科學家模擬小行星碰撞對氣候和植物的影響

IBS氣候物理中心（ICCP）的研究人員發表在《科學雜誌》上的一項新的氣候建模研究發表在韓國帕桑國立大學的研究人員，提出了一種新的情況，講述了我們星球上的氣候和生命如何改變，以應對潛在的未來，以應對潛在的未來中型（〜500 m）小行星的罷工。

A new climate modeling study presents a scenario of how climate and life on our planet would change in response to a potential future strike of a medium-sized (~500 m) asteroid.

一項新的氣候建模研究提出了一種方案，即我們星球上的氣候和生命將如何改變中型（〜500 m）小行星的未來罷工。

The solar system is full of objects with near-Earth orbits. Most of them do not pose any threat to Earth, but some of them have been identified as objects of interest with non-negligible collision probabilities. Among them is the asteroid Bennu with a diameter of about 500 m, which, according to recent studies, has an estimated chance of 1-in-2700 of colliding with Earth in September 2182. This is similar to the probability of flipping a coin 11 times in a row with the same outcome.

太陽系中充滿了近地軌道的物體。他們中的大多數不會對地球構成任何威脅，但是其中一些被確定為具有不可忽略的碰撞概率的感興趣對象。其中包括小行星Bennu，直徑約為500 m，根據最近的研究，估計在2182年9月與地球碰撞的機會估計有可能。這類似於翻轉硬幣11的概率。連續有相同的結果。

To determine the potential impacts of an asteroid strike on our climate system and on terrestrial plants and plankton in the ocean, researchers from the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea set out to simulate an idealized collision scenario with a medium-sized asteroid using a state-of-the-art climate model. The effect of the collision is represented by a massive injection of several hundred million tons of dust into the upper atmosphere. Unlike previous studies, the new research also simulates terrestrial and marine ecosystems, as well as the complex chemical reactions in the atmosphere.

為了確定小行星罷工對我們氣候系統以及海洋陸地植物和浮游生物的潛在影響，韓國Pusan National University IBS氣候物理中心（ICCP）的研究人員開始模擬與理想化的碰撞方案使用最先進的氣候模型的中型小行星。碰撞的作用是大量注入了幾億噸灰塵到上層大氣中的作用。與以前的研究不同，新研究還模擬了陸地和海洋生態系統，以及大氣中的複雜化學反應。

Using the IBS supercomputer Aleph, the researchers ran several dust impact scenarios for a Bennu-type asteroid collision with Earth. In response to dust injections of 100–400 million tons, the supercomputer model simulations show dramatic disruptions in climate, atmospheric chemistry, and global photosynthesis in the 3–4 years following the impact (Figure 1).

研究人員使用IBS超級計算機Aleph，為Bennu型小行星與地球碰撞進行了幾種塵埃衝擊方案。為了響應100-4億噸的塵埃注射，超級計算機模型模擬顯示了影響後的3-4年，氣候，大氣化學和全球光合作用發生了巨大破壞（圖1）。

For the most intense scenario, solar dimming due to dust would cause global surface cooling of up to 4˚C, a reduction of global mean rainfall by 15%, and severe ozone depletion of about 32%. However, regionally, these impacts could be much pronounced.

對於最激烈的情況，由於灰塵而引起的太陽變暗會導致全球表面冷卻高達4°C，全球平均降雨量減少15％，而嚴重的臭氧耗竭約為32％。但是，從區域上講，這些影響可能很明顯。

“The abrupt impact winter would provide unfavorable climate conditions for plants to grow, leading to an initial 20–30% reduction of photosynthesis in terrestrial and marine ecosystems. This would likely cause massive disruptions in global food security,” says Dr. Lan Dai, postdoctoral research fellow at the ICCP and lead author of the study.

“突然的影響冬季將為植物生長提供不利的氣候條件，從而導致陸地和海洋生態系統的光合作用最初降低20–30％。 ICCP博士後研究員，研究的主要作者Lan Dai博士說：“這可能會造成全球糧食安全的大規模干擾。”

When the researchers looked into ocean model data from their simulations, they were surprised to find that plankton growth displayed a completely different behaviour. Instead of the rapid reduction and slow two-year-long recovery on land, plankton in the ocean recovered within 6 months and even increased afterwards to levels not even seen under normal climate conditions.

當研究人員從模擬中研究海洋模型數據時，他們驚訝地發現浮游生物的增長表現出完全不同的行為。海洋中的浮游生物在6個月內恢復，甚至在正常的氣候條件下甚至沒有看到水平，而不是在土地上迅速減少和長達兩年的恢復，而是恢復了。

“We were able to track this unexpected response to the iron concentration in the dust,” says Prof. Axel Timmermann, Director of the ICCP and co-author of the study. Iron is a key nutrient for algae, but in some areas, such as the Southern Ocean and the eastern tropical Pacific, its natural abundance is very low.

ICCP主任兼研究合著者Axel Timmermann教授說：“我們能夠跟踪對灰塵中鐵濃度的意外反應。”鐵是藻類的關鍵營養素，但是在某些地區，例如南大洋和東部熱帶太平洋地區，其自然豐度非常低。

Depending on the iron content of the asteroid and of the terrestrial material, that is blasted into the stratosphere, the otherwise nutrient-depleted regions can become nutrient-enriched with bioavailable iron, which in turn triggers unprecedented algae blooms. According to the computer simulations, the post-collision increase of marine productivity would be most pronounced for silicate-rich algae—referred to as diatoms. Their blooms would also attract large amounts of zooplankton—small predators, which feed on the diatoms.

根據被爆破到平流層的小行星和陸地材料的鐵含量，原本營養不良的區域可能會用可生物利用鐵富集營養，從而誘發前所未有的藻類膨脹。根據計算機模擬，對於富含矽酸鹽的藻類而言，海洋生產率的爆發後提高將最為明顯，以矽酸鹽為矽藻。它們的花朵還會吸引大量的浮游動物 - 小捕食者，這些掠食者以矽藻為食。

“The simulated excessive phytoplankton and zooplankton blooms might be a blessing for the biosphere and may help alleviate emerging food insecurity related to the longer-lasting reduction in terrestrial productivity,” adds Dr. Lan Dai.

Lan dai博士補充說：“模擬過多的浮游植物和浮游動物的盛開可能對生物圈來說是一種祝福，可能有助於減輕與陸地生產力降低長期降低有關的新出現的糧食不安全。”

“On average, medium-sized asteroids collide with Earth about every 100–200 thousand years. This means that our early human ancestors may have experienced some of these planet-shifting events before with potential impacts on human evolution and even our own genetic makeup,” says Prof. Timmermann.

“平均而言，中型小行星與地球相撞約100–200千年。這意味著，我們的早期人類祖先可能已經經歷了這些星球轉變事件中的某些事件，並可能對人類進化甚至我們自己的遺傳構成產生影響。” Timmermann教授說。

The new study in Science Advances provides new insights into the climatic and biospheric responses to collisions with near-Earth orbit objects. In the next step the ICCP researchers from South Korea plan to study early human responses to such events in more detail by using agent-based computer models, which simulate individual humans, their life cycles and their search for food.

科學進步的新研究為氣候和生物圈對與近地軌道物體的碰撞的反應提供了新的見解。下一步，ICCP的ICCP研究人員計劃通過使用基於代理的計算機模型來詳細研究對此類事件的早期反應，這些計算機模型模擬了人類，他們的生命週期和尋找食物。