Hacking the atmosphere: Geoengineering gets a reality check

改造大气层：地球工程面临现实考验

Jim Franke pulls away the cover page of a presentation on the wraparound desk in his office, revealing an illustration of an odd-looking aircraft with massive wings stretching out from a stubby fuselage. The uncrewed plane is soaring thousands of meters higher than commercial jets fly—so high you can see the curvature of the Earth. It’s precisely the type of aircraft one would need to begin artificially cooling the planet.

吉姆·弗兰克（Jim Franke）掀开了他办公室环形办公桌上一份演示文稿的封面，露出一架外形奇特的飞机插图：它有着粗短的机身，却伸展着巨大的机翼。这架无人驾驶飞机在比商用客机高出数千米的高空翱翔——高到足以看到地球的弧度。这正是人类开始人工冷却地球所需要的那种飞机。

Those outsize wings would keep the plane and its payload aloft in the stratosphere, about a dozen miles (or 20 kilometers) above the surface, where the air is much thinner—as little as 5% the density near the ground. Once at altitude, the plane would release materials that could, after a few steps of chemistry, reflect sunlight back into space. “If you want to get to 20 kilometers in the near term, this is probably the best bet,” says Franke, a research assistant professor at the University of Chicago.

这些巨大的机翼能让飞机及其载荷保持在平流层中，即距离地面约 12 英里（或 20 公里）的高度。那里空气稀薄得多，密度仅为地面的 5% 左右。一旦到达该高度，飞机就会释放出某种物质，经过一系列化学反应后，这些物质可以将阳光反射回太空。“如果你想在短期内达到 20 公里的高度，这可能是最好的选择，”芝加哥大学的研究助理教授弗兰克说。

Franke is one of a small but growing cohort of scientists focused on the engineering challenges associated with solar geoengineering, the controversial idea that we could deliberately intervene in the climate system to counteract global warming. The concept came from volcanoes. Massive eruptions in the past have reduced temperatures worldwide by blasting sulfur dioxide and other compounds into the stratosphere, where they convert into sunlight-scattering particles.

弗兰克是一小群致力于太阳地球工程工程挑战的科学家之一。这是一个充满争议的构想，即我们可以通过人为干预气候系统来抵消全球变暖。这一概念源于火山喷发。过去的大规模火山喷发曾将二氧化硫和其他化合物喷射到平流层，这些物质转化为散射阳光的颗粒，从而降低了全球气温。

Hundreds of studies in recent decades have suggested that a human attempt to mimic this mechanism would work quickly and efficiently—at least within the confines of climate models. But these computer simulations are approximations of how the real world works. They gloss over numerous challenges. Like the fact that aircraft capable of carrying the necessary loads to the necessary altitudes don’t exist. Or that we don’t know for sure how to release material so that most of it turns into tiny reflective aerosols instead of, say, clumping together and falling out of the sky.

近几十年来，数百项研究表明，人类模仿这一机制的尝试将是快速且有效的——至少在气候模型的范围内是这样。但这些计算机模拟只是对现实世界运作方式的近似。它们掩盖了许多挑战。例如，目前尚不存在能够将必要载荷运送到必要高度的飞机；又如，我们并不确定如何释放这些物质，才能确保它们大部分转化为微小的反射气溶胶，而不是聚集成团并从空中掉落。

Or even what specific substance we would want to load onto an aircraft, given open questions about safety, cost, and effectiveness. Amid these compounding unknowns, more and more research on solar geoengineering is moving beyond computer simulations, delving into the detailed design and practical engineering work that would be needed before we could carry out a campaign to dial down temperatures.

考虑到安全性、成本和有效性方面尚存疑问，我们甚至不知道究竟应该在飞机上装载什么特定物质。在这些错综复杂的未知因素中，越来越多关于太阳地球工程的研究正超越计算机模拟，深入到在实施降温计划前所需的详细设计和实际工程工作中。

The tasks required range from inventing high-altitude aircraft to mastering the precise chemistry and delivery mechanisms for dispersing materials to building out the monitoring infrastructure that we’ll need in order to know if any of it actually works. The question of whether we should geoengineer the planet has no clear-cut answer. It might save millions of lives by reducing the dangers of catastrophic heat waves, floods, droughts, and famines.

所需的任务包括：发明高空飞机、掌握分散物质的精确化学反应和输送机制，以及建立监测基础设施，以便我们了解这些措施是否真的有效。关于我们是否应该对地球进行地球工程改造，目前还没有明确的答案。它或许能通过减少灾难性热浪、洪水、干旱和饥荒的危险来挽救数百万人的生命。

But many fear it’s too dangerous to even consider, much less seriously study, arguing that we can’t possibly predict the spiraling consequences of manipulating such large, complex, interconnected planetary systems. Critics argue that the building momentum in this phase of research will make it ever more likely that someone, somewhere in the world, will eventually pull the trigger on geoengineering, no matter the remaining unknowns or the dangers for certain parts of the world.

但许多人担心这太危险了，甚至不应考虑，更不用说进行严肃研究。他们认为，我们根本无法预测操纵如此庞大、复杂且相互关联的行星系统所带来的连锁后果。批评者认为，这一研究阶段不断增长的势头将使世界上的某个人、在某个地方最终扣动地球工程的“扳机”变得越来越可能，无论还存在多少未知因素，也无论这对世界某些地区意味着什么危险。

“I do think it’s very dangerous because of what we know about science and technology,” says Jennie Stephens, a professor of climate justice at Maynooth University in Ireland. “The more investment that’s made, the further the advances, the more likely it is that it will be deployed.”

“我认为这非常危险，因为我们了解科学技术的发展规律，”爱尔兰梅努斯大学气候正义教授珍妮·斯蒂芬斯（Jennie Stephens）说。“投入越多，进展越快，它被部署的可能性就越大。”

But proponents of this practical research argue that playing out how we’d mount a solar geoengineering program will improve our understanding of the potential benefits and risks, helping to ensure that if anyone does try to tweak the climate, they might at least do so in an informed and potentially safer way.

但这些实用研究的支持者认为，推演我们将如何开展太阳地球工程计划，将提高我们对潜在收益和风险的理解，从而有助于确保如果有人真的试图调整气候，他们至少能在知情且可能更安全的方式下进行。

It’s still very much a niche field. Much of the work now underway is happening at the Climate Systems Engineering Initiative (CSEi) at the University of Chicago, which formally launched in 2024 under the leadership of the prominent geoengineering researcher David Keith. Franke, a professional engineer before earning his doctorate in geosciences, is overseeing a series of overlapping research projects and collaborations aimed at resolving many of the engineering uncertainties.

这仍然是一个非常小众的领域。目前正在进行的大部分工作都在芝加哥大学的气候系统工程倡议（CSEi）进行，该倡议于 2024 年在著名地球工程研究员大卫·基思（David Keith）的领导下正式启动。弗兰克在获得地球科学博士学位前是一名专业工程师，他目前负责监督一系列重叠的研究项目和合作，旨在解决许多工程上的不确定性。

That includes working out the designs now on his desk—renderings of the type of aircraft that could be used in the initial phase of a geoengineering program. Franke argues that more computer simulations are simply not going to answer the big remaining questions in the field, including the most compelling one: the “boogeyman” of what could go wrong.

这包括完善他桌上的设计图——即可能用于地球工程计划初始阶段的飞机渲染图。弗兰克认为，更多的计算机模拟根本无法回答该领域遗留的重大问题，包括最引人关注的一个：即可能出错的“心魔”。

“I’m kind of personally skeptical that additional model development or more simulations are going to satisfactorily resolve those things,” he says. “And so I’m not really that interested in turning the crank on more models.” For Franke, it’s time for the next step: “We’re interested in seeing how you’d actually do this thing if you wanted to do it.”

“我个人对通过进一步的模型开发或更多的模拟来令人满意地解决这些问题持怀疑态度，”他说。“所以我对运行更多的模型并不感兴趣。”对弗兰克来说，现在是迈出下一步的时候了：“我们感兴趣的是，如果你真的想做这件事，你到底该怎么做。”

What we don’t know: Solar geoengineering is often portrayed as a relatively cheap and easy fix for climate change. But as researchers take a harder look at the nuts and bolts, they’re finding considerable uncertainties, missing tools, and unbuilt infrastructure. None of that may be a showstopper, but we’ll need time and money to develop the components necessary to implement even the early stages of a solar geoengineering program. What this research is about, at its core, is not actually launching something, but figuring out what it would take to do so.

我们所不知道的：太阳地球工程常被描述为一种相对廉价且简单的气候变化解决方案。但随着研究人员更深入地审视其具体细节，他们发现了相当多的不确定性、缺失的工具和尚未建立的基础设施。这些可能都不是无法逾越的障碍，但我们需要时间和金钱来开发实施太阳地球工程计划早期阶段所需的组件。这项研究的核心不在于真正启动某个项目，而在于弄清楚要做到这一点需要什么。