According to reports from the US Drought Monitor, a historic drought plaguing large swaths of the country since spring has again grown larger and more intense. Total areas under drought conditions are, once more, above 60% of the contiguous United States. This is about a 1.5 percent increase over last week’s drought measure. Severe and exceptional drought, the worst conditions measured, expanded to cover fully 19 percent of the contiguous US, also an increase of about 1.5 percent over last week’s measurement.
Hardest hit areas remain in or near the nation’s breadbasket. South Dakota, Nebraska, Kansas, Colorado, Oklahoma, and Wyoming are states currently suffering the most from ongoing drought. Minnesota, Iowa, Arkansas, Texas, New Mexico, Utah, Georgia, and Nevada are also feeling strong direct impacts.
Forecasts for the next few months show a persisting drought that will likely pose a continuing threat to US crops throughout the winter and on into spring, possibly extending again into summer. The potential for conditions to worsen, again, in Texas should be cause for watchful concern as the season progresses. Texas is still recovering from the extreme drought of 2010-2011. A second blow during 2013 would prove very harmful to the state’s agriculture.
Over the past few weeks, the US wheat crop has taken a severe hit from the persistent and now re-emerging drought. Crop conditions, as of about a week ago, were the worst seen in 27 years. Risks are currently very high that the US wheat harvest for this year will be substantially lower, resulting in higher food prices at home and an intensifying food crisis abroad.
In Missouri, an area which felt strong impacts to its corn crops before drought somewhat abated for the state, Mississippi River levels are again low enough to warrant concern of a shut-down. Annually, the Army Corps of Engineers cuts off river flows to the Mississippi in order to ensure adequate reservoir storage for next year and to protect against flooding from melt run-off. This year’s shut down may bring river levels as low as 6 feet, which would effectively cut off traffic along a 200 mile stretch of waterway. If this happens, as much as 7 billion dollars worth of grain may be stranded up-river. Much of this grain goes to international markets. Such a closure would both result in damages to local economies as well as, potentially, food shortages and increasing prices abroad.
The culprit for this lingering and increasingly damaging drought is likely a blocking high that has continued to emerge over the nation’s heartland, fixing the weather pattern there to one that is both hotter and dryer than normal. These huge dips and swells in the Jet Stream are spurred by eroding sea ice boundaries in the Arctic which result in large shifts to the circumpolar winds. In turn, these wind changes alter the Jet Stream, making the emergence of blocking patterns like the one enhancing the current US drought far more likely.
Climate models have also predicted much drier conditions for the US West as global temperatures rise from an average range of .6 degrees Celsius higher than normal to as much as 2 degrees Celsius higher than normal by 2040-2050. It is likely that we began to see this climate-change induced drying during the early 2000s as average global temperatures reached .6 degrees Celsius above the 20th century average. Average global temps are now around .8 degrees Celsius higher and continuing to inch upward, so the US West is likely to experience periods of intensifying drought through the 2010s and worsening into the 2020s. By the 2030s and 2040s far worse conditions can only be avoided via large-scale curtailment of global greenhouse gas emissions.