North American Hydroclimate During Past Warms States: A Proxy Compilation‐Model Comparison for the Last Interglacial and the Mid‐Holocene

Wet, Cameron de; Ibarra, Daniel E.; Belanger, Bryce; Oster, Jessica L.

doi:10.1029/2022pa004528

Cited by 2 publications

(1 citation statement)

References 133 publications

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“…These two variables are related and together indicate a more arid MH climate in this model: a positive value for the latent heating term indicates warming due to less energy lost to the latent heat of evaporation (essentially, less latent heat flux from the surface); a negative sensible heating term indicates more sensible heat flux because the land is drier (Sutton et al., 2007). FGOALS‐g3 seems to simulate a larger change in aridity in the southern tropics region compared to other PMIP4 models, a signal that is also observed in other subtropical regions for this model (de Wet et al., 2023).…”

Section: Resultssupporting

confidence: 64%

Causes of Past African Temperature Change in PMIP Simulations of the Mid‐Holocene

Marshall,

Morrill,

Dee

et al. 2024

Paleoceanog and Paleoclimatol

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Current‐generation climate models project that Africa will warm by up to 5°C in the coming century, severely stressing African populations. Past and ongoing work indicates, however, that the models used to create these projections do not match proxy records of past temperature in Africa during the mid‐Holocene (MH), raising concerns that their future projections may house large uncertainties. Rather than reproducing proxy‐based reconstructions of MH warming relative to the Pre‐Industrial (PI), models instead simulate MH temperatures very similar to or slightly colder than the PI. This data‐model mismatch could be due to a variety of factors, including biases in model surface energy budgets or inaccurate representation of the feedbacks between temperature and hydrologic change during the “Green Sahara.” We focus on the differences among model simulations in the Paleoclimate Modeling Intercomparison Project Phases 3 and 4 (PMIP3 and PMIP4), examining surface temperature and energy budgets to investigate controls on temperature and the potential model sources of this paleoclimate data‐model mismatch. Our results suggest that colder conditions simulated by PMIP3 and PMIP4 models during the MH are in large part due to the joint impacts of feedback uncertainties in response to increased precipitation, a strengthened West African Monsoon (WAM) in the Sahel, and the Green Sahara. We extend these insights into suggestions for model physics and boundary condition changes, and discuss implications for the accuracy of future climate model projections over Africa.

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Section: Resultssupporting

confidence: 64%

Causes of Past African Temperature Change in PMIP Simulations of the Mid‐Holocene

Marshall,

Morrill,

Dee

et al. 2024

Paleoceanog and Paleoclimatol

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North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

Oster,

Macarewich,

Lofverstrom

et al. 2023

Sci. Adv.

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Atmospheric rivers (ARs) bring concentrated rainfall and flooding to the western United States (US) and are hypothesized to have supported sustained hydroclimatic changes in the past. However, their ephemeral nature makes it challenging to document ARs in climate models and estimate their contribution to hydroclimate changes recorded by time-averaged paleoclimate archives. We present new climate model simulations of Heinrich Stadial 1 (HS1; 16,000 years before the present), an interval characterized by widespread wetness in the western US, that demonstrate increased AR frequency and winter precipitation sourced from the southeastern North Pacific. These changes are amplified with freshwater fluxes into the North Atlantic, indicating that North Atlantic cooling associated with weakened Atlantic Meridional Overturning Circulation (AMOC) is a key driver of HS1 climate in this region. As recent observations suggest potential weakening of AMOC, our identified connection between North Atlantic climate and northeast Pacific AR activity has implications for future western US hydroclimate.

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North American Hydroclimate During Past Warms States: A Proxy Compilation‐Model Comparison for the Last Interglacial and the Mid‐Holocene

Cited by 2 publications

References 133 publications

Causes of Past African Temperature Change in PMIP Simulations of the Mid‐Holocene

Causes of Past African Temperature Change in PMIP Simulations of the Mid‐Holocene

North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

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