Climate change is increasingly becoming a focal point of discussion; it's a topic on everyone's lips. The conversation ranges from severe weather events to activist movements like Extinction Rebellion, which has engaged in acts of civil disobedience. The once distant threat of climate change, thought to only affect future generations, is now a pressing concern for us.

Opinions are sharply divided on this issue. One faction warns of impending doom, which many perceive as alarmist, while others dismiss the situation altogether, claiming it to be natural or insignificant.

Often, people express their confusion—“I'm not a climate scientist, so I can't say.” Even at the highest levels of discourse, scientific understanding appears limited, which explains the success of climate sceptics. Unlike medical professionals, who effectively communicate their expertise to patients, climate scientists have not conveyed their findings to the public in a comparable manner. As a result, while there's a general wariness about climate catastrophe, people tend to trust doctors when they receive troubling health news.

The absence of prominent figures, such as the late Stephen Schneider, has left a void in climate communication. This has led many to conclude that climate science is overly complicated, though the basic principles are straightforward and commonly found in high school physics curricula. We've understood the greenhouse effect since the 1820s!

It's time to engage in this dialogue without hesitation or vague reassurances. We must equip ourselves with solid arguments. The stakes are too high to ignore.

Here are seven fundamental points that everyone should understand about climate change.

1. CO2 Heats the Atmosphere Carbon dioxide may not evoke the same fear as hydrochloric acid or uranium-232, but it is essential for life on Earth. Without CO2, the planet would be inhospitably cold, with ice sheets extending to New York City and average global temperatures plummeting by 15.5 degrees Celsius.

CO2 is one of several greenhouse gases. It allows shortwave radiation (visible and ultraviolet light) from the sun to penetrate the atmosphere, where the Earth absorbs this energy and then emits it as longwave radiation (infrared light). Greenhouse gases trap this energy, warming the planet much like glass in a greenhouse.

In 1861, John Tyndall identified CO2 as a greenhouse gas that absorbs heat. Our understanding of this phenomenon has only grown since then. For the foundational physics to be incorrect would imply that a vast amount of basic science is flawed, which seems unlikely.

2. Carbon Dioxide is the World's Thermostat CO2 serves to warm the Earth, and increasing its concentration will elevate global temperatures. The challenge lies in determining how much. CO2 constitutes only 0.04% of the atmosphere, while oxygen and nitrogen make up the majority. However, only greenhouse gases absorb infrared light, meaning that even minor increases in these gases can have disproportionate effects relative to their concentration.

This principle is evident in everyday life. One cup of coffee is harmless, but twenty cups could be fatal, just as a tiny amount of arsenic is deadly.

How potent is CO2? It accounts for approximately 9-26% of the Earth's greenhouse effect, depending on cloud cover, while water vapor and clouds contribute between 36-72%. This is because raising temperatures increases atmospheric water vapor, which further enhances warming. If we exclude water vapor's influence, CO2 is responsible for 80% of the greenhouse effect.

3. Fossil Fuels Equal CO2 The term "fossil fuels" reflects their origin. Over millions of years, plants absorbed CO2 and released oxygen through photosynthesis. Geological processes later compressed and transformed this organic matter into fossil fuels.

When we burn these fuels, a simple chemical reaction occurs: C + O2 = CO2

Sceptics may argue that humans contribute only 3% of the world's CO2 emissions, but they overlook the fact that the remainder is released through natural processes, which have maintained a balance for millennia. We are now disturbing this equilibrium.

Imagine a bathtub where water flows in and out at the same rate, keeping the level steady. If we increase the inflow, the water will rise until it eventually spills over. CO2 measurements from the Mauna Loa observatory have shown an increase from under 320 ppm in 1960 to over 400 ppm today. We are releasing carbon at a rate that nature took millions of years to sequester, and this rate is accelerating.

4. This Isn't New Some people question the alarm over climate change, suggesting that increased CO2 could boost plant growth and that a warmer world is preferable to a colder one. But is this true?

Current CO2 levels are the highest they have been in 3 million years, during the Pliocene epoch when levels ranged from 356-410 ppm. The continents were positioned similarly to today, and temperatures were significantly warmer—3-4 degrees Celsius above pre-industrial levels—with sea levels 25 meters higher. Polar regions experienced even more dramatic temperature increases.

We are poised to exceed 410 ppm in the coming years without stabilizing at that level. Historical events like the Palaeocene-Eocene Thermal Maximum (PETM) show that when CO2 levels soared above 1000 ppm, temperatures rose by 5-8 degrees Celsius, leading to drastic changes in ecosystems.

5. Heat Fuels the Weather The planet is undeniably warming, and we've observed more frequent extreme weather events, such as droughts and hurricanes. What connects these phenomena to CO2?

Heat is energy, and when it accumulates in the atmosphere, it influences the climate. This energy excites water molecules, leading to widespread evaporation. In humid areas, this can result in heavy rainfall and flooding, while drier regions may suffer from drought as moisture is whisked away by winds.

Higher temperatures also create more energetic storms. Tropical storms need sea surface temperatures of at least 26.5 degrees Celsius, typically found near the equator. As these storms travel along warm currents, they can grow more intense, resulting in larger hurricanes and typhoons.

6. Life is Slow. The Climate is Slower. Although human activities are impacting the climate at an unprecedented rate in geological terms, from our limited perspective, these changes may seem gradual. Humans have short lifespans, which makes it difficult to appreciate long-term trends.

Currently, about half the CO2 we emit remains in the atmosphere; the rest is absorbed by oceans and vegetation. It takes around 30 years to remove half the atmospheric CO2, with the remaining portion lingering for centuries or even millennia.

Climate models help us predict future conditions based on extensive data, including temperature, CO2 levels, ocean currents, and ice cap reflectivity. By comparing these models to historical data, we can assess their accuracy and reliability.

7. It’s Already Happening Global temperatures have already increased by about 1 degree Celsius, and we are experiencing the consequences.

In 2010, a heatwave in Moscow resulted in 55,000 deaths. By 2016, Baghdad endured extreme heat for months, and Chennai faced severe water shortages affecting millions. Additionally, long-term climate changes may have exacerbated the Syrian conflict, leading to significant migration.

Coral reefs and marine life are struggling due to rising ocean acidity, with the Great Barrier Reef losing over half of its coverage from 1985 to 2012. Wildfires are becoming more frequent, with the U.S. witnessing a doubling of large wildfires since the 1970s.

As we confront increasingly severe weather events, it's essential to understand that the time to act is now. We must take this knowledge and use it to advocate for change. While the situation may seem grim, history shows that no movement that has engaged 3.5% of the population has failed. Together, we can reshape the future.

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