Kristin Rypdal

Climate forcing from the transport sectors

Although the transport sector is responsible for a large and growing share of global emissions affecting climate, its overall contribution has not been quantified. We provide a comprehensive analysis of radiative forcing from the road transport, shipping, aviation, and rail subsectors, using both past- and forward-looking perspectives. We find that, since preindustrial times, transport has contributed ≈15% and 31% of the total man-made CO2 and O3 forcing, respectively. A forward-looking perspective shows that the current emissions from transport are responsible for ≈16% of the integrated net forcing over 100 years from all current man-made emissions. The dominating contributor to positive forcing (warming) is CO2, followed by tropospheric O3. By subsector, road transport is the largest contributor to warming. The transport sector also exerts cooling through reduced methane lifetime and atmospheric aerosol effects. Shipping causes net cooling, except on future time scales of several centuries. Much of the forcing from transport comes from emissions not covered by the Kyoto Protocol.

Costs and global impacts of black carbon abatement strategies

Abatement of particulate matter has traditionally been driven by health concerns rather than its role in global warming. Here we assess future abatement strategies in terms of how much they reduce the climate impact of black carbon (BC) and organic carbon (OC) from contained combustion. We develop global scenarios which take into account regional differences in climate impact, costs of abatement and ability to pay, as well as both the direct and indirect (snow-albedo) climate impact of BC and OC. To represent the climate impact, we estimate consistent region-specific values of direct and indirect global warming potential (GWP) and global temperature potential (GTP). The indirect GWP has been estimated using a physical approach and includes the effect of change in albedo from BC deposited on snow. The indirect GWP is highest in the Middle East followed by Russia, Europe and North America, while the total GWP is highest in the Middle East, Africa and South Asia. We conclude that prioritizing emission reductions in Asia represents the most cost-efficient global abatement strategy for BC because Asia is (1) responsible for a large share of total emissions, (2) has lower abatement costs compared to Europe and North America and (3) has large health cobenefits from reduced PM10 emissions.

Climate effects of emission standards: the case for gasoline and diesel cars.

Passenger transport affects climate through various mechanisms involving both long-lived and short-lived climate forcers. Because diesel cars generally emit less CO(2) than gasoline cars, CO(2) emission taxes for vehicle registrations and fuels enhance the consumer preference for diesel cars over gasoline cars. However, with the non-CO(2) components, which have been changed and will be changed under the previous and upcoming vehicle emission standards, what does the shift from gasoline to diesel cars mean for the climate mitigation? By using a simple climate model, we demonstrate that, under the earlier emissions standards (EURO 3 and 4), a diesel car causes a larger warming up to a decade after the emissions than a similar gasoline car due to the higher emissions of black carbon and NO(X) (enhancing the O(3) production). Beyond a decade, the warming caused by a diesel car becomes, however, weaker because of the lower CO(2) emissions. As the latter emissions standards (EURO 5 and 6) are phased in, the short-term warming due to a diesel car becomes smaller primarily due to the lower black carbon emissions. Thus, although results are subject to restrictive assumptions and uncertainties, the switch from gasoline to diesel cars encouraged by CO(2) taxes does not contradict with the climate mitigation focusing on long-term consequences.

The molecular structure of monomeric base-free bis(neopentyl)manganese by gas electron diffraction

The gas electron diffraction pattern of bis(neopentyl)manganese is consistent with a monomer with ∠CMnC = 180° and Mn–C = 210.4(6) pm.

Molecular structures of titanium(IV) and vanadium(IV) amides and alkoxides

Gas-phase electron diffraction data for Ti(NMe2)4, V(NMe2)4 and V(OBut)4 obtained with nozzle temperatures of 130–156 °C are consistent with molecular models of S4 symmetry. The metal to ligand bond distances (ra) are Ti–N 191.7(3), V–N 187.9(4) and V–O 177.9(6) pm, respectively. A set of bonding radii for TiIV, VIV, CrIV and WVI for use with the modified Schomaker–Stevensen rule is proposed. The valence angle bisected by the S4 axis in the titanium amide, N–Ti–N 114.2(17)°, indicates that the co-ordination tetrahedron is slightly flattened. The corresponding angles in the vanadium amide and alkoxide are N–V–N 100.6(5)° and O–V–O 115.1(19)°, indicating that the co-ordination polyhedron in the former is significantly elongated, while in the latter it is significantly flattened. The shapes of the co-ordination tetrahedra in these and related molecules are discussed in terms of donation of π electrons from N or O into low-lying d orbitals on the metal atom.