Monsoon Responses to Climate Changes—Connecting Past, Present and Future

Seth, Anji; Giannini, Alessandra; Rojas, Maisa; Rauscher, Sara A.; Bordoni, Simona; Singh, Deepti; Camargo, Suzana J.

doi:10.1007/s40641-019-00125-y

Cited by 61 publications

(43 citation statements)

References 199 publications

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“…Thus, even considering the limitations of our idealized setting, we could interpret the results as indicators of a possible increase in monsoonal precipitation over the eastern TP and along its southern margin. CMIP5 simulations, in general, project enhanced precipitation over land in all NH Monsoonal systems (Kitoh et al 2013;Lee and Wang 2014;Seth et al 2019), which is in line with our results.…”

Section: Conclusion and Discussionsupporting

confidence: 91%

Response of the Asian summer Monsoons to a high-latitude thermal forcing: mechanisms and nonlinearities

et al. 2020

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This study investigates mechanisms and nonlinearities in the response of the Asian Summer Monsoons (ASM) to high-latitude thermal forcings of different amplitudes. Using a suite of runs carried out with an intermediate-complexity atmospheric general circulation model, we find that the imposed forcings produce a strong precipitation response over the eastern ASM but a rather weak response over the southern ASM. The forcing also causes a precipitation dipole with wet conditions over the eastern Tibetan Plateau (TP) and dry conditions over the Bay of Bengal (BoB) and southeast Asia. A moderate increase of precipitation along the southern margin of the TP is also produced. Simulations designed to isolate the causal mechanisms show that thermodynamic interactions involving the tropical surface oceans are far less important than the water-vapour feedback for the transmission of information from the high-latitudes to the ASM. Additionally, we assess the nonlinearity of the ASM precipitation response to the forcing amplitude using a novel application of the empirical orthogonal function method. The response can be decomposed in two overlapping patterns. The first pattern represents a precipitation dipole with wet conditions over the eastern TP and dry conditions over BoB, which linearly increases with forcing amplitude becoming quasi-stationary for large forcing amplitudes (i.e. amplitudes leading to Arctic temperature anomalies larger than 10 °C). The second pattern is associated with increased precipitation over the southeastern TP and is nonlinearly dependent on forcing, being most important for intermediate forcing amplitudes (i.e. amplitudes leading to Arctic temperature anomalies between 5 and 10 °C).

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Section: Conclusion and Discussionsupporting

confidence: 91%

Response of the Asian summer Monsoons to a high-latitude thermal forcing: mechanisms and nonlinearities

et al. 2020

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“…148 Although there has been disagreement between paleoclimate and modern observations, physical theory, and numerical simulations of monsoonal changes, many of these discrepancies have been explained by considering regional aspects, such as zonal asymmetries in the circulation, land/ocean differences in surface fluxes, and the character of convective systems. 98,99,190,198,199 Poleward expansion of the tropical belt is expected to drive a corresponding shift in midlatitude storm tracks, yet driving mechanisms differ between hemispheres. Greenhouse gas forcing drives a stronger poleward expansion in the Southern Hemisphere than the Northern Hemisphere.…”

Section: Large-scale Responses In Atmospheric Circulation Patternsmentioning

confidence: 99%

Advances in understanding large‐scale responses of the water cycle to climate change

Allan

Barlow

Byrne

et al. 2020

Annals of the New York Academy of Sciences

317

153

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Globally, thermodynamics explains an increase in atmospheric water vapor with warming of around 7%/°C near to the surface. In contrast, global precipitation and evaporation are constrained by the Earth's energy balance to increase at ∼2-3%/°C. However, this rate of increase is suppressed by rapid atmospheric adjustments in response to greenhouse gases and absorbing aerosols that directly alter the atmospheric energy budget. Rapid adjustments to forcings, cooling effects from scattering aerosol, and observational uncertainty can explain why observed global precipitation responses are currently difficult to detect but are expected to emerge and accelerate as warming increases and aerosol forcing diminishes. Precipitation increases with warming are expected to be smaller over land than ocean due to limitations on moisture convergence, exacerbated by feedbacks and affected by rapid adjustments. Thermodynamic increases in atmospheric moisture fluxes amplify wet and dry events, driving an intensification of precipitation extremes. The rate of intensification can deviate from a simple thermodynamic response due to in-storm and larger-scale feedback processes, while changes in large-scale dynamics and catchment characteristics further modulate the frequency of flooding in response to precipitation increases. Changes in atmospheric circulation in response to radiative forcing and evolving surface temperature patterns are capable of dominating water cycle changes in some regions. Moreover, the direct impact of human activities on the water cycle through water abstraction, irrigation, and land use change is already a significant component of regional water cycle change and is expected to further increase in importance as water demand grows with global population.

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“…The northward shift of the ITCZ in the MH is due to energetic constrains associated with the changes in orbital forcing causing a warming of the NH and a cooling of SH during boreal summer relative to PI (Merlis et al, 2013;Schneider et al, 2014;Seth et al 2019). The ITCZ is associated with more favorable conditions for cyclogenesis by increasing the ambient vorticity and therefore the TC activity (Merlis et al, 2013).…”

Section: Change In Tc Density and Frequencymentioning

confidence: 99%

“…In particular, Knutson et al (2013; and Walsh et al (2016) point towards higher frequency of the most intense storms in a warmer future climate. These changes in TC activity may be influenced by a displacement of the Intertropical Convergence Zone (ITCZ) or by the northward extension of the West African Monsoon (WAM) through impacts on the energy fluxes of the global oceanic and atmospheric circulation (Schneider et al, 2014;Seth et al, 2019). Recent studies (Biasutti, 2013;Giannini & Kaplan, 2019) suggest a possible strengthening of the WAM, with increased rainfall over the Sahel region with a potential greening of this area as well as a reduction of airborne dust emissions (Evan et al, 2016) in the near future.…”

mentioning

confidence: 99%

Atlantic Hurricane response to Sahara greening and reduced dust emissions during the mid-Holocene

Dandoy¹,

Pausata²,

Camargo³

et al. 2020

Preprint

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Abstract. We use a high-resolution regional climate model to investigate the changes in Atlantic tropical cyclone (TC) activity during a warm climate state, the mid-Holocene (MH: 6,000 yrs BP). This period was characterized by increased boreal summer insolation, a vegetated Sahara, and reduced airborne dust concentrations. A set of sensitivity experiments were conducted in which solar insolation, vegetation and dust concentrations were changed in turn to disentangle their impacts on TC activity. Results show that the greening of the Sahara and reduced dust loadings (MHGS+RD) lead to a larger increase in the number of Atlantic TCs (27 %) relative to the pre-industrial climate (PI) than the orbital forcing alone (MHPMIP; 9 %). The TC seasonality is also highly modified in the MH climate, showing a decrease in TC activity during the beginning of the hurricane season (June to August), with a shift of its maximum towards October and November in the MHGS+RD experiment relative to PI. MH experiments simulate stronger hurricanes compared to PI, similar to future projections. Moreover, they suggest longer lasting cyclones relative to PI. Our results also show that changes in the African Easterly Waves are not relevant in altering the frequency and intensity of TCs, but they may shift the location of their genesis. This work highlights the importance of considering vegetation and dust changes over the Sahara region when investigating TC activity under a different climate state.

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Monsoon Responses to Climate Changes—Connecting Past, Present and Future

Cited by 61 publications

References 199 publications

Response of the Asian summer Monsoons to a high-latitude thermal forcing: mechanisms and nonlinearities

Response of the Asian summer Monsoons to a high-latitude thermal forcing: mechanisms and nonlinearities

Advances in understanding large‐scale responses of the water cycle to climate change

Atlantic Hurricane response to Sahara greening and reduced dust emissions during the mid-Holocene

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