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Global warming to hurt Australian agriculture
by Neena Bhandari
Sydney, Feb 9 2001 (IPS) -- The heavy floods and bushfires that Australia has experienced this summer are only a preview of what climate change has in store for the country.
Indeed, changing weather patterns in the coming years due to the gradual warming of the Earth will affect agricultural-based businesses and communities the most, says a report released here Thursday called ‘Climate Change and Agriculture in New South Wales: The Challenge for Rural Communities.’
twnside.org.sg
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Pentagon: "global warming requires immediate action"
The Pentagon's planning scenario says that global warming "should be elevated beyond a scientific debate to a US national security concern." It declares that "future wars will be fought over the issue of survival rather than religion, ideology or national honour."
The Pentagon foresees fishing wars between Spain and Portugal. Pakistan, India, and China - all armed with nuclear weapons - skirmish at their borders over refugees, access to shared rivers, and arable land. Bangladesh becomes uninhabitable. Drought hits the American breadbasket. Britain's weather begins to resemble Siberia. India, South Africa, and Indonesia are ripped apart by civil war.
And ultimately, the report forecasts a decrease in the planet's human carrying capacity, leading to sharp reductions in the world's population due to starvation, disease, and war.
greenpeace.org
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An Abrupt Climate Change Scenario and
Its Implications for United States National Security
PETER SCHWARTZ & DOUG RANDALL / GBN Global Business Network October 2003
The research suggests that once temperature rises above some threshold, adverse weather conditions could develop relatively abruptly, with persistent changes in the atmospheric circulation causing drops in some regions of 5-10 degrees Fahrenheit in a single decade. Paleoclimatic evidence suggests that altered climatic patterns could last for as much as a century, as they did when the ocean conveyor collapsed 8,200 years ago, or, at the extreme, could last as long as 1,000 years as they did during the Younger Dryas, which began about 12,700 years ago.
In this report, as an alternative to the scenarios of gradual climatic warming that are so common, we outline an abrupt climate change scenario patterned after the 100-year event that occurred about 8,200 years ago. This abrupt change scenario is characterized by the following conditions:
Annual average temperatures drop by up to 5 degrees Fahrenheit over Asia and North America and 6 degrees Fahrenheit in northern Europe
Annual average temperatures increase by up to 4 degrees Fahrenheit in key areas throughout Australia, South America, and southern Africa.
Drought persists for most of the decade in critical agricultural regions and in the water resource regions for major population centers in Europe and eastern North America.
Winter storms and winds intensify, amplifying the impacts of the changes. Western Europe and the North Pacific experience enhanced winds.
The report explores how such an abrupt climate change scenario could potentially de-stabilize the geo-political environment, leading to skirmishes, battles, and even war due to resource constraints such as:
Food shortages due to decreases in net global agricultural production
Decreased availability and quality of fresh water in key regions due to shifted precipitation patters, causing more frequent floods and droughts
Disrupted access to energy supplies due to extensive sea ice and storminess
mindfully.org
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The most recent assessment by the Intergovernmental Panel on Climate Change (IPCC) projected that global average surface
temperature would increase by between 1.4 to 5.8°C over the period 1990 to 2100, while sea-levels could rise by between nine and 88 centimetres (IPCC 2001a). Temperatures have already increased by 0.6°C over the 20th century, and most of this warming is attributable to human activities (IPCC 2001a).
The rise in temperatures will influence crop yields by
? shifting optimal crop growing zones;
? changing patterns of precipitation (quantity and variability) and potential evapotranspiration;
? reducing winter storage of moisture in snow and glacier areas;
? shifting the habitats of crop pests and diseases;
? affecting crop yields through the effects of carbon dioxide and temperature; and
? reducing cropland through sea-level rise and vulnerability to flooding.
The overall impact of these effects will vary by elevation, soil type, crop and other local factors. This variability, along with the
uncertainties of very long-term climate forecasting, especially at the regional level, makes discussion of the effects of climate
change on crop production tentative at best. Generalizations can usually only indicate ranges of possible scenarios. Overall, there may be benefits for agriculture in many temperate zones, where the length of the growing period will increase, costs of overwintering livestock will fall, crop yields may improve and forests may grow faster.
Loss of land to sea-level rise: Some of the world’s most densely populated areas could lose fertile arable land, especially in low-lying delta areas such as those of the Nile, the Mekong and the Ganges-Brahmaputra. A one metre sea-level rise, for example, could result in the loss of 5 800 km2 in the lower Nile delta, affecting 15 per cent of Egypt’s habitable land (Nicholls 1994).
In Bangladesh, a one metre rise could flood almost 30 000 km2, affecting over 13 per cent of the population, while in Vietnam 40 000 km2 could be lost affecting 23 per cent of the population (Table 1) (IPCC 2001b). Even where land is not flooded, soil quality may decline due to salinization of soils and groundwater sources and increased risk of tidal surges.
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Climate change and agriculture...
Agricultural surfaces and climate changes
Climate change is likely to increase the amount of arable land near the poles by reduction of the amount of frozen lands. Sea levels are expected to get up to one meter higher by 2100, though this projection is disputed. Rise in sea level would result in agricultural land loss, in particular in areas such as South East Asia. Erosion, submergence of shorelines, salinity of the water table due to the increased sea levels, could mainly affect agriculture through inundation of low-lying lands.
en.wikipedia.org
unep.org |
