For much of Earth’s history, weather cycles were quite predictable.
They ebbed and flowed like clockwork as the planet’s tilt and orbit around the sun shifted.
Every 40,000 years or so, the gravitational pull of the sun would make the Earth tilt slightly towards it. Then every 100,000 years, the Earth’s orbit around the sun would turn from its regular circular pattern to more like an oval, moving it further away from the sun.
All of these changes influenced how much heat and light reached the Earth’s northern hemisphere, where ice sheets grow. These seemingly minor shifts in the Earth’s movement brought about a rhythm of ice ages and hot periods that have influenced the formation of life on our planet.
But in the past two centuries, scientists have recognized an abnormal shift in this pattern. Extreme weather has become more common, while the Earth is becoming noticeably warmer.
These changes in our climate have led to heated debates about what’s causing them. Using cherry-picked misinformation, anti-science pundits claim that the changes in our climate are caused by the Earth’s natural cycles. Climate scientists, on the other hand, point to increased human activity and the burning of fossil fuels as the main offenders.
In this article, we explain how weather cycles form, and why they’re not the real drivers of climate change.
What are weather cycles?
Weather cycles are recurring changes in the atmospheric conditions around us.
Caused by movements and chemical changes in air pressure, ocean currents, sunlight, and other natural factors, weather cycles have been fairly predictable, as evidenced by the seasons of the year.
They lead to changes in our environment, such as the melting of sea ice and permafrost. Scientists have found that climate records reconstructed from tree rings, ice cores, and coral reefs show that significant changes in our weather, and our climate, occur slowly over several centuries or even millennia.
How long is a climate cycle?
Climate cycles are longer, averaged weather cycles. Whereas weather cycles come and go after a few days or months, climate cycles can last for about 10,000 years or more.
These climate cycles are usually a series of ice ages that are followed by warmer interglacial periods. Each ice age could last about a hundred thousand years. The ice ages were triggered by changes in the Earth’s orbit, often referred to as Milankovitch cycles, that affected the amount of solar energy that reached the planet.
But it wasn’t just the Earth’s movements that influenced these climate shifts. At the start and end of each ice age, changes in atmospheric levels of carbon dioxide played a key role in driving average global temperatures up and down.
Climate scientists believe that after the end of the last ice age about 20,000 years ago, average global temperatures rose from 3 degrees celsius to 8 degrees celsius. It didn’t happen suddenly but over about 10,000 years, which puts the pace at which temperatures rise to roughly 1 degree celsius every 2,000 years.
What are the weather cycles of the Earth?
The weather cycles that we see most often are the El Niño-Southern Oscillation (ENSO) and its opposite, La Niña.
Both are interactions between ocean temperatures and atmospheric patterns that bring wet, warm, and dry conditions to different parts of the planet. They occur every 3 to 7 years over the Pacific Ocean. Each episode of El Niño and La Niña lasts between 9 to 12 months.
These two climate patterns don’t happen often, but when they do, they can create significant impacts on our economies and ecosystems.
El Niño, for example, disrupts trade winds blowing west from South America to Asia. The warm water that would normally flow with these winds is pushed back toward the west coast of the Americas.
This shift causes the Pacific jet stream to move through the southern part of the United States, resulting in warm, dry conditions in the Northwest and increased rainfall across the Southwest. The warmer sea surface waters cause winters to be wetter across the Southern United States.
Particularly intense El Niño events can cause quite a lot of harm. Severe El Niños have brought droughts to Australia and India, and higher than usual amounts of hurricanes to the Pacific.
La Niña, on the other hand, occurs less frequently than El Niño and has the opposite effect. Episodes of La Niña have helped dry the Southwestern United States as well as parts of East Africa.
It pushes more warm water toward Asia and brings cold, nutrient-rich water to the surface around the west coast of the Americas. While this environment creates a nice habitat for cold-water marine life such as squid and salmon, it can have disastrous consequences for humans.
La Niña events allow stronger Atlantic hurricanes to form and increase the likelihood of long, stubborn droughts to materialize in the Southern United States.
Scientists predict that both of these weather cycles will become more intense in the coming years as climate change accelerates.
How is climate change changing the weather cycles of the planet?
There’s increasing evidence that human activity is causing the climate to change at an unprecedented scale.
In over 300 peer-reviewed studies of extreme weather events around the world, scientists found a direct link between human-induced carbon emissions and the rate at which wildfires, hurricanes, and floods are happening.
As we burn fossil fuels to power our homes and travel from place to place, we release greenhouse gasses that accumulate in the atmosphere. These gasses trap heat and cause average global temperatures to rise rapidly. A small rise in global temperatures is enough to cause oceans to become warmer, which is believed to exacerbate weather cycles such as El Niño and La Niña.
Researchers from the National Oceanic and Atmospheric Association have found that unmitigated climate change will increase the frequency of these weather events, perhaps even intensifying them. Already, El Niño episodes in the past decade have led to extensive coral bleaching and severe tropical Pacific storm activity, like what was seen between 2014 and 2016.
As these trends continue, we’re more likely to see knock-on effects in other weather patterns. Droughts, heatwaves, and floods are three weather events that have the most impact on humans. Here’s a look at how climate change will intensify them:
Climate change may make droughts last longer
Warmer temperatures could enhance evaporation from the soil. Without enough water, plants and animals living, or being grown, in naturally dry areas could die out semi-permanently as the water cycle becomes disrupted in these places.
Longer La Niña events may further worsen the impact of droughts. Drier conditions could lead to more wildfires, and possibly even conflicts, as people fight to secure water for their livelihoods.
The Southwestern United States is particularly sensitive to droughts. A decrease in water availability there could put people at risk of food shortages and ecosystem breakdown.
It could make heat waves more intense
In May 2015, over 2,000 people in India perished during a ten-day heatwave with highs of up to 45 degrees celsius. It was one of the highest global average temperatures recorded in recent history, with effects felt throughout the entire planet.
Longer, hotter seasons may slowly become the norm as global average temperatures rise. Coupled with other changes such as the urban heat island effect, temperatures in cities could remain at record-breaking highs throughout the day and night.
Climate change could increase the frequency of storms and floods
With the possible rise in El Niño and La Niña events, coastal areas could be battered by more frequent and severe storms.
These storms may not only destroy homes; they may also cause widespread flooding that will take longer than normal to subside. It’s estimated that by 2100, coastal flooding could cause up to $14 trillion in damages.
The most vulnerable areas include the Northeastern United States, Northwestern Europe, and Southeast Asia.
Do weather cycles explain away claims of climate change?
No.
Natural weather cycles cannot be the sole cause of climate change because they don’t fit the short timescale in which large amounts of carbon dioxide have accumulated in our atmosphere.
The sharp rise in carbon dioxide levels, and the corresponding increase in average global temperatures, within a few decades, can be explained by carbon-emitting activities. We emit 33.1 billion metric tons of carbon dioxide per year through the use of cars, coal-fired power plants, and other carbon-emitting activities.
Climate skeptics often refute this view under the basis that previous climate changes were caused by natural cycles, and therefore the current climate change we’re going through is no different. It’s unfortunately a flawed argument for two main reasons.
Firstly, it overlooks the speed at which the current climate change is occurring. Increases in global temperatures, as well as changes in weather patterns, require hundreds if not thousands of years to happen. Scientists have discovered that since the Industrial Revolution a little over 200 years ago, the planet has warmed by about 1-degree celsius.
During this time, we relied heavily on fossil fuels for our manufacturing, transportation, and construction needs. We also cleared entire swathes of forests and introduced livestock farming to almost all corners of the globe.
Secondly, satellites have detected amounts of carbon dioxide and methane in our atmosphere that are 150% to 250% higher compared to levels during pre-industrial times.
As these greenhouse gasses get trapped in our atmosphere, they warm our planet at a rate that is roughly ten times faster than the rate noticed after the last Ice Age 10,000 years ago.
If all of these changes were caused by natural weather cycles, they would occur over a much longer period. In the 300,000 years that humans have roamed the Earth, this is the first, and possibly the last time, that we’re causing the climate to collapse because of our activities.
Can anything be done about it?
As an individual, one of the best things you can do to fight climate change is to reduce your reliance, and support, for fossil fuels. You could switch your home to solar-powered electricity or cycle to work every day to reduce your carbon footprint.
You could also open a climate-friendly checking and savings account with Aspiration. We’re a financial platform that doesn’t lend any money to fossil fuel companies. Ever.
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