The constant back and forth between drought and flooding that dominates summer headlines appears to be worsening and it's taking its toll on the agricultural industry. For the average person, it can be frustrating when news anchors link these headlines to climate change or global warming, especially since they often don't explain how or why. Eco-literacy matters, and it's worth taking a moment to focus on the differences, connections between climate change and global warming, and the implications of both, not just for the US agricultural industry but for the energy sector as well.
Climate change and global warming are not the same thing. Global warming may lead to climate change and climate change may imply warming temperatures, but these are correlations, not cause and effect. Simply put, global warming is an increase in average surface temperatures here on earth, and temperatures have risen 0.75 degrees C over the last 150 years. Climate change, on the other hand, refers to long-term changes in weather patterns. In fact, climate analyses are based on 30 year averages of weather patterns that include things like temperature, wind, precipitation, sunlight, humidity and assorted other meteorological variables that determine weather. Another important distinction is weather vs. climate. Weather is the day to day variation of the meteorological conditions of the atmosphere in a given area, whereas climate takes the average of these conditions over a much longer (30-year) time period.
So how does this tie in to US agriculture and energy? Changes in the jet stream seem to be the cause of the woes for farmers in the Midwest, exposing us to longer periods of extreme weather. The trends appear to be long-term, and may be evidence of climate change in the region. Furthermore, they appear to be linked to global warming. How so? Arctic and North Atlantic Oscillations.
The Artic Oscillation refers to a circular wind pattern around the artic that is weakened by global warming and strengthened by cooling. As global temperatures warm, the difference in temperature between the equator and the poles is lessened, resulting in weaker equator-to-pole wind flows, which, in turn, results in a weakened Artic Oscillation. Weak (or negative) Artic Oscillations have a spillover effect for the North Atlantic Oscillation, also known as the jet stream.
Changes in the strength and location of high and low pressure systems in the Atlantic play a role. The reduced temperature gradient that weakens the Artic Oscillation causes changes in the pressure system, which allows the jet stream to sink very low in the US. The effects of this process are felt most strongly in winter. Think single digit temperatures and television meteorologists talking about a polar air mass that has moved in because of a change in the jet stream. This is a short term weather phenomenon caused by global warming which appears to be causing measurable changes in climate over the past decade.
The implications for agriculture and energy are serious and, in the Midwest, are especially noticeable during summer. Flash droughts, caused by dry air masses moving south as a result of changes in the Artic/North Atlantic Oscillations, are just one problem. The 2012 drought racked up $35 billion in losses alone. Additionally, excessive rain is caused by fluctuations in the jet stream that allow moist air masses to dominate as the jet stream rebounds back and forth reports NOAA. The flooding associated with such air masses can delay or prevent farming activities, leading to higher food prices due to shortages in supply.
Wild weather has economic effects all around the country. When triple-digit heat waves hit major cities, electricity consumption for cooling spikes. According to the EIA, this increased demand leads to higher energy prices. Florida citrus disasters caused by cold air make buying orange juice much more costly. Lastly, increased heating oil usage and lost economic productivity from increased snowfall across the country increase prices as well.
These economic ramifications are cause for alarm, and there are other losses associated with climate change that make it a pressing issue. Understanding how changes in one part of the system, such as warming and subsequent jet stream alterations, can lead to cascading affects in the rest of the system, such as agriculture and energy, is the basis for developing appropriate 21st century Nexus policies.