Tectonic–climatic interaction
As the geological record of past climate changes over millions of years is sparse and poorly resolved, many questions remain unresolved regarding the nature of tectonic-climate interaction, although it is an area of active research by geologists and palaeoclimatologists.
Depending on the vertical and horizontal magnitude of a mountain range, it has the potential to have strong effects on global and regional climate patterns and processes including: deflection of atmospheric circulation, creation of orographic lift, altering monsoon circulation, and causing the rain shadow effect.
One example of an elevated terrain and its effect on climate occurs in the Southeast Asian Himalayas, the world's highest mountain system.
[2] The monsoon season in Southeast Asia occurs due to the Asian continent becoming warmer than the surrounding oceans during the summer; as a low-pressure cell is created above the continents, a high-pressure cell forms over the cooler ocean, causing advection of moist air, creating heavy precipitation from Africa to Southeast Asia.
[6] It is possible to create erosion in the absence of precipitation because there would be a decrease in vegetation, which typically acts as a protective cover for the bedrock.
[6] Models also suggest that certain topographic features of the Himalayan and Andes region are determined by an erosional/climatic interaction as opposed to tectonism.
Some scientists hypothesize that the tectonic processes of plate subduction and mountain building are products of erosion and sedimentation.
[8] When there is an arid climate influenced by the rain shadow effect in a mountainous region, sediment supply to the trench can be reduced or even cut off.
By examining igneous rocks, it is possible to derive a chain of events that led from the original melt of the magma to the crystallization of the lava at Earth's surface.
A plume of heat from the mantle will melt rocks, creating a hot spot, which can be located at any depth in the crust.
Tuttle and Bowen accomplished their work by using experimental petrologic laboratories that produce synthetic igneous materials from mixes of reagents.
Felsic magmas are very viscous and travel to the surface of the Earth slower than mafic melts whose silica levels are lower.
[12] The methods by which petrologists examine igneous rocks and synthetically produced materials are optical petrography, X-ray diffraction (XRD), electron probe microanalysis (EPMA), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and many others.
[13] Volcanic gasses can be indirectly measured using Total Ozone Mapping Spectrometry (TOMS), a satellite-remote sensing tool which evaluates SO2 clouds in the atmosphere.
[11][14] TOMS’ disadvantage is that its high detection limit can only measure large amounts of exuded gases, such as those emitted by an eruption with a Volcanic Explosivity Index (VEI) of 3, on a logarithmic scale of 0 to 7.
Rain containing elevated concentrations of SO2 kills vegetation, which then reduces the ability of the area's biomass to absorb CO2 from the air.
[15] Because of its high reactivity with other molecules, increased sulfur concentrations in the atmosphere can lead to ozone depletion and start a positive warming feedback.
[14] Volcanoes with a felsic melt composition produce extremely explosive eruptions that can inject massive quantities of dust and aerosols high into the atmosphere.
These particulate emissions are potent climate forcing agents, and can provoke a wide variety of responses including warming, cooling, and rainwater acidification.
Such volcanic material injected into the stratosphere blocks solar radiation, heating that layer of the atmosphere and cooling the area beneath it.
Volcanic emissions contain trace amounts of heavy metals, which can affect the hydrosphere when they are injected into the lower reaches of the atmosphere.
When large quantities of these emissions are concentrated into a small area they can damage ecosystems, negatively affect agriculture, and pollute water sources.
[15] Examples of the environmental and health impacts are agricultural loss due to acid rain and particulate shading, damage to ecosystems, and pollution in the hydrosphere.
[15] This year round behavior of emitted material yields mild effects on the atmosphere in comparison to larger eruptions.
More intense eruptions, i.e., those with higher magma discharge rates, are more likely to loft the reactive sulfur gases into the stratosphere where they can generate climatically effective aerosol.
[16] The observation made by the model matches what is seen in nature: volcanoes in tropical climates have greater eruption heights than those in the poles.
Glacial growth is promoted when summer heat is weak and winter cold is enhanced and when glaciers grow larger, they get heavier.
[18] Carbon dioxide levels in the Cretaceous could have been as high as 3.7 to 14.7 times their present amounts today causing an average 2.8 to 7.7 degrees Celsius.
[18] Tectonically, movements of the plates and a sea level fall could cause an additional 4.8 degrees Celsius globally.
[18] The combined effect between magmatic and tectonic processes could have placed the Cretaceous Earth 7.6 to 12.5 degrees Celsius higher than today.
