12.2 Influence of plate tectonics on climate and ocean circulation
4 min read•august 16, 2024
Plate tectonics shapes Earth's climate and oceans in profound ways. Continental positions affect heat distribution, while mountain building creates diverse regional climates. These processes influence atmospheric circulation, ocean currents, and global temperature patterns.
Tectonic activity also drives long-term climate shifts. The opening and closing of ocean gateways alter circulation patterns, while volcanic emissions and weathering impact atmospheric CO2 levels. These changes can trigger transitions between icehouse and greenhouse conditions.
Continents and Global Climate
Land-Ocean Distribution and Heat Patterns
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- Continental configuration influences global heat distribution and atmospheric circulation patterns
- Affects the ratio of land to ocean surface area
- Impacts heat capacity and thermal inertia of Earth's surface
- Position of continents relative to the equator affects the albedo effect
- Influences amount of solar radiation absorbed or reflected by Earth's surface
- Higher albedo in polar regions (ice and snow) reflects more sunlight
- Lower albedo in tropical regions (dense vegetation) absorbs more sunlight
- Ocean currents shaped by continent arrangement affect heat transfer
- Warm currents (Gulf Stream) transport heat from equatorial to polar regions
- Cold currents (Humboldt Current) bring cooler water towards the equator
- Large landmasses create continental climates
- Characterized by extreme temperature variations (hot summers, cold winters)
- Reduced precipitation in interior regions due to distance from moisture sources
Tectonic-Driven Climate Shifts
- Plate tectonic changes in continental positions lead to significant climate shifts
- Ice ages occur when continents are positioned near poles (Gondwana supercontinent)
- Greenhouse periods develop when continents are dispersed (Cretaceous period)
- affects global atmospheric circulation patterns
- Changes in land-sea distribution alter Hadley, Ferrel, and polar cells
- Impacts locations of major wind systems (trade winds, westerlies)
- Supercontinent formation and breakup influence climate extremes
- 's interior experienced severe continental climate (extreme aridity)
- Breakup of Pangaea led to more moderate climates and increased biodiversity
Plate Tectonics and Ocean Formation
Ocean Basin Morphology
- Plate tectonic processes create and modify
- Seafloor spreading at mid-ocean ridges forms new oceanic crust
- at trenches recycles old oceanic crust back into the mantle
- Affects size, shape, and depth of ocean basins (Pacific vs. Atlantic Ocean)
- Mid-ocean ridges and trenches affect deep ocean circulation
- Ridge systems create barriers and channels for deep water flow
- Trenches serve as pathways for cold, dense water to sink into the deep ocean
- Seafloor topography influences major ocean currents and gyre formation
- Seamounts and submarine ridges deflect currents (Kuroshio Current)
- Basin shape affects gyre circulation patterns (North Atlantic Gyre)
Oceanic Gateways and Circulation
- Plate movements create or close oceanic gateways
- Opening of Drake Passage (~41 million years ago) enabled circumpolar current
- Closure of Panama Isthmus (~3 million years ago) separated Atlantic and Pacific
- Changes in ocean circulation patterns alter global heat distribution
- Formation of Antarctic Circumpolar Current isolated Antarctica, leading to glaciation
- Gulf Stream intensification after Panama Isthmus closure warmed North Atlantic
- Uplift of continental margins affects coastal upwelling
- Plate collisions can elevate coastal areas (Andes Mountains)
- Enhanced upwelling brings nutrient-rich waters to surface, impacting marine ecosystems
- Influences regional climate (coastal fog, cooler temperatures)
Mountain Building and Regional Climates
Orographic Effects on Weather
- Orogenesis creates topographic barriers affecting atmospheric circulation
- interrupt prevailing winds (Rocky Mountains, Andes)
- Alters jet stream patterns and storm tracks
- creates distinct climatic zones
- Windward slopes receive increased precipitation (Olympic Mountains)
- Leeward sides experience arid conditions (Great Basin Desert)
- High-elevation ranges induce orographic lifting
- Forces air masses to rise, cool, and release moisture (Sierra Nevada)
- Creates wet microclimates on windward slopes (temperate rainforests)
- Mountain building alters regional wind patterns
- Katabatic winds form as cold air descends mountain slopes (Santa Ana winds)
- Valley and mountain breezes develop due to differential heating
Monsoon Systems and Precipitation
- Extensive mountain ranges influence monsoon systems
- Tibetan Plateau intensifies Asian monsoon by creating strong temperature gradient
- Andes Mountains affect South American monsoon circulation
- Mountains modify atmospheric pressure gradients
- Enhanced land-sea temperature differences strengthen monsoon circulation
- Affects timing and intensity of seasonal precipitation patterns
- Orographic lifting amplifies monsoon rainfall
- Western Ghats in India receive intense monsoon precipitation
- Creates distinct wet and dry seasons in many tropical and subtropical regions
Plate Tectonics vs Climate Change
Carbon Cycle and Atmospheric CO2
- Plate tectonic processes influence the global carbon cycle
- Volcanism releases CO2 into the atmosphere (mid-ocean ridges, subduction zones)
- Weathering of silicate rocks removes CO2 from atmosphere (Himalayan uplift)
- Burial of organic matter in sedimentary basins sequesters carbon
- Mountain building enhances chemical weathering
- Increased exposure of fresh rock surfaces accelerates CO2 drawdown
- Can lead to long-term cooling trends (Late Cenozoic cooling)
- Changes in ocean basin configuration affect CO2 solubility
- Cooler oceans can absorb more CO2, reducing atmospheric concentrations
- Warmer oceans release CO2, potentially amplifying greenhouse effects
Tectonic-Driven Climate Transitions
- Formation and breakup of supercontinents trigger climate shifts
- Pangaea breakup led to increased humidity and reduced continental interiors
- Assembly of Gondwana coincided with late Ordovician glaciation
- Changes in ocean circulation patterns impact global climate states
- Opening of Southern Ocean gateway led to Antarctic glaciation
- Closure of Tethys Sea altered heat transport, affecting European climate
- Continental distribution across latitudes affects global albedo
- Concentration of landmasses at high latitudes increases global albedo
- Equatorial landmasses decrease albedo, potentially warming global climate
- Plate tectonic activity influences transitions between climate states
- Icehouse conditions develop with high albedo and enhanced CO2 drawdown
- Greenhouse periods occur with low albedo and increased volcanic CO2 emissions
Key Terms to Review (18)
Cenozoic Era: The Cenozoic Era is the most recent geological era, spanning from about 66 million years ago to the present. It is characterized by significant developments in mammalian and avian life, major climatic shifts, and the continuing movement of tectonic plates that influence global geography, climate, and ocean circulation patterns.
CO2 emissions from tectonics: CO2 emissions from tectonics refer to the release of carbon dioxide into the atmosphere as a result of geological processes associated with plate tectonics. These emissions primarily occur through volcanic activity, where magma from the Earth's mantle brings carbon compounds to the surface, and through the metamorphism of carbonate rocks during subduction processes. This natural release of CO2 plays a crucial role in influencing long-term climate patterns and ocean circulation.
Continental Drift: Continental drift is the theory that continents have moved slowly over geological time from their original positions to their current locations. This concept helps explain the formation of continents and ocean basins, as well as the distribution of various geological features and living organisms across the globe.
Eustatic Changes: Eustatic changes refer to global changes in sea level resulting from variations in the volume of water in the oceans or alterations in ocean basin capacity. These changes can occur due to several factors, including glacial melting, thermal expansion of water, and tectonic activity, ultimately influencing climate patterns and ocean circulation on a global scale.
Gyres: Gyres are large systems of circulating ocean currents, typically influenced by the wind patterns and the Earth's rotation. They play a crucial role in regulating the climate by redistributing heat across the planet, thus impacting weather patterns and oceanic ecosystems.
Isostatic Rebound: Isostatic rebound refers to the process of Earth's crust rising after the removal of overlying material, such as ice sheets or sediment. This phenomenon occurs as the lithosphere, which is the rigid outer layer of the Earth, adjusts to changes in surface load, allowing the crust to reach a new equilibrium state. As glaciers melt or sediments are eroded, the weight on the crust decreases, causing it to rise and often resulting in changes to landscapes and even affecting sea levels.
Monsoons: Monsoons are seasonal wind patterns that cause significant changes in precipitation and temperature, typically associated with the Indian Ocean and Southeast Asia. They result from differential heating between land and sea, which leads to strong winds that bring moisture-laden air during certain seasons, often causing heavy rainfall. The unique climate created by monsoons has a profound impact on agriculture, ecosystems, and human activities in affected regions.
Mountain Ranges: Mountain ranges are a series of peaks and ridges formed by tectonic forces, where the Earth's crust is uplifted, folded, or faulted. They are often associated with the collision of tectonic plates, resulting in distinct geological features and ecosystems that influence both the landscape and climate.
Ocean basins: Ocean basins are large geological depressions in the Earth's crust that hold the world's oceans. They are formed by tectonic processes, including plate tectonics, and play a crucial role in the distribution of water on Earth. The structure and evolution of ocean basins influence global climate patterns, ocean circulation, and even the formation and breakup of supercontinents.
Orographic effect: The orographic effect refers to the changes in atmospheric conditions that occur when air masses are forced to ascend over topographic barriers, such as mountains. This phenomenon can lead to increased precipitation on the windward side of the mountains while creating dry conditions on the leeward side, known as a rain shadow. This effect has significant implications for climate patterns and vegetation distribution in regions influenced by mountains.
Paleoclimate: Paleoclimate refers to the climate of a particular region or the Earth as a whole during previous geological periods, inferred from geological evidence. It helps scientists understand how climate has changed over millions of years due to various factors, including changes in plate tectonics, ocean circulation, and atmospheric composition.
Pangaea: Pangaea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras, roughly 335 to 175 million years ago, when it began to break apart. This vast landmass is significant as it provides insights into the historical movements of tectonic plates, influencing geological formations and the distribution of ancient flora and fauna across the planet.
Plate Tectonic Theory: Plate tectonic theory is the scientific concept that explains the movement of the Earth's lithosphere, which is divided into several large and small tectonic plates. These plates float on the semi-fluid asthenosphere beneath them, and their interactions are responsible for many geological phenomena such as earthquakes, volcanic activity, mountain building, and oceanic trench formation. Understanding this theory is essential to comprehend how plate movements influence not just the physical landscape but also broader environmental factors like climate and ocean circulation patterns.
Rain Shadow Effect: The rain shadow effect is a meteorological phenomenon where one side of a mountain range receives significantly more precipitation than the other side, resulting in distinct climatic conditions. This occurs because moist air rises over the mountains, cools, and loses moisture as rain on the windward side, while the leeward side remains dry and often experiences arid conditions. The phenomenon illustrates how geological features can greatly influence local climate and vegetation patterns.
Rift: A rift is a linear zone where the Earth's lithosphere is being pulled apart, resulting in the formation of a rift valley or a rift system. These geological features are significant because they can influence ocean circulation patterns and affect climate by altering landforms, sea levels, and oceanic currents over time.
Subduction: Subduction is the geological process where one tectonic plate moves under another and sinks into the mantle as the plates converge. This process is crucial in shaping Earth’s features, influencing everything from the formation of oceanic trenches to the creation of mountain ranges and volcanic activity.
Thermohaline circulation: Thermohaline circulation refers to the large-scale movement of ocean water driven by differences in temperature and salinity, which affect water density. This process plays a crucial role in regulating climate and influencing ocean currents, as it facilitates the mixing of surface and deep waters, redistributing heat and nutrients around the globe. The circulation is vital for sustaining marine ecosystems and is interconnected with plate tectonics, which can alter oceanic basins and ultimately influence regional climates.
Volcanic eruptions: Volcanic eruptions are geological events where magma from beneath the Earth's crust is expelled to the surface, often resulting in lava flows, ash clouds, and pyroclastic flows. These eruptions can significantly alter landscapes and influence both local and global environments, impacting climate patterns and ocean circulation.