If the climate is changing, what challenges can be expected in crop and livestock production?

Is the climate changing?  Have weather events of the past several years been precursors of challenging weather in years to come?  There seem to be two issues that intertwine, one is whether the climate is changing, and the other is the cause of any change, if there is change at all.  If change is not occurring, we can write off the aberrant weather as the result of Mother Nature being fickle.  If change is occurring, what can we expect in the way of temperature and moisture in years to come where crop production will be important for global survival?

Climate change is one of those divisive issues that create enemies out of long time friends, just like other social issues of the day, along with politics and religion.  The Cornbelt climate has changed over time.  No one remembers the Ice Age that covered the upper Midwest, but its effects are apparent.  Fern fossils and dinosaur bones are found in the northern reaches of Canada where that type of flora and fauna could not exist today.  Subsequently, there is no doubt the Earth has heated and cooled over time.  If it is on a warming trend as some weather records hint, and regardless of what is causing that, what can future generations of farmers expect to challenge them in crop and livestock production?  That is the focus of a newly-released USDA report on climate change. With a cursory examination of the report, it does not seem to make an overt attempt to point fingers at the cause, but identifies what changes agriculture can expect from different weather than we are accustomed to, and the changes that humans can make to reduce the risks to production posed by a changing climate.
Selected quotations from the Executive Summary:
"Climate change poses unprecedented challenges to U.S. agriculture because of the sensitivity of agricultural productivity and costs to changing climate conditions."
"By midcentury, when temperature increases are expected to exceed 1°C to 3°C and precipitation extremes intensify, yields of major U.S. crops and farm returns are projected to decline."
"As temperatures increase over the next century, shifts may occur in crop production areas because temperatures will no longer occur within the range, or during the critical time period for optimal growth and yield of grain or fruit."
"The effects of elevated CO2 on grain and fruit yield and quality, however, are mixed; reduced nitrogen and protein content observed in some nitrogen-fixing plants causes a reduction in grain and forage quality. This effect reduces the ability of pasture and rangeland to support grazing livestock."
"Optimum animal core body temperature is often maintained within a 2°C to 3°C range. For many species, deviations of core body temperature in excess of 2°C to 3°C cause disruptions of performance, production, and fertility that limit an animal's ability to produce meat, milk, or eggs."
"Warmer, more humid conditions will also have indirect effects on animal health and productivity through promotion of insect growth and spread of diseases."
"Erosion is of particular concern. Changing climate will contribute to the erosivity from rainfall, snowmelt, and wind. Rainfall's erosive power will increase if increases in rainfall amount are accompanied by increases of intensity."
"Rising temperatures and shifting precipitation patterns will alter crop-water requirements, crop-water availability, crop productivity, and costs of water access across the agricultural landscape."
"Effective adaptive action undertaken by the multiple dimensions of the U.S. agricultural system offers potential for capitalizing on the opportunities presented by climate change, and minimizing the costs via avoidance or reduction of the severity of detrimental effects from changing climate."
"Adaptation measures such as developing drought, pest, and heat stress resistance in crops and animals, diversifying crop rotations, integrating livestock with crop production systems, improving soil quality, minimizing off-farm flow of nutrients and pesti cides, and other practices typically associated with sustainable agriculture are actions that may increase the capacity of the agricultural system to minimize the effects of climate change on productivity."
"Because agricultural systems are human-dominated ecosystems, the vulnerability of agriculture to cli mate change is strongly dependent on the responses taken by humans to adapt to climate change effects."
Summary:
Higher temperatures, increased humidity, and a greater frequency of severe weather patterns all are elements of a change in climate, regardless of whether the cause is a natural phenomenon or man-made.   Such weather changes can have an adverse impact on plant and animal production.  Crops--such as corn and soybeans—can exhibit declines in yield and profitability.  Livestock are more susceptible to disease issues and insect infestation in areas of increased temperature and humidity.  To maintain agricultural productivity, humans must take necessary actions to better adapt to the effects of climate change.

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