历史上德国莱茵河上的普法尔茨伯爵石堡等收费城堡，是通过人为限制廉价航道获取“经济租金”的典型案例，而这种寻租行为正面临在全球重现的风险。在2月爆发的海湾战争后，战前承担全球约20%石油运输的霍尔木兹海峡面临通行收费威胁：伊朗政府正考虑对过往船只征税，阿曼可能跟进，而美国总统特朗普甚至宣称美国作为“霍尔木兹海峡守护者”也应收取费用。经济学家安妮·克鲁格（Anne Krueger）的寻租理论指出，贸易限制会引发破坏性寻租竞争，而在现代海上航道中，这种竞争正演化为无人机袭击与海上劫持等致命冲突。
过去两个世纪中，自由航行作为全球公共品主要依赖霸权国家的实力支撑，符合查尔斯·金德尔伯格（Charles Kindleberger）的霸权稳定理论。1857年列强终结了丹麦对波罗的海的征税，1868年国际条约彻底废除了莱茵河通行费；远洋航运则先后由19世纪的大英帝国（1820年起在波斯湾建立条约体系）与1971年接棒的美国提供安全庇护。然而，随着特朗普政府收缩海外驻军以及廉价无人机大幅拓展威胁射程，美国的护航意愿与能力正在减退。尽管有人寄望“中等强国”联合护航，但经济学研究表明，缺乏主导力量的联盟容易陷入“搭便车”和地缘博弈的困境。
除了地缘寻租风险，更为严峻的挑战在于全球物理公共品的恶化与气候危机。欧洲长达三个月的极端热浪和干旱导致莱茵河考布段水位暴跌至仅6厘米，打破了2018年创下的25厘米历史最低纪录，导致重载油轮无法通行；牛津经济研究院估计，这一航运中断将导致今年德国GDP增速直接损失0.2个百分点。当今世界不仅面临地缘政治主体重新对开放航道设卡寻租的倒退风险，更面临全球公共品供给体系日益失序与气候环境承载力衰竭的双重危机。
Historically, toll castles on the Rhine such as Pfalzgrafenstein extracted "economic rents" by rendering natural waterways artificially scarce—a rent-seeking model threatening to resurface in modern geopolitics. Following the outbreak of the Gulf war in February, the Strait of Hormuz, which handled roughly 20% of global oil shipments pre-war, faces potential tolls as Iran considers levying fees, Oman contemplates joining, and Donald Trump suggests America charge passing vessels as the strait's "guardian". As economist Anne Krueger theorized in 1974, artificial trade restrictions breed unproductive and destructive rent-seeking contests, manifesting modernly through lethal drone warfare and maritime skirmishes.
For two centuries, freedom of navigation persisted as a public good sustained by maritime hegemons under Charles Kindleberger’s hegemonic stability theory. Regional tolls were dismantled internationally—such as the abolition of Danish Baltic Sound dues in 1857 and Rhine tolls in 1868—while global sea lanes were secured first by Britain (beginning with 1820 Persian Gulf treaties) and later by America after 1971. Today, this security architecture is unravelling as America retreats from its overseas policing role and cheap drones render power projection asymmetric. While proposals suggest coalitions of "middle powers" could safeguard maritime corridors, economic research warns that distributed power balances typically trigger free-riding and strategic paralysis.
Beyond geopolitical rent extraction, the erosion of natural public goods presents immediate economic shocks. A severe three-month European heatwave and drought has plunged Rhine water levels at Kaub to just six centimetres, shattering the previous record low of 25cm in 2018 and preventing heavily laden tankers from navigating the river; consultancy Oxford Economics estimates this bottleneck will shave 0.2 percentage points off German GDP this year. The global economy thus faces a dual breakdown: state actors seeking to monetize previously free international waters, alongside a diminishing collective capacity to maintain essential infrastructural and climatic public goods.
Source: The high cost of phantom tollbooths
Subtitle: Freedom of navigation is worth preserving
Dateline: 8月 20, 2026 03:30 上午