCC report, climate scientist Detlef Van Vuuren, described to MIT Review the urgency of this moment: “It’s crunch time, now.”