Advice for physics majors wanting to work in climate

If you are majoring in physics and thinking about applying your talents to the problem of climate change, the list of ideas below is designed for you. Please note that the list I give here is necessarily incomplete: as a physicist, you have the potential to work on the climate problem from nearly any angle. What I mention below are just a few of the directions you might take, informed by my journey from a PhD in string theory to my current understanding of the climate problem. If you are interested in joining our group at UC Berkeley, two such options are given at the end.

There are a number of climate-relevant technologies that would benefit from your efforts to make them better and cheaper. You could:

• Become an applied physicist working on solar photovoltaics (PV) by pursuing a PhD in a department of physics, applied physics, or material science. Solar PV is the one technology that we could deploy today at scale to meet all of humanity's current and future power needs. (Wind can make a big dent, and will be essential, but we will need to develop deep-offshore platform and transmission solutions before the same can be said of it.) There are many different PV technologies that are competing to be the cheapest source of renewable power, and the world needs smart people working on them to drive down the cost as quickly as possible.
• Become an applied physicist working on batteries by pursuing a PhD in a department of physics, applied physics, or material science. To dispatch solar power at night, or during storms, or in a car, you need batteries. Lithium-ion batteries have a high energy density and so are great for electric vehicles. Flow batteries are heavier and bigger, but have the potential to store an enormous amount of energy very cheaply, which we need to smooth out the day-night cycle and to provide reliable power through multi-day periods of low sun and wind (the so-called Dunkelflaute problem).
• Become an applied physicist working on hydrogen by pursuing a PhD in a department of physics, applied physics, or engineering. Hydrogen could play several different roles in our future energy systems: as a way to store energy seasonally (in the midlatitudes where many of us live, solar PV generates about three times less power in the winter than in the summer), or in solving the Dunkelflaute problem, or as an intermediate product in the sustainable generation of synthetic fuels for long-haul aircraft, or even as a direct fuel for aircraft. We need to drive down the cost of generating hydrogen with electrical hydrolysis (the vast majority of hydrogen today is made from methane in a process that rejects the C in CH4 as CO2). We need better fuel cells to convert hydrogen back to electricity. We need better hydrogen-powered turbines and jet engines.
• Become an engineer working to #ElectrifyEverything. Since all carbon-free sources of usable energy come in the form of electricity (with the exception of a tiny amount of energy that we can get from bioenergy crops), we need to electrify everything. This means: our cars must be powered by electricity (not oil); our range tops, ovens, water heaters, and heating and air-conditioning units must all be powered by electricity (not gas); our heavy industries must generate high temperatures using electricity (not coal, oil, or gas); and we need high-speed rail as a replacement for domestic air travel to move our bodies using electricity (not oil). You do not necessarily need a PhD to work on these things. Find companies that are making the things we must all buy, install, and use, and help them make their products better and cheaper.

Not all of the options available to you are equally worthy of your time and effort, and some are best avoided. I recommend that you:

• Avoid nuclear fusion. As the saying goes, power generation from nuclear fusion is only 50 years away, and has been for the past 50 years. The gigantic International Thermonuclear Experimental Reactor (ITER) being built in southern France operates on the principle of "magnetic confinement". ITER is still far from operational, and it has been in the works since the time of Reagan and Gorbachev. Even when it does get up and running, it will not generate electricity; indeed, harnessing the fusion energy for electrical power would require an even more advanced reactor that is much larger and much more expensive. Power from magnetic confinement fusion is an unproven and exorbitantly expensive technology that has no chance of solving climate change. The other proposed approach to generating power from nuclear fusion is "inertial confinement fusion", but that technique is even less plausible.
• Avoid fossil fuels. You might think this is commonsense: after all, fossil fuel is the very stuff that causes global warming. But many university faculty are generously funded by the fossil-fuel industry to study carbon capture and sequestration (CCS) and to publish reports telling policy makers what an important part of the climate solution fossil fuels will be. But CCS is a technology that, for all intents and purposes, does not exist: the United States has zero successful CCS projects (and a fair number of spectacular failures). With the dramatic reduction in the cost to generate electricity with solar and wind, fossil-fuel power plants with CCS are not economically competitive sources of low-carbon power. From the perspective of the fossil-fuel industry, however, the success of CCS is not the real goal: by funding universities to study CCS, they maintain a pipeline of engineers with the expertise to work in oil and gas, and they co-opt universities into supporting the notion that we need fossil fuels to solve the problem caused by fossil fuels.
• Avoid geoengineering. Several technological fixes have been proposed to compensate for global warming in the future without needing to do the hard work of supplanting fossil fuels today. These fixes include injecting reflective particles into the stratosphere and sucking carbon dioxide out of the air (called "air capture"). Reflective particles have the potential to wreck the ozone layer, they do nothing about ocean acidification, and they must be continually injected into the stratosphere for as long as the atmosphere's CO2 anomaly remains high. Air capture of carbon dioxide is an old technology (think submarines and spacecraft), but returning the atmosphere to its preindustrial concentration would require passing roughly the entire atmosphere through air-capture machines, which would take hundreds of years, and the resulting CO2 would need to be sequestered, which would run up against the same problems that plague CCS. At best, geoengineering would incur exorbitant costs and would commit our children, grandchildren, etc. to dealing with our mess for hundreds of years (air capture) or many thousands of years (reflective particles). These technologies are unlikely to be deployed at scale at any time in the future, but the attention they get today gives many people the false comfort that somehow technology will save us, reducing the imperative of fixing the problem now.

Finally, there are two options that physics majors can pursue in our group at UC Berkeley:

• Become a climate scientist by pursuing a PhD in an Earth-science department, like the Department of Earth and Planetary Science (EPS) here at UC Berkeley. Climate scientists are responsible for what the public and policymakers know about the climate crisis. They are the most qualified to educate others about the problem and about the general steps that must be taken. Among the subfields of Earth science, atmospheric dynamics and atmospheric radiation are traditionally considered good fits for physicists since they are areas of applied physics that place you in the center of the climate problem (the radiative forcing is in the atmosphere) and where the immediate consequences manifest. And there are many important questions: Why does warming make storms more intense? For how long will the concentration of each greenhouse gas remain elevated in the atmosphere? Do clouds amplify or dampen the warming? Can human physiology cope with future heat waves? What is our current committed sea-level rise? How likely is a runaway climate state? Pursuing a PhD in the Romps group through the EPS Department entails answering fundamental questions about global warming and its impacts, all while acquiring the big-picture understanding of the climate system needed to advise governments, institutions, and the public.
• Become a professional climate-science communicator by pursuing a PhD in climate-science education, as can be done with the SESAME program here at UC Berkeley with one foot in the EPS Department and the other in the Graduate School of Education. The United States has been an obstacle to international progress on global warming for much of the past 30 years, in large part because of the successful disinformation campaign that fossil-fuel companies have waged in the US during that time. As a result of that campaign, the American public is confused about even the most basic aspects of global warming (e.g., what causes it), and a large swath of the American public is uncertain that global warming is even happening. Educating people about the problem is among the most important things anyone can do, and you can make it your career. And we urgently need answers to many questions: Is there a single "gateway belief" that underpins all other perceptions about climate? Like the proverbial frog in a boiling pot, why do people fail to recognize that their daily weather is affected by global warming? Why does the public connect unrelated issues (plastic pollution, recycling, the ozone hole) to climate change? What can be learned from the fossil-fuel industry's successful disinformation campaign? Pursuing a PhD in the Romps group through the SESAME program entails studying both climate science and climate-science communication, exploring the public's understanding of our climate and methods we can use to rapidly improve that understanding.