Effects of Climate Change on Nebraska

I was recently startled to learn that my home state of Nebraska is projected to be one of the states hardest hit by climate change over the coming century. In fact, in the A2 (business-as-usual) emissions scenario, which could see atmospheric concentrations of carbon dioxide more than double to 857 parts per million (ppm) or more by 2100, Nebraska could see the second highest average temperature increase of any state in the United States: a whopping 10.3° Fahrenheit.

This article will attempt to lay out some of the projected effects of climate change on the state of Nebraska in simple, accessible language, and discuss some of the actions Nebraskans can take to adapt to these changes.

The emissions scenarios in this article are based on the IPCC's Fourth Assessment Report, published in 2007.

1. A2 Emissions Scenario. Business as usual. Carbon emissions continue to climb steadily to reach an atmospheric carbon dioxide concentration of 857 ppm by 2100.
2. A1B Emissions Scenario. A gradual leveling off of emissions, resulting in a level of 711 ppm by 2100.
3. B1 Emissions Scenario. A decrease in emission rates over the next century, for a total concentration of 538 ppm by 2100.

Current atmospheric carbon dioxide levels are approximately 390 ppm, and rising at a rate of about 2 ppm every year. Pre-industrial CO2 levels were about 275-280 ppm.

It is worth noting that these emissions scenarios are already considered to be out of date by scientists, many of whom now argue that 450 ppm is the maximum "safe" concentration that we can reach without triggering dangerous climate feedback loops that could drive atmospheric CO2 levels in the A2 business-as-usual scenario up over 1000 ppm by 2100.

The projected impacts of climate change on Nebraska include:

Warmer Temperatures

As mentioned above, Nebraska is expected to be one of the states most severely affected by temperature increases in the coming century.

Projected increase in average annual temperature by 2100, in degrees Fahrenheit:

Unfortunately, this increase in temperature is expected to be larger in the summer than the winter. For example, some scientists estimate that Nebraska's average summer temperatures could increase 6° F by 2050, but only 4° F in winter.

In the worst case scenario, neighboring Kansas could expect to see 120 days per year with temperatures over 90° F, with temperatures of 122° F not unheard of. Similar figures in Nebraska could severely threaten crop yields for the state, as many plants become stressed at temperatures higher than 95° F, especially if soil moisture is inadequate. Corn yields, for example, decline an average of 1.5 bushels per acre for every day the temperature goes above 95° F during pollination and grainfill.

Higher temperatures could also lead to an increase in heat-related deaths and illnesses among both humans and livestock, and to a decline in air quality. Warmer temperatures are known to encourage the production of ozone, an important component of the atmospheric ozone layer in the stratosphere, but the major component of smog near the surface. Decreased outdoor air quality due to smog and other pollution can exacerbate lung problems such as asthma and bronchitis, especially in young children and the elderly.

Increased Damage By Pests, Weeds, Diseases, and Invasive Species

Milder winters are expected to lead to increased populations and earlier emergence of urban and agricultural pests, including ticks, mosquitoes, and rodents. It may also allow pests, diseases, and invasive species that were previously confined to southern regions to move north.

For Nebraska's farmers, this could offset increased plant growth due to higher atmospheric CO2 levels and combine with heat stress to cause a serious decline in yields. For more on the effect of increased carbon dioxide levels on plants, check out Are Rising Carbon Dioxide Levels Better For Plants?

Increased Surface Evaporation

Another serious effect of higher temperatures could be increased evaporation from soil, plants, and bodies of water. This could dry up shallow prairie potholes across the state, eliminating critical breeding habitat for waterfowl and other wildlife species and endangering the primary source of water to replenish the massive underground Ogallala Aquifer, one of the most important sources of water for the state.

Of the eight states that lie over the massive Ogallala Aquifer, Nebraska contains by far the largest percentage - nearly 2/3 of the aquifer's total volume. Partly as a result, we have not over-taxed the aquifer as severely as many states further south, but increased evaporation from the surface could reduce the aquifer's ability to replenish itself and increase the danger of destroying this priceless resource.

Increased surface evaporation could also affect Nebraska's rivers, particularly the wide, shallow Platte. Fed primarily by declining snow melt in the Rockies, our rivers are expected to decline in volume throughout the coming century, and some may become seasonal. Meanwhile, increases in average water temperature could threaten populations of certain types of fish, including trout.

Increased Precipitation... Or Not

Some of this increase in surface evaporation is likely to be offset by projected increases in precipitation across much of the state, with the greatest increases likely in the northeastern part of the state.

However, this comes with risks of its own, including a higher risk of heavy downpours and an accompanying increase in flooding, erosion, and other problems.

Under the higher emissions scenario, some regions of southwestern Nebraska could expect drier conditions, contributing to increased likelihood of drought in those regions.

The changes outlined above are only projected, and if the world reacts promptly to the threat posed by global climate change - or if we experience powerful natural events such as a decline in the level of solar energy reaching the earth - they may not come to pass.

However, with consequences so potentially harmful, it is wise to make plans for how we can mitigate the effect of these changes.

Here are some suggestions:

• Improve energy efficiency of buildings. In order to stay comfortably cool in summer and warm in winter, Nebraskans will need to improve the energy efficiency standards of our building codes. Experimenting with high efficiency alternative techniques such as green roofs, strawbale construction, and underground homes may be one way to maintain reasonable heating and cooling bills in the face of substantially hotter summers and milder, but still freezing, winters.
• Increase mass transit opportunities. Improving mass transit in Nebraska's larger cities and along its busiest highways can help reduce ozone production and maintain good air quality despite the expected increase in temperatures.
• Improve stormwater runoff management. Reducing stormwater runoff with techniques such as permeable pavements, rain gardens, and rainwater harvesting can reduce surface and groundwater pollution, prevent floods, and help replenish the Ogallala Aquifer.
• Encourage healthy populations of black tailed prairie dogs. Recent studies have proved concerns about competition with cattle to be unjustified, and the extensive systems of underground tunnels and burrows created by these native rodents were once a major source of replenishment for the Ogallala Aquifer. With the aquifer at risk of drying up in some parts of Nebraska and the Plains as a whole, protecting existing towns and reintroducing prairie dogs in regions where they have been eradicated can help maintain its health.
• Improve riparian buffer zone management. Properly designed riparian buffer zones can help mitigate floods, reduce erosion, and cool water temperatures, preserving habitat for trout and other cool water fish and wildlife.
  
• Increase tree cover. The home of Arbor Day already has a long history of tree planting, but in the face of climate change, we should redouble our efforts, especially in cities, where urban tree cover can play a major role in reducing the urban heat island effect and maintaining comfortable summer temperatures. In rural regions of Eastern Nebraska, increasing cultivation of tree crops such as fruits, nuts, and wood also offers an opportunity to maintain the financial health of agricultural communities while reducing surface evaporation and carbon emissions caused by regular tilling.
• Improve range management. Although Nebraska has not experienced as severe a problem with overgrazing as many drier states to the west, both the risk and the consequences of overgrazing are likely to become more severe in the future. Establishing good range management practices now will help preserve vegetation cover and reduce surface evaporation. Drier regions of Western Nebraska should consider abandoning grain crops and restoring perennial pastures to reduce soil moisture lost to tillage.
• Use mulch and cover crops to reduce surface evaporation. Mulch and cover crops shade and cool the soil, reducing evaporation. They can also help prevent erosion from heavy downpours.
• Increase soil humus. Soils rich in organic matter store moisture better than degraded soils and can help reduce mitigate the effects of both floods and drought. Improving soil health also improves the health of plants, enabling them to fight off pests and diseases more effectively.
• Improve pest management. Integrated pest management and similar techniques that combine wise use of of chemical pesticides with organic techniques such as farmscaping that are designed to improve overall plant health offer more sustainable pest management strategies than relying purely on chemicals, especially in the face of expected increases in oil prices.
• Preserve intact ecosystems. Intact ecosystems are better able to fight off invasions by exotic plants and animals than fragmented ones, preserving Nebraska's biodiversity.
• Exploit Nebraska's clean energy resources. Nebraska has some of the finest renewable energy resources in the nation, and could become one of the centers of the clean energy revolution with proper investment. Wind energy offers particular promise for our state: Nebraska ranks sixth in the nation in wind energy potential: an estimated 868 million megawatts per year with current technology. Nebraska also offers respectable solar energy potential. Clean energy can not only reduce our state's carbon emissions, it can also improve our economy. At current levels of growth, the wind industry alone is expected to add 500,000 new jobs nationwide by 2020.