Ensemble mean of CMIP5 Sea Surface Temperature projections under climate change and their reference climatology

A software was developed in the framework of the GEOWOW project for computing the mean of the output of an ensemble of climate change models from the World Climate Research Programme (WCRP) Coupled Model Intercomparaison Project Phase 5 (CMIP5). The ensemble mean for the time projections of the Sea Surface Temperature (SST) under climate change and the corresponding climatology were computed: this paper describes the data set and its properties. The generated datasets are of interest for ecologists willing to assess future changes of marine ecosystems, and can be used under Creative Common Attributions license.

How well do CMIP5 climate simulations replicate historical trends and patterns of meteorological droughts?

Assessing the uncertainties and understanding the deficiencies of climate models are fundamental to developing adaptation strategies. The objective of this study is to understand how well Coupled Model Intercomparison-Phase 5 (CMIP5) climate model simulations replicate ground-based observations of continental drought areas and their trends. The CMIP5 multimodel ensemble encompasses the Climatic Research Unit (CRU) ground-based observations of area under drought at all time steps. However, most model members overestimate the areas under extreme drought, particularly in the Southern Hemisphere (SH). Furthermore, the results show that the time series of observations and CMIP5 simulations of areas under drought exhibit more variability in the SH than in the Northern Hemisphere (NH). The trend analysis of areas under drought reveals that the observational data exhibit a significant positive trend at the significance level of 0.05 over all land areas. The observed trend is reproduced by about three-fourths of the CMIP5 models when considering total land areas in drought. While models are generally consistent with observations at a global (or hemispheric) scale, most models do not agree with observed regional drying and wetting trends. Over many regions, at most 40% of the CMIP5 models are in agreement with the trends of CRU observations. The drying/wetting trends calculated using the 3 months Standardized Precipitation Index (SPI) values show better agreement with the corresponding CRU values than with the observed annual mean precipitation rates. Pixel-scale evaluation of CMIP5 models indicates that no single model demonstrates an overall superior performance relative to the other models

South Asian summer monsoon projections constrained by the Intedacadal Pacific Oscillation

A reliable projection of future South Asian summer monsoon (SASM) benefits a large population in Asia. Using a 100-member ensemble of simulations by the Max Planck Institute Earth System Model (MPI-ESM) and a 50-member ensemble of simulations by the Canadian Earth System Model (CanESM2), we find that internal variability can overshadow the forced SASM rainfall trend, leading to large projection uncertainties for the next 15 to 30 years. We further identify that the Interdecadal Pacific Oscillation (IPO) is, in part, responsible for the uncertainties. Removing the IPO-related rainfall variations reduces the uncertainties in the near-term projection of the SASM rainfall by 13 to 15% and 26 to 30% in the MPI-ESM and CanESM2 ensembles, respectively. Our results demonstrate that the uncertainties in near-term projections of the SASM rainfall can be reduced by improving prediction of near-future IPO and other internal modes of climate variabilit

Climate Change and Sea Level Rise Projections for Boston

While the broad outlines of how climate change would impact Boston have been known for some time, it is only recently that we have developed a more definitive understanding of what lies ahead. That understanding was advanced considerably with the publication of Climate Change and Sea Level Rise Projections for Boston by the Boston Research Advisory Group (BRAG).The BRAG report is the first major product of "Climate Ready Boston," a project led by the City of Boston in partnership with the Green Ribbon Commission and funded in part by the Barr Foundation. The BRAG team includes 20 leading experts from the region's major universities on subjects ranging from sea level rise to temperature extremes. University of Massachusetts Boston professors Ellen Douglas and Paul Kirshen headed the research.The BRAG report validates earlier studies, concluding Boston will get hotter, wetter, and saltier in the decades ahead (see figures below). But the group has produced a much more definitive set of projections than existed previously, especially for the problem of sea level rise. BRAG also concluded that some of the effects of climate change will come sooner than expected, accelerating the urgency of planning and action

Do global warming-induced circulation pattern changes affect temperature and precipitation over Europe during summer?

Future climate change projections are not limited to a simple warming, but changes in precipitation and sea level pressure (SLP) are also projected. The SLP changes and the associated atmospheric circulation changes could directly mitigate or enhance potential projected changes in temperature and precipitation associated with rising temperatures. With the aim of analysing the projected circulation changes and their possible impacts on temperature and precipitation over Europe in summer [June–July–August (JJA)], we apply an automatic circulation type classification method, based on daily SLP, on general circulation model (GCM) outputs from the Coupled Model Intercomparison Project phase 5 (CMIP5) database over the historical period (1951–2005) and for climate under two future scenarios (2006–2100). We focus on summer as it is the season when changes in temperature and precipitation have the highest impact on human health and agriculture. Over the historical observed reference period (1960–1999), our results show that most of the GCMs have significant biases over Europe when compared to reanalysis data sets, both for simulating the observed circulation types and their frequencies, as well as for reproducing the intraclass means of the studied variables. The future projections suggest a decrease of circulation types favouring a low centred over the British Isles for the benefit of more anticyclonic conditions. These circulation changes mitigate the projected precipitation increase over north-western Europe in summer, but they do not significantly affect the projected temperature increase and the precipitation decrease over the Mediterranean region and eastern Europe. However, the circulation changes and the associated precipitation changes are tarnished by a high uncertainty among the GCM projections