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A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa
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Observations and simulations link anthropogenicgreenhouse and aerosol emissions with rapidly
increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by *40 longitude ([4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55E–140W) since at least 1948, explaining more variance than anomalies associated with the El Nin˜o-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend
toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980–2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Nin˜o-like’ conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications,
informing agricultural development, environmental conservation, and water resource planning.
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Ecological responses to recent climate change
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There is now ample evidence of the ecological impacts of recent climate change, from polar terrestrial to tropical marine environments. The responses of both flora and fauna span an array of ecosystems and organizational hierarchies, from the species to the community levels. Despite continued uncertainty as to community and ecosystem trajectories under global change, our review exposes a coherent pattern of ecological change across systems. Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are already clearly visible.
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Predicting satellite-derived patterns of large-scale disturbances in forests of the Pacific Northwest Region in response to recent climatic variation
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Across the Pacific Northwest, the climate between 1950 and 1975 was exceptionally cool and wet compared
with more recent conditions (1995–2005). We reasoned that the changes in climate could result in expanded
outbreaks of insects, diseases, and fire. To test this premise, we first modeled monthly variation in photosynthesis
and growth of the most widely distributed species, Douglas-fir (Pseudotsuga menziesii), using a
process-based model (3-PG) for the two periods. To compare with remotely sensed variables, we converted
modeled growth potential into maximum leaf area index (LAImax), which was predicted to range from 1 to 9
across the region. On most sites, varying soil moisture storage capacity (θcap) from 200 to 300 mm while
holding soil fertility constant, made slight but insignificant difference in simulated LAImax patterns. Both
values of θcap correlated well with LAI estimates acquired from NASA's MODIS satellites in June, 2005
(r2= 0.7). To evaluate where 15 coniferous tree species might be prone to wide-scale disturbance, we used
climatically-driven decision-tree models, calibrated in the 1950–1975 period, to identify vulnerable areas
in 1995–2005. We stratified predictions within 34 recognized ecoregions and compared these results with
large-scale disturbances recorded on MODIS imagery acquired between 2005 and 2009. The correlation
between the percent of species judged as vulnerable within each ecoregion and the percent of forested
areas recorded as disturbed with a MODIS-derived Global Disturbance Index was linear and accounted for
65 to 73% of the observed variation, depending on whether or not disturbance by fire was excluded from
the analysis. Based on climate projections through the rest of the rest of the 21st century, we expect continued
high levels of disturbance in ecoregions located beyond the climatically buffering influence of the Pacific
Ocean.
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How Much More Rain Will Global Warming Bring?
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Climate models and satellite observations both indicate that the total amount of water in the
atmosphere will increase at a rate of 7% per kelvin of surface warming. However, the climate
models predict that global precipitation will increase at a much slower rate of 1 to 3% per kelvin. A
recent analysis of satellite observations does not support this prediction of a muted response of
precipitation to global warming. Rather, the observations suggest that precipitation and total
atmospheric water have increased at about the same rate over the past two decades.
SCIENCE VOL 317 13 JULY 2007
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Slowly Warming
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A chart about global Warming
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Spatial patterns and policy implications for residential water use
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The front yard makes a powerful visual statement about the
occupants of the residence. As visible statements, yards are likely
to induce a behavioral response on the part of neighboring
residents. As an example, residents may strive to keep their
yard as green and lush as their neighbors. For Kelowna, British
Columbia, a highly significant positive spatial lag for summer
water use implies some degree of spatial emulation in water using
behavior. Other variables such as lot size, building size, assessed
value, presence of a pool, etc. impact on water use as expected. The
presence of a spatial lag implies a spatial multiplier for water
saving innovations. If local water managers and policy makers can
influence the spatial pattern of water saving innovations, they may be
able to increase the size of the multiplier effect. Similar spatial policies
may also be applicable to other socially influenced behaviors that
leave a spatial signature, such as protecting ecologically significant
habitats in urban areas
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Columbia Water Center White Paper America’s Water Risk: Water Stress and Climate Variability
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The emerging awareness of the dependence of business on water has resulted in increasing awareness of the concept of “Water Risk” and the diverse ways in which water can pose threats to businesses in certain regions and sectors. Businesses seek to secure sustainable income. To do so, they need to maintain a
competitive advantage and brand differentiation. They need secure and stable supply chains. Their exposure risks related to increasing scarcity of water can come in a variety of forms at various points in the supply chain. Given increasing water scarcity and the associated deterioration of the quantity and quality of water sources in many parts of the world, many “tools” have been developed to map water scarcity riskor water risk. Typically, these tools are based on estimates of the average water supply and demand in each unit of analysis.Often, they are associated with river basins, while business is associated with cities or counties. They provide a useful first look at the potential imbalance of supply and demand to businesses.
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Safe Havens, Safe Passages for Vulnerable Fish and Wildlife
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Some of the best-known and most-cherished mountains on Earth are set in the
Canadian Rockies of British Columbia and Alberta. Indeed, the mention of
Banff, Jasper, Kootenay or Yoho National Parks evokes images of snow-capped
peaks, thundering falls and turquoise waters, numerous natural wonders and
majestic wildlife. The adjoining Provincial Parks in British Columbia – Mount
Robson, Mount Assiniboine, and Hamber – are just as spectacular, if not quite
as renowned. Waterton Lakes National Park in Alberta and Glacier National
Park in Montana – brought together in 1931 as an International Peace Park by
the respective Rotary Clubs – exemplify international cooperation and wilderness
and wildlife without borders. All 9 of these parks have been designated as
World Heritage Sites in recognition of their outstanding natural importance to
the common heritage of humanity.
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Conservation VALUE OF ROADLESS AREAS FOR VULNERABLE FISH AND Wildlife Species in the Crown of the Continent Ecosystem, Montana
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The Crown of the Continent Ecosystem is one of the most spectacular landscapes
in the world and most ecologically intact ecosystem remaining in the
contiguous United States. Straddling the Continental Divide in the heart of the
Rocky Mountains, the Crown of the Continent Ecosystem extends for >250
miles from the fabled Blackfoot River valley in northwest Montana north to Elk
Pass south of Banff and Kootenay National Parks in Canada. It reaches from
the short-grass plains along the eastern slopes of the Rockies westward nearly
100 miles to the Flathead and Kootenai River valleys. The Crown sparkles with
a variety of dramatic landscapes, clean sources of blue waters, and diversity of
plants and animals.Over the past century, citizens and government leaders have worked hard to
save the core of this splendid ecosystem in Montana by establishing world-class
parks and wildernesses – coupled with conservation of critical wildlife habitat
on state and private lands along the periphery. These include jewels such as
Glacier National Park, the Bob Marshall-Scapegoat-Great Bear Wilderness,
the first-ever Tribal Wilderness in the Mission Mountains, numerous State of
Montana Wildlife Management Areas (WMAs), and vital private lands through
land trusts such as The Nature Conservancy. Their combined efforts have
protected 3.3 million acres and constitute a truly impressive commitment to
conservation. It was a remarkable legacy and great gift …but, in the face of new
challenges, it may not have been enough.
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Projections of Future Drought in the Continental United States and Mexico
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Using the Palmer drought severity index, the ability of 19 state-of-the-art climate models to reproduce observed
statistics of drought over North America is examined. It is found that correction of substantial biases in
the models’ surface air temperature and precipitation fields is necessary. However, even after a bias correction,
there are significant differences in the models’ ability to reproduce observations. Using metrics based on the
ability to reproduce observed temporal and spatial patterns of drought, the relationship between model performance
in simulating present-day drought characteristics and their differences in projections of future drought
changes is investigated. It is found that all models project increases in future drought frequency and severity.
However, using the metrics presented here to increase confidence in the multimodel projection is complicated
by a correlation between models’ drought metric skill and climate sensitivity. The effect of this sampling error
can be removed by changing how the projection is presented, from a projection based on a specific time interval
to a projection based on a specified temperature change. This modified class of projections has reduced
intermodel uncertainty and could be suitable for a wide range of climate change impacts projections.
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