7 Points You Need to Know About Climate Change

Climate change is coming to dominate the debate; it’s on the tip of everyone’s tongue. People talk. Be it extreme weather events or activist groups such as Extinction Rebellion (who took to the streets in the act of “civil disobedience”), the once distant and far off vision — the one that was supposed to affect our grandkids — is coming for us.

Views are polarised, as with everything these days. One side predicts the apocalypse, seeming hysterical to much of the public, who accept climate change but are dubious of its severity. The other side denies anything is even wrong, or that it’s either natural or nothing to be worried about.

Too often do people throw their hands up in despair — “Oh, — I don’t know about all this, I’m not a climate scientist”. Even at the highest reaches of the debate, science is thin on the ground. No wonder the sceptics do good business. Climate scientists haven’t transferred their knowledge to the public in the same way that say doctors do. So, people are wary of climate disaster, but they’ll trust the doc who tells them, sadly, they have cancer.

Great speakers such as Stephen Schneider (who passed away in 2010) have left vacant positions. And so, we’ve concluded climate science is hard, too esoteric. That might be true at the fringes (the bleeding edge), but the basics are so simple they’re taught in every high school physics textbook. We’ve known the science of the greenhouse effect since the 1820s!

No more shying away from the debate, or giving vague feelgood answers. We’ve got to have our arguments bolted to our hip. We have to win this. We don’t have a choice.

So, here are seven key points everyone needs to understand about climate change.

1. CO2 Heats the Atmosphere

Carbon dioxide doesn’t quite have the scare factor of hydrochloric acid or uranium-232. CO2 sounds boring. But without CO2 life on earth could not exist. It would be freezing for a start. Ice sheets would stretch as far south as New York City, and global temperatures would be 15.5 degrees Celsius lower.

All because of CO2. Perhaps not so boring after all.

CO2 is one of many greenhouse gases. It lets in shortwave radiation (visible and ultraviolet light) from sunlight which passes through the atmosphere. The earth absorbs the energy and radiates it back towards space in the form of longwave radiation (infrared light, e.g. heat — when metal is heated it glows red because the infrared light is bleeding into the visible spectrum). Greenhouse gases absorb the energy. Thereby warming the earth, just like glass in a greenhouse, hence the name.

In 1861, John Tyndal identified CO2 as a greenhouse gas capable of absorbing heat rays, and our knowledge has only deepened. The physics is foundational, and for it to be wrong would mean an awful lot of basic science is wrong as well. Perhaps, but it seems unlikely.

2. Carbon Dioxide is the World’s Thermostat

CO2 warms the earth. Therefore, if we increase CO2, the world will warm. The question is, how much? CO2 makes up only a fraction of the atmosphere at 0.04%. Oxygen and Nitrogen make up the bulk. But these gases do not absorb infrared light, only the greenhouses gases do. Therefore, if only a small fraction of the earth’s atmosphere is receptive to infrared light, even small changes in these gases can have outsized effects relative to their concentration.

We understand this in our everyday lives. A cup of coffee won’t kill you, but twenty cups might give you a heart attack, whereas a drop of arsenic is deadly. It’s just more potent.

How potent is CO2?

Well, CO2 is responsible for between 9–26% of the earth’s greenhouse effect, depending on the cloud cover. Surprisingly, water vapour and clouds are responsible for between 36–72%. That’s because the best way to increase atmospheric water vapour is to turn the temperature up (as every visitor to a sauna knows), and CO2 is the method of warming. It increases the amount of moisture in the atmosphere, raising temperatures further. If we discount the effect of water vapour, CO2 accounts for 80% of the greenhouse effect.

Carbon dioxide is the world’s thermostat.

3. Fossil fuels = CO2

They’re called fossil fuels for a reason. Over millions of years, plants extracted CO2 out of the atmosphere and emitted oxygen via the process of photosynthesis. Millions more years passed and by various geological processes this dead plant matter, whether from land or sea, compacted and condensed till we got the fossil fuels we know today.

Burn that ancient carbon, and a simple chemical reaction occurs.

C + O2 = CO2

It’s that simple. Sceptics will readily point out humans release only 3% of the world’s CO2. But they’ve missed the point. The rest of the CO2 that is released is natural (from processes such as decomposition, respiration, ocean degassing, and volcanic eruptions), and for tens-of-thousands of years has been balanced with the CO2 absorbed. But now, we are tipping the balance.

Picture a bathtub. Every minute, 10 litres of water goes in, and through the plughole 10 litres of water leaves. Whatever the level in the bath, it will remain constant. Now imagine we turn the tap, so 10.3 litres of water enters the tub. Slowly and surely the water will rise as more water enters than leaves. The bath will inevitably overflow, the question is when.

Measurements from the Mauna Loa observatory in Hawaii show increases in CO2 from less than 320 ppm (parts per million) in 1960 to over 400 ppm today. A truly whopping amount. It’s not surprising; we are emitting in decades what nature took millions of years to extract. And we are accelerating. In the 1960s, we put 0.6 ppm per year into the atmosphere, whereas the past decade has been closer to 2.3 ppm per year.

The water in the bath is rising, but what happens when it overflows?

4. This isn’t New

Some ask, what’s the worry? CO2 will be a boost to plant growth, and a warmer planet is better than a colder one. I wouldn’t mind living near a sunny beach. Well, is this accurate?

Current CO2 levels are the highest for 3 million years, back in the Pliocene era, when levels were around 356–410 ppm. The continents were in roughly the same place, as well as oceanic currents — a snapshot into our future. Scientists found temperatures were significantly warmer. The average global temperature was 3–4 degrees Celsius above pre-industrial levels. Sea levels were 25 m higher.

Temperatures at the poles rose more extremely than anywhere else, 11–16 degrees Celsius warmer. Amazingly, explorers discovered fossilised beech leaves from this period in the Transantarctic mountains.

We look likely to overshoot 410 ppm in the next few years, let alone stabilise at it. We must go back further.

During the Palaeocene-Eocene Thermal Maximum (PETM) 55.5 million years ago, the earth saw massive carbon injections from a range of hotly debate sources. North and South America hadn’t joined. India meandered from Madagascar to Asia, the Himalayas all but an inevitability. Average temperatures rose by 5–8 degrees Celsius. Vegetation roasted in Spain. CO2 dissolved into the oceans, turning them acidic (CO2 forms carbonic acid). Palm mangroves grew in England and Belgium. Conditions at the poles were almost subtropical, being 23 degrees Celsius higher than today.

CO2 reached over 1000 ppm. The rate at which CO2 entered the atmosphere was 0.3–1.7 gigatons of carbon per year (GtC/yr). Humans today add around 10 GtC/yr, much faster than during the PETM. The PETM took over 20,000 years, a blink in geological time, but glacial when compared with today. Many scientists have noted the parallels. John Higgins and Daniel Schrag, from Harvard University, stated in May 2006: “The PETM represents one of the best natural analogues in the geologic record to the current rise in atmospheric CO2 due to burning of fossil fuel.”

5. Heat Fuels the Weather

The planet is warming, that much seems clear. But you might have also seen talk of extreme weather, like droughts and hurricanes, becoming more common. What’s the link with CO2?

The mechanism is simple. Heat is a form of energy. When trapped by the atmosphere, it affects the climate. In particular, it excites water molecules leading to evaporation on a global scale. As moisture saturates the humid atmosphere, local environments collapse.

In damp climates rainfall increases, but when it comes it arrives in torrents, carving up the landscape in landslides and floods. Whereas in dry climates, the water evaporates into the atmosphere and carried away on the wind. Killing plants and turning soil to sand.

A hotter world means more energy for a storm to feed off. Tropical storms require sea surface temperatures of 26.5 degrees Celsius to form [16], usually occurring close to the equator. These storms then follow the warm currents. In the Caribbean or Mid-Atlantic, they barrel up the US East Coast, alternately in the Pacific push up the East Asian Pacific Rim (such as Japan). Limits are placed on the size and trajectory of storms by the energy available — cold waters or dry land sap the hurricane’s ferocity. Therefore, in a hotter world, more energy fuels bigger hurricanes or typhoons, creating behemoths knows as “hyper canes”.

During the end-Permian hothouse, hurricanes may have reached to the Arctic. Floods will be more extreme covering a greater area, as these large systems dump billions of gallons of seawater onto land.

Worryingly, hurricanes may affect areas previously untouched or unthinkable.

In 2004, Hurricane Catarina surprised meteorologists as it formed in the South Atlantic, striking the coast of Brazil. Not just due to warmer waters, but also due to atmospheric factors such as wind shear from the South Atlantic being weaker. But the point is stark. More heat means more storms in more places. Already, the number of Category 4 and 5 hurricanes has roughly doubled since the mid-1970s.

Think of a pot of water, the more energy you put in, the more it boils over.

6. Life is Slow. The Climate is Slower.

Humans may be affecting the climate rapidly in geological time, but it still seems slow from our limited perspective. Humans don’t live very long. Sorry about that.

Currently, about half the CO2 we release into the atmosphere stays there; the other half is taken by the oceans or by plants. It takes 30 years to remove half the atmospheric CO2 — centuries for the next 30%. The final 20% will still be there in thousands of years. The process moves to the pace of the oceanic currents.

What will happen in the meantime has become the domain of the climate model.

Models have a bad rep. But our lives depend on them, from shipbuilding to product testing. Models revolutionised the way we do things, as we transitioned from merely thinking about a subject to testing it practically. First with scaled-down versions, and then eventually inside a computer. Models are science made flesh. They’re not perfect, but they’re the best tool we have.

Climate models work by dissecting the earth’s surface into grids. Then, using a vast amount of information (e.g. temperature, CO2 concentration, oceanic currents, reflectivity of the ice cap), they calculate how the climate will change in each grid square.

Climate models are calibrated or tested in a process called “hind-casting”. Here we input the information we have from a previous era of earth’s history, e.g. PETM, and we see if a similar course of events is shown in the climate model to what we know happened in real life. If it does, we know the model is accurate.

Contrary to reports that the predictions are off, they’re pretty good. Here are some notable examples:

Notice how we followed the worst-case scenario of the IPCC projections with sea level rising the highest predicted.

Hansen et al. 1981 predicted the future temperature rise with remarkable accuracy, and contrary to reports by critics of James Hansen, actually underestimated temperature rise (-20%).

The Third IPCC report slightly underestimate future warming by -14%.

The fifth IPCC report was again incredibly accurate in predicting both past and future climate. This model slightly overestimates (+16%) the effect of climate change, but this is explained by natural variability, small volcanic eruptions and lower-than-expected solar output not included in the post-2005 projections.

7. It’s Already Happening

Already global temperatures have risen about 1 degrees Celsius; we are feeling the effects.

In 2010, a heatwave in Moscow killed 55,000 people. Six years later, the city temperatures broke a 137-year record for July (a scorching 31.8 degrees Celsius). In 2016, Iraq, Iran and Kuwait endured a terrible heatwave, Baghdad suffered 43‏ degrees Celsius heat for two months. Zainab Guman told The Washington Post “It’s like everything on your body — your skin, your eyes, your nose — starts to burn”.

India this year saw 9 million people in Chennai (formerly Madras) endure a devastating water shortage as lakes and reservoirs were parched. People queued around the block to fill jerry cans with the precious resource. Booming populations combined with drier climates and failing groundwater reservoirs are set to devastate agriculture and force millions to move.

The Syrian conflict sparked the most significant mass movement of people since WWII. Priorly, the area saw long-term drying likely due to climate change, with some suggesting it exacerbated the conflict.

Coral reefs and shellfish around the world are struggling to survive due to ocean acidification. The Great Barrier Reef declined 50.7% (of the original cover) between 1985 to 2012 due to bleaching and tropical cyclones. Coral reefs make-up just 0.1% of the ocean area, but contain 25% of marine life. Each one truly a thalassic Garden of Eden.

Wildfires are becoming increasingly common. The US has seen the number of large wildfires (greater than 1000 acres) double since the 1970s. In summer 2019, Greenpeace Russia estimated 3.3m hectares of Siberia were burning with temperatures inside the Arctic Circle ranging from 34.8 degrees Celsius in Markusvinsa, Sweden to 21 degrees Celsius in Alert, Canada (only 900 km from the North Pole). The animals and communities which live there felt the disastrous effects. Massive flames engulf Southern California and major parts of Australia in 2019. It won’t be the last time.

At the other extreme, in August 2016, Louisiana saw a diluvial deluge cause $8.7 billion of damage in floods, covering a vast area of land. It was classed as a 1 in 500-year event. But scientists found climate change had increased the chance by at least 40%.

What happens when we reach 2 or 3 or even 6 degrees by the end of the century, which some models suggest is possible in a business as usual scenario. Who knows? And who wants to find out?

You made it to the end. Congratulations! However, there is a catch. Hopefully, you learned something. If you did, you know something you can’t un-know. Don’t let the information slip away. Do something with it.

We aren’t in a fairy-tale. There is no hero. And if God exists, he’s letting us ride this one out. It’s up to you. There is one glimmer of hope, though. Something called the 3.5% rule. It states that no popular movement which has engaged 3.5% of the populace in active participation has failed. We can do that, surely. We can change the future.

Find all the sources used throughout the article here.

Michael Yip

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