The scientific verdict is in: “The scale of recent changes across the climate system as a whole and the present state of many aspects of the climate system are unprecedented over many centuries to many thousands of years.” So says a panel of scientists in a United Nations report released this morning.
The Intergovernmental Panel on Climate Change (IPCC) released the Working Group I contribution to the Sixth Assessment Report (AR6) entitled Climate Change 2021: The Physical Science Basis on August 9, 2021. In the report, the 234 authors from 66 countries assess the science of climate change, together with a Summary for Policymakers and an interactive atlas showing global impacts as they vary by region. The report lays out in stark terms the threats facing the world from climate change. The scientists conclude, according to the IPCC, that “some of the changes already set in motion—such as continued sea level rise—are irreversible over hundreds to thousands of years. However, strong and sustained reductions in emissions of carbon dioxide (CO2) and other greenhouse gases would limit climate change.”
It’s Getting Hotter
Rising atmospheric and ocean temperatures generally increase the risk of extreme weather events, making them both more severe and more frequent. The science is complicated, and research is, by definition, an endless process. The new IPCC report reinforces many of the predictions of earlier climate research while shedding new light on the complexities, variabilities and uncertainties of how the collective failure to embrace positive climate action could actually play out.
The IPCC report, approved on Friday by 195 member governments of the IPCC and released today, finds that, without “immediate, rapid and large-scale reductions in greenhouse gas emissions”, it will be nearly impossible to limit the increase in global temperatures to the target of 1.5° to 2°C above pre-industrial levels set out in the Paris Agreement in 2015 so as to mitigate devastating climate impacts. But there is room for both hope and fear.
In a statement accompanying the release of the report, IPCC Working Group I Co-Chair Valérie Masson-Delmotte called the findings “a reality check.” The report breaks down impacts on a regional basis, noting that temperature rise, severe weather, and water cycle impacts (like rainfall, snow, drought and extreme storms) will affect some regions and environments (including cities) more severely than other places. Coastal flooding, winds, and melting glaciers, polar ice and permafrost will also have disparate impacts, as will changes in oceans and marine ecosystems such as warming, ocean acidification and reduced oxygen levels.
Globally, 2020 and 2016 were the two hottest years on record, with average surface temperatures more than 1° Celsius (over 2° Fahrenheit) above the historical average for the 20th century. Worse, the last five years were not only the hottest period in the last 100 years; they may well be the coolest period in the next 100 years. Adverse impacts of climate change are already apparent to many observers as glaciers and polar ice caps melt, sea levels rise, wildfires rage in California, the Siberian Arctic and Europe’s Mediterranean countries, floods devastate Germany, India, China and parts of Latin America, and severe drought and extreme heat threaten habitats, water supplies, and communities across western North America, Brazil, Madagascar, India, Iran and Australia.
For the energy sector in the United States, the IPCC Working Group I science report may give added impetus to the pending legislative proposals by President Joseph R. Biden, Jr. and many members of Congress to couple significant new infrastructure investment with a transition to cleaner sources of energy. On August 5, 2021, President Biden signed an Executive Order calling for at least “50 percent of all new passenger cars and light trucks sold in 2030 [to] be zero-emission vehicles, including battery electric, plug-in hybrid electric, or fuel cell electric vehicles.”
Electrification of the transportation sector on such a massive scale will require significant investment in new power generation capacity (especially for renewable energy sources like wind and solar power), as well as new transmission lines, energy storage, distributed generation and smart-grid technologies. That new energy investment will be in addition to the incremental added capacity already planned to meet organic demand growth, expected coal-plant retirements, and increased load requirements for power-hungry digital infrastructure (including broadband, data centers and 5G mobile telephony).
The IPCC AR6 report may also result in more definitive commitments by the United States and other leading nations for new emissions rules and ambitious targets to reduce greenhouse gas emissions as part of the Paris Agreement process. The report also highlights the need to reduce methane emissions in addition to CO2 and other greenhouse gases. Methane emissions are of particular relevance to natural gas and petroleum production, processing, transportation and storage, as well as to waste management and agriculture. Given the continued prevalence of fossil fuels in generating power and thermal energy for utility and industrial uses, notably carbon-intensive cement and petrochemical plants, carbon capture, utilization and sequestration (CCUS) may become a necessary part of the tool kit to reduce CO2 emissions along with the broader decarbonization trend in the energy sector. Expansion of CCUS will depend on cost, public acceptance, technological advancements and public policy incentives (like Section 45Q tax credits in the United States).
Other Scientific Studies
The IPCC Working Group I enlisted hundreds of scientists to assess literature published through 2020 and did not conduct its own new scientific research. The research in the IPCC report – which looked at more than 14,000 referenced papers – has all been previously published and predates this year’s weather events. It is a snapshot of the latest research as of the end of last year. As such, the report does not include the most recent 2021 scientific papers on climate science, including the well-publicized recent study suggesting that a weakening of the Atlantic Meridional Overturning Circulation (AMOC) current system threatens to destabilize the Gulf Stream, which would have severe impacts on global climate, and other recent studies that showed faster decline and higher variability in polar sea ice thickness and updated models based on data related to the complicated and perhaps counter-intuitive relationships among the polar jet stream, melting Arctic sea ice, winter weather and ocean temperatures. Nonetheless, the synthesis of recent scientific research by IPCC Working Group I in AR6 and its Summary for Policymakers will likely have a real impact on governmental initiatives and highlight the critical need for accelerated investments in resilience and sustainability.
Sustainability and Resilience Differ
Sustainability and resilience are not the same thing. Sustainable investments preserve or enhance the quality of life without jeopardizing the quality of life for future generations or vulnerable populations. The “energy transition” and decarbonization of the transportation sector, for example, serve sustainability goals by replacing fossil fuel-fired thermal power plants and internal combustion engines with cleaner alternatives like wind and solar power and renewable-powered electric vehicles or green hydrogen.
In contrast, resilience is what you need when the pace of sustainable investments is too slow. Hardening critical infrastructure, making cities and systems better able to adapt to climate change and speeding recovery from adverse climate impacts (like extreme weather events, flooding, rising sea levels, droughts and heat) require resilience. As the scientific research in the new IPCC report makes clear, for livability, we need both sustainability and resilience, to walk and to chew gum at the same time.
The IPCC is the international body created in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Program (UNEP) “to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation.” IPCC assessments provide a scientific basis for governments at all levels to develop climate related policies without being prescriptive about the specific measures to take. The new report was designed to look comprehensively at a number of interrelated areas, including (among others): the changing state of the climate system and human influence on it; scenario-based projections of the future climate; global carbon and other biogeochemical cycles and feedbacks; and global and regional impacts on oceans, water cycles, and weather. The report released today is the first installment of AR6, which when completed in 2022 will include input from two other working groups (Working Group II, dealing with impacts, adaptation and vulnerability; and Working Group III, dealing with the mitigation of climate change), plus other task forces, highlighting the risks that climate change poses and the likely implications of response options.
Variables & Scenarios
Many of the headlines about the new IPCC report will focus dramatically on the worst-case scenarios. It is worth remembering that the IPCC’s Working Group I makes no predictions as to the probabilities of any particular scenario coming to pass. The scenarios considered by the IPCC in AR6 show likely impacts of climate change depending on the degree to which we reduce greenhouse gas emissions, slowing the rate at which planetary temperatures are rising due to human activity. The projections of future climate impacts in the new report consider different scenarios (called Socioeconomic Shared Pathways or SSPs), provided by other IPCC working groups, in addition to different projections on greenhouse gas emissions and remediation or mitigation policies. These SSPs consider variability in future population, economic growth, education, urbanization and technology trends and include five paradigms: a world of sustainability-focused growth and equality (SSP1); a “middle of the road” world where trends broadly follow their historical patterns (SSP2); a fragmented world of “resurgent nationalism” (SSP3); a world of ever-increasing inequality (SSP4); and a world of rapid and unconstrained growth in economic output and energy use (SSP5). Each scenario can be paired with varying degrees of greenhouse gas emissions reductions or increases, depending on public policies and private activity. None of these scenarios fully considers the feedback loops inherent in climate models, as climate impacts can be cumulative, non-linear and correlative, and the different socio-economic and political responses (positive or negative) to climate impacts are, at best, challenging to predict. The future will in all likelihood be somewhere between the best-case and worst-case scenarios, but that is an uncomfortably wide range.
This new IPCC science report and broader AR6 policy considerations will drive negotiations at the 26th UN Climate Change Conference of the Parties (COP26) in Glasgow on October 31 to November 12, 2021 through four workstreams: mitigation, adaptation, finance, and collaboration. According to the United Kingdom host presidency for COP26, the express mission of COP26 is to “secure global net zero by mid-century and keep 1.5 degrees within reach” by asking nations, as contemplated by the Paris Agreement, to set “ambitious 2030 emissions reductions targets that align with reaching net zero by the middle of the century” through such steps as accelerating the phase-out of coal, curtailing deforestation, speeding up the switch to electric vehicles, and investment in renewables. The COP26 agenda also recognizes that “the climate is already changing and will continue to change even as we reduce emissions, with devastating effects.” Accordingly, COP26 delegates will be asked to “work together to enable and encourage countries affected by climate change to protect and restore ecosystems” and to “build defenses, warning systems and resilient infrastructure and agriculture to avoid loss of homes, livelihoods and even lives.”
In large part, the new IGCC Working Group I science report confirms and hones the predictions made in prior reports (in 1990, 1995, 2001, 2007 and 2013). It reflects scientific progress in correlating specific weather patterns and oceanic conditions with longer-term climate change and atmospheric pollution. The scientific research shows how much we have learned – and how much more research is needed – to refine the dynamic, complex meteorological and geophysical models that will enable us to better understand, forecast and mitigate climate impacts on both natural systems and human societies.
At a high level, three salient conclusions stand out from the IGCC report. First, scientific research confirms that climate change from greenhouse gas emissions and other human activity is already having catastrophic impacts on ecosystems and societies around the world, all of which are quite likely to intensify, with potentially disastrous social, political, economic and environmental effects. Second, the acceleration over the past decade of both climate impacts and sophisticated research into climate science has been staggering. Third, thanks in no small part to that research and the massive public and private investment it facilitates, we have the power to alter the present course, to prevent the worst outcomes, and through collaboration and innovation to invest in ways that make the world both more sustainable and more resilient.