Climate at a Glance: Bees and Climate Change

American Honeybee gathering pollen. Licensed from 123rf.com

Key Takeaways:

  • The biggest mortality issue facing beekeepers is Colony Collapse Disorder (CCD), which is unrelated to climate change.
  • Despite CCD, the U.S. Department of Agriculture (USDA) reports U.S. honey production has remained steady.
  • Market demand for honey in the U.S. has increased, and is being met by imported honey. With honey to spare from other countries, there is no evidence global climate change is reducing bee populations or honey production.

Summary:

Many media outlets have repeatedly claimed that climate change is decimating wild bee populations throughout North America. The most recent claims are based on January 12, 2021 study highlighted by Science News.1 The study, however, is flawed, in part, because it fails to account for the primary cause of bee mortality: Colony Collapse Disorder (CCD). In non-scientific jargon, CCD occurs when entire hives suddenly experience population crashes. CCD has been called the honeybee’s biggest enemy by scientific researchers.

The U.S. Environmental Protection Agency (EPA) says:2

“There have been many theories about the cause of CCD, but the researchers who are leading the effort to find out why are now focused on these factors:

  • Increased losses due to the invasive varroa mite (a pest of honey bees).
  • New or emerging diseases such as Israeli Acute Paralysis virus and the gut parasite Nosema.
  • Pesticide poisoning through exposure to pesticides applied to crops or for in-hive insect or mite control.
  • Stress bees experience due to management practices such as transportation to multiple locations across the country for providing pollination services. 
  • Changes to the habitat where bees forage.
  • Inadequate forage/poor nutrition.
  • Potential immune-suppressing stress on bees caused by one or a combination of factors identified above.

None of the many possible contributors to CCD identified above are due to climate change. Moreover, it is very likely that since wild and domestic bees share pollination zones, CCD’s invasive varroa mite has been transmitted to wild honeybees as well.

The widely cited 2021 study claimed rising temperatures pose a threat to wild honey bees, saying: “[The] study found that the most critical factor influencing wild bee abundance and species diversity was weather, particularly temperature and precipitation.” The study then went on to cite “very hot summers” as a primary cause to bee loss.

There has been a modest increase in average temperature over the last century in North America; however, record setting high summer temperatures have not been increasing at all. In fact, as the EPA notes, most record high temperatures occurred during the dust bowl period of the 1930’s as seen in Figure 1 below.3

Figure 1. This figure shows the annual values of the U.S. Heat Wave Index, from 1895 to 2020. These data cover the contiguous 48 states. This index defines a heat wave as a period lasting at least four days with an average temperature that would only be expected to occur once every 10 years, based on the historical record. The index value for a given year depends on how often heat waves occur and how widespread they are. Source: Graph from Environmental Protection Agency, “Climate Change Indicators: Heat Waves,” https://www.epa.gov/climate-indicators/climate-change-indicators-heat-waves


Additionally, despite issues with CCD and modestly higher temperatures, the U.S. has managed to maintain honey production according to the USDA, as seen in Figure 2.

Figure 2. Demand for honey increasingly met through imports as U.S. production plateaus. Source USDA.

However, demand for honey in the U.S. has increased and is being met by increased imports from elsewhere in the world. The USDA says this about Figure 2.4

“U.S. imports of honey have surged by 73 percent in the last 10 years, reaching a near-record 433 million pounds in 2020. While domestic honey production has remained stable at around 156 million pounds per year, American consumers’ taste for honey and honey-sweetened products has grown.”

Data show there is honey to spare for the U.S. market and suggests any global bee crisis is unrelated to climate change.

References:

  1. Science Magazine, “Climate change reduces the abundance and diversity of wild bees,” January 12, 2021, https://www.sciencedaily.com/releases/2021/01/210112085357.htm and Melanie Kammerer Sarah C. Goslee Margaret R. Douglas John F. Tooker Christina M. Grozinger. Wild bees as winners and losers: Relative impacts of landscape composition, quality, and climateGlobal Change Biology, 2021 DOI: 10.1111/gcb.15485
  2. Environmental Protection Agency, “Colony Collapse Disorder,” accessed August 3, 2022, https://www.epa.gov/pollinator-protection/colony-collapse-disorder
  3. Graph from Environmental Protection Agency, “Climate Change Indicators: Heat Waves,” accessed August 3, 2022, https://www.epa.gov/climate-indicators/climate-change-indicators-heat-waves
  4. United States Department of Agriculture, “Demand for honey increasingly met through imports as U.S. production plateaus”, Chart, June 18, 2021, accessed August 5, 2022, https://www.ers.usda.gov/data-products/chart-gallery/gallery/chart-detail/?chartId=101457