The Effect of Climate Change on Plants and Pollinators

Global warming isn't just about hotter days; it's also throwing off the natural balance between plants and their pollinators. As temperatures rise and seasons shift, bees and other pollinators are finding it harder to sync up with the blooming flowers they rely on.

For the past four years, Elsa Godtfredsen, a plant biologist at the Rocky Mountain Biological Laboratory in Gothic, Colorado, has been studying this phenomenon. Set against the breathtaking backdrop of the Rocky Mountains, Godtfredsen and her team have been monitoring four species of wildflowers and their interactions with bumblebees. Their research aims to model the impacts of climate change on these delicate relationships.

“Subalpine and alpine ecosystems are changing rapidly,” says Godtfredsen. “We’re trying to see if these species can persist in ecosystems that are going to continue changing unless we see drastic shifts in policy.”

Early Snowmelt and Its Consequences

Warmer winters mean that snow in these regions melts earlier, causing flowers to bloom before bumblebees emerge from their winter sleep. This timing mismatch can be disastrous: without enough pollinator visits, plants can't make seeds and reproduce, reducing the number of flowers for future pollinators.

“We’re seeing a ubiquitous trend: Generally, when snowmelt happens earlier, we see flowering earlier as well,” Godtfredsen explains. And it's not just in Colorado. Spring is arriving earlier all over the world, from Japan to the United States and the United Kingdom. This shift affects not only plants but also animals and insects that rely on temperature cues for their seasonal activities.

The Domino Effect of Climate Change

The repercussions of these timing mismatches are widespread. For instance, tree swallows in the U.S. are nesting earlier, but their chicks face higher mortality rates due to unpredictable weather, which reduces the availability of insects for food. Similarly, Arctic plants are emerging earlier in Greenland, causing many caribou calves to die because the spring plant growth they rely on comes before the calving season.

Among the most concerning victims of these shifts are insect pollinators like bees, flies, butterflies, and moths. These small creatures are crucial for our food system, helping to pollinate a third of major food crops and contributing around $15 billion annually to U.S. agriculture. However, climate change is causing about 60 percent of plants and insects to fall out of sync.

Real-World Examples and Research Findings

Chris Wyver, a postdoctoral scientist at the University of Reading, has found that Bramley apples in the UK now bloom earlier due to warmer springs and increased rainfall. While their pollinators are also emerging earlier, they are less sensitive to the temperature cues that trigger apple bloom. This mismatch could threaten apple yields if it continues.

Other crops like cranberries, Brazil nuts, and passion fruit are also experiencing earlier bloom times. If these mismatches worsen, they could exacerbate pollinator declines, which currently cause a 3 to 5 percent drop in global fruit, vegetable, and nut production annually. This decline in production leads to reduced access to diverse and nutritious diets, potentially resulting in over 400,000 deaths annually.

A Glimpse into the Future

The strongest impacts of these mismatches will likely be felt in regions that already experience food insecurity, where supply chains are less reliable. In some cases, managed honey bees can make up for losses if timing mismatches cause significant native pollinator declines. However, this solution has its limits. “If we have to turn to honey bees, the question is, will there be enough?” Wyver asks. “I worry it’s just going to create a bidding war for honey bees that’s going to make food more expensive.”

DIY Conservation Efforts

In early April, Godtfredsen’s colleagues from the Rocky Mountain Biological Lab laid large black shade cloths on the snow to spur it to melt faster, mimicking earlier spring conditions. Once the snow melts, they remove the cloths to allow plants to grow. The team then compares data between these early snowmelt plots and normal conditions, looking at flower and pollinator activity.

“What we’re seeing is a common narrative in climate change research,” says Godtfredsen. “Some species are going to benefit from this scenario, and some will suffer.”

Practical Steps for Everyone

While this research is crucial, there are simpler ways we can all contribute to pollinator conservation. Planting native flora that local pollinators depend on can help boost their populations. Weeding and avoiding pesticides also provide easier access to food sources for these vital insects.

“Improving habitat for native fauna is something anyone can do,” says Godtfredsen. “Conservation and stewardship can start in your very own backyard.”

By taking these small steps, we can all play a part in ensuring the survival of our planet’s invaluable pollinators, keeping the delicate balance of our ecosystems intact.