最後の氷河期におけるバイオマス燃焼の急激な変化
Ben Riddell-Young1,2, James Edward Lee3, Edward J Brook4
1College of Earth, Ocean, and Atmospheric Sciences (CEOAS), Oregon State University, Corvallis, OR, USA. Benjamin.riddell-young@noaa.gov.
Nature
|January 1, 2025
まとめ
過去の氷河期におけるメタン (CH4) の変化は,急激な気候変動に関連した野火の活動の増加によって引き起こされました. この研究では 氷の核のイソトープを用いて 大気中のCO2レベルに影響を及ぼす 火事によるメタン排出量の増加を明らかにしました
科学分野:
- 古代気候学
- 大気化学
- 地上生物化学
背景:
- 大気中のメタン (CH4) の変動は,過去の気候動態と炭素循環を理解するために重要です.
- 氷の核の記録は,ダンズガード・オシュガー (DO) やハインリッヒ (HE) のような急激な気候現象に関連した急速なCH4変動を示しています.
- これらのCH4変化の正確な要因は不明であり,同位体分析が必要である.
研究 の 目的:
- 最後の氷河期における急激な大気中のCH4の変化の原因を調査する.
- 安定同位体測定を用いてCH4の変動源を制限する.
- CH4の排出と急激な気候変化と炭素循環への影響を関連付けること
主な方法:
- 南極の氷核 (WAISディバイドとタロスドーム) から安定した同位体 (δ13C-CH4とδD-CH4) を数十年スケールで測定した.
- DOおよびHEイベント中のCH4パルスと同期した同位体シフトの分析.
- 同位体データを解釈し,排出源の変化を推論するためにボックスモデルを使用する.
主要な成果:
- HE CH4パルスとの同期で観測された δ13C-CH4の急激な ~ 1 ‰ の濃縮.
- 突発的な~0. 5 ‰の δ13C-CH4 濃度増加は,DO CH4 濃度増加と並行して観察された.
- 突発的なCH4の変化における δD-CH4の最小の変動は,微生物または地質的な源における限られたシフトを示唆する.
結論:
- HEsとDOイベントの間の急激な熱帯雨のシフトは,地球規模での野火の拡大を示し,13C濃縮された熱生成CH4の排出量を90-150%増加させた可能性が高い.
- これらの火によるCH4排出は,HEsに関連した突然のCO2増加の3分の1を占める可能性があります.
- 火災や地球上の炭素循環は 過去の急激な気候変化に合わせて 明らかに変化しました
関連する概念動画
01:50Global Climate Change
24.2K
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
24.2K
01:50Threats to Biodiversity
22.1K
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...
22.1K
02:26Ecological Disturbance
17.0K
An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced change in an ecosystem. The impact of an ecological disturbance, which can depend on its intensity, frequency, and spatial distribution, plays a significant role in shaping the species diversity within the ecosystem.
17.0K
01:14The Carbon Cycle
37.0K
Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
37.0K
02:17Ecological Succession
17.1K
Ecological succession is influenced by the processes of facilitation, inhibition, and toleration. Facilitation occurs when early successional species create more favorable ecological conditions for subsequent species, such as enhanced nutrient, water, or light availability. In contrast, inhibition happens when early successional species create unfavorable ecological conditions for potential successive species, such as limiting resource availability. In some cases, later successional species...
17.1K
00:54What are Biogeochemical Cycles?
31.0K
The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited amounts. Therefore, these nutrients must be recycled through both biotic and abiotic components of the ecosystem, in processes generally called biogeochemical cycles.
31.0K