美国哈佛大学Adams Danica课题组在最新研究中，报道了早期火星上由地壳水合作用引起的间歇性温暖气候。这一研究成果发表在2025年1月15日出版的国际学术期刊《自然—地球科学》上。

据了解，地质记录表明，古代火星表面蕴藏着大量的液态水，这种资源随着水合作用和大气逸出等过程而逐渐减少。然而，早期火星上相对温暖的气候是如何在微弱的年轻太阳下支持液态水的，这一点一直存在争议。在富CO₂的大气中，H₂等温室气体可能通过碰撞诱导的吸收而促进变暖，但是否有足够的H₂来抑制变暖尚不清楚。

在这里，该课题组人员将气候和光化学模型结合起来，在现有观测的限制下，模拟早期火星的大气化学如何对水—岩石反应和气候变化做出响应。结果发现，在短暂的火山活动的辅助下，熔融水化和氧化产生的H₂可能产生足够的氢气通量，从而短暂地形成温暖潮湿的气候。

研究人员估计火星经历了连续的暖期，总持续时间约为4000万年，每次事件持续时间≥10⁵年，与山谷网络的形成时间尺度一致。通过地表氧化剂汇下沉或地球轴向倾斜的变化，大气中CO₂的减少可能导致行星氧化还原状态的突然转变，并过渡到CO主导的大气和寒冷气候中。

附：英文原文

Title: Episodic warm climates on early Mars primed by crustal hydration

Author: Adams, Danica, Scheucher, Markus, Hu, Renyu, Ehlmann, Bethany L., Thomas, Trent B., Wordsworth, Robin, Scheller, Eva, Lillis, Rob, Smith, Kayla, Rauer, Heike, Yung, Yuk L.

Issue&Volume: 2025-01-15

Abstract: Geological records indicate that the surface of ancient Mars harboured substantial volumes of liquid water, a resource gradually diminished by processes such as the chemical alteration of crustal materials by hydration and atmospheric escape. However, how a relatively warm climate existed on early Mars to support liquid water under a fainter young Sun is debated. Greenhouse gases such as H₂ in a CO₂-rich atmosphere could have contributed to warming through collision-induced absorption, but whether sufficient H₂ was available to sustain warming remains unclear. Here we use a combined climate and photochemical model to simulate how atmospheric chemistry on early Mars responded to water–rock reactions and climate variations, as constrained by existing observations. We find that H₂ outgassing from crustal hydration and oxidation, supplemented by transient volcanic activity, could have generated sufficient H₂ fluxes to transiently foster warm, humid climates. We estimate that Mars experienced episodic warm periods of an integrated duration of ~40 million years, with each event lasting ≥105 years, consistent with the formation timescale of valley networks. Declining atmospheric CO₂ via surface oxidant sinks or variations in the planet’s axial tilt could have led to abrupt shifts in the planet’s redox state and transition to a CO-dominated atmosphere and cold climate.

DOI: 10.1038/s41561-024-01626-8

Source: https://www.nature.com/articles/s41561-024-01626-8