"Climate change is already affecting the American people."
That was the first line in a draft report of the National Climate Assessment released Friday and produced by a group of more than 240 scientists. Researchers are updating two earlier reports on climate change released for the federal government in 2000 and 2009. The entire report effectively condenses some of the most updated research and observations on climate change, as well as how the country is or isn't responding.
The report summary and chapter on agriculture offer several statements raising concern about challenges facing crop and livestock production in the coming decades.
The influence of human activities means past climate conditions are no longer a sufficient indicator of future conditions.
Temperatures have risen about 1.5 F since 1895, but about 80% of the increase has come since 1980. Due to rising global greenhouse emissions, temperatures are going to rise 2-4 F in the next few decades over most areas of the country.
Weather volatility has increased in recent decades. Over the last 50 years, much of the U.S. has seen an increase in prolonged stretches of excessively high temperatures, more heavy downpours and in some regions more severe droughts.
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Food security is emerging as an issue of concern, both within the U.S. and across the globe, and is affected by climate change.
Surface and groundwater supplies in many regions are already stressed by increasing demand for water as well as declining runoff and recharge. In many regions, climate change increases the likelihood of water shortages and competition for water among agricultural, municipal and environmental uses. At the same time, water quality challenges are increasing, particularly sediment and contaminant concentrations after heavy downpours.
Adverse impacts to crops and livestock over the next 100 years are expected. Over the next 25 years or so, the agriculture sector is projected to be relatively resilient, even though there will be increasing disruptions from extreme heat, drought, and heavy downpours. U.S. food security and farm incomes will also depend on how agricultural systems adapt to climate changes in other regions of the world.
Planning for adaptation (to address and prepare for impacts) and mitigation (to reduce emissions) is increasing, but progress with implementation is limited. The level of current efforts is insufficient to avoid increasingly serious impacts of climate change that have large social, environmental and economic consequences.
In the Midwest, longer growing seasons and rising carbon dioxide have increased yields of some crops, although these benefits have already been offset in some instances by occurrence of extreme events such as heat waves, droughts, and floods.
In the Great Plains, rising temperatures are leading to increased demand for water and energy and impacts on agricultural practices.
In the agricultural section of the report, more key points:
Many agricultural regions will experience declines in crop and livestock production from increased stress due to weeds, diseases, insect pests, and other climate change-induced stresses.
Current loss and degradation of critical agricultural soil and water assets by increasing extremes in precipitation will continue to challenge both rain-fed and irrigated agriculture unless innovative conservation methods are implemented.
Agriculture has been able to adapt to recent changes in climate; however, increased innovation will be needed to ensure the rate of adaptation of agriculture and the associated socioeconomic system can keep pace with future climate change.
To read chapters of the draft report or read information on how to comment on the report, go to http://www.globalchange.gov/…
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