What do the various emissions scenarios published by the IPCC really mean? Is the worst-case RCP8.5 scenario “bollox,” as some have asserted, or it useful? Are we already doomed to experience seven feet of sea level rise and five degrees Celsius of warming globally, or is there still a chance that we can limit warming to two degrees? And if so…how likely is it that we can hit that target? How much can our energy transition efforts, both now and in the foreseeable future, do to mitigate that warming? Should our scenarios err on the side of being too extreme to account for unknown feedback effects and tipping points that may come in the future, or should we try to be as accurate as possible with our modeling, given the available data and scientific tools?
In this 11th part of our miniseries on climate science, we attempt to answer these questions and help our listeners sort out the various perspectives, from the tame to the apocalyptic, that feature in the current debates about our climate future. We hope that it will leave you with a much better understanding of what the climate scenarios really mean, how likely they are, and what the actual trajectory of climate change might be. We’re not out of the woods by any means, but our prospects may be better than you think!
In this tenth part of our series on climate science, we explore a new paper outlining a climate scenario that would limit warming to 1.5 °C without relying on negative emission technologies. It does so by detailing numerous pathways that could lead the world toward much lower total primary energy consumption, including a heavy focus on the demand side, quantifying the impact of behavioral changes and different ways of providing energy services, rather than simply focusing on consuming energy.
This doesn’t mean that actually following the pathways outlined in this model will be easy, or that staying under 1.5 degrees of warming is going to happen automatically. In fact, some of the behavioral changes that would be needed might be as difficult as implementing a carbon tax (or, for that matter, implementing CCS at scale). But this outlook does respond to our main complaints with the existing body of climate and energy scenarios—that they generally depend on negative emissions technologies like CCS, and that they don’t adequately take into account measures and policies that are already reducing our energy demand and accelerating the energy transition. Our guest in this episode is one of the co-authors of the paper: Charlie Wilson, a researcher at the Tyndall Centre for Climate Change Research, and an Associate Professor in Energy & Climate Change at the University of East Anglia in the UK. His expertise on consumer adoption of technology, behavior and policy as they relate to energy and climate change mitigation gives him a unique perspective on this research that we think you’ll find illuminating and thought-provoking.
In this ninth part of our mini-series on climate science, we turn to one of the key suspects in extreme weather events we have experienced in recent years—the shifting shape of the North Atlantic jet stream. And the fingerprints of the changing jet stream can be found in tree ring data. The guest in this episode has studied three centuries of European tree rings and found that the shape of the jet stream, along with clear deviations from historical weather, began in the 1960s, pointing to a connection to the changing climate. Other researchers have come to similar conclusions by studying things like the difference between Arctic and mid-latitude temperatures over time. And they conclude that increases in greenhouse gas emissions will make the jet stream increasingly wavy in the future, exacerbating such extreme weather events.
In this eighth part of our mini-series on climate science, we tackle the subject of ice and melting, and how much sea-level rise it may produce. What if that viral story about a starving polar bear may not even have been accurate? What does it really mean when we say that a worst-case climate model projects 11 feet of sea level rise, and is that even a plausible scenario? What does it mean to say that sea ice is melting at the fastest rate in 1,500 years? How much sea level rise might actually result from ice shelves breaking off? And how can we relate the latest studies on melting glaciers and ice caps to degrees of global warming or meters of sea level rise? These aren’t easy questions to answer, but our guest in this episode has about as good a shot at answering them as anyone. His nuanced and deeply informed view of what’s happening to our glaciers and ice caps in this 90-minute interview is refreshing, thoughtful, and provocative, and offers an educational counterpoint to the usual simple projections of climate doom.
In this seventh episode of our mini-series on climate change, we explore what carbon budgets really mean, and what they indicate about the pathways that might allow us to keep global warming below two degrees C.
Amid all the unavoidable uncertainty in modeling warming and the effects of our actions, what do we really know about how much warming we might see in the future? If it turned out that our carbon budget is larger than we used to think it was, would that change our policy direction? And which policy paths should we advocate?
Our guest in this episode, Dr. Glen Peters, is a veteran researcher on climate change whose current research focuses on the causes of recent changes in carbon dioxide emission trends at the global and country level, and how these changes link to future emission pathways consistent with global climate objectives. And after listening to this nearly two-hour conversation, as well as our previous six episodes on climate science, you will have a much better idea of how much warming we may yet expect!
Modeling the future of our climate is a complex task that not too many people understand. What do we know about how the Intergovernmental Panel on Climate Change (or IPCC) modeling actually works? Why has the modeling community decided to model emissions separately from socioeconomic scenarios? When we hear that the RCP8.5 emissions scenario is considered a “business as usual” scenario, what assumptions are we making about all that business? And are those assumptions reasonable? Is there a climate scenario that represents an optimistic view of energy transition over the coming decades? And if so, what does it assume about the energy technologies that we will switch away from, and switch to?
These and many other questions are answered in this two-hour discussion on emissions modeling by an expert climate modeler from the National Center for Atmospheric Research (NCAR), who co-chairs the working group on future scenarios for impacts, adaptation and vulnerability indicators of the International Committee On New Integrated Climate Change Assessment Scenarios. It’s a wonktastic deep dive into an esoteric subject… and it just may leave you feeling a lot more hopeful about the prospects for energy transition, and for our planet.
When we hear about the emissions scenarios used in the Intergovernmental Panel on Climate Change (IPCC) reports, do we really understand what they’re assuming about future fossil fuel combustion? And what do these emissions scenarios imply about the steps needed to achieve climate policy goals and decarbonize our energy system? For example, when you hear about the worst-case warming scenario known as RCP8.5, do you know that it is based on projections for a 10-fold increase in global coal consumption through the end of this century? Or that many of the estimates of future fossil fuel combustion in these scenarios are based on very old assumptions about how the energy system could develop in the future? And how can we square scenarios like these with our contemporary reality, in which coal is in decline and the world is turning to renewables because they have become the cheapest options for generating power? How should we actually think about the influence that the global energy system will have on the climate over the next century? In this fifth part of our mini-series on climate science, researcher (and Energy Transition Show producer) Justin Ritchie helps us understand what the IPCC scenarios really mean, and how they can be improved to offer better policy guidance.
In this fourth episode of our climate science mini-series, we dive into the carbon cycle to understand how the greenhouse gas emissions from fossil fuels accumulate in the atmosphere. We also discuss how climate science is taught, the concepts that students struggle to understand, and what the science of human reasoning and teaching can tell us about how best to communicate this enormously complex subject to a lay audience. Our guest is Dr. Sara Harris, a professor at the University of British Columbia in Vancouver, who is an expert at teaching climate science, and who has published a book titled Understanding Climate Change: Science, Policy and Practice, as well as a self-paced free online course called “Climate Change: The Science."
In this third episode of our mini-series on climate science, we talk with paleoclimate scientist Robert Kopp of Rutgers University about what Earth’s past climate can tell us about its future, especially where it concerns sea level rise. We also discuss his research on the relationship between climate science and the economy, and how a transdisciplinary approach using natural sciences, social sciences, engineering, and urban planning can help us tackle the challenges that climate change poses to the world’s coastlines…and how tools like the social cost of carbon and appropriate discount rates can help address those challenges, from New Jersey to Florida, no matter what Trump does with federal policy. Finally, we discuss how ratings agencies and risk adjustors need to start factoring in climate risk, and why they haven't so far.
In this second episode of our mini-series on climate science, we begin to dive a bit deeper on narrower subjects, starting with a look at how we take the Earth’s temperature, on land, on the sea surface, and deeper in the ocean depths. Along the way, we discuss temperature measurements at the heart of the “Climategate” nothingburger, the 2013 “Pausebuster” paper proving the supposed “pause” or “hiatus” in global warming trends didn’t actually happen, and a recent kerfuffle over that paper. We also find out if the melting of permafrost and undersea methane clathrates could lead the planet into runaway global warming, and discuss some research on the net emissions effect of switching from coal to gas in power generation, including the thorny issue of fugitive emissions from natural gas production and distribution. And finally, we’ll take another look at the question of decoupling economic growth from energy consumption, and how emissions are counted in the first place. After listening to this interview, you’ll be well-equipped to listen critically to both the latest scientific findings on global temperatures, and to the arguments of global warming skeptics. Plus, we’ll talk about the implications of Trump’s proposed budget, which would gut the very agencies that deliver these crucial scientific measurements.