Climate changes and the local environment:Mohave County is located in Northwestern Arizona, and includes part of the Grand Canyon National Park, as well as several federally recognized Native American Reservations. Its annual average temperatures have risen by an average of 0.2°F per decade between 1895 and 2016. However, this average hides the fact that average temperatures in the county and the state were mostly stable until roughly 1975. After that year, the trend in average temperatures began rising very quickly, and this caused a worrying increase in the frequency and intensity of wildfires and droughts. These weather and climate-related events have had devastating effects in the local environment. As much as 15 per cent of Arizona is covered by national forests, and the hotter and drier conditions have made it easier for wildfires to occur. According to U.S. Forest Service records, large wildfires (of more than 1,000 acres) in the state have increased from approximately 5 per year before 1980, to a current average of near 20. Drought has affected the Colorado river, a source of water for over 30 million people, including a large share of Mohave County and the State of Arizona. For example, the Upper Colorado Basin has seen more common and severe droughts in the last 50 to 90 years. In the period between 2000 and 2014, the river’s flow declined by 19 per cent compared to the average between 1906 and 1999. Researchers have estimated that warmer temperatures account for up to one-sixth of these losses, which are approximately equal to enough water to support 1 million households for a year. How we know:These climate and weather reconstructions are based on several tools made available online by several United States agencies, such as the National Oceanic and Atmospheric Administration (NOAA)’s State Annual and Seasonal Time Series. This site is useful to see the evolution of temperatures at the state level since 1895, and its information is obtained from the U.S. Climate Divisional Dataset, used often for agricultural matters. NOAA’s Climate at a Glance tool is intended for studying the changes and variability of climate, and has adjusted the data to take into account artificial effects that affect climate, such as urbanization. Another important resource is the United States Drought Monitor, which develops weekly maps of drought conditions across the country, and uses climate, soil, and water data, together with reports from 350 experts across the country. The U.S. Climate Resilience Toolkit helps people become informed about their risks and opportunities related to the changing climate, and to help them become more resilient. One of its tools is the Climate Explorer, which allows users to explore the potential damaging effects of climate on the population and their valued possessions, such as land and crops. To do this, it shows projections of temperatures, precipitation, and others for two possible futures: one in which humans make a moderate attempt to reduce their carbon emissions, and another in which humans continue to act as usual. Some of the biggest effects of climate change in Arizona have been linked to health concerns, disruptions in the water supply for farms and cities, and the destruction of the environment with wildfires. In the summer of 2017, the state made nationwide news when numerous flights were cancelled in Phoenix due the excessive heat. These extreme temperatures caused near 1,300 deaths between 2005 and 2015, and the number of heat-related illnesses has been increasing, according to a medical director at the Banner University Medical Center in Phoenix. The Environmental Protection Agency (EPA) has reported that more than 2 per cent of the land in Arizona has burned per decade since 1984, and the smoke produced often damages the quality of the air and water, and creates health problems for the population. In Mohave County, the most significant human consequences of climate change can be found in the water supply disruption to households, and in the Native American communities. Decreasing water reserves in important bodies of water like Lake Mead, and the increasing water needs due to growing cities and new farms that move from California’s even more extreme water shortage, have led to severe concerns and restrictions on water use. Native American tribes have seen their traditional practices challenged, as they are typically very dependent on agriculture and the raising of livestock, which in turn depend on weather and the availability of water. For the Mohave tribe, a drier Colorado River means a disruption to their traditions, as they believe that the river was created by their ancient deity Mastamho as part of their sacred landscape. Despite this worrisome picture, in a Climate Central report, Arizona’s government received a failing grade for its average level of wildfire preparedness, and a near-failing grade for its drought preparedness, as its plans do not account for the devastating effects of climate change. Further reading:The Future is Drying Up. NY Times Magazine Where the River Runs Dry. The New Yorker The $2.4 Billion Plan to Water California by Draining the Mojave. Wired Wildfires, Once Confined to a Season, Burn Earlier and Longer. NY Times Article author: Alejandro Carrera Rodriguez, Georgetown University
Article editor: Dr. Dagomar Degroot, Georgetown University
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Climate changes and the local environment:Genesee County, Michigan has warmed steadily for more than a century. Although average annual temperatures in the state have climbed more slowly than the global trend, they have still risen by around 0.6° C (1.1° F) relative to twentieth-century averages. Michigan is known for its long and snowy winter seasons. Rising temperatures, however, have sharply shortened the length of winter across the state. The total number of days in the winter season with at least 2.5 cm (1 inch) of snow cover has declined sharply since 1920, with most of the decline happening since 1980. As winter grows shorter, snow falls less frequently. Yet that does not necessarily mean that winters have become less snowy across the state. Snowfall trends from county to county vary widely, in large part because water in the nearby Great Lakes cools more slowly than air. If the lakes are largely ice-free, warm water can heat up otherwise cool air blowing into Michigan. The air then absorbs moisture and deposits it as "lake-effect" snow in some, but not all of, Michigan. Now that the Great Lakes are ice-free for much longer than they were, on average, in the twentieth century, blizzards have grown more common in Michigan even as winters have grown shorter. Overall, precipitation in all seasons has increased across Michigan, at a rate of roughly 1.5 mm/year since the 1930s. Much of the increase has come not through extreme events, but a steady rise in wet days that follow wet days. There are signs that cloudiness is now more frequent than it was in the twentieth century. In this context, Genesee County in Michigan has recently endured particularly extreme and destructive weather. In March 2012, for example, temperatures in a normally cold month soared to a record-shattering 31° C (88° F). In January 2014, a severe snowstorm dropped 18 inches of snow on the county, the second-heaviest fall since 1975. How we know:These reconstructions rely on the National Oceanic and Atmospheric Administration (NOAA) State Annual and Seasonal Time Series and a freely available report, "Historical Climate Trends in Michigan and the Great Lakes Region," by Dr. Jeffrey Andresen of the Department of Geography at Michigan State University. NOAA's State Annual and Seasonal Time Series relies largely on weather station measurements. Adresen's report largely draws on data collected by weather instruments but also includes information from other sources, such as observations from aircraft. Human consequences:Heat waves and blizzards brought about by rising temperature trends have imposed high costs on Michigan, including Genesee county. Nation-wide statistics suggest that the elderly, especially those with limited mobility and insufficiently insulated or air conditioned houses, are in great danger during both extreme heat and blizzards. Heat waves can also damage roads and train tracks, impose strains on energy and water resources, and lower crop yields if they arrive in key development stages. Yet in Michigan, a trend towards wetter weather may also have had beneficial impacts for regional agriculture. Computer simulations show that increases in soil moisture available to corn at mid-season, and a rise in plant-available water in the soil profile over the whole season, have both increased corn yields across Michigan. Until now, global warming has therefore had a complex mix of beneficial and destructive impacts on Michigan, and therefore on Genesee county. Article author: Diana Lowitt, Georgetown University
Article editor: Dr. Dagomar Degroot, Georgetown University Climate changes and the local environment:Average annual temperatures across California have been rising since the nineteenth century, a trend that has sharply accelerated since around 1970. Average temperatures across all seasons in Tulare County in south central California have mirrored that statewide pattern. As the county warmed, it suffered a series of severe droughts, which are usually defined as long-lasting moisture deficits that have environmental and social consequences. Droughts in the county involve three sources of water: surface water at low elevations, snow at high elevations, and groundwater buried below the surface. Precipitation in much of California has long varied by as much as 50% from year to year. Hotter temperatures, however, are increasing the rate of evaporation across California, including in Santa Barbara County. That has affected both mountain snow and lowland liquid water, and has made local droughts even longer and drier than they once were. One of the most severe droughts in the county's history recently began in February 2012 and lasted into 2017. The driest stretch of the drought started in February 2014 and endured until January 2017. It was part of a broader Californian drought that started in coastal areas several years earlier, and was up to 27% more likely to occur in our warmer climate. Longer, drier summers and an earlier snowmelt have caused drier forest conditions in southwest California, which has increased the amount of available kindling for wildfires to consume. These conditions have increased the size and duration of wildfires in California, and dramatically lengthened the wildfire season in Santa Barbara county. How we know:These reconstructions rely on several easy to use tools that are available online: the National Oceanic and Atmospheric Administration (NOAA) State Annual and Seasonal Time Series, the NOAA Weekly Palmer Drought Indices, the National Drought Mitigation Center's United States Drought Monitor, and the United States Geological Survey (USGS) interactive website. NOAA's State Annual and Seasonal Time Series relies largely on weather station measurements. NOAA's Palmer Drought Indices use a standard way of measuring drought that considers both water supply and demand in a soil moisture model. Negative values represent droughts, and positive values represent wet conditions. The United States Drought Monitor uses a number of drought indicators, including the Palmer Drought Indices, that consider both environmental and social manifestations of water shortages. The interactive tools made available by the USGS draw on open data provided by a range of United States government agencies, including the Army Corps of Engineers and the Bureau of Reclamation. Human consequences:Droughts can sharply reduce the quantity of water in reservoirs and aquifers across California, which often supply water to local residents. Reservoirs, which collect precipitation, and aquifers, which are the groundwater storage spaces, both contribute to Santa Barbara’s water supply. This supply is crucial for both commercial and industrial use. If global warming continues, Santa Barbara’s premium wine industry could be significantly affected. This is because distinct grape species can only thrive in specific temperature ranges. If Santa Barbara fails to produce grapes that can tolerate higher temperatures, then the decline in suitable land could be up to 20%. Wine is currently the third-most produced commodity in Santa Barbara county, and wine sales comprise nearly a tenth of the county's economy. One of the main water sources that supplies residents in Santa Barbara county is the Lake Cachuma reservoir. The reservoir supplies 85 percent of the water supply for over 250,000 residents of Goleta district in Santa Barbara county. Its available water supply plummeted during the California drought. As of October 1st 2017, it is still only 43% full. The lack of water in the Cachuma reservoir, in conjunction with the drought, will force Santa Barbara county to search for alternative water sources. Just recently, the county decided to reopen its desalination plant to supply more water to their residents. The reactivation of this plant cost the county an estimated $71 million, not including the cost of maintaining the plant. It will supply 3 million gallons of water per day to residents to cover 30% of the city’s water usage. In a warmer and drier future, such desperate measures may well be necessary across California. Article author: Madeline Lee, Georgetown University
Article editor: Dr. Dagomar Degroot, Georgetown University Climate changes and the local environment:Average annual temperatures across California have been rising since the nineteenth century, a trend that has sharply accelerated since around 1970. Average temperatures across all seasons in Tulare County in south central California have mirrored that statewide pattern. As the county warmed, it suffered a series of severe droughts, which are usually defined as long-lasting moisture deficits that have environmental and social consequences. Droughts in the county involve three sources of water: surface water at low elevations, snow at high elevations, and groundwater buried below the surface. Precipitation in much of California has long varied by as much as 50% from year to year. Hotter temperatures, however, are increasing the rate of evaporation across California, including in Tulare County. That has affected both mountain snow and lowland liquid water, and has made local droughts even longer and drier than they once were. One of the most severe droughts in the county's history recently began in 2014 and lasted until early 2017. It was part of a broader Californian drought that started in coastal areas several years earlier, and was up to 27% more likely to occur in our warmer climate. How we know:These reconstructions rely on several easy to use tools that are available online: the National Oceanic and Atmospheric Administration (NOAA) State Annual and Seasonal Time Series, the NOAA Weekly Palmer Drought Indices, and the National Drought Mitigation Center's United States Drought Monitor. NOAA's State Annual and Seasonal Time Series relies largely on weather station measurements. NOAA's Palmer Drought Indices use a standard way of measuring drought that considers both water supply and demand in a soil moisture model. Negative values represent droughts, and positive values represent wet conditions. The United States Drought Monitor uses a number of drought indicators, including the Palmer Drought Indices, that consider both environmental and social manifestations of water shortages. The above reconstructions also draw on an important study in Geophysical Research Letters, which estimates the possible contribution of global warming to the 2012-2014 drought in California. Human consequences:Severe droughts since the 1970s have badly hurt Californian farmers. In 2015 alone, farmers could not grow crops on nearly 500,000 acres of farmland, which accounted for a large share of the drought's annual economic cost to the state of nearly $3 billion. Tulare county was among the hardest-hit communities. The county has been one of the most productive agricultural counties in the United States. Its economy depends on the dairy industry, as well as crops such as oranges and grapes, which all require abundant water. Not only did these industries suffer particular hardships during the drought, but the drought also lasted longer in Tulare than it did in most other Californian counties. In 2014, the Tulare county Board of Supervisors declared a state of emergency and requested water transfers into the county from other parts of California. Yet hundreds of local wells remained dry into 2017. Many of the county's farms resorted to over-exploiting groundwater that may never fully recover, leaving them more vulnerable to future droughts that a changing climate will make longer and drier. While the recent drought has now ended, it may have long-lasting consequences for local agriculture. Further reading:
Article author: Dr. Dagomar Degroot, Georgetown University
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