Forecast: climate conversations with Michael White

Jonathan Foley is the Executive Director of the California Academy of Sciences, the previous director of the Institute on the Environment at the University of Minnesota and the founder of the Center for Sustainability and the Global Environment at the University of Wisconsin. In many ways, Jon is one of the foremost thinkers and actors about the science of sustainability. But Jon has nothing even resembling the air of an operator or empire builder. He’s candid, provocative, and personable. After our interview at the Cal Academy, Jon invited me to visit the museum, and along the way was stopped by three elderly patrons trying to find the way to the roof. Jon said goodbye to me, and walked them to the elevator. It’s this kind of relatability and keenness for people that, in part, make Jon’s efforts to build connection and community so successful. Jon’s also a great photographer, as seen in the images he kindly shared with Forecast. Jon grew up in Maine, loving the natural world and knowing that his passion lay in science.  But that’s not to say that his early years were idyllic. As described in a moving post on his blog, The Macroscope, Jon’s mother died from ALS when he was only 17, and his father descended into alcoholism. In some of her final words, Jon’s mother made him promise to do the best that he could, for the world. That’s a big load to take on, and John’s pathway to carrying it took him through an early career in pure physics. But that seemed, in the end, too abstract. One discussion with particle physicists highlights the problem: I kept on asking ‘why are we doing this’ … and 20 really smart people with PhDs … none of them can answer that question Jon moved on, but the immediate pathway still wasn’t clear: I wanted to be an astronomer, a marine biologist and an ecologist all at the same time Eventually, John found inspiration in the work of Bob Dickinson, even though he was working with paleoclimatologist John Kutzbach in grad school. He went on to make some major advances in adding the biosphere to climate models, for example in the development of the IBIS model. Yet … I was kind of a misfit in grad school  … hanging out with all these ecologists Maybe a result of being a misfit, or perhaps because he has “a little bit of academic ADD”, Jon moved on to trying to understand the emerging issues surrounding sustainability, politics, economics, and physical sciences. Rapidly, he began to realize that science wasn’t the whole story, and that our political and economic systems in fact tend to go out of their way to ignore physics and, more importantly, ethics. Jon’s major academic question before coming to the Cal Academy was something on the order of “how can we feed humanity without destroying the planet”. Agriculture, to degrees that are still not broadly appreciated, is a huge strain on the planet: From a biodiversity, water, land, and future climate change perspective [agriculture] is the number one planetary emergency After years of making major scientific advances but frustratingly limited broader impact, it was time for a change. The position at the Cal Academy arose — and with some prodding from his family — Jon ultimately accepted the rather huge leap. Now, Jon is taking the Academy forward in some amazing ways, guided by their awesome mission statement: “To explore,

How, exactly, does one get to be an editor of a Nature-branded journal? What do we do? How do we decide what to publish? And what’s up with all our journals? In this episode of Forecast, I hash out these issues with Bronwyn Wake, the chief editor of Nature Climate Change. But don’t worry … if you’re thinking about becoming an editor, working in a bar is not a prerequisite. I’m 46 and bald, but when people meet me, they frequently say that they were expecting someone even older, and, I suspect, sporting an extravagant beard and wearing a thin-elbowed tweed jacket. The reality is that the editors across our journals span a range of ages from freshly-minted PhDs to editors who have been in the job for decades. And, unusually for a scientific career, there is excellent gender balance! Editing can also allow you to have — really! — a reasonable work-life balance in a challenging and intellectually stimulating career. So, if you’re nodding your head in agreement at Nature’s blood-curdling feature on the brutal challenges of starting a scientific career, editing is something to think about. Most of our editors have broad interests and a preference for a non-academic lifestyle. Bron’s voyage to editing took her through undergraduate degrees in Japanese and chemistry, working in a bar, almost teaching English overseas, chance encounters with science opportunities (in Antarctica), interesting work as a postdoc but no clear avenue to a permanent position. As is the case for a lot of us, Bron “…really enjoyed the research and the field work…” but the rest of the academic pathway wasn’t too compelling. Bron attended a Nature career fair in London and felt that editing might fit the bill. After an hour-long chat with my boss at Nature, Karl Ziemelis, Bron interviewed at Nature Climate Change and was soon hired. As is often the case, there was a chance for promotion, and Bron now runs the journal. Running a journal, though, is no picnic. Nature Climate Change was our first journal working in the social sciences, and attracting the best work from these communities took a huge effort, and remains challenging. The range of content is correspondingly vast, spanning climate impacts to battery packs: Managing brings new challenges. Staff moved on to launch other projects within the company, and recruiting can seem endless. Bron juggles manuscripts with writing editorials and Research Highlights, editing News & Views, coordinating with the art and production teams, and commissioning content. Still, for Bron, the job is not all-consuming: unlike in academia, you can usually shut off your work brain when the day is done. If all this sounds appealing, and you’re interested in learning some more about a career as an editor, let me know via forecastpod@gmail.com or m.white@us.nature.com and I’d be happy to chat.   Music: Anemic Alloy! by SubRosa CC BY-NC-SA 3.0. Available on Soundcloud. Tweet

Climate scientists are used to the idea of climate mitigation. But few are involved in the nitty-gritty of what climate mitigation might look like at the local or even neighborhood level. Daniel Aldana Cohen from the Department of Sociology at the University of Pennsylvania is digging into the politics and sociology of urban carbon emissions. A dizzying array of forces are at work. Family debates on urbanism Daniel’s interest in the science and sociology of urban emissions arose from the same sort of incredibly implausible events and circumstances that seem to orbit nearly every guest on Forecast. This time: father was a writer and back-to-the-lander who hated cities; mother loved cities and was a children’s book publisher; family compromised by living in rural France every fourth year or so, with the rest of the time in Toronto; both parents rebelled against science; childhood faith that somebody would solve the climate change problem crushed by reality; early exposure to social justice travesties; interest in magazine writing diverted to research focus by Elizabeth Kolbert‘s brilliant work in the New Yorker on climate change. The surprisingly simpatico interests of urban elites and urban justice Possibly arising from his own family’s rejection of and affection for urbanism, Daniel chose to revisit the long-standing ideals of urbanism. Can we have fantastic, equitable and decarbonized cities? In a Bloomsburg-esq fantasy world, yes: government policies create a luxury economy bubbling with a glittery green stew of financial services, young professionals, walkable streets and bike paths. Think Seattle in the Amazon age. Eventually, trickle-down greening occurs, and there’s a net reduction of emissions. Only, no, on many levels. The policies that spawned modern Manhattan also led to mass gentrification and displacement. And as Daniel shows in his contribution to Rebecca Solnit‘s blisteringly great series of atlases, a full-cost accounting for Manhattan reveals that the core of the green city is also the most rapacious consumer of carbon: Is there a way forward, to create both the cities and climate mitigation we’d like to see? Ironically, as Daniel has heard from modern urban planners, we might get the desired outcome by not talking about climate in the first place: “Social justice and climate justice actually went really well together … it’s just better not to talk about climate change at all”.   Focusing on housing, and not talking about the environment, can actually lead to the exact environmental changes that would otherwise be desired by an explicitly mitigation-focused effort. In the end, social justice and the fantasy low carbon city seem to have the same goals. Building a new research community This is not to say that this is an easy goal to achieve. The community working on the micro-scale processes that determine global urban emissions is tiny; academic institutions are not actively encouraging young scholars to pursue the necessary interdisciplinary work; and there is almost no literature on realistically attributing emissions to specific cities and neighborhoods (the map above represents one such effort). Daniel is working to reach across the dauntingly-wide chasm between sociology and physical science, and runs his own podcast, Hot and Bothered at Dissent magazine. Daniel also co-authored a Nature Comment on urban sustainability,

Amelia Shevenell from the University of South Florida specializes in big ideas about paleoceanography and the Antarctic Ice Sheet. She’s also keen to push the methodological envelope, which can be risky if things go pear shaped. For Amelia, though, the work resulted in papers in Science (Mg/Ca) and Nature (TEX86). The method, while of course important, is not the main motivation. Instead, it’s the huge, gaping holes in our knowledge of Southern Hemisphere climate variability that seem to motivate Amelia. The questioning and search for challenges was there from the start. In high school, Amelia’s uncle unleashed her on climate variability over the past century in the Durham NH area. Coring away, when I was scooping ice cream. Amelia had plenty of inspiration from her family, including Great Aunt Mary Sears. The family spirit of exploration and possibility was infectious, and Amelia double majored in geology and studio art. She still does pottery (example above) and, unbeknownst to her, worked for years with actor Jeff Bridges (full story at the end of the podcast). Throughout, Amelia’s been interested in how Antarctic functions within the climate system. And it’s weird, sometimes. During the Miocene Climate Optimum, “It’s almost like we’re having ice growth during a period of warming … and nobody’s really said that out loud”. Now, Amelia is working with her colleagues to link together the deep sea records with shelf- and land-based evidence to try and understand the shockingly large ice sheet variability that seems to have happened at millennial time scales. Getting all this done, while raising a family and going for tenure at USF, isn’t for the faint of heart. Although she was tenured at UCL, Amelia chose to return to the US for family and financial reasons (living in London on a geoscientist’s salary is, in British understatement, a bit difficult). Now, Amelia’s mom is next door and helping with child care, and her husband sounds epic. But it’s all-consuming, nonetheless. Still, as you’ll hear in the interview, the practical realities of family and career haven’t done anything to diminish Amelia’s enthusiasm for her science! Music: Running Waters by Jason Shaw CC BY 3.0 US; Siesta by Jahhzar CC BY-SA 3.0. Copyright: This episode of Forecast is under a CC BY-SA 3.0 license. Tweet

Tree rings are one of the key tools in paleoclimate research, and might seem like nothing more than big, woody thermometers. But tree-ring science is ever evolving, constantly debated, and — while it has answered some major questions — still grapples with making the connection to broader climate questions. Paleoclimatologist Scott St. George from the University of Minnesota works on both the guts of tree rings as climate recorders, and their linkage to the wider climate system. Doing so, however, didn’t always seem like a great idea, and Scott experienced some initial horror at having entered the field … The despair didn’t last long, and Scott was soon making major advances in using tree rings to research past floods. We talk about these early discoveries, the furor over the missing ring debate, and how the field is now trying to explicitly link tree rings to variations in atmospheric circulation. The tentacles of Scott’s ideas, however, extend far beyond a narrow interest in tree-ring science, and we have a craic about a couple. Scott and I both share the perception that scientific talks could be … improved somewhat. Mine included! I think presentations can be a sort of intellectual defense system. As Scott puts it: But unlike me, Scott has taken the time to think about scientific presentations, what tends to go wrong, and how we can all craft a more meaningful talk … oftentimes by talking less, and especially by having some empathy for your audience. You don’t have to get it all done at once: Scott’s website is a great resource for ideas on how to streamline and hone presentations, and he has a veritable treasure-chest of excellent and thought-provoking graphics. During the course of teaching a monstrously huge undergrad class, Scott grew frustrated with presenting the standard NASA GISS graph of industrial era climate change, and had long thought that there must be a better way. Ultimately, he was able to convince undergrad Dan Crawford to translate the graph into music. The results spawned a pretty incredible level of interest, and show that there’s a real interest in presenting climate science in ways that make sense to and connect with people. Science and geopolitics have always been intermixed, sometimes to great effect, other times less so. Witness the recent CSIRO debacle. Scott began his career in the Geological Survey of Canada during a time of interest in climate science, but once the Harper administration was in full suppress-scientists mode, Scott new he’d have to look for other options to pursue his long-term interests. For Scott, this meant leaving Canada and moving to Minnesota. A loss for Canada, but I’m glad that Scott’s found his way, now to a tenured academic position at a great university. Music: Organ Grinder Swing by ChēēZ π CC BY-NC-SA 4.0; Planetary Bands, Warming World by Daniel Crawford CC BY-NC 4.0; Oh! By Jingo! by All-Star Trio Public Domain Mark 1.0. Tweet

Over the past few months I’ve discussed with a variety of guests the emerging idea of trying to keep global warming below 1.5 °C, and our family of journals has certainly been active on the topic, particularly with regard to feasibility and mitigation pathways. But I thought it would be a good idea to find out what the IPPC is actually doing on the topic, as one of their three special reports. IPCC Working Group I co-chair Valérie Masson-Delmotte kindly agreed to come back on the podcast for a quick catch-up on the recent 1.5 scoping meeting held in Geneva. At this point, discussions are extremely preliminary, but it is clear that the IPCC is undergoing a fairly huge change in culture, at least for the special reports. Most notably, the entire framing of the debates, questions, and approaches is taking place across the three working groups. Additionally, the author group chose to bring in outside scientific consultants to bolster their expertise, for example in ethics. As Valérie says, the scoping meeting was: It’s still early days for the report, but I think it will provide an unusually broad discussion of the social and ecological issues that are inextricably intertwined with trying to reach any particular mitigation or climate goal. One notable point of discussion was the potential of the human, as well as climate, system to undergo abrupt change. If you’re keen to read more on the 1.5 threshold, you can check out the across-journal collection from Nature, Nature Climate Change and Nature Geoscience. Music: Stance Gives You Balance by Hogan Grip, Creative Commons license CC BY-NC-SA 3.0. Tweet

I think I first learned of Rob DeConto when I saw his paper entitled Thresholds for Cenozoic bipolar glaciation, published soon after my arrival at Nature.  Specific and testable thresholds for the initiation of large scale glaciation in Antarctica and the Northern Hemisphere? Interesting! Soon after, I handle Rob’s next two papers at Nature: Modelling West Antarctic ice sheet growth and collapse through the past five million years (led by David Pollard) and Obliquity-paced Pliocene West Antarctic ice sheet oscillations (led by Tim Naish). Published in the same issue, the two papers showed — from the ANDRILL observations and a simple “hybrid” ice sheet model — that the West Antarctic Ice Sheet waxed and waned over a few thousand years, sometimes retreating to almost nothing. Interesting! Then my colleague Juliane Mossinger handled Rob’s provocative paper Past extreme warming events linked to massive carbon release from thawing permafrost, suggesting that the Paleocene-Eocene Thermal Maximum could have been caused by terrestrial carbon cycle processes on an ice-free continent. Rob was essentially new to the field, but dove in anyway: Interesting, interesting stuff (and that’s not even delving into Rob’s other publications in Science and Nature Geoscience). Where did all these disparate ideas, skills, models and insights come from? As it turns out, they come from one of the most seemingly straightforward careers I’ve yet come across: childhood interests in geoscience and outdoor recreation > Earth Science degree at UC Boulder > graduate work at UC and NCAR with people like Bill Hay, Starley Thompson and Warren Washington > faculty position at the University of Massachusetts-Amherst > long-term involvement in the awesome Urbino Summer School for Paleoclimatology > Tinker Muse Prize > geoscience superstardom. It was, as Rob says: Yes, but … that doesn’t mean it’s easy. A huge chunk of our conversation centers around Rob’s long-running collaborations with David Pollard, which surely has to be one of the great partnerships of modern geoscience. It was just luck that they were both in Starley Thompson’s group at NCAR, and luck that they ended up being quasi-neighbors on the East Coast. Rob had long realized that — even with the deglaciation of Greenland, West Antarctica and peripheral glaciers and ice sheets — modelers still could not produce the ~ 20 m sea level rise in the Pliocene warm period. For a while, Rob was convinced that surface melt must be the answer, which could in turn lead to hydrofracturing. Nope! Increased basal lubrication?* Still not enough! Sitting in the audience at Rob’s EGU talk, David Pollard wondered if Richard Alley’s ideas on ice cliffs might be important. But how, exactly, would cliffs come into play? David and Rob turned to an elegant theoretical model from Jeremy Bassis describing the maximum height an ice cliff could attain, from structural properties: about 100 m, it turned out. All of which, when put together, leads to the marine ice cliff instability (MICI) mechanism. Rob and David looked to the Pliocene and last interglacial to better constrain the model parameterization.

Language is spectacularly imprecise. Susan Joy Hassol from Climate Communication has made a career out of studying how to — and how not to — use language to most effectively communicate climate science to a broad audience. Well, you might think, surely this isn’t too complicated. But step back for a moment and think about some of the terms you’ll see on a daily basis in the formal language of climate scientists speaking to one another: THC, aerosols, enhance, error, bias, negative emissions, positive feedback, positive trend. These words might sound innocuous enough in a scientific context, but to a non-scientist, or even to scientists from a different field, these words can have entirely different meanings: the active ingredient in marijuana, spray cans, make better, mistake, preconceived notion, bad emissions, something good, a helpful development. Susan has worked for years to collate a list of these and other trigger words, as well as suggested replacements. If you see yourself using potentially confusing terminology in public communication, then you might like to check out the articles in Physics Today and EOS on the resources page of Susan’s website (which, by the way, is an excellent resource for all manner of climate communication info!). Susan’s career provides a great example of how to build a non-academic career in climate science. It’s possible, but you need a passion for what you’re doing, and the ability to pull together a diverse line of work. Susan started with a long stint as a writer/communicator for the Aspen Global Change Institute, followed by an increasingly diverse portfolio including one-on-one coaching, running communication workshops, writing a documentary for HBO, serving as the Senior Science Writer for the National Climate Assessments,  and a great deal of public outreach, including a terrific TEDx talk. Susan grew up in a four-generation apartment in Brooklyn, with Yiddish spoken. Her parents always said she was a good communicator, and that’s certainly remained true. From her years of experience with climate communication, some of Susan’s take-home messages are: * Good communication means “simple, clear messages repeated often by a variety of trusted sources”. * Stories are important: you have to speak for the facts, which don’t speak for themselves. * Speak a common language: “…while there is always complexity, I find that the basic story in many cases is really pretty straightforward”. * Use analogies. Instead of talking about gigatons of annual meltwater from Greenland, try saying that it is like the water use of LA for a year. * Talk about hope and urgency in climate discussions. Hope and worry motivate action; fear and despair do not. * Emphasize that we still have a choice. Do you want just a few more days per year like the currently hottest day … or a month more? Sometimes, community inertia on communication is so strong that it can difficult to break through. Susan was invited to speak at a National Academy meeting on the recent reduced rate of global warming — you know where I’m going with this — and emphasized that “hiatus” was a misleading term, both scientifically and for communication. But the message didn’t take: “…everybody shook their head and agreed with me and then they kept on calling it the hiatus”. The point, perhaps,

Maybe once a year I have a nightmare that I’m back in grad school, grinding out an interminable PhD in some entirely new field. Ed Hawkins from the National Centre for Atmospheric Science actually did head back for a new degree and a new career, but, luckily for climate science, it seems to have been more of a dream than a nightmare. Ed got his start in the Master of Physics program at Oxford, where the intense, small-group discussion and examination was pretty intense, to put it mildly: “If you hadn’t done enough that week you got found out, certainly”. Straight after Oxford, Ed moved on to a PhD in astrophysics from the University of Nottingham. There, Ed worked on minor topics, you know, like mapping out the entire universe. Prior to prepping for the interview, I was completely unaware of Ed’s first career, but it turns out that much of this work on the 2dF Galaxy Redshift Survey is massively cited, with five papers with more than 300 citations in Web of Science. Ed has an H-index of 13 from his first career alone! But the topics in astrophysics proved to be too divorced from immediate societal relevance, and at the time Ed wasn’t too sure about academia in general. So it was off to the IT industry for a year. Happily for us, IT proved a bit of a bore, and Ed’s interests drifted towards weather, climate and something more tangible than astrophysics. As Ed says, “I wanted my research, if I was going to pursue a career, to be more directly relevant to the real world and policy making”. That’s when he returned for a Master’s degree from the University of Reading. Ed is now well-known for his work on model processes, uncertainty and predictability, with specific work on a wide range of topics like the the Atlantic Multidecadal Oscillation, sea ice, temperature vs. precipitation, extremes, and regional climate change. As is the case in many of the Forecast interviews, contextualizing the importance of internal climate variability emerges as a major theme, to be explored, at least in part, through large, perturbed initial condition ensembles. Sea ice is a classic case in which one could easily mistake a short observational record as a forced trend. “It’s a very tricky problem to try and untangle all of these factors, and try and understand what it is the underlying trend, due to increasing global temperatures and what is due to variability on top of that trend”. But untangling the answer is at the heart of providing policy-relevant science, and Ed is focusing on using observations to query whether or not models are simulating the correct processes. Recovering old weather data, too, provides huge opportunities to contextualize modern processes, extremes especially. Another classic example of the untangling process is the hiatus/pause/slow down — a period of reduced global warming beginning ~ 1998, ending in 2015. In AR5, the IPCC authors realized that observations were on the low end of model simulations, presenting an apparent challenge to the modeling community. Ed talks me through how the initial debates led to better — and fairer — model-data comparisons and improvements in the observational reconstructions. Now, the community appears to be moving towards more of a consensus that the initial mismatch is, when done properly, not nearly as serious as initially thought. That, however, is not all. Oh no. Ed also produced the massively viral spiral graphic on climate change, runs a terrific

Gabi Hegerl is famous for her work seeking to understand the processes driving climate variability, but she was initially destined to study language arts, and started off with seven years* of schooling in Latin. Schools in Germany, at least in Gabi’s time, tended to place students into career tracks quite early, and for Gabi that meant language. But she never loved it, and soon realized “I always really enjoyed maths, even though it seemed a bit pointless”. It turns out that her father, a lawyer, had an unfulfilled ambition to be a mathematician. But for reasons that remain unclear, he didn’t tell Gabi of his interests, and actively encouraged her to go into law. Due to the horrendous boredom of the subject, though, Gabi demured, initially pursing her interests in archaeology at the Ludwig-Maximilians University in Munich. Describing archaeology, Gabi says “I found it really interesting but I found it just frustratingly illogical”. There was far too much fuzziness in data and interpretation, and she could never make it work entirely. Reviewing her interests and skills, Gabi finally concluded that maths (and art!) were  immensely satisfying and continually challenging. I think the interview contains a terrific description of why people might study applied maths — a combination of a vast intellectual construct, the sense of building on prior knowledge, a simple end result, and direct applicability to real-world problems. These interests in maths led Gabi to switch her PhD from computer logic to numerical fluid dynamics, focused on a Siemens-funded and high-risk project seeking to model fluid flow in the throat. A long way from climate science! Juggling career options, and applying to software companies, Gabi was intrigued by the mismatch between mapped and actual glacial extents in her climbing haunts in the Alps and decided to — almost out of the blue — apply to the Max Planck Institute for Meteorology in Hamburg, working with Klaus Hasselmann and Hans von Storch. Gabi thought of the climate work as an experiment, something to try out. But von Storch said it only made sense if an academic career was the final goal. Ultimately, Gabi agreed, even thought the salary was lower than in industry and she had to wrestle with family and relationship entanglements. “I felt putting myself to very hard work is much nicer if you feel it brings about something useful”. Now, after a scientific career spanning the MPI, the University of Washington, Texas A&M, Duke and now the University of Edinburgh, Gabi is known for her pioneering work on the detection and attribution of climate change, climate extremes, and climate sensitivity. We discuss the surprisingly large and long-lasting impacts of volcanoes on climate, disentangling internal vs. external controls on climate, why spectral analysis isn’t too satisfying without a mechanism,  whether or not models simulate extremes for the right reasons, how to work with Bayesian statisticians. For me, though, the most interesting section of the interview comes in our discussion of Gabi’s work with her late husband, Tom Crowley, and the aftermath of his death in 2014. Even after years of working with the climate community, I can think of scientists as independent constructs, visible by their papers and community activities, but not as part of a human system. The reality, of course, is intensely human. Gabi experienced one of the most wrenching life changes one can imagine,

Jerry Mitrovica from Harvard University sits at the surprisingly wobbly interface between the solid Earth, oceans and ice. Trained in serious geophysics, Jerry quickly found a niche in explaining how movements of the Earth’s mantle – in three dimensions – control the apparent variation of past sea levels. In many cases, this means pointing out that many or all of our records of past sea level are fundamentally altered by processes like dynamic topography and isostatic rebound. Jerry was born to a Greek mother and Albanian father. Their meeting in the aftermath of WW II remains fuzzy, but they soon immigrated to Melbourne, where Jerry was born as the youngest of seven siblings. Although Melbourne supported a small and vibrant Albania expat community, the move never gelled for family, and they moved to Toronto. The shift proved difficult, as Jerry’ charismatic and intellectual father died soon after, leaving the family in dire financial straits. The local Albanian community responded by pooling together money for a down payment on a house, where Jerry’s mother lived for the rest of her life, but still … “It was my mother trying to keep the family together and survive … a widow with seven children in her late 40s”. Jerry, however, loved Toronto, staying for all of his subsequent schooling and his initial academic career. He initially tried a PhD at Cambridge, but felt isolated and adrift. The overseas experiment lasted only a month, and Jerry returned to Toronto, where he had a strained relationship with his PhD advisor. As he says, “I wouldn’t say my PhD in Toronto was the happiest time in my life.” But the experience at Cambridge provided considerable motivation to get through, and to thrive. “I thought that leaving Cambridge after a month was a failure. I didn’t want to fail again.” Along the way, Jerry got some key advice: “You know, you’re a theorist…you need to go to a place where data is primary”. He did, joining Irwin Shapiro at the Harvard-Smithsonian Center for Astrophysics, and it provided to be one of those fortuitous collaborations that seem to define the careers of successful scientists. “It’s just one of these wonderful things that you luck into in life, that I worked with people that were trying to build that capability, at just the time I had developed the expertise to model that.” Jerry made predictions about rates of post-glacial isostatic rebound before the requisite GPS data existed. The predictions proved to be correct, but at the time it was a bit terrifying, and Jerry had real fears about the career consequences of being wrong “Graduate students and postdocs, even though many of them won’t admit this to you, feel extremely vulnerable. You don’t want to make a major mistake, because that’s when you’re looking for a job”. Jerry is now famous for bringing geophysical insights to the sea level debate: gravitational attraction, sea level fingerprints, rotational shifts, isostatic rebound, and near field and far field effects have now fully oozed into the field to such an extent that it is almost impossible to imagine interpreting any sort of sea level record – be it tide gauges, salt marshes, corals, beach terraces – without considering the possible confounding effects. For many of these records, “It’s a lens alright, but it’s a contaminated, distorted lens”. Without a solid geological interpretation, some pretty big miscalculations can result. Now, Jerry is collaborating with his students and people like Bob Kopp to bring a statistical approach to the interpretation of modern sea level rise,

Tina van de Flierdt from the Department of Earth Science and Engineering at Imperial College London is an international leader in the use of geochemical proxies – particularly neodymium (Nd) – for reconstructing past ocean circulation, water masses and weathering. But her childhood and early interests pointed in a different direction. Tina grew up on a dairy farm in rural western Germany, raised by parents who were largely tied to the land but entirely supportive of her outside interests and desire to attend summer camp away from home. By her late teens, Tina knew she had a keen interest in geology, but didn’t realize that it existed as a field. It took the combination of an inspirational teacher and a sharp career counselor to set her down the path that’s led her to where she is today. Initially, however, Tina wanted to be a hard rock geochemist, or to study volcanoes and mantle processes — passions that drew her to work in Namibia. Then, following an off-hand comment by a friend, Tina sent her CV to Alex Halliday, at the time working at ETH Zurich. Although she had no particular interest in paleoceanography, the moment she entered the lab, Tina thought “…well, screw it, I’ll do paleoceanography”. That’s all it often takes to switch gears entirely. Tina then dove into early work on the use of Nd to trace water masses, and was a first-hand participant in the seemingly inevitable progression of a new proxy from optimism to pessimism and later reconciliation. Along the way, Tina helped to lead the GEOTRACES program, a massive international effort to disentangle the many influences on geochemical tracers. As I keep hearing on the podcast, it was a case of being in the right place at the right time, particularly if that place was Lamont. Tina is particularly interested in the marine-terminating sector of the East Antarctic Ice Sheet during past warm periods. With her team, Tina is already producing evidence to suggest that it may be as sensitive to warming as the West Antarctic Ice Sheet. If so, the implications for sea level rise are obviously startling, and Tina is now working to move from qualitative statements to a quantitative reconstruction of past mass loss. For a long time, the modeling community was well ahead in trying to generate these sorts of estimates, but as Tina tells it, the geochemists are rapidly catching up and the field is now in a fantastic-sounding state of collaboration and mutual stimulation of ideas. We talk through several career topics, too: watching out for open-ended technical analysis in your early days; the unexpected rewards of teaching; the merits and problems of the UK academic assessment process; and management of peer review, particularly now that Tina is an editor at Geochimica et Cosmochimica Acta. Tweet

Reto Knutti and I are both interested in cake. Reto, as an analogy for the problems society faces when trying to divide up the allowable carbon emissions among historically greedy and newly desirous consumers. Me, because I love cake (ok, it’s also a great analogy). Reto is a stellar climate physicist, working on many angles of climate system, including climate sensitivity, ocean circulation, aerosols, radiative forcing, changes in extremes, and allowable carbon emissions (most recently at Nature, he co-authored a paper on how regional extremes scale with global mean temperature — figure below). Hard core IPCC Working Group I stuff, you could say. But Reto is also interested in climate and society interactions. He’s done dozens of outreach activities, has clear ideas about how to engage with non-scientists, and thinks deeply about what models are and how to use them. So I decided to steer the conversation more towards social/policy/economics angles … fields in which neither one of us has formal training, making it all the more fun. Reto has certainly tried hard to build scientific bridges among fields. In his experience, the theoretical and practical challenges in working across disciplines are enormous and the immediate benefits can be scant. For Reto, working with economists and social scientists: produced “…some of the hardest papers to write, ever”. And some of this work is cited hardly or not at all. If you don’t start, though, you’ll never get anywhere, and Reto doesn’t seem to regret any of the considerable effort he’s put into “non-core” activities. In this vein, I posed a series of quasi-unanswerable questions (paraphrased): Q: How do you get society to stop eating so much cake? A: Perhaps by massive regulation or massively reduced use, but neither seems likely. Massive investment in research and technology might be a better way forward. Q: What’s the best way to engage with a range of civic and financial institutions on climate change? A: Keep facts and values separate: “rather than telling people what they need to do, you tell them what the facts are, what the options are, and you let them basically think on their own about what they could do or what they need to do”. Shared values definitely helps. Q: Given that the EU and the US are at approximately similar points on the Kuznets curve, why do they have such different attitudes towards climate? A: The EU tends to think more as a society and less as an individual, and the US has fundamentally different geographical constraints and faith in technology to solve problems. Q: How do you decide whether or not there are fundamental limitations to model projections … or put another way, is there a question for which the answer is so uncertain that modelers shouldn’t even provide an answer (inspired by Lenny Smith)? A: That’s a tough one, and actively debated in the modeling community. At the least, you can evaluate against the paleo record, check for consistency across models, and compare to modern observations. But the potential still exists that models could be missing some sort of critical physics or constraints. The potential for this kind of “miss” is probably highest for the things that are really relevant for society, like extremes and abrupt change. Reto kindly indulged my open-ended questions about these and many other thorny issues. We did, of course, eventually get around to talking about some actual physics of the climate system!

For Valérie Masson-Delmotte, climate science is like a jigsaw puzzle. Unlike a house of cards, where the removal of one element causes the whole thing to crash down, the central picture of a puzzle is still apparent when pieces — maybe even many pieces — are missing. Valérie works, at least in part, to fill in the missing pieces, using tools like ice cores, climate models, and statistics. I guess you could say that Valérie is an ice core scientist, but that’s like saying that Eric Ripert knows how to cook fish. Yes he does, and he’s great at it, but that kind of misses the bigger picture. In fact I would have a hard time trying to pin down what Valérie does, because the range is so broad, spanning monsoon modeling, polar climate variability, interpretation of δ18O, age models, volcanic impacts on climate … I suppose it’s simplest to say that Valérie is trying to understand past climate variability and the underlying processes, on an astonishing variety of fronts. A great example of how Valérie and her colleagues are bringing together multiple archives and techniques is a recent Nature paper on the reconstruction of the North Atlantic Oscillation. That’s not all, though. Valérie is the co-chair of Working Group I for the sixth IPCC assessment report, a children’s book author, and the mother of two teenage daughters. It seems like nearly everyone gets into science by some roundabout way. In Valerie’s case, her early interest in archaeology morphed into engineering. But then, in the process of deciding whether or not to stay in science, a chance encounter with a popular science article on the Vostok ice core led to her cold-calling the French scientists who were involved in the project, and soon, the day after finishing her PhD on monsoon modeling, a postdoc at the new LSCE with the great Jean Jouzel. The timing was perfect and, for a brief time, Valérie and her colleagues could pursue any sort of curiosity-driven science they wanted. Those days are long gone, but Valérie is still a passionate supporter of long-term, curiosity-driven science. One theme that keeps emerging in my interviews with climate scientists is the way in which larger cultural practices inform how science gets done. For Valérie, French culture has some specific practices, particularly around raising questions. As she says, “We are not taught to ask questions … questions are supposed to reflect how smart you are … but not acknowledge your ignorance”. Yet it doesn’t seem that Valérie has any issues asking tough, reasonable questions, like when she takes me to task for not accepting important methodological advances for publication in Nature (at least in climate). Our interview, recorded at the end of the March 2016 IPICS meeting in Hobart, Tasmania, was a great chance to hit some of the nitty-gritty of ice core science. We hash through CO2 offsets, age model synchronization with speleothems and tephra, integration of ice core records with ocean and non-polar terrestrial records, and the hunt for the oldest ice. Tweet

I first heard of Piers Sellers some time in the mid-1990s, on a trip to the southern BOREAS field site when I was in my master’s program at the University of Montana. The talk was something on the order of “… have you heard? Piers is entering the astronaut program!” which, at the time, came as a complete non-sequitur to me. Why would someone at the peak of an influential scientific career at NASA choose to walk away? At the time, Piers had already made some fundamental progress in at least three areas of science: bringing land-atmosphere interactions and ecology into atmospheric and climate models; working with Compton Tucker to show that weather satellites can be used to generate global estimates of plant productivity; and organizing unprecedented field campaigns like FIFE and BOREAS to show how it all came together — that yes, you really can scale physiological processes from cellular to global levels. As my grad advisor Steve Running says: nontrivial accomplishments. Then, 20 years later, I started making my list of who I’d like to interview for Forecast, and Piers was on the list. It’s a long list, though, and Piers’ background edges more towards biogeochemistry and away from physical climate — my area at Nature. But then I read Piers’ moving Opinion piece at the NY Times, in which he announced his diagnosis of Stage 4 pancreatic cancer. I realized I’d better try as soon as possible, and with the help of Compton Tucker — one of Piers’ closest friends and neighbor — I was able  to arrange a call. If you read the NY Times piece, it’ll come as no surprise, but Piers was incredibly gracious, funny, optimistic and passionate about life and science, which, for Piers, are more or less the same thing. I learned, at last, that he’d been trying for some time to get into the astronaut program. Once in, he stayed for 15 years, conducting three space walks and six trips to the international space station. Eventually, he wanted to make space for younger astronauts to join the program and chose to return to NASA, this time as acting Deputy Director of the Sciences and Exploration Directorate … AND … Acting Director of the Earth Sciences Division at NASA’s Goddard Space Flight Center. The three careers span an incredible range: individual scientist, astronaut (or operator, as Piers calls it), and administrator. Now, Piers estimates that he has about 500 days left, and has narrowed in on family and work as the highest priority — with climate change at the forefront. But it’s not all serious stuff. Piers also tells me how he brought his grade school’s charter into space … although maybe it was a copy! Tweet