Abstract:
Several renowned latest-generation climate models exhibit equilibrium climate sensitivities beyond those characterizing the previous generation. The thus large range spanned by current models suggests that any such model values cannot be taken at face value when assessing the actual climate sensitivity. Constraining the climate sensitivity using observational data is complicated by poorly understood cooling due to aerosols. At the extreme end of current estimates, historical aerosol-induced cooling almost completely offsets the warming due to CO2. It is therefore desirable to produce robust estimates of both the climate sensitivity and historical aerosol-induced cooling as both strongly predict future warming projected by these models. I will present a methodology that uses all models participating in the Detection and Attribution Model Intercomparison Project to come up with estimates of both quantities consistent with historical temperature observations.
The oxidizing capacity of the troposphere is its ability to cleanse itself of various gaseous pollutants. It is critical to understanding the budgets of organic compounds including methane. The literature is split over whether the oxidizing capacity is strengthening, constant, or even weakening during recent decades. I will present a new study that uses two long-term measurement timeseries of radiocarbon monoxide (14CO) from New Zealand and Antarctica to show that indeed the oxidizing capacity has been strengthening at southern middle and high latitudes. Simulations by our chemistry-climate model, expanded to simulate 14CO, reproduce this finding, albeit with a smaller multidecadal trend. Combined with AerChemMIP results, the balance of evidence now tilts in favour of a global strengthening of the oxidizing capacity since 1997. Such a strengthening implies stronger-than-documented increases in methane emissions over this period.
What is the Joint Oslo Seminar (JOS):
- Atmospheric and climate sciences have a stronghold in Oslo among the four institutions University of Oslo, the Meteorological Institute, CICERO and NILU.
- This joint seminar invites renowned international experts to contribute to an informal series of lectures, meant to create interaction with the Oslo atmospheric and climate science community on recent highlights and analysis in the field.
- Normally seminars will be held on Thursdays (12:15 pm -1pm).