Plants influence extreme heat events by regulating land-atmosphere water and energy exchanges. The contribution of plants to changes in future heat extremes will depend on the responses of vegetation growth and physiology to the direct and indirect effects of elevated CO₂. Here we use a suite of earth system models to disentangle the radiative versus vegetation effects of elevated CO₂ on heat wave characteristics. Vegetation responses to a quadrupling of CO₂ increase summer heat wave occurrence by 20 days or more-30-50% of the radiative response alone-across tropical and mid-to-high latitude forests. These increases are caused by CO₂ physiological forcing, which diminishes transpiration and its associated cooling effect, and reduces clouds and precipitation. In contrast to recent suggestions, our results indicate CO₂-driven vegetation changes enhance future heat wave frequency and intensity in most vegetated regions despite transpiration-driven soil moisture savings and increases in aboveground biomass from CO₂ fertilization.

中文翻译：

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植物二氧化碳生理强迫对极端高温的放大。


植物通过调节陆地-大气水和能量交换来影响极端高温事件。植物对未来极端高温变化的贡献将取决于植被生长和生理对CO ₂升高的直接和间接影响的反应。在这里，我们使用一套地球系统模型来理清 CO ₂升高对热浪特征的辐射与植被影响。植被对四倍 CO ₂的反应使热带和中高纬度森林的夏季热浪发生时间延长 20 天或更长，仅辐射反应的 30-50%。这些增加是由CO ₂生理强迫引起的，它减少了蒸腾作用及其相关的冷却效应，并减少了云和降水。与最近的建议相反，我们的结果表明，尽管蒸腾作用驱动了土壤水分节约，并且CO ₂施肥导致地上生物量增加，但CO ₂驱动的植被变化增强了大多数植被地区未来热浪的频率和强度。