Search

Loss and damage funds are intended to support low-income regions experiencing impacts of human-caused climate change. Currently, event attribution should only play a limited role in determining loss and damage spending, but this role could grow as the field advances.

Transient climate response (TCR), transient response at 140 years (T140), and equilibrium climate sensitivity (ECS) indices are intended as benchmarks for comparing the magnitude of climate response projected by climate models. It is generally assumed that TCR or T140 would explain more variability between models than ECS for temperature change over the 21st century, since this timescale is the realm of transient climate change. Here we find that TCR explains more variability across Coupled Model Intercomparison Project phase 5 than ECS for global temperature change since preindustrial, for 50 or 100 year global trends up to the present, and for projected change under representative concentration pathways in regions of delayed warming such as the Southern Ocean. However, unexpectedly, we find that ECS correlates higher than TCR for projected change from the present in the global mean and in most regions. This higher correlation does not relate to aerosol forcing, and the physical cause requires further investigation. We compare transient climate response (TCR), 140 year TCR (T140), and equilibrium climate sensitivity (ECS) as measures of projected warmingT140 provides the highest R2with the warming relative to preindustrial, but R2is higher with ECS in 100 year trends from circa 1960 onwardThere are large spatial differences in the fit of temperature projections to sensitivity, with lower values in regions of delayed warming

The term ‘downscaling’ refers to the process of translating information from global climate model simulations to a finer spatial resolution. There are numerous methods by which this translation of information can occur. For users of downscaled information, it is important to have some understanding of the properties of different methods (in terms of their capabilities and limitations to convey the change signal, as simulated by the global model), as these dictate the type of applications that the downscaled information can be used for in impact, adaptation, and vulnerability research. This article provides an appraisal of downscaling in terms of its perceived purpose and value for informing on plausible impacts due to climate change and for underpinning regional risk assessments. The concepts climate realismand physical plausibility of changeare introduced to qualify the broad scale properties associated with different categories of downscaling approaches; the former concerning the skill of different approaches to represent regional climate characteristics and the latter their skill in simulating regional climate change. Aspects of change not captured by global climate models, due to resolution or regional factors, may be captured by downscaling. If these aspects are of interest, then downscaling may be useful once it has been demonstrated to add value. For cases where the broad scale change to the mean climate is of interest, or where there is no demonstrated added value from downscaling, then there is a wide range of regionalization methods that are suitable for practitioners in the impact, adaptation, and vulnerability field. WIREs Clim Change2015, 6:301–319. doi: 10.1002/wcc.339

Environmental context. Emissions of methyl iodide of a biological origin from inshore and coastal waters can be an important component of the atmospheric budget of iodine. Iodine from this and other sources is important in the natural ozone cycle in the troposphere and stratosphere, and may play a role in the formation of new small particles that can then grow to seed clouds. The specific coastal ecology at each location is important to the magnitude and characteristics of this methyl iodide source.  Abstract. Methyl iodide concentration in seawater and in the air directly above the sea was measured at an inshore site adjacent to the Cape Grim Baseline Air Pollution Station (Cape Grim BAPS) near a bed of Bull Kelp (Durvillaea potatorum) over daylight cycles and along a transect out to 5 km offshore. Most inshore samples had low and variable methyl iodide concentrations in seawater (14.8?57.7 pM) and in air immediately above the sea (2.1?3.8 parts per trillion by volume), with a partial tidal influence. A period of elevated methyl iodide concentration in the water (144.5 pM) and in air above the sea surface (5.5 pptv) was immediately followed by a measurement of new particles at the Cape Grim BAPS. This correlation provided indirect evidence that emission of methyl iodide from kelp is connected to the new particle formation pathway, but there was no evidence of a direct causal link. Elevated levels of atmospheric methyl iodide were not detected at the station (adjacent to the site but on top of a 94-m cliff) at the same time, which suggests the effect was localised above the sea surface. A rapid decrease of methyl iodide out to 5 km suggested that a source at the coastal reef was greater than from pelagic phytoplankton; this source could be the intertidal kelp beds.

Environmental context. Kelp at Mace Head, Ireland, produces large quantities of iodine when exposed to sunlight at low tide and this iodine results in the rapid production of particles. Cape Grim, Tasmania, also has large colonies of kelp (Durvillaea potatorum) but its role in particle formation appears limited. A flux chamber was used to better understand the response of Durvillaea potatorum to light stress and ozone.  Abstract. Brown kelp, in particular Laminara digitata at Mace Head, Ireland, has been shown to emit iodine when under stress, resulting in new particle formation. The Cape Grim Baseline Air Pollution Station, Tasmania, is surrounded by rocky reefs that support large colonies of the brown kelp Durvillaea potatorum. During an intensive campaign in February 2006 at Cape Grim, levels of IO, OIO and methyl iodide remained at background levels and no particle formation events could be associated with locally generated precursor iodine species.  In order to better understand the limitations of the local kelp to provide a source of precursor species, samples of Durvillaea potatorum were collected from the beach below the Cape Grim Station and tested for their capacity to initiate particle formation using a flux chamber technique. Particles were observed only when the kelp was exposed to both very high levels (>100 ppb) of ozone and natural solar radiation. There was a high correlation between ozone level and particles produced. The particles resulting from exposure to high levels of ozone were aromatic and volatile.  Durvillaea potatorum appears to plays a very limited role in contributing to particle formation at Cape Grim, but it does represent a source of atmospheric iodine under photo-oxidative stress, of 18 pmol g?1 (fresh weight) min?1 and is likely to have a significant role in atmospheric chemistry at this site.

Environmental context. Understanding the role of clouds in assessing the impact of climate change is a challenging issue. It is thought that plankton and seaweed contribute to the formation of clouds by emitting gases that lead to the particle production necessary for cloud formation. Macroalgae (kelp) at Mace Head, Ireland, produce large quantities of iodine when exposed to sunlight at low tide and this iodine results in the rapid production of particles. Cape Grim, Tasmania, also has large colonies of kelp and the role of Bull Kelp (Durvillaea potatorum) in particle production was assessed.  Abstract. Iodine emissions from coastal macroalgae have been found to be important initiators for nucleation events at Mace Head, Ireland. The source of this iodine is the large beds of the brown kelp Laminaria digitata, which are significantly exposed at low tide.  On the coast around Cape Grim, Tasmania, there are beds of the brown kelp Durvillaea potatrum. The Precursors to Particles 2006 (P2P 2006) campaign at the Cape Grim Baseline Air Pollution Station in late summer (February) 2006 focused on the role of this local kelp in providing precursor gases to particle formation.  Durvillaea potatorum does not produce iodated precursor gases at the levels observed at Mace Head. IO was measured at 0.5 0.3 ppt, while OIO was below detection limits (9 ppt). The dominant atmospheric iodated species was methyl iodide and the average concentration measured at the Cape Grim Station was 1.5 0.3 pptv in baseline conditions, but showed significant variation in discrete samples collected immediately above the ocean surface.  Nucleation events were not detected at the Cape Grim Station, except for one period where the plume of a local bushfire interacted with air of marine origin. The passage of four fronts did not result in nucleation bursts and measurements on the beach 94 m below the Cape Grim Station suggested that Durvillaea potatorum was only a weak source of new particles.