Why Climate Extremes Matter More Than Averages

Why Climate Extremes Matter More Than Averages

Lessons from a 5-Year Study of Desert Bees

When we talk about climate change, averages tend to dominate the conversation. We hear about average temperatures, average rainfall, and average emissions. However, ecological systems rarely respond to averages alone. They often respond to extremes, variability, and historical conditions.

A newly published, peer-reviewed study appearing in Ecological Entomology offers a clear illustration of this reality. Co-funded by Arva and co-authored by Arva scientist Dr. Joshua Ladau, the research examines how bee communities respond to temperature and precipitation extremes in the urban Chihuahuan Desert. The findings highlight why climate impacts are often nonlinear, delayed, and deeply context-dependent.

A Long-Term Look at Climate Stress

The study followed bee populations over five years in El Paso, Texas, which is an urban environment within the Chihuahuan Desert. Researchers collected more than 2,600 bees across 32 genera, pairing monthly ecological surveys with detailed weather data from NOAA.

Rather than focusing solely on average conditions, the study examined several key variables:

• Extreme heat events
• Above and below average precipitation
• Lag effects, including how rainfall from the previous year influenced outcomes in the present day
• Differences between ground-nesting and cavity-nesting bees

This long-term, systems-level approach allowed the team to observe patterns that short-term studies frequently miss.

What the Researchers Found

1. Extreme heat tends to reduce bee abundance even when average temperatures rise. Moderate warming can increase bee activity, but often only up to a certain point. Once temperatures crossed into extreme ranges, bee abundance declined sharply. This pattern was observed across multiple seasons.
2. Not all bees respond in the same way. Ground-nesting bees appeared significantly more sensitive to extreme temperatures and precipitation variability than cavity-nesting bees. Nesting strategy, which is a key life-history trait, played a major role in determining potential vulnerability.
3. Rainfall from the previous year is a significant factor. Bee abundance generally increased following wetter than average conditions in the prior year. This lag effect suggests that climate impacts are frequently cumulative and can influence survival over longer timescales.
4. Climate variability can reshape communities, not just populations. The composition of bee communities shifted between dry and wet seasons. Different nesting strategies dominated under different conditions. These changes likely reflect broader ecosystem responses to stress rather than isolated species-level effects.

Why This Matters Beyond Pollinators

Bees are often studied because they are ecologically important and highly responsive indicators of environmental change. What this study reveals about bees can apply more broadly to the biological and agricultural systems facing climate stress. The findings reinforce several key principles:

• Extremes often drive outcomes more than averages do.
• Thresholds typically exist beyond which resilience may break down.
• Lag effects are common, meaning today’s outcomes are often shaped by yesterday’s conditions.
• Local context is vital, especially in already-stressed environments like deserts and urban heat islands.

These dynamics are just as relevant when modeling soil carbon, crop performance, or supply-chain climate risk as they are when studying pollinators.

Connecting Science to Climate Decision-Making

At Arva, we work at the intersection of climate data, biological systems, and real-world decision-making. This research underscores why credible climate solutions require long-term data and attention to variability. Understanding climate impacts means moving beyond smooth curves and simple averages. It means recognizing that systems often respond unevenly to a changing climate.

Studies like this help bridge ecological science and climate action. They provide the nuance needed to design programs, models, and strategies that hold up in the real world. Arva co-funded this study because our aim is to learn how to make agro-ecosystems more robust. This includes understanding the adjacent natural ecosystems on which we depend for water cycles and pollination. This study is one of many Arva is funding to uncover the critical controls that determine the future potential of agronomic productivity for our farmers.

Source: resjournals.onlinelibrary.wiley.com/doi/10.1111/een.70048