Role of syn-orogenic burial and/or uplift and erosion in thermal regimes

Thrustbelts ◽  
2005 ◽  
pp. 298-314
2021 ◽  
Author(s):  
Dennis Höning

<p>Earth’s long-term carbonate-silicate cycle is continuously perturbed by processes of mountain building and erosion. Mountain uplift near convergent plate boundaries causes steep slopes, which in turn imply high rates of continental erosion. Erosion rates ultimately affect the weatherability and thereby the regulation of Earth’s climate. Using a simple 1D-model that includes the outlines processes, I investigate the resulting climate oscillations over timescales from thousands to millions of years. With a simple model of the long-term carbon cycle that includes biological enhancement of weathering and marine biogenic calcite precipitation, I study the role of Earth’s biosphere in damping these oscillations [1]. I show that both mechanisms play a role: Biological enhancement of weathering damps oscillations mainly on timescales > 1 Ma and marine calcification mainly on shorter timescales. Altogether, the results indicate that Earth’s biosphere contributes to a stable climate over a wide range of timescales.</p><p>In the context of anthropogenic emissions, a dramatic elevation in the atmospheric CO<sub>2</sub> and related temperature is known to damage Earth’s biosphere [2] and may even trigger runaway processes [3]. The results presented here indicate that a damaged biosphere may furthermore cause the Earth system to react more sensitive to oscillations from geological forcing and may also affect climate recovery.</p><p>References:</p><p>[1] Höning 2020, Geochem. Geophys. Geosyst. 21(9), e2020GC009105<br>[2] Sully et al. 2019, Nat. Comm. 10, 1264<br>[3] Lenton 2013, Annu. Rev. Environ. Resour. 38, 1-29</p>


2004 ◽  
Vol 55 (8) ◽  
pp. 759 ◽  
Author(s):  
Brendan G. McKie ◽  
Peter S. Cranston ◽  
Richard G. Pearson

In temperate regions of the northern hemisphere, where stream thermal regimes fluctuate seasonally and predictably, temperature has a role in niche segregation and maintenance of patterns of lotic diversity and distribution, as described by the ‘Thermal Equilibrium Hypothesis’. In Australia, the role of temperature in regulating patterns of diversity and distribution has been obscure, as seasonal variation in stream temperatures can be exceeded by stochastic fluctuation in flow. The thermal responses of five lotic Chironomidae (Diptera) species, contrasting in biogeographic (evolutionary) history, from warm tropical and cool temperate Australian populations, were investigated. All species, including postulated cool-stenotherms, showed broadly eurythermic developmental and morphological responses, and maintained both survivorship and oocyte production at elevated temperatures despite reductions in overall body size. There were subtle differences among species according to biogeographic affinity, with tolerances of Gondwanan species, which were narrower than those of cosmopolitan species, best characterised as ‘mesothermic’, but there was little divergence between populations. These results have implications for the understanding of diversity and distribution of Australian chironomids, and indicate that applicability of the Thermal Equilibrium Hypothesis to Australian lotic faunas may be limited.


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