By Bru Pierce, Founder of Envisionation

When we discuss climate change today, it's important to understand where we are in the grand timeline of Earth's development and its climatic history. As whole Earth system specialists, we frequently encounter misconceptions about how our planet's climate has evolved over billions of years. Allow me to take you on a journey through time to put our current climate crisis into proper perspective.

The Remarkable Journey of Life

First, congratulations are in order. The mere fact that you're reading this represents something extraordinary: you are part of an unbroken chain of events stretching back 4 billion years. Your DNA carries the legacy of every generation that has preceded you, reaching back through the vast expanse of evolutionary time.

This journey began on what was essentially a lump of coagulated space debris, remnants of ancient galaxies and stars that had completed their life cycles. From this cosmic detritus emerged the world we recognise today. Everything around you has been shaped by life itself, which has continuously geoengineered its own environment whilst simultaneously evolving its integrated biodiversity.

The transformation was neither quick nor simple. It took an extraordinary 3 billion years to create any sort of atmosphere that could support life as we know it. Before that pivotal moment, you would have required a spacesuit to survive on planet Earth. This puts into perspective just how remarkable our living planet truly is.

Cycles of Freeze and Thaw

Earth's climate history reads like an epic novel filled with dramatic chapters. Some 750 million years ago, our planet experienced what scientists call "Snowball Earth" - a period when the entire globe was frozen solid. The planet subsequently warmed, then froze again, creating a pattern of dramatic climate swings that dwarfs anything we've experienced in human history.

Eventually, life gained a stronger foothold, and the great forests emerged. These ancient woodlands would eventually become the coal deposits and hydrocarbons that have powered our industrial civilisation. Following this period, the first vertebrate animals appeared, setting the stage for the age of dinosaurs, which came to an abrupt end approximately 65 million years ago.

The Deep Time Perspective

When we examine Earth's 4-billion-year timeline, patterns emerge that help contextualise our current situation. For the first 3 billion years relatively simple life forms gradually change the atmosphere. Significant transitions occurred when all existing continents merged into a single supercontinent before gradually separating into the configurations we recognise today.

The dinosaur era presents a fascinating comparison point. During their reign, global temperatures averaged 10°C warmer than today's levels, with no ice anywhere on the planet. As we move forward through geological time, we see the first glaciation beginning in Antarctica around 40 million years ago.

By 10 million years ago, global temperatures were merely 2°C warmer than present levels. Shortly thereafter, glaciation began to affect the Northern Hemisphere. This sets up one of the most important periods for understanding our current climate context.

The Ice Age Cycles

Around 2 million years ago, something significant occurred that fundamentally altered Earth's climate patterns. Temperatures began oscillating on regular 100,000-year cycles. This might have been the result of a large asteroid passing through our solar system, slightly altering Earth's orbital mechanics and creating a wobble that continues to influence our climate today.

This period encompasses the last five ice ages, each representing a dramatic climate shift. During the depths of these ice ages, average global temperatures dropped 2.5 to 3°C below what we consider normal. Conversely, during the warmest interglacial periods, temperatures rose to approximately current levels, or at most 1.5°C above.

This ice age period represents the Earth you would recognise, populated by lions, tigers, elephants, and familiar bird species, though many have since gone extinct. Particularly throughout the last two ice age cycles, a time when human beings were emerging. Most importantly, this cooler climate has been the norm for at least the past 500,000 years that life we would recognise has existed.

The Holocene: Our Climatic Goldilocks Zone

Our civilisation developed during a remarkably stable climatic period called the Holocene, which began roughly 10,000 years ago. This period has provided the "just right" conditions that allowed human society to flourish. However, when we examine the broader climate record, we discover that most life on Earth actually evolved to thrive in conditions that were 1-3°C cooler than our current baseline.

This revelation fundamentally challenges how we think about "normal" climate conditions. The stability we've enjoyed throughout recorded history represents an exceptional period rather than the planetary norm.

Today's Unprecedented Change

Now, let's examine where we stand today. We're currently 1.5°C warmer than pre-industrial averages, and we're heading towards 2°C of warming by 2035, possibly sooner. This trajectory takes us into genuinely uncharted territory for human existence.

When we examine the relationship between temperature, CO2 levels, and sea level over the past 400,000 years, clear patterns emerge. CO2 levels have tracked closely with temperature throughout the last four ice age cycles, typically ranging between 280-300 parts per million during stable periods.

Today's CO2 concentration stands at 426 parts per million. Dramatically higher than anything seen in the geological record of human evolution. This isn't simply an incremental change; it's a fundamental departure from the conditions under which our species and our ecosystems evolved.

The Path Ahead: Understanding the Stakes

At 2°C of warming, we eventually face the disappearance of the northern hemisphere ice. At 4°C, our current trajectory under business-as-usual scenarios would result in no ice remaining anywhere on Earth. This ice-free world would result in sea levels 70 metres higher than today.

Whilst it takes time for ice to melt completely, even a few metres of sea level rise would prove catastrophic for human civilisation. Consider that the majority of the world's population lives in coastal areas, and our major cities, agricultural regions, and infrastructure have all developed assuming current sea levels.

The sea level record shows dramatic swings corresponding to ice age cycles. During the last ice age, sea levels dropped 100 metres below current levels. As the planet warmed into our current interglacial period, seas gradually rose to present levels. Now, however, we're heading towards conditions that will push sea levels far higher than anything human civilisation has ever experienced.

The Urgency of Now

This geological perspective reveals the truly extraordinary nature of our current climate crisis. We're not simply dealing with gradual change; we're witnessing a rapid departure from the climatic conditions that allowed our species and ecosystems to evolve and thrive.

The greenhouse gas concentrations we've already achieved guarantee significant changes to Earth's climate system. The question isn't whether change will occur, but how dramatic that change will be and whether we can adapt quickly enough to preserve the civilisation we've built during this brief period of climatic stability.

Understanding this deep-time perspective doesn't diminish the urgency of action; it amplifies it. We're conducting an unprecedented experiment with the only planet we have, pushing it towards conditions not seen since long before humans existed. The window for maintaining anything resembling the stable climate that nurtured our civilisation is rapidly closing.

The choice we face isn't between change and no change; it's between managed adaptation to moderate warming or catastrophic disruption from extreme climate change. Earth's climate history shows us exactly what's at stake.

Bru Pearce is available for Consultancy and Speaking events: Book a meeting

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