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Estimating Cloud Feedbacks Over Global Oceans Using AMSR-E Data

This study examines the role of low cloud feedback in climate sensitivity and its impact on global warming projections. It highlights the confusion between cloud changes and temperature changes, emphasizing that cloud feedback represents a significant uncertainty in these models. While some models predict a strong positive feedback from clouds, satellite data suggests a potential negative feedback effect. The research uses AMSR-E and CERES data to investigate radiative fluxes and the implications of natural cloud variations on CO2 forcing, shedding light on the complexities of climate feedback mechanisms.

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Estimating Cloud Feedbacks Over Global Oceans Using AMSR-E Data

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  1. Using AMSR-E toEstimate Cloud FeedbacksOver the Global Oceans Roy W. Spencer Principal Research Scientist The University of Alabama in Huntsville 3 June, 2010

  2. Low cloud feedback the largest uncertainty (reflected SW) How temperature change => cloud change has been confused with cloud change => temperature change -Spencer & Braswell, 2008; 2010 Feedback (climate sensitivity) represents the single largest uncertainty in global warming projections

  3. Global Warming in Models isGreatly Magnified by Positive Cloud Feedback Warming in models amplified by clouds & vapor (~3 deg. C by 2100) Warming from CO2 only Satellite data suggests clouds reduce warming (~0.5°C by 2100)

  4. Aqua CERES vs. AMSU Tropospheric Temp.suggests negative net (LW+SW) feedback(slope of regression line)

  5. But a simple forcing-feedback modelshows a wide variety of regression slopesare possible for a givenfeedback

  6. Aqua CERES Shows Accumulation ofEnergy….but where is the warming? CERES Radiative Fluxes Increasing CO2 forcing AMSR-E SST

  7. Can AMSR-E CLW be used as a surrogate for CERES SW?(3-day avgs, 60N-60S Oceans, ~8 years)

  8. AMSR-E does not “see” a decrease in SW

  9. CERES SW vs. Tair Suggests NEGATIVE Feedback IPCC Models: -0.95 to +0.98

  10. CERES SW vs. Tair Suggests NEGATIVE Feedback IPCC Models: -0.95 to +0.98

  11. AMSR-E –est. SW vs. Tair Suggests NEGATIVE Feedback IPCC Models: -0.95 to +0.98

  12. Satellite Observations Show that Natural Cloud Variations are Potentially a Much Larger Forcing than Increasing CO2 Satellite-Observed Change in Cloud forcing (assuming LW+SW feedback parameter = 6) Change in CO2 Forcing (theoretically calculated)

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