Abstract. Recent analyses show the importance of methane shortwave absorption, which many climate models lack. In particular, Allen et al. (2023) used idealized climate model simulations to show that methane shortwave absorption mutes up to 30 % of the surface warming and 60 % of the precipitation increase associated with its longwave radiative effects. Here, we explicitly quantify the radiative and climate impacts due to shortwave absorption of the present-day methane perturbation using the Community Earth System Model version 2. Our results corroborate that present-day methane shortwave absorption mutes the warming and wetting effects of longwave absorption. For example, the global mean cooling in response to the present-day methane shortwave absorption is -0.10 ± 0.04 K, which offsets 29 % of the surface warming associated with present-day methane longwave radiative effects. Similarly, we explicitly estimate 66 % of the precipitation increase associated with the longwave radiative effects of the present-day methane perturbation is offset by shortwave absorption. Unlike other solar absorbers (i.e., black carbon), the decrease in global mean precipitation under methane shortwave absorption is driven by both fast (atmospheric absorption) and slow (surface temperature cooling) responses. Finally, we show that the present-day methane shortwave radiative effects, relative to its longwave radiative effects, are about five times larger as compared to those under idealized carbon dioxide perturbations. The unique responses to methane shortwave absorption are related to its vertical atmospheric solar heating profile. Methane remains a potent greenhouse gas and continued endeavors to decrease methane emissions are necessary to stay below the 1.5 °C global warming threshold.

中文翻译：

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相对于工业化前的条件，当今的甲烷短波吸收减弱了地表变暖和湿润

摘要。最近的分析表明了甲烷短波吸收的重要性，而许多气候模型都缺乏这一点。特别是，艾伦等人。 (2023) 使用理想化气候模型模拟表明，甲烷短波吸收可减弱高达 30% 的地表变暖和 60% 与其长波辐射效应相关的降水增加。在这里，我们使用社区地球系统模型版本 2 明确量化了当前甲烷扰动的短波吸收造成的辐射和气候影响。我们的结果证实，当前甲烷短波吸收减弱了长波吸收的变暖和湿润效应。例如，响应当前甲烷短波吸收的全球平均降温为 -0.10 ± 0.04 K，这抵消了与当前甲烷长波辐射效应相关的地表变暖的 29%。同样，我们明确估计与当今甲烷扰动的长波辐射效应相关的降水增加的 66% 被短波吸收抵消。与其他太阳能吸收器（即黑碳）不同，甲烷短波吸收下全球平均降水量的减少是由快速（大气吸收）和缓慢（表面温度冷却）响应驱动的。最后，我们表明，目前的甲烷短波辐射效应相对于其长波辐射效应，大约是理想二氧化碳扰动下的五倍。对甲烷短波吸收的独特响应与其垂直大气太阳加热剖面有关。甲烷仍然是一种强效温室气体，为了将全球变暖控制在 1.5 °C 阈值以下，需要继续努力减少甲烷排放。