File Name: global warming and changes in drought .zip
Climate change increases the odds of worsening drought in many parts of the United States and the world in the decades ahead. Regions such as the U. There are a number of ways climate change may contribute to drought.
Droughts occur naturally, but climate change has generally accelerated the hydrological processes to make them set in quicker and become more intense, with many consequences, not the least of which is increased wildfire risk.
A drought is an event of prolonged shortages in the water supply, whether atmospheric below-average precipitation , surface water or ground water. A drought can last for months or years, or may be declared after as few as 15 days. Periods of heat can significantly worsen drought conditions by hastening evaporation of water vapour.
Global warming and changes in drought
In , California had the driest year on record. Drought can call to mind images of dry, cracked earth; low reservoir levels; and barren fields, yet these are actually examples of different types of drought, each of which is measured differently. We most often think about drought in relation to precipitation, assessing the degree of dryness in comparison to a local or regional average and the duration of the dry period. This is known as a meteorological drought , which is highly specific to a region as average precipitation may vary considerably spatially. We can also think about hydrological drought , or how decreased precipitation affects streamflow, soil moisture, reservoir and lake levels, and groundwater recharge. Farmers are most concerned with agricultural drought when available water supplies are not able to meet crop water demands. Agricultural droughts can occur for a variety of reasons, including low precipitation, the timing of water availability, or decreased access to water supplies.
The potential future effects of global climate change include more frequent wildfires, longer periods of drought in some regions and an increase in the number, duration and intensity of tropical storms. Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner. Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves. Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities. According to the IPCC, the extent of climate change effects on individual regions will vary over time and with the ability of different societal and environmental systems to mitigate or adapt to change.
Most studies on the impact of climate change on regional water resources focus on long-term average flows or mean water availability, and they rarely take the effects of altered human water use into account. When analyzing extreme events such as floods and droughts, the assessments are typically confined to smaller areas and case studies. At the same time it is acknowledged that climate change may severely alter the risk of hydrological extremes over large regional scales, and that human water use will put additional pressure on future water resources. In an attempt to bridge these various aspects, this paper presents a first-time continental, integrated analysis of possible impacts of global change here defined as climate and water use change on future flood and drought frequencies for the selected study area of Europe. The global integrated water model WaterGAP is evaluated regarding its capability to simulate high and low-flow regimes and is then applied to calculate relative changes in flood and drought frequencies. The regions most prone to a rise in flood frequencies are northern to northeastern Europe, while southern and southeastern Europe show significant increases in drought frequencies. In the critical regions, events with an intensity of today's year floods and droughts may recur every 10—50 years by the s.
Few areas of the world are completely immune to droughts and their often-devastating impacts on water resources, ecosystems and people. Regions as diverse as California , the Eastern Mediterranean , East Africa , South Africa and Australia have all experienced severe — and, in some cases, unprecedented — droughts in recent years. As with other climate and weather extremes , such as storms and floods, these events have spurred strong interest in questions surrounding the impact of climate change. For example, is climate change making droughts more frequent or severe? And can we expect climate change to contribute to increased drought risk and severity in the future? The most recent research shows climate change is already making many parts of the world drier and droughts are likely to pack more punch as the climate warms further.
This chart shows annual values of the Palmer Drought Severity Index, averaged over the entire area of the contiguous 48 states. Positive values represent wetter-than-average conditions, while negative values represent drier-than-average conditions. A value between -2 and -3 indicates moderate drought, -3 to -4 is severe drought, and -4 or below indicates extreme drought.
Кокетка до мозга костей, трижды разведенная, Мидж двигалась по шестикомнатным директорским апартаментам с вызывающей самоуверенностью. Она отличалась острым умом, хорошей интуицией, частенько засиживалась допоздна и, как говорили, знала о внутренних делах АНБ куда больше самого Господа Бога. Черт возьми, - подумал Бринкерхофф, разглядывая ее серое кашемировое платье, - или я старею, или она молодеет.