碳排放是否會影響人類認知？

Lots of climate change literature points out that atmospheric carbon dioxide levels have never in the entire history of the human species been as high as they are today. Over the past 800,000 years, until the start of the Industrial Revolution, carbon dioxide in the atmosphere varied from about 200 to 300 parts per million (ppm). Since the early 1800s, the concentration has increased nearly 50%, from 280 ppm to 411 ppm in 2019.

許多氣候變化的文獻指出，在整個人類歷史上，大氣中的二氧化碳水平從來沒有像今天這樣高。在過去的80萬年中，直到工業(yè)革命開始，大氣中的二氧化碳含量在百萬分之200到300之間變化。自19世紀初以來，該濃度已從280 ppm增加到2019年的411 ppm，增幅近50%。

This change, and even the whole idea of conditions unprecedented in our evolutionary history, often seems rather abstract. But carbon dioxide levels in the atmosphere could have direct effects on human physiology – perhaps eroding the keen intelligence and capacity for abstract thinking that we like to think of as a hallmark of our species, a new study suggests.

這種變化，甚至是我們進化史上史無前例的整個條件概念，往往顯得相當抽象。但是，一項新的研究表明，大氣中的二氧化碳水平可能會直接影響人類的生理機能——也許會侵蝕我們喜歡把抽象思維視為人類特征的敏銳智慧和能力。

There’s a fair bit of research on carbon dioxide and cognitive function in humans. This started out because scientists wanted to know about the effects on people in tight quarters like submarines and aircraft. More recently, they’ve looked at how carbon dioxide accumulates in densely populated, sometimes poorly ventilated indoor spaces such as schools and office buildings.

關(guān)于二氧化碳和人類認知功能的研究相當多。這是因為科學(xué)家們想知道像潛艇和飛機這樣的狹小空間對人的影響。最近，他們研究了二氧化碳如何在人口稠密、有時通風不良的室內(nèi)空間(如學(xué)校和辦公樓)積聚。

Broadly speaking, such studies suggest that people’s cognitive functioning suffers when they are in a space with increased carbon dioxide in the air. Sometimes the relationship is linear (as in the case of overall decision-making ability) and sometimes there is a big drop off at higher concentrations (as with complex strategizing).

廣義地說，這些研究表明，當人們身處空氣中二氧化碳含量增加的空間時，他們的認知功能會受到影響。有時這種關(guān)系是線性的(如在整體決策能力的情況下)，有時在較高的集中度下會有很大的下降(如復(fù)雜的戰(zhàn)略制定)。

But this research has received little attention from climate scientists until now, perhaps because climate scientists are mostly concerned with outdoor carbon dioxide levels and carbon dioxide-cognition research has focused on the indoor environment.

但這項研究迄今為止很少受到氣候科學(xué)家的關(guān)注，也許是因為氣候科學(xué)家主要關(guān)注室外的二氧化碳水平，而二氧化碳認知研究則側(cè)重于室內(nèi)環(huán)境。

A team of researchers from the University of Colorado and the University of Pennsylvania set out to bridge the gap. They started with scenarios developed by the Intergovernmental Panel on Climate Change, which predict atmospheric carbon dioxide concentrations at the end of the century ranging from 420 ppm if carbon emissions are drastically reduced to 930 ppm if emissions levels of recent years continue.

來自科羅拉多大學(xué)和賓夕法尼亞大學(xué)的一組研究人員著手縮小差距。他們從政府間氣候變化專門委員會開發(fā)的情景開始，該情景預(yù)測到本世紀末大氣中的二氧化碳濃度，如果碳排放量大幅減少，則為420 ppm，如果近年來的排放水平持續(xù)降低，則為930 ppm。

They accounted for higher carbon dioxide levels frequently seen in cities because of fossil fuel burning—a so-called “urban carbon dioxide dome” that amounts to about 66 ppm. Then they applied a set of equations based on known relationships between outdoor and indoor carbon dioxide levels. Indoor carbon dioxide concentrations are always higher than outdoor levels, to a degree depending on the building’s ventilation system, how many people are inside exhaling carbon dioxide with every breath, and how large the space is.

它們造成了由于化石燃料燃燒而在城市中經(jīng)常出現(xiàn)的較高的二氧化碳含量，所謂的“城市二氧化碳圓頂”約為66 ppm。然后，他們根據(jù)室外和室內(nèi)二氧化碳水平之間的已知關(guān)系應(yīng)用了一組方程式。室內(nèi)二氧化碳的濃度總是高于室外，在一定程度上取決于建筑物的通風系統(tǒng)，每口呼氣中有多少人呼出二氧化碳以及空間有多大。

Finally, they cross-referenced the resulting indoor carbon dioxide concentrations with the results of studies on carbon dioxide and cognition. “The model predictions are quite arresting,” the researchers write in the journal GeoHealth. If today’s high carbon emissions were to continue, “we may be in for a ~25% reduction in our indoor basic decision-making ability, and a ~50% reduction in more complex strategic thinking, by the year 2100 relative to today.”

最后，他們將得出的室內(nèi)二氧化碳濃度與二氧化碳和認知研究的結(jié)果交叉引用。研究人員在《地球健康》(GeoHealth)雜志上寫道：“模型預(yù)測相當令人信服。”。如果今天的高碳排放繼續(xù)下去，“到2100年相對今天，我們的室內(nèi)基本決策能力可能會下降約25%，更復(fù)雜的戰(zhàn)略思維可能會下降約50%。”

“These results are almost entirely avoidable” if emissions are reduced to levels consistent with the Paris Agreement, they add.

他們補充說，如果排放量減少到與《巴黎協(xié)定》一致的水平，“這些結(jié)果幾乎完全可以避免。”。

The results are a first pass at the problem—the researchers’ model is relatively simple—but they show that more attention to these questions is needed.

研究結(jié)果是解決這個問題的第一步。研究者的模型相對簡單，但他們表明需要更多的關(guān)注這些問題。