by Rebecca Chillrud
May 26, 2020
Temperatures are on the rise in the Chesapeake Bay watershed, and farms throughout the region are already experiencing the impacts. Temperature plays a major role in plant growth, and major crops and livestock can experience negative impacts from heat stress.
Our atmosphere acts like a blanket surrounding the earth. When we burn fossil fuels for energy, we release carbon dioxide, which thickens the blanket. The additional heat that is trapped causes global temperatures to rise and disrupts the climate.
One impact of climate change in the Chesapeake region is changing precipitation patterns and more extreme weather, both of which can impact agriculture as seen in the video above. Temperature impacts to agriculture are discussed below.
How are temperatures changing across the Chesapeake?
The Chesapeake Bay Program tracks air and water temperature using data reaching back to 1901. These data show that temperatures in the Chesapeake region have been on the rise for years. While certain local conditions may vary, the warming trend across the region is clear. A study by the U.S. Geological Survey found that overall air temperatures increased 1.98 degrees F in the Chesapeake Bay region from 1960 to 2010.
Unfortunately, the projected rate of warming for the region isn’t slowing down. Depending on how much we reduce our global emissions—from energy, transportation, food production and other sectors—projections indicate our air temperature will warm 4.5 F to 10 F in the watershed by the 2080s.
Effects on agriculture
Changing climatic conditions will have mixed effects on farms throughout the Chesapeake watershed, and not all of them are negative. Warmer temperatures throughout the year means a longer growing season. In addition, the higher concentrations of carbon dioxide in the atmosphere act as a fertilizer for crops, allowing them to grow larger. These positive effects may be a benefit to overall agricultural production in the short term.
However, if emissions are not reduced, the effects of intense heat will outweigh these benefits by the second half of the century as temperatures continue to rise. Plants that grow in high temperatures go through the stages of their life cycles more quickly, allowing less time for the part of the plant that we eat to grow.
A longer growing season will also mean a greater demand for resources like water and fertilizer. Water stress is already likely in many areas due to changing precipitation patterns, so a longer growing season could further exacerbate this stress. Excess fertilizer contributes to nutrient pollution, as runoff carries it into nearby rivers and streams. According to 2010 estimates from the Chesapeake Bay Program’s suite of modeling tools, chemical fertilizers account for 17% of the nitrogen and 19% of the phosphorous entering the Bay, while manure, which is often used as a fertilizer, accounts for 19% of the nitrogen and 26% of the phosphorous.
Higher temperatures can also increase the formation of ozone, a gas that has different impacts depending on where it is in the atmosphere. Ground-level ozone forms when pollutants, like those from cars or power plants, react in heat and sunlight. While the ozone layer in the atmosphere protects us from UV rays, ozone that forms at the ground level is harmful to human health and toxic to many plants, including wheat and soybeans. Increased ozone levels can lead to decreased yields in these crops.
Rising temperatures are also expected to have an impact on pests and weeds. Weed species, like witchweed, cogongrass and itchgrass, and insect pests that are typically found south of the Chesapeake region will be able to expand their range northward. Pests that are currently dormant during the winter months may be able to be active year-round, increasing their destructive potential. While pesticides and herbicides are often used to deal with these nuisance species, scientific studies have discovered potential links between pesticide exposure and:
- the suppression of behavioral and immune systems in fish,
- the development of intersex conditions in fish, and
- the impaired reproduction of fish-eating birds.
It’s not just plants that are feeling the effects of higher temperatures—livestock animals throughout the region are also being impacted. Heat waves can cause health problems for livestock, as their bodily functions start to break down if it’s too hot for them to maintain a healthy body temperature. Heat stress can make animals susceptible to disease and can also cause lowered milk production.
Livestock may also be indirectly affected by the impacts to plants. Animals that graze in pastures may see those grasses suffer from heat stress, leaving less for them to eat, and lower crop production could impact animals that feed on grain. In addition, plants that grow under higher carbon dioxide concentrations have lower nutritional value, so animals will need to eat more to get the same amount of nutrients.
Rising temperatures may also lead to pests and diseases that harm animals becoming more prevalent. Parasites and pathogens may be better able to survive shorter, warmer winters, and pests may expand their ranges northward.
What can we do?
One of the best ways to address these health problems is to reduce our greenhouse gas emissions. By reducing our use of fossil fuels, we produce less carbon dioxide and limit the amount of heat that is trapped by our atmosphere. The degree to which we reduce our emissions will be the biggest factor in determining future temperatures in the region. The impacts from an increase of 10 F by the 2080s will be much more severe than those from an increase of 4.5 F.
Driving or flying less, reducing energy use in your home, adopting a climate-friendly diet and switching to renewable energy are all great ways to reduce your carbon footprint. In some cases, reducing greenhouse gas emissions also means fewer instances of the pollutants that cause ground-level ozone. Check out our How To’s and Tips page for even more ideas.
However, because the carbon dioxide we have already emitted can stay in the atmosphere for a long time, a certain amount of increased warming is inevitable. Chesapeake farmers can take some actions to try to adapt to this warming. Certain crop varieties are naturally more tolerant to high heat conditions, so selecting these crops could be a good strategy for farmers. For example, by the 2050s, corn and wheat production will likely be more severely impacted by warming than soybean production, though by the end of the century, heat stress will severely impact all three.
Learn more about how climate change is impacting the Chesapeake.