Federal Advisory Committee Draft Climate Assessment Report Released for Public Review


Click on the thumbnail graphic for the map of expected temperature increases for the Southwestern United States.

Click here to read their letter “Climate Change and the American People. Here’s an excerpt:

Climate change, once considered an issue for a distant future, has moved firmly into the present. This report of the National Climate Assessment and Development Advisory Committee concludes that the evidence for a changing climate has strengthened considerably since the last National Climate Assessment report, written in 2009. Many more impacts of human-caused climate change have now been observed. Corn producers in Iowa, oyster growers in Washington State, and maple syrup producers in Vermont have observed changes in their local climate that are outside of their experience. So, too, have coastal planners from Florida to Maine, water managers in the arid Southwest and parts of the Southeast, and Native Americans on tribal lands across the nation.

Americans are noticing changes all around them. Summers are longer and hotter, and periods of extreme heat last longer than any living American has ever experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours, though in many regions there are longer dry spells in between.

Coyote Gulch friend and teacher, Reagan Waskom, is one of the lead authors of the chapter about the Southwest. Here’s an excerpt:

Key Messages

  • 1. Snowpack and streamflow amounts are projected to decline, decreasing water supply for cities, agriculture, and ecosystems.
  • 2. The Southwest produces more than half the nation’s high-value specialty crops, which are irrigation-dependent and particularly vulnerable to extremes of moisture, cold, and heat. Reduced yields from increased temperatures and increasing competition for scarce water supplies will displace jobs in some rural communities.
  • 3. Increased warming, due to climate change, and drought have increased wildfires and impacts to people and ecosystems in the Southwest. Fire models project more wildfire and increased risks to communities across extensive areas.
  • 4. Flooding and erosion in coastal areas is already occurring and is damaging some areas of the California coast during storms and extreme high tides. Sea level rise is projected to increase, resulting in major damage as wind-driven waves ride upon higher seas and reach further inland.
  • 5. Projected regional temperature increases, combined with the way cities amplify heat, will pose increased threats and costs to public health in Southwestern cities, which are home to more than 90 percent of the region’s population. Disruptions to urban electricity and water supplies will exacerbate these health problems.
  • Introduction

    The Southwest is the hottest and driest region in the U.S., where the availability of water has defined its landscapes, history of human settlement, and modern economy. Climate changes pose challenges for an already parched region that is expected to get hotter and, in its southern half, significantly drier. Increased heat and changes to rain and snowpack will send ripple effects throughout the region’s critical agriculture sector, affecting the lives and economies of 56 million people – a population that is expected to increase by 38 million by 2050. Severe and sustained drought will stress water sources already over-utilized in many areas, forcing increasing competition among farmers, urban dwellers, and the region’s varied plant and animal life for the region’s most precious resource.

    The region’s populous coastal cities face rising sea levels, extreme high tides, and storm surges, which pose particular risks to highways, bridges, power plants, and sewage treatment plants. Climate challenges also increase risks to critical port cities, which handle half of the nation’s incoming shipping containers.

    Agriculture, a mainstay of the regional and national economies, faces uncertainty and change. The Southwest produces more than half of the nation’s high-value specialty crops, such as vegetables, fruits, and nuts.

    The severity of future impacts will depend upon the complex interaction of pests, water supply, reduced chilling periods, and more rapid changes in the seasonal timing of crop development due to projected warming and extreme events.

    Climate changes will increase stress on the region’s rich diversity of plant and animal species. Widespread tree death and fires, which already have caused billions of dollars in economic losses, are projected to increase, forcing wholesale changes to forest types, landscapes, and the communities that depend on them (See also Ch 7: Forestry).

    Tourism and recreation, generated by the Southwest’s winding canyons, snow-capped peaks, and Pacific Ocean beaches, provide a significant economic force that also faces climate change challenges. The recreational economy will be increasingly affected by reduced streamflow and a shorter snow season, influencing everything from the ski industry to lake and river recreation.

    Click here to go to the website to download the whole report.

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