Thursday, October 23, 2008

Maryland Climate Action Plan: Impacts

Did I happen to mention that the Maryland Climate Action Plan is 4 bajillion pages long? Seriously. It is also chock full of information that you will never read because it is 4 bajillion pages long. So here is what I am going to try to do: distill my favorite parts from the plan. Want to get all of the information? Read it yourself.

Part I: Predicted changes to Maryland from climate change

I have spent several years compiling a list of predicted global warming impacts to Maryland from various sources. My standard paragraph:

In Maryland, conservative impacts based on IPCC predictions over the next century include increased drought and water shortages; more intense storms and hurricanes; increased flooding; harm to the Chesapeake Bay including more dead zones and damage to the crab, oyster, and sportfishing industries; loss of native brook trout populations; wetlands loss; harm to fisheries and waterfowl; accelerated beach erosion; dangerous heat waves; loss of duck hunting; forest loss, especially to hemlocks; increased gypsy moths; loss of the maple syrup industry in Western Maryland; loss of the Baltimore Oriole and black-eyed Susan, Maryland’s state bird and flower; extinction of species in subarctic habitats in Western Maryland; loss of skiing industry income; loss of the honey industry in Maryland; changes to USDA hardiness zones for agriculture and gardening; worse acid rain and more ground-level ozone; more code red air quality days; and a loss of significant land mass especially coasts and wetlands, including Blackwater Refuge, Ocean City, Baltimore's Harborplace, and Smith, Hoopers and Bloodsworth Islands. These changes would have enormous consequences for the economic vitality and health of our communities.
I am happy to report that my list is now dwarfed by Chapter 2: Comprehensive Assessment of Climate Change Impacts in Maryland. I paraphrase:
  • Climatic regimes will continue to vary across Maryland. Western Maryland has cooler winters and summers and less precipitation during the winter than the rest of the state. Changes will occur on top of these regional differences, perhaps with some greater warming during the summer to the west than on the Eastern Shore.
  • Temperature is projected to increase substantially, especially under higher emissions.
    Average temperature is projected to increase by about 3°F by mid-century and is likely unavoidable. The amount of warming later in the century is dependent on the mitigation of greenhouse gas emissions, with summer temperatures projected to increase by as much 9°F, and heat waves extending throughout most summers.
  • Increased precipitation in winter and spring, summer droughts;
  • Increased peak flooding in urban environments exacerbated by an increase in impervious surfaces where water can not percolate;
  • Increased precipitation would supply reservoirs but not alleviate overdraft of aquifers.
    Water supplies in the greater Baltimore area should not be diminished, but the adequacy of summer water supplies in the greater Washington region is less certain. Any increases in precipitation are unlikely to alleviate the present over-withdrawal of groundwater and summer droughts may increase groundwater demand for irrigation.
  • Rapid increases in stream temperatures, limiting habitat suitability for native fishes and other organisms;
  • Higher peak flows and degraded streams would also transmit more nutrients and sediments to the Chesapeake Bay and its tidal tributaries, contributing to water quality impairment in the estuaries...higher temperatures and stronger density stratification in the estuaries would tend to exacerbate water quality impairment, the alleviation of which is the prime restoration objective;
  • Very significant changes are also likely to occur that affect sediment delivery and sedimentation in the estuaries, but are difficult to quantitatively predict. These include potential increases in sediment loads from rivers as a result of increased runoff and more erosive extreme discharge events, including those caused by hurricanes, and from shoreline and wetland erosion as a result of accelerated sea-level rise;
  • Crop production may increase initially, but then decline later in the century if emissions are not reduced. The longer growing season and higher carbon dioxide levels in the atmosphere are likely to increase crop production modestly during the first half of the century. Later in the century, crop production is likely to be reduced due to heat stress and summer drought under the higher emissions scenario. Milk and poultry production would be also reduced by heat stress;
  • The maple-beech-birch forest of Western Maryland is likely to fade away and pine trees to become more dominant in Maryland’s forests;
  • Forest productivity in terms of timber produced is likely to decline late in the century under the higher emissions scenario as a result of heat stress, drought, and climate-related disturbances such as fires and storms;
  • The biodiversity of plants and animals associated with Maryland’s forests is likely to decline. Habitat alterations resulting from climate change may force out 34 or more bird species, including the emblamatic Baltimore oriole, although southern species may replace them;
  • A lengthening of the growing season from a current average 239 days to as many as 278 days by the end of the century.
  • Sea-level rise is very likely to accelerate, inundating hundreds of square miles of wetlands and land. Projections that include accelerating the melting of ice would increase the relative sea-level along Maryland’s shorelines by more than 1 foot by mid-century and 3 feet by late century if greenhouse gas emissions continue to grow. If sea level rises by 3 feet, most tidal wetlands would be lost—about 200 square miles of land would be inundated. New tidal wetlands developed on newly flooded land would not offset the loss of existing wetlands and significant negative effects on living resources dependent on these wetlands would result. Moreover, if sea level were to rise by 3 or more feet, this would mean that rapid and probably uncontrollable melting of land-based ice was underway and that sea level would rise at an even greater rate during subsequent centuries;
  • Rains and winds from hurricanes are likely to increase, but changes in their frequency cannot now be predicted. The destructive potential of Atlantic tropical storms and hurricanes has increased since 1970 in association with warming sea surface temperatures. This trend is likely to continue as ocean waters warm. Whether Maryland will be confronted with more frequent or powerful storms depends on storm tracks that cannot yet be predicted. However, there is a greater likelihood that storms striking Maryland would be more powerful than those experienced during the 20th century and would be accompanied by higher storm surges—made worse because of higher mean sea level—and greater rainfall amounts;
  • Large decreases are projected in winter snow volume (25% less in 2025 to 50% less in 2100 regardless of emission scenario). While Maryland does not receive large amounts of snowfall compared with states to the north7, these reductions are large enough to reduce the spring river discharge associated with melting snow. Also, snow accumulation is very likely to be less common in western Maryland, thus affecting winter recreational activities.
  • In the Chesapeake Bay, Northern species such as soft shell clams and eelgrass are likely to be eliminated later in the century, almost certainly if greenhouse gas emissions are not mitigated. Southern species are very likely to increase in abundance because the milder winters would allow or enhance overwintering populations.
  • As ocean water becomes more acidic, shellfish production could be affected.
  • Health risks due to heat stress are very likely to increase...heat waves are projected to greatly increase risks of illness and death before the end of the century, with an average of 24 days per summer exceeding 100°F. Respiratory illnesses are likely to increase, unless air pollution is greatly reduced. More ground-level ozone, responsible for multiple respiratory illnesses, is formed under prolonged, high temperatures.
  • There is already a recorded trend toward earlier start of honey production in the Piedmont region. Honey production requires both temperatures high enough to maintain larval bees and an ample source of nectar from flowering trees, thus integrating two measures of climate change.
  • Potential salt contamination of aquifers and freshwater intakes as the boundary between fresh and brackish water shifts with rising sea level.

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