lmd_Boucher2015_abstracts.html

2015 .

G. Myhre, O. Boucher, F.-M. Bréon, P. Forster, and D. Shindell. Declining uncertainty in transient climate response as CO₂ forcing dominates future climate change. Nature Geoscience, 8:181-185, March 2015. [ bib | DOI | ADS link ]

Carbon dioxide has exerted the largest portion of radiative forcing and surface temperature change over the industrial era, but other anthropogenic influences have also contributed. However, large uncertainties in total forcing make it difficult to derive climate sensitivity from historical observations. Anthropogenic forcing has increased between the Fourth and Fifth Assessment Reports of the Intergovernmental Panel of Climate Change (IPCC; refs , ), although its relative uncertainty has decreased. Here we show, based on data from the two reports, that this evolution towards lower uncertainty can be expected to continue into the future. Because it is easier to reduce air pollution than carbon dioxide emissions and because of the long lifetime of carbon dioxide, the less uncertain carbon dioxide forcing is expected to become increasingly dominant. Using a statistical model, we estimate that the relative uncertainty in anthropogenic forcing of more than 40% quoted in the latest IPCC report for 2011 will be almost halved by 2030, even without better scientific understanding. Absolute forcing uncertainty will also decline for the first time, provided projected decreases in aerosols occur. Other factors being equal, this stronger constraint on forcing will bring a significant reduction in the uncertainty of observation-based estimates of the transient climate response, with a 50% reduction in its uncertainty range expected by 2030.

R. Wang, Y. Balkanski, O. Boucher, P. Ciais, J. Peñuelas, and S. Tao. Significant contribution of combustion-related emissions to the atmospheric phosphorus budget. Nature Geoscience, 8:48-54, January 2015. [ bib | DOI | ADS link ]

Atmospheric phosphorus fertilizes plants and contributes to Earth's biogeochemical phosphorus cycle. However, calculations of the global budget of atmospheric phosphorus have been unbalanced, with global deposition exceeding estimated emissions from dust and sea-salt transport, volcanic eruptions, biogenic sources and combustion of fossil fuels, biofuels and biomass, the latter of which thought to contribute about 5% of total emissions. Here we use measurements of the phosphorus content of various fuels and estimates of the partitioning of phosphorus during combustion to calculate phosphorus emissions to the atmosphere from all combustion sources. We estimate combustion-related emissions of 1.8 Tg P yr^-1, which represent over 50% of global atmospheric sources of phosphorus. Using these estimates in atmospheric transport model simulations, we find that the total global emissions of atmospheric phosphorus (3.5 Tg P yr^-1) translate to a depositional sink of 2.7 Tg P yr^-1 over land and 0.8 Tg P yr^-1 over the oceans. The modelled spatial patterns of phosphorus deposition agree with observations from globally distributed measurement stations, and indicate a near balance of the phosphorus budget. Our finding suggests that the perturbation of the global phosphorus cycle by anthropogenic emissions is larger thanpreviously thought.