Iain Robertson

Bio: Iain Robertson is an academic researcher from Swansea University. The author has contributed to research in topics: Stable isotope ratio & Dendrochronology. The author has an hindex of 35, co-authored 76 publications receiving 4237 citations. Previous affiliations of Iain Robertson include University of Cambridge & Council of Scientific and Industrial Research.

Exorcising the `segment length curse': summer temperature reconstruction since AD 1640 using non-detrended stable carbon isotope ratios from pine trees in northern Finland

Abstract: Stable carbon isotope ratios from the latewood cellulose of 12 trees from two sites in northern Finland are used to construct an isotope chronology covering AD 1640 to 2002. By measuring isotopic ratios of every sample independently it is possible to identify and remove the juvenile portion of each 13 C series, correct the individual series for anthropogenic changes in atmospheric carbon dioxide isotopic ratios and concentrations, and to quantify changes in signal strength through time. Most importantly, it is pos- sible to demonstrate that there are no long-term trends in the carbon isotope series that are related to tree age. This means that it is not necessary to detrend the series and so they have the potential to retain cli- mate information at all temporal frequencies. The correlation between the non-detrended carbon isotope series and July/August mean temperature is high (r 0.72) and comparison with meteorological records suggests that the dominant control over tree ring 13 C at these high latitude, moist sites is photosynthetic rate rather than stomatal conductance. Summer temperature reconstructions based on three different cal- ibrations are presented, with verification based on a mixture of jacknife and split period designs, provid- ing robust and near identical results. Reconstructed late summer temperatures in the early 1900s are very low but the years centred around AD 1660 and 1760 appear to have experienced warmer summers than the late twentieth century, thus our late summer reconstruction does not show a recent warming trend. Our results are in agreement with other palaeoclimate reconstructions for northern Fennoscandia, which show late twentieth-century warming occurring predominantly in the winter. Our results suggest that, where replication and common signal strength are sufficiently high, stable carbon isotope dendroclimatology may provide high resolution proxy time series that also record climate information at lower temporal frequen- cies, thus avoiding the 'segment length curse' that can apply to palaeoclimate reconstructions based on other tree ring parameters such as ring widths and density.

Climate Change 2007: Impacts, Adaptation and Vulnerability.

Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

The climate hazards infrared precipitation with stations--a new environmental record for monitoring extremes.

Abstract: The Climate Hazards group Infrared Precipitation with Stations (CHIRPS) dataset builds on previous approaches to ‘smart’ interpolation techniques and high resolution, long period of record precipitation estimates based on infrared Cold Cloud Duration (CCD) observations. The algorithm i) is built around a 0.05° climatology that incorporates satellite information to represent sparsely gauged locations, ii) incorporates daily, pentadal, and monthly 1981-present 0.05° CCD-based precipitation estimates, iii) blends station data to produce a preliminary information product with a latency of about 2 days and a final product with an average latency of about 3 weeks, and iv) uses a novel blending procedure incorporating the spatial correlation structure of CCD-estimates to assign interpolation weights. We present the CHIRPS algorithm, global and regional validation results, and show how CHIRPS can be used to quantify the hydrologic impacts of decreasing precipitation and rising air temperatures in the Greater Horn of Africa. Using the Variable Infiltration Capacity model, we show that CHIRPS can support effective hydrologic forecasts and trend analyses in southeastern Ethiopia.

Drought-Induced Reduction in Global Terrestrial Net Primary Production from 2000 Through 2009

Abstract: Terrestrial net primary production (NPP) quantifies the amount of atmospheric carbon fixed by plants and accumulated as biomass. Previous studies have shown that climate constraints were relaxing with increasing temperature and solar radiation, allowing an upward trend in NPP from 1982 through 1999. The past decade (2000 to 2009) has been the warmest since instrumental measurements began, which could imply continued increases in NPP; however, our estimates suggest a reduction in the global NPP of 0.55 petagrams of carbon. Large-scale droughts have reduced regional NPP, and a drying trend in the Southern Hemisphere has decreased NPP in that area, counteracting the increased NPP over the Northern Hemisphere. A continued decline in NPP would not only weaken the terrestrial carbon sink, but it would also intensify future competition between food demand and proposed biofuel production.

Climate Change 1995

Abstract: Climate Change 1995 is a scientific assessment that was generated by more than 1 000 contributors from over 50 nations. It was jointly co-ordinated through two international agencies; the World Meteorological Organization and the United Nations Environment Programme. The assessment was completed by the Intergovernmental Panel on Climate Change (IPCC) with a primary aim of reviewing the current state of knowledge concerning the impacts of climate change on physical and ecological systems, human health, and socioeconomic factors. The second aim was to review the available information on the technical and economic feasibility of the potential mitigation and adaptation strategies.