Author Archives: karmour

Atmospheric Sciences major Dave Bonan published in GRL

Dave Bonan, a rising senior undergraduate majoring in Atmospheric Sciences at UW, has published his first paper in the journal Geophysical Research Letters. Ever wondered how tropical cloud feedbacks impact Arctic warming, or why the magnitude of polar amplification is so uncertain across models? Dave has the answers in Sources of Uncertainty in the Meridional Pattern of Climate Change.

New paper in GRL by Alex Haugstad!

New paper in Geophysical Research Letters by Masters student Alex Haugstad: Relative roles of surface temperature and climate forcing patterns in the inconstancy of radiative feedbacks [pdf]

Radiative feedbacks robustly vary over time in transient warming simulations. Published studies offer two explanations: (i) evolving patterns of ocean heat uptake (OHU) or radiative forcing give rise to OHU or forcing “efficacies” and (ii) evolving patterns of surface temperature change. This study seeks to determine whether these explanations are indeed distinct. Using an idealized framework of an aquaplanet atmosphere-only model, we show that radiative feedbacks depend on the pattern of climate forcing. Yet the same feedbacks arise when the temperature pattern induced by that climate forcing is prescribed in the absence of any forcing. These findings suggest the perspective that feedbacks are influenced by efficacies of forcing and OHU is equivalent to the perspective that feedbacks are dependent on the temperature patterns induced by those forcings. Prescribed surface temperature simulations are thus valuable for studying the temporal evolution of radiative feedbacks.

Climate sensitivity in the news!

Models, observations not so far apart on planet’s response to greenhouse gas emissions. (UW News article by Hannah Hickey)

Will Earth’s climate get more sensitive to CO2? Only better satellites can say. (IEEE Spectrum article by Peter Fairley)

Once more with feeling: Climate models don’t exaggerate warming. (Ars Technica article by Scott K. Johnson)

Despite Debate, Estimates of Humanity’s Impact on Climate Change Are Accurate. ( article by Robert Eshelman)

New paper! Energy budget constrains on climate sensitivity

New paper in Nature Climate Change: Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks [pdf]

Equilibrium climate sensitivity — defined as the long-term near-surface air temperature change that would result from a doubling of atmospheric CO2 — is a key metric of climate change. Global energy budget constraints suggest a climate sensitivity around 2°C, which is lower than that suggested by other estimates, such as from palaeoclimate reconstructions, process-based observational analyses (e.g., emergent constraints), and global climate model simulations. A key, but often unstated, assumption of these energy budget constraints is that the same climate sensitivity inferred today also applies to the distant future. Yet, global climate models robustly show that feedbacks vary over time, with a strong tendency for climate sensitivity to increase as equilibrium is approached. This paper considers the implications of inconstant climate feedbacks for energy budget constraints on climate sensitivity.

The analysis shows that the long-term value of climate sensitivity is, on average, 26% above that inferred during transient warming within global climate models, with a larger discrepancy when climate sensitivity is high. Moreover, model values of climate sensitivity inferred during transient warming are found to be consistent with energy budget observations, indicating that the models are not overly sensitive. Using model-based estimates of how climate feedbacks will change in the future, in conjunction with recent energy budget constraints, produces a current best estimate of equilibrium climate sensitivity of 2.9°C (1.7–7.1°C, 90% confidence). The findings suggest that climate sensitivity estimated from global energy budget constraints is in agreement with values derived from other methods and simulated by global climate models.

Presentations at AGU 2016

Our group has several presentations at the 2016 AGU Fall Meeting in San Francisco. Come check them out!

Monday, 12/12 8am-noon: Kyle Armour, A11F-0078, Understanding the spatial patterns of ocean heat uptake and storage (Moscone South – Poster Hall)

Thursday, 12/15 9:30-9:45am: Alex Haugstad, A41K-07 Do radiative feedbacks depend on the structure and type of climate forcing, or only on the spatial pattern of surface temperature change? (Moscone West – 3010)

Thursday, 12/15 1:40-6pm: Dylan Oldenburg, C43B-0749 Robust increase in ocean heat transport into the Arctic under greenhouse gas forcing (Moscone South – Poster Hall)