A Walk Through Earth's Climate History
Unraveling the Threads of Change
In the vast tapestry of Earth's existence, the climate has undergone immense fluctuations long before human beings became aware of its nuances, and certainly before our activities began influencing it. The climate of our planet has witnessed periods ranging from ice ages to iceless ages, volcanic winters, and atmospheres dominated by methane and ammonia. Dr. Sammy, in this enlightening episode titled "A Walk Through Earth's Climate History," urges us to explore the intricate cycles that have shaped our climate for hundreds of millions of years, offering a unique perspective on the current climate challenges we face.
Throughout Earth's history, a series of cycles, both incredibly long and lasting only a few thousand years, have played a pivotal role in shaping the climate. Dr. Sammy emphasizes that these cycles will persist long after our presence on Earth ceases to exist. The episode invites viewers to take a stroll down Earth's climate history lane, aiming to find answers to the pressing question of our current predicament and how deep into hot water we truly find ourselves.
Over the past 540 million years, Earth's climate has oscillated between two primary states: greenhouse and ice house climates. Greenhouse periods boast abundant liquid water and minimal ice at the poles, while ice house conditions witness the presence of large ice sheets at both poles. The most recent transition occurred around 55 million years ago during the thermal maximum, a peak in the last greenhouse state. This transition marked the beginning of the ice age we are currently experiencing.
The Earth's climate doesn't change arbitrarily; there are reasons behind these shifts. Dr. Sammy introduces the theory of a massive bloom of freshwater fern called Azolla in the Arctic Ocean about 55 million years ago. The fern, upon decomposing, sank to the seafloor, taking a substantial carbon load with it. This event, coupled with reduced carbon dioxide in the atmosphere, initiated a cooling process that led to the onset of an ice age. This example illustrates how living organisms, like the Azolla fern, can influence the climate over extended periods.
The episode then explores the broader influencers of Earth's climate, including the Sun's variations in brightness, orbital eccentricity, and changes in the Earth's axial tilt. These factors contribute to fluctuations in solar radiation and temperature over varying time scales. The Earth's orbit, transitioning from nearly circular to elliptical, results in orbital eccentricity cycles lasting about a hundred thousand years. Additionally, changes in the Earth's axial tilt occur in cycles of approximately 42,000 years, influencing the distribution of solar energy across the planet.
The narrative touches upon the early stages of Earth's formation, where a molten lava surface gradually cooled to allow the formation of oceans and land masses. The emergence of oxygen, driven by photosynthetic algae called cyanobacteria, led to the great oxygen catastrophe, a critical event in Earth's history. Oxygen levels rose dramatically, impacting anaerobic life forms and setting the stage for the evolution of aerobic organisms.
As Earth evolved, so did its climate. The episode highlights significant periods, such as the Cambrian explosion and the asteroid impact around 65 million years ago, which triggered an impact winter and reshaped the planet's ecosystems. The transition from greenhouse to ice house climates about 35 million years ago marked the formation of glaciers in Antarctica, contributing to the current ice age.
The discussion culminates with a focus on the present scenario, where human activities, particularly the burning of fossil fuels, have accelerated climate change. Dr. Sammy introduces the iconic "hockey stick" graph, depicting the rapid increase in average global temperatures during the 20th century. Recent research, utilizing fossilized plankton, extends the temperature record back 11,300 years, revealing that current temperatures are rising faster than they have in the past 100 years.
In conclusion, "A Walk Through Earth's Climate History" provides a comprehensive overview of the intricate cycles that have shaped our planet's climate over millions of years. It emphasizes the dynamic interplay between living organisms, atmospheric composition, and celestial factors. The episode serves as a reminder that while Earth's climate has weathered various challenges, the current human-induced changes pose unprecedented threats. It calls for collective action to address climate change and safeguard the delicate balance of our planet's ecosystems for future generations.
About the Creator
Līva
World is interesting place. Scary, but worth living.
Nature is full of surprises and people are... well, people are something else.
Art is the best doctor.
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Chinese EVs Closing In on America After Canadian Tariffs Deal
The electric vehicle race is no longer just about climate goals or consumer choice — it has become a geopolitical contest. And in early 2026, a subtle but powerful move by Canada may have tilted the board. By agreeing to sharply reduce tariffs on Chinese electric vehicles, Canada has opened a door that the United States has worked hard to keep shut. While Chinese EVs are still largely barred from the American market, they are now edging closer than ever — not by crossing the border directly, but by entering through Canada. This development raises a pressing question: Are Chinese EVs closing in on America, and what does that mean for the future of North American auto markets? The Deal That Changed the Game Canada’s new agreement with China allows up to 49,000 Chinese-made electric vehicles per year to enter the Canadian market at a tariff rate of just over 6%, a dramatic drop from the previous 100% tariff that effectively blocked them. On paper, the quota seems small. In reality, it carries enormous symbolic and strategic weight. For years, both Canada and the United States aligned closely on keeping Chinese EVs out, citing concerns over unfair subsidies, national security, and the protection of domestic auto industries. This new deal marks a clear shift — and a divergence from U.S. policy. Canada didn’t make the decision in isolation. The EV tariff reduction was part of a broader trade reset with China, tied to agricultural exports such as canola and efforts to stabilize a strained economic relationship. Why Chinese EVs Matter So Much China is the undisputed leader of the global electric vehicle industry. Its manufacturers produce EVs at scale, often at prices Western automakers struggle to match. Brands like BYD, Nio, and Xpeng have already expanded aggressively into Europe, Southeast Asia, and parts of the Middle East. North America has remained one of the final fortified markets — until now. Chinese EVs are appealing not just because they’re cheaper, but because they’ve rapidly improved in quality, range, and technology. For consumers priced out of North American and European EV models, Chinese vehicles offer something rare: affordability without sacrificing features. Canada’s decision gives Chinese automakers their first legitimate foothold in North America — and footholds tend to grow. Why the U.S. Is Nervous The United States still enforces a 100% tariff on Chinese EV imports, making them effectively unsellable in the American market. But Canada’s move has triggered concern in Washington. U.S. officials argue that Chinese EVs entering Canada could indirectly pressure American markets, influence supply chains, and weaken Washington’s leverage in future trade negotiations. There’s also a political dimension. Both major U.S. parties have framed Chinese dominance in EVs as a strategic threat — not just to auto jobs, but to technological leadership. Modern EVs collect vast amounts of data, and lawmakers have raised concerns about cybersecurity and foreign data access. While Chinese EVs aren’t rolling onto American roads yet, their presence just across the border changes the conversation. Canada’s Risk — and Opportunity Inside Canada, the reaction has been mixed. Automotive hubs like Ontario worry that opening the market could undermine domestic manufacturing and strain relations with the U.S., Canada’s largest trading partner. Some leaders have called the deal “lopsided,” warning it could cost jobs if American retaliation follows. Others see opportunity. A more competitive EV market could lower prices for Canadian consumers and accelerate EV adoption. It may also attract Chinese investment into Canada itself — including factories, battery plants, and supply chain partnerships. If Chinese automakers choose to build in Canada rather than simply export to it, the country could position itself as a bridge between Chinese EV innovation and North American demand. That balancing act — between economic opportunity and political risk — defines Canada’s strategy. Are Chinese EVs Really ‘Closing In’ on America? For now, the answer is: not directly — but strategically, yes. Chinese EVs sold in Canada won’t automatically flood the U.S. market. Regulations, trade rules, and tariffs still stand in the way. But proximity matters. Supply chains overlap. Consumer awareness spreads. Manufacturing footprints expand. There’s also the possibility of a workaround: Chinese companies could eventually build EVs in North America to bypass tariffs altogether. This idea has already been floated — but it faces fierce resistance from U.S. lawmakers and unions. Still, history shows that once a global industry leader gains regional access, momentum often follows. What This Means for Consumers For Canadian buyers, the impact could be immediate: more choice and lower prices in an EV market that has long been criticized for being expensive and limited. For American consumers, the effect will be indirect — at least at first. But increased competition could eventually pressure U.S. automakers to reduce prices, improve features, and accelerate innovation. The larger question is whether North America wants competition or insulation — and how long insulation can realistically last in a globalized EV economy. The Bigger Picture: A Global EV Power Shift Canada’s tariff deal reflects a broader reality: China’s dominance in electric vehicles is reshaping global trade, whether governments like it or not. Europe is already grappling with an influx of Chinese EVs. Emerging markets are embracing them. And now, North America has its first real crack in the wall. This isn’t just about cars. It’s about who controls the future of clean transportation, supply chains, and industrial policy. Final Thoughts Chinese EVs aren’t driving down American highways yet — but after Canada’s tariff deal, they’re closer than ever. This move doesn’t spell immediate disruption, but it does signal a shift. One country has decided that economic pragmatism outweighs political alignment. And in doing so, Canada may have opened the door to a new phase of EV competition in North America. Whether that door swings wider — or slams shut — will depend on how the U.S., automakers, and consumers respond. One thing is certain: the EV race just entered a new chapter.
By Muhammad Hassanabout an hour ago in Earth
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