🚨New study finds #SolarGeoengineering methods have divergent hydrological outcomes in China.
Only equatorial Stratospheric Aerosol Injection (#SAI) could mitigate the “North-Drought, South-Flood” pattern, while MCB & CCT risk worsening it.
DETAILS🧵1/11
Only equatorial Stratospheric Aerosol Injection (#SAI) could mitigate the “North-Drought, South-Flood” pattern, while MCB & CCT risk worsening it.
DETAILS🧵1/11
2/ China’s hydroclimate is long shaped by the NDSF pattern: aridity in the north, flooding in the south.
Warming threatens to intensify this divide via glacier retreat and stronger monsoon variability.
How would climate interventions alter this?
Warming threatens to intensify this divide via glacier retreat and stronger monsoon variability.
How would climate interventions alter this?
3/ Zhang et al. tested three SRM strategies:
• SAI (Stratospheric Aerosol Injection)
• MCB (Marine Cloud Brightening)
• CCT (Cirrus Cloud Thinning)
All benchmarked against high-emissions (RCP8.5) & moderate mitigation (RCP4.5).
• SAI (Stratospheric Aerosol Injection)
• MCB (Marine Cloud Brightening)
• CCT (Cirrus Cloud Thinning)
All benchmarked against high-emissions (RCP8.5) & moderate mitigation (RCP4.5).
4/ Results revealed that all #ClimateIntervention strategies achieved comparable global cooling, but their regional hydrological effects differed sharply.
5/ SAI → increased precipitation / surface runoff in the north, decreased in the south → mitigates NDSF.
MCB → raised southern flood risk.
CCT → deepened northern drought.
RCP4.5 → reduced southern floods but worsens northern dryness.
MCB → raised southern flood risk.
CCT → deepened northern drought.
RCP4.5 → reduced southern floods but worsens northern dryness.
6/ Why SAI works differently?
It reduces inter-hemispheric & equator-to-pole temperature gradients.
This weakens & shifts the East Asian summer monsoon northward.
Result: more rainfall in northern China, less in the south.
It reduces inter-hemispheric & equator-to-pole temperature gradients.
This weakens & shifts the East Asian summer monsoon northward.
Result: more rainfall in northern China, less in the south.
7/ The mechanism observed in this study is consistent with observed circulation & rainfall anomalies following the 1991 Mount Pinatubo eruption, which is "a rare real-world analogue of equatorial aerosol injection."
8/ When considering extremes, SAI again showed relative promise:
It reduced the frequency of major southern floods (10–20 yr recurrence) while keeping northern drought risks comparatively stable.
By contrast, MCB and CCT each exacerbate opposite hazards
It reduced the frequency of major southern floods (10–20 yr recurrence) while keeping northern drought risks comparatively stable.
By contrast, MCB and CCT each exacerbate opposite hazards
9/ Circulation analysis shows SAI also weakens the Hadley cell, shifts the East Asian subtropical westerly jet poleward, and moves the Western Pacific subtropical high northward.
Together, these adjustments steer summer rainfall into northern China.
Together, these adjustments steer summer rainfall into northern China.
10/ By contrast, MCB brightens low marine clouds, creating zonal asymmetries that strengthen southern rainfall
CCT reduces cirrus cover, which dries out the upper troposphere & suppresses northern precipitation
Thus, both strategies worsen NDSF divide rather than mitigate it
CCT reduces cirrus cover, which dries out the upper troposphere & suppresses northern precipitation
Thus, both strategies worsen NDSF divide rather than mitigate it
📝For more details, read the study entitled "Divergent impacts of climate interventions on China’s north-south water divide" here:
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#SAI #MCB #CCT #Geoengineeringnature.com/articles/s4324…
🧵11/11
#SAI #MCB #CCT #Geoengineeringnature.com/articles/s4324…
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