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A megacity in a changing climate: the case of Kolkata
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Projections by the Intergovernmental Panel on Climate Change suggest that there will be an increase in the frequency and intensity of climate extremes in the 21st century. Kolkata, a megacity in India, has been singled out as one of the urban centers vulnerable to climate risks. Modest flooding during monsoons at high tide in the Hooghly River is a recurring hazard in Kolkata. More intense rainfall, riverine flooding, sea level rise, and coastal storm surges in a changing climate can lead to widespread and severe flooding and bring the city to a standstill for several days. Using rainfall data, high and low emissions scenarios, and sea level rise of 27 cm by 2050, this paper assesses the vulnerability of Kolkata to increasingly intense precipitation events for return periods of 30, 50, and 100 years. It makes location-specific inundation depth and duration projections using hydrological, hydraulic, and urban storm models with geographic overlays. High resolution spatial analysis provides a roadmap for designing adaptation schemes to minimize the impacts of climate change. The modeling results show that de-silting of the main sewers would reduce vulnerable population estimates by at least 5 %.
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Investment, transformation and leadership CDP S&P 500 Climate Change Report 2013 On behalf of 722 investors representing US$87 trillion in assets
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Sample text : Fears are increasing over future climate change impacts as we see more extreme weather events, Hurricane Sandy the most noted with damages totalling some $42 billion.2 The unprecedented melting of the Arctic ice is a clear climate alarm bell, while the first 10 years of this century have been the world’s hottest since records began, according to the World Meteorological Organization.
The result is a seismic shift in corporate awareness of the need to assess physical risk from climate change and to build resilience.
For investors, the risk of stranded assets has been brought to the fore by the work of Carbon Tracker. They calculate around 80% of coal, oil and gas reserves are unburnable, if governments are to meet global commitments to keep the temperature rise below 2°C. This has serious implications for institutional investors’ portfolios and valuations of companies with fossil fuel reserves.
The economic case for action is strengthening. This year, we published The 3% Solution3 with the World Wildlife Fund showing that the US corporate sector could reduce emissions by 3% each year between 2010 and 2020 and deliver $780 billion in savings above costs as a result. 79% of US companies responding to CDP report higher ROI on emissions reduction investments than on the average business investment.
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Thinking Long Term
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Thousand-year records of animal population patterns and climate yield insights into the impacts of environmental change.
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OCEAN–ATMOSPHERE COUPLING Mesoscale eddy effects
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1st paragraph: Because of its enormous heat capacity, the ocean plays a critical role in regulating the Earth’s climate. Up to about a decade ago, it was generally believed that, outside the tropics, the ocean responds only passively to atmospheric forcing1. However, with the advent of satellite measurements of sea surface temperature and surface winds with resolutions down to about 50 km, it became apparent that the strong gradients in sea surface temperature that are associated with meanders in the Gulf Stream, the California Current and most other ocean currents can directly affect surface winds1–3.
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Suppressing Impacts of the Amazonian Deforestation by the Global Circulation Change
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Analyzing the Global Historical Climatology Network, outgoing longwave radiation, and NCEP–NCAR reanalysis data over the Amazon Basin, the authors find a clear interdecadal increasing trend over the past four decades in both rainfall and intensity of the hydrological cycle. These interdecadal variations are a result of the interdecadal change of the global divergent circulation. On the contrary, the impact of the Amazon deforestation as evaluated by all numerical studies has found a reduction of rainfall and evaporation, and an increase of temperature in the Amazon Basin extending its dry season. Evidently, the interdecadal trend of the basin’s hydrological cycle revealed from observations functions in a course opposite to the deforestation scenario. Results of this study suggest that future studies analyzing the impact of the basin-scale deforestation on the regional hydrological cycle and climate should be reassessed with multidecade numerical simulations including both schemes handling the land-surface processes and the mechanism generating proper interdecadal variation of the global divergent circulation.
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WWF: China Ecological Footprint Report 2012 Consumption, Production and Sustainable Development
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From the Executive Summary p. 3 : "We have only one planet and the time has come to transform our present lifestyle and consumption patterns in order to halt the degradation of the Earth’s natural capital, and to secure
ecosystem services as the foundation for economic and social development."
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Genetic signatures of a demographic collapse in a large-bodied forest dwelling primate
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It is difficult to predict how current climate change will affect wildlife species adapted to a tropical rainforest environment. Understanding how population dynamics fluctuated in such species throughout periods of past climatic change can provide insight into this issue. The drill (Mandrillus leucophaeus) is a large-bodied rainforest adapted mammal found in West Central Africa. In the middle of this endangered monkey’s geographic range is Lake Barombi Mbo, which has a well-documented palynological record of environmental change that dates to the Late Pleistocene. We used a Bayesian coalescent-based framework to analyze 2,076 base pairs of mitochondrial DNA across wild drill populations to infer past changes in female effective population size since the Late Pleistocene. Our results suggest that the drill underwent a nearly 15-fold demographic collapse in female effective population size that was most prominent during the Mid Holocene (approximately 3-5 Ka). This time period coincides with a period of increased dryness and seasonality across Africa and a dramatic reduction in forest coverage at Lake Barombi Mbo. We believe that these changes in climate and forest coverage were the driving forces behind the drill population decline. Furthermore, the warm temperatures and increased aridity of the Mid Holocene are potentially analogous to current and future conditions faced by many tropical rainforest communities. In order to prevent future declines in population size in rainforest-adapted species such as the drill, large tracts of forest should be protected to both preserve habitat and prevent forest loss through aridification. Bayesian Skyline Plot, bottleneck, climate change, Cross-Sanaga-Bioko forests, drill, Mandrillus.
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A statistical procedure to determine recent climate change of extreme daily meteorological data as applied at two locations in Northwestern North America
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An iterative chi-square method is applied to determine recent climate change of extremes of daily minimum temperature at two locations between an 18- year recent period and a 36-year prior period. The method determines for each of two locations in northwestern North America, Bozeman, Montana, USA and Coldstream, British Columbia, Canada, which values of the extreme daily weather elements are most significantly different between the prior years and the recent years and gives a measure of the weekly significance of that difference. Determination was made of the average percent of each recent year date (plotted weekly) that was im- pacted by extreme weather due to climate change as well as the percentage change in the frequency of the number of extreme days for each period of contiguous significant weeks. During the recent period at both locations, most weeks experienced a greater number of days of extreme high minimum temperature and a fewer number of days of extreme low minimum temperature. The weekly percentage changes indicate that extreme high minimum temperatures at both Bozeman and Coldstream are increasing at the rate of about 10% per decade, with a close corresponding decrease of extreme low minimum temperatures. The major changes in climate were very similar at both locations, with greatest warming occurring during the late winter and early spring and during the late July to August period.
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A century of climate and ecosystem change in Western Montana: what do temperature trends portend?
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Abstract The physical science linking human-induced increases ingreenhouse gasses to the warming of the global climate system is well established, but the implications of this warming for ecosystem processes and services at regional scales is still poorly understood. Thus, the objectives of this work were to: (1) describe rates of change in temperature averages and extremes for western Montana, a region containing sensitive resources and ecosystems, (2) investigate associations between Montana temperature change to hemispheric and global temperature change, (3) provide climate analysis tools for land and resource managers responsible for researching and maintaining renewable resources, habitat, and threatened/endangered species and (4) integrate our findings into a more general assessment of climate impacts on ecosystem processes and services over the past century. Over 100 years of daily and monthly temperature data collected in western Montana, USA are analyzed for long-term changes in seasonal averages and daily extremes. In particular, variability and trends in temperature above or below ecologically and socially meaningful thresholds within this region (e.g., −17.8◦C (0◦F), 0◦C (32◦F), and 32.2◦C (90◦F)) are assessed. The daily temperature time series reveal extremely cold days (≤ −17.8◦C) terminate on average 20 days earlier and decline in number, whereas extremely hot days (≥32◦C) show a three-fold increase in number and a 24-day increase in seasonal window during which they occur. Results show that regionally important thresholds have been exceeded, the most recent of which include the timing and number of the 0◦C freeze/thaw temperatures during spring and fall. Finally, we close with a discussion on the implications for Montana’s ecosystems. Special attention is given to critical processes that respond non-linearly as temperatures exceed critical thresholds, and have positive feedbacks that amplify the changes.
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Differences and sensitivities in potential hydrologic impact of climate change to regional-scale Athabasca and Fraser River basins of the leeward and windward sides of the Canadian Rocky Mountains respectively
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Sensitivities to the potential impact of Climate Change on the water resources of the Athabasca River Basin (ARB) and Fraser River Basin (FRB) were investigated. The Special Report on Emissions Scenarios (SRES) of IPCC projected by seven general circulation models (GCM), namely, Japan’s CCSRNIES, Canada’s CGCM2, Australia’s CSIROMk2b, Germany’s ECHAM4, the USA’s GFDLR30, the UK’s HadCM3, and the USA’s NCARPCM, driven under four SRES climate scenarios (A1FI, A2, B1, and B2) over three 30-year time periods (2010–2039, 2040– 2069, 2070–2100) were used in these studies. The change fields over these three 30-year time periods are assessed with respect to the 1961–1990, 30-year climate normal and based on the 1961–1990 European Community Mid-Weather Forecast (ECMWF) re-analysis data (ERA-40), which were adjusted with respect to the higher resolution GEM forecast archive of Environment Canada, and used to drive the Modified ISBA (MISBA) of Kerkhoven and Gan (Adv Water Resour 29(6):808– 826, 2006). In the ARB, the shortened snowfall season and increased sublimation together lead to a decline in the spring snowpack, and mean annual flows are expected to decline with the runoff coefficient dropping by about 8% per ◦C rise in temperature. Although the wettest scenarios predict mild increases in annual runoff in the first half of the century, all GCM and emission combinations predict large declines by the end of the twenty-first century with an average change in the annual runoff, mean maximum annual flow and mean minimum annual flow of −21%, −4.4%, and −41%, respectively. The climate scenarios in the FRB present a less clear picture of streamflows in the twenty-first century. All 18 GCM projections suggest mean annual flows in the FRB should change by ±10% with eight projections suggesting increases and 10 projecting decreases in the mean annual flow. This stark contrast with the ARB results is due to the FRB’s much milder climate. Therefore under SRES scenarios, much of the FRB is projected to become warmer than 0◦C for most of the calendar year, resulting in a decline in FRB’s characteristic snow fed annual hydrograph response, which also results in a large decline in the average maximum flow rate. Generalized equations relating mean annual runoff, mean annual minimum flows, and mean annual maximum flows to changes in rainfall, snowfall, winter temperature, and summer temperature show that flow rates in both basins are more sensitive to changes in winter than summer temperature.
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