大気中のCO2は,植物の急激な変化を局所的に引き起こすが,地球規模では起こらない
Steven I Higgins1, Simon Scheiter
1Institut für Physische Geographie, Goethe Universität Frankfurt am Main, 60438 Frankfurt am Main, Germany. higgins@em.uni-frankfurt.de
Nature
|July 6, 2012
まとめ
人為的な気候変動は,地球システムを新しい状態に押し込む可能性があります. 熱帯の生態系は,二酸化炭素のレベルが上昇しているため,より高いバイオマスまたは木質状態に移行する可能性が高い.
科学分野:
- 地球システム科学 地球システム科学
- 気候変動 生物学
- エコロジー エコロジー エコロジー
背景:
- 地球系科学者は,国家を急激にシフトさせることができる大規模な構成要素であるティッピング要素について懸念しています.
- 大規模な植生系が転覆行動を示す可能性は十分に理解されていません.
- 熱帯の草原,サバンナ,森林の生態系は,地球システムの重要な構成要素です.
研究 の 目的:
- 熱帯植生系が代替状態に転移する可能性があるかどうかを調査する.
- 大気中の二酸化炭素の増加が植生状態に与える影響を判断する.
- 植生体制の変化のタイミングと場所に影響を与える要因を分析する.
主な方法:
- 気候変動シナリオに対する植物の反応のモデリング.
- 熱帯の草原,サバンナ,森林の生態系における転換点の分析.
- CO2濃度,気温上昇,火災の重症度,降雨の変動による影響の評価.
主要な成果:
- 熱帯の草原,サバンナ,森林の生態系は,代替状態に移行する可能性が高い.
- 大気中のCO2濃度の上昇は,より高いバイオマスおよび/または木質植物の優位性のある状態への移行を促すでしょう.
- これらのシフトのタイミングは,気温上昇率,火災の深刻さ,降雨量,そしてビスタブルな植生地帯の移動に依存します.
結論:
- 陸上の生態系における大規模な方向的体制のシフトは,気候変動による可能性が高い.
- 異なる地域における非同期的なシフトは,地球システムに対する全体的な影響を軽減するかもしれないが,排除することは出来ない.
- これらの植生の臨界点を理解することは,将来の地球システム状態を予測するために極めて重要です.
関連する概念動画
01:50Global Climate Change
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.
01:14The Carbon Cycle
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.
01:27Microbes and Climate Change
Microorganisms are pivotal agents in Earth's biogeochemical cycles, significantly influencing climate dynamics through their metabolic activities. These microbes modulate the levels of key greenhouse gases by both contributing to and helping mitigate climate change.Microbial Contributions to Greenhouse Gas EmissionsRising global temperatures accelerate microbial metabolism, which, in turn, speeds up the decomposition of organic matter. This process releases carbon dioxide (CO₂) through...
02:26Ecological Disturbance
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.
01:18Variation of Atmospheric Pressure
Change in atmospheric pressure with height is particularly interesting. The decrease in atmospheric pressure with increasing altitude is due to the decreasing gravitational force per unit area as we move away from the surface of the earth.
Assuming the air temperature is constant at a given altitude and that the ideal gas law of thermodynamics describes the atmosphere to a good approximation, one can find the variation of atmospheric pressure with height.
Let p(y) be the atmospheric pressure at...
Assuming the air temperature is constant at a given altitude and that the ideal gas law of thermodynamics describes the atmosphere to a good approximation, one can find the variation of atmospheric pressure with height.
Let p(y) be the atmospheric pressure at...
02:04Regulation of Transpiration by Stomata
During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma—derived from the Greek word for “mouth.” Stomata open and close in response to a variety of environmental cues.