What is Actualism in Earth Science? Lessons from Drought Cycles

Introduction

Droughts are often blamed on human activity, but Earth’s history shows they’re part of natural cycles. By studying proxies—ancient clues like tree rings, lake mud, or air trapped in ice—we can understand these patterns. Proxies are physical evidence, like tree rings showing dry years or mud layers revealing low lake levels. This page explores how Actualism in Earth Science helps us explain droughts using real, observable processes. We’ll look at historical droughts in North America, including California, and Australia, showing how they cycle in and out over time. This challenges the idea that CO2 is the main cause of droughts and highlights the importance of looking at the past to understand the present.

What is Actualism?

Actualism in Earth Science is the idea that we can explain Earth’s history by looking at processes we see happening today. For example, if ocean currents cause droughts now, they likely did the same in the past. This approach relies on hard evidence, like tree rings or lake mud, rather than unproven theories. When studying droughts, Actualism means we look at natural cycles—like changes in ocean currents such as El Niño (warmer Pacific waters causing heavy rain) or La Niña (cooler waters often linked to droughts)—to understand why they happen. It helps us avoid jumping to conclusions, like assuming CO2 causes every drought, when history shows these events are part of Earth’s normal climate patterns.

North American Droughts Through History

North America has faced severe droughts for centuries, often called megadroughts when they last decades or longer. From 900 to 1300 AD, during the Medieval Warm Period, the Southwest U.S. and northern Mexico saw dry conditions spanning centuries, with the worst around 1140–1159. Tree rings from the Colorado River basin show 17 long periods of low water flow, far worse than modern times, though wetter years broke up the dryness. Lake mud from places like Mono Lake in California reveals low water levels, where trees grew in exposed lakebeds, only to be flooded later when rains returned. These droughts, lasting up to 20–30 years at their worst, disrupted Native American societies, like the Ancestral Puebloans, who had to abandon settlements.

A later megadrought in the late 1500s lasted about 40 years, affecting early European settlers. Tree rings show 1587–1589 was the driest three-year period in 800 years, likely contributing to the disappearance of the Roanoke Colony in North Carolina. Established in 1585, the colony vanished by 1590, possibly due to food shortages during this drought, which also forced Spanish settlers in South Carolina to abandon their colony in 1587. The Little Ice Age that followed (1300–1850) had its own droughts, but wasn’t dry continuously—wetter periods, like the early 1700s, broke up the dryness, much like the Medieval Warm Period’s cycles. In modern times, the U.S. saw major droughts, like the 1930s Dust Bowl, which lasted nearly a decade and turned farmland to dust across the Great Plains. California’s 2012–2016 drought was severe, with the lowest snowpack in 500 years and 102 million trees dying. Many worried it was a permanent change, but record rainfall in 2016–2017 ended it, and by 2025, reservoirs are at 118% of normal, showing how droughts cycle in and out.

Australia’s Natural Drought Cycles

Australia’s climate is naturally dry, with frequent droughts often tied to ocean currents like El Niño. From 1997 to 2009, the “Millennium Drought” caused water shortages and wildfires, raising fears of a new, permanent dry state. But by 2022, wetter La Niña conditions returned, and no part of Australia was in drought. This mirrors historical patterns—droughts come and go, driven by natural cycles, not a single cause like CO2. Australia’s story shows how these events are part of the climate’s normal rhythm, much like in North America.

Misconceptions About Drought Causes

Many assume CO2 is the main cause of modern droughts, but history shows otherwise. Southwest U.S. droughts today are often blamed on CO2, yet tree rings reveal similar events centuries ago, long before industrial activity. Computer models can help when based on proxy data—like tree rings showing past drought patterns—but they often make unproven predictions, like permanent droughts, that don’t match reality. California’s drought ended despite such claims, as did Australia’s. Funding can push research to focus on CO2, but Actualism reminds us to look at observable cycles, like ocean currents, which have driven droughts for millennia. Ignoring these patterns overlooks the full picture.

Conclusion

Actualism teaches us to explain droughts using processes we can observe, like ocean currents and sunlight changes. North America’s medieval megadroughts, the 1580s drought that may have doomed the Roanoke Colony, California’s recent drought ending in 2017, and Australia’s recovery by 2022 show these events cycle naturally. Climate has changed for 4.5 billion years, with droughts as a normal part. Blaming CO2 alone ignores history and relies on unproven ideas. Instead, we should study past patterns to understand today’s climate, focusing on facts over speculation.

Introduction