Climate Change and Its Very Real Effects

Even back when I was in elementary school over 20 years ago, climate change was already an established science and a big topic. Kids’ science shows talked about climate change and its effects and science textbooks had sections about it. Today, no scientific body of national or international standing disputes it. With high temperature records being broken nearly year after year, it’s not hard to see why.

But for the greater part of the 21^st century so far, politics infected the science. Conservative groups and politicians waged a campaign of disinformation trying to portray climate change as some sort of “liberal” hoax. It’s still going today. In some ways, it’s even worse now that the Trump administration is actively removing the US government’s own climate scientists from government positions, burying government studies that show evidence of human-caused climate change, and altering the wording of government documents to make it seem like climate change isn’t really happening.

I lived through it all, and it was infuriating. I even met some of the people who were convinced by this “climate skeptic” nonsense when I was attending university (UCLA, no less). The whole thing turned the state of US public climate awareness into something of a laughing stock in the eyes of the rest of the world. But now, as more drastic effects of climate change are starting to take place, it’s finally starting to be taken seriously by a majority of Americans. And not a moment too soon if we are to prevent to worst effects from happening.

What is Climate Change?

Although global warming and climate change are interchangeable in the public’s view, in science, they are slightly different. Global warming is the warming of the Earth’s climate due to an increase in greenhouse gasses (mainly carbon dioxide, methane, and nitrous oxide), of which human activity is the primary source. Climate change is the long-term alteration of the Earth’s climate as a whole and encompasses global warming and all the effects of that warming.

There’s a myth circulating around the Internet that the term “global warming” had to be changed to “climate change” because Earth wasn’t really warming. It’s completely false. Both terms have been used in scientific literature for decades (and are still used today), and Earth is indeed warming. In fact, the only known person who advocated a change like this was Frank Luntz, a Republican political strategist, who issued a memo to conservative politicians advising them to use the term “climate change” instead of “global warming” because it was less “frightening” to the public.

What Is Causing Climate Change?

The main driver of climate change is us by far. In 2010 alone, humans released the greenhouse gas equivalent of 49 billon tonnes (gigatonnes) of carbon dioxide, and it’s likely only increased since then. Roughly 76% of it was actual carbon dioxide from burning fossil fuels and land use changes (mainly deforestation), 16% was from methane (mainly from livestock, landfills, agriculture, mining, and natural gas use), 6% was from nitrous oxide (mainly from agriculture), and the remaining 2% was from fluorinated gasses.

Carbon dioxide, like methane and nitrous oxide, is a greenhouse gas. When sunlight hits Earth’s surface, it’s reemitted as infrared radiation (heat), which greenhouse gasses absorb and reemit. That allows the planet to trap heat that would otherwise be lost to space. In fact, Earth would be below freezing if it weren’t for these gasses. But too much greenhouse gas and you start seeing the effects of global warming we’re seeing today.

What makes carbon dioxide the most important greenhouse gas in terms of climate change is that we release a lot of it, and it stays in the atmosphere for a very long time (30-95 years). Water vapor is actually the most dominant greenhouse gas, but the amount of it in the atmosphere depends solely on temperature and pressure. If there’s too much, it rains out within nine days, and if there’s too little, evaporation will add some. So, the amount of it in the atmosphere pretty much stays constant. Methane and nitrous oxide are both more powerful than carbon dioxide as greenhouse gasses, but methane only lasts about 12 years in the atmosphere, and there’s not enough of either gas to rival the effect of carbon dioxide in the long term.

Hundreds of gigatonnes of carbon dioxide get transferred naturally between Earth’s vegetation, land, and oceans every year. This is the carbon cycle. For example, plants take it in to build their tissues and release it when they die or lose their leaves. You can actually see this seasonal change in the following graph.

The Keeling Curve, which shows the effect of seasonal changes on carbon dioxide levels. Note that the seasonal changes are not enough to explain the upward spike in carbon dioxide levels. Source: https://en.wikipedia.org/wiki/File:Mauna_Loa_CO2_monthly_mean_concentration.svg

Although the roughly 30 gigatonnes of carbon dioxide humans release is small compared to that, it’s enough to make a difference. That’s because while the Earth’s land, vegetation, and oceans normally absorb more carbon dioxide than they release (they even have the capacity to absorb about 40% of human emissions, too), that 30 gigatonnes is enough to exceed their absorption capacity. The rest stays in the atmosphere and accumulates year after year.

How We Know It’s Us and Not Other Causes

In order to come to the conclusion that humans are the main drivers of climate change and not other natural sources, climate scientists did a lot of “fingerprinting” studies. For example, we know it’s not the sun because solar activity has been relatively constant as the following graph shows. In addition, increased solar activity would heat up the entire atmosphere. What we observe is only the heating of the troposphere (the lowest part of the atmosphere), which is consistent with greenhouse heating.

Graph showing solar activity compared to Earth’s temperature. Source: NASA (https://climate.nasa.gov/causes/)

Another key “fingerprint” is the carbon isotope ratio in the atmosphere. There’s no carbon-14 in fossil fuels (it’s radioactive, so it’s long since decayed away), and plants (which fossil fuels are made of) have a distinct ratio of carbon-13 to carbon-12 (they prefer carbon-12 over carbon-13). So, burning lots of fossil fuels would increase the ratio of carbon-12 in the atmosphere compared to carbon-13 and carbon-14, which is what scientists observe.

Other natural factors, such as volcanic activity, were also taken into account, and no models that had natural influences alone could produce the amount of warming we see today. Volcanic activity in particular releases only about 150-270 million tonnes of carbon dioxide a year, far less than the tens of billions humans release.

While natural influences (such as small variations to Earth’s orbit and axis of rotation and solar luminosity changes) do have the potential to alter Earth’s climate, they work over centuries to millions of years instead of just decades. The influences those forces have over such a short time period is minuscule.

Effects of Climate Change

A warming world is the most obvious effect of global warming (more/stronger heat waves, milder/shorter winters), but there are many other effects as well. So many of the world’s systems are linked to the climate, so any changes to it lead to widespread disruptions elsewhere.

Melting Ice and Rising Oceans

As the world warms, more ice melts and adds water to the ocean. Most of the world’s glaciers are diminishing, and some are in danger of disappearing completely. In addition, while melting sea ice does nothing to sea levels by itself, coastal sea ice slows the flow of glaciers to the ocean. If the ice in the glaciers reaches the ocean, it adds to the sea level.

Antarctica in particular has seen drastic amounts of melting recently. Just a month ago in early February 2020, Esperanza Base (at the northern tip of the Antarctic peninsula, the part closest to South America) measured a record temperature of 18.3 °C (64.9 °F) during a 9-day heat wave, which is nuts. Temperatures there usually only get to about 3.7 °C (38.7 °F) at that time of year. The following picture shows what it did to nearby Eagle Island, Antarctica.

The extent of ice melt on Eagle Island, Antarctica during the February 2020 heat wave. Source: NASA (https://earthobservatory.nasa.gov/images/146322/antarctica-melts-under-its-hottest-days-on-record)

In addition to melting ice, just the thermal expansion of water also contributes to rising oceans. Water expands as is gets warmer, so even if there was no additional water going into the oceans, the sea level would still rise in a warming world. In fact, it accounts for about a third of the observed increase in sea level rise.

The global average sea level in 2018 was 8.1 cm (3.2 in) higher than the 1993 average. It’s increasing by 3.6 mm (0.14 in) a year, and the rate is accelerating. Depending on how bad the warming gets, the oceans could be about 0.3 m (1 ft) to 2.5 m (8.2 ft) higher than 2000 levels by 2100.

Rising oceans threaten coastal cities and communities that house hundreds of millions of people by increasing the strength of storm surges and flooding, by increasing coastline erosion, and by increasing the chance of coastal freshwater aquifers being contaminated by saltwater.

Acidification and Oxygen Depletion of the Oceans

When the oceans absorb carbon dioxide, it increases their acidity through the formation of carbonic acid and its subsequent dissociation into bicarbonate and hydrogen ions.

While the oceans are unlikely to become truly acidic (pH < 7), the increased pH affects many marine animals. Corals and other organisms that build calcium carbonate skeletons/shells have a harder time doing so in more acidic environments. Those that can still do so require more energy. That means they’ll have less energy for other things like growth and reproduction. In addition, calcium carbonate is more likely to dissolve in more acidic environments.

Warmer water also holds less oxygen than cooler water. Oceans absorb around 90% of the excess heat from global warming. All that extra heating means more areas of low oxygen, which harms marine organisms.

Weaker Oceanic Currents

A portion of the Atlantic meridonial overturning circulation in the North Atlantic. Solid lines are warmer waters traveling along the surface, while dotted lines are colder waters traveling in the deep ocean. Source: R. Curry, Woods Hole Oceanographic Institution/Science/USGCRP

Temperature differences in the world’s oceans drive many important ocean currents. One of them is the Atlantic meridional overturning circulation (AMOC), shown above. The current is driven by warm water rising (it becomes less dense) near the equator and cold water sinking (it becomes more dense) in the North Atlantic. When the oceans are warmer as a whole, the temperature difference between those parts decreases, which weakens the current’s strength. In fact, it’s about 15% weaker than it was in the mid-20^th century.

The warm water it brings to northern latitudes helps keep the temperatures there more stable. If it were to shut down completely, those areas would experience drastic cooling. The areas where the current is rising (upwelling) also transport a lot of nutrients from the deep ocean up to the surface.

Since saltwater is denser than freshwater, an increase in freshwater from melting ice can also affect the strength of ocean currents. The less salty water tends to stay near the surface, which reduces the ability of water to move down in the water column.

Intensification of the Water Cycle

Due to the increased overall temperature, evaporation would increase roughly everywhere. But, because of existing weather patterns and geography, all that extra water in the atmosphere won’t get distributed evenly. Places that get a lot of rain now will tend to get even more rain, while dry places won’t see much more. The result is more intense droughts in dry places and more flooding in wet places. Droughts also increase the chance of wildfires, as we’ve been seeing recently in California, Alaska, and Australia.

Stronger Storms and More Extreme Weather Events

The extra water vapor and heat in the atmosphere intensifies storms. Climate scientists expect that in a warmer world, severe weather events are more likely and stronger. And indeed, we’ve been seeing stronger hurricanes and more frequent flooding events.

Ironically, the increased overall heat that powers up storms also weakens the strongest wind currents on Earth. Like with ocean currents, warm air rises and moves toward colder air up north, where it sinks. As it moves northward, the Coriolis effect deflects it eastward. The net effect is a jet stream, a band of high-speed wind. During winter months, the poles don’t get sunlight, which results in very cold temperatures. Since the strength of the jet stream is dependent on the temperature difference, this results in a very powerful jet stream that encircles the polar regions (polar vortex).

The Arctic in particular is very sensitive to warming. Since there’s no land there, it’s either open ocean or sea ice. Oceans have low albedo (very dark) and absorb a lot of sunlight, while sea ice has high albedo (very bright) and reflects a lot of it. So, if sea ice melts, it flips from a sun-reflecting area to a sun-absorbing one, which increases the temperature and promotes even more sea ice loss.

That decreases the temperature difference needed to sustain the jet steam that contains the polar vortex. When that jet stream gets weaker, it becomes wavy and can dip southward, bringing frigid air from the polar vortex with it. Likewise, when it bends northward, hot air from the tropics follows it. That’s what’s responsible for all the freak winter weather/unseasonal heat waves in the US lately.

More Widespread Pests and Disease

Many pests, such as mosquitoes, are inactive during the cold, winter months. Warmer temperatures make milder winters more likely, which increases the amount of time that these pests are active. In addition, many pests transfer disease. If they’re active for longer stretches of time, the chance of them spreading certain diseases becomes more likely. With the current coronavirus outbreak, it’s not hard to see how diseases that are normally confined to certain areas of the globe can start spreading to new areas.

Ecosystem Disruption and Damage

Life on Earth can adapt to changes in the climate, but they need time. If the changes are too fast, many organisms simply can’t adapt and die off. This is especially true of organisms that live in cold environments. While many organisms can move northward or to higher altitudes to escape the higher temperatures, those that already live there have no place to go.

For example, the polar bear needs sea ice to hunt for food. Due to the reduced sea ice from global warming, it’s now a vulnerable species. Another example is the bumblebee in North America. These bees are native to North America, so many North American plants depend on them for pollination. But due to their large size, they have trouble cooling down in warmer temperatures, leading to large population declines.

Climate change also disrupts marine life. In addition to the ocean acidification and oxygen depletion effects I discussed earlier, climate change also hurts coral reefs. When stressed (either due to higher temperatures or pH), corals expel the symbiotic algae that gives them nutrients and their vivid colors. This leads to coral bleaching. Corals can survive bleaching, but more frequent bleaching events, as we’re seeing now, reduce that chance. Coral reefs provide habitats for a huge variety of organisms and help reduce coastal erosion.

When a species moves or dies off, it has often has an impact on the local food chain. If enough species do that, the local food chain could change drastically or even collapse.

Alterations to the Food Supply

The disruption to ecosystems around the world extends to our food supply as well. As the world warms, existing croplands may become less suitable for growing food. Marine species can migrate, depriving some coastal communities of their main source of food/income. Droughts can threaten staple crops that entire countries depend on. All of these factors will likely lead to increased food price volatility as the dynamics of our food supply change.

In addition, climate change is also affecting the quality of crops. The warmer temperatures is making some staple crops, such as rice and wheat, lose nutrients. This can further exacerbate existing malnutrition problems.

Population Displacement

Unsurprisingly, coastal communities are most vulnerable to the effects of climate change. Some communities are literally at risk of being washed away. For example, the Magdalen Islands in Quebec, Canada has seen some serious erosion recently. Some places have lost about 4 m (14 ft) over the last decade. The sea ice that used to protect the shoreline is diminishing rapidly, leaving nothing to stop the waves from wearing away the coastal cliffs.

Food and water shortages from droughts or aquifer contamination will also stress populations around the globe. They’ll have to either adapt or move elsewhere. In addition, those shortages have a tendency to inflame existing conflicts.

Furthermore, increases in temperature may actually make some humid places literally too hot to live. If carbon dioxide emissions continue increasing at their current rate, parts of South Asia could exceed a wet-bulb temperature (takes humidity into account) of 35 °C (95 °F) by the end of the century. That’s the limit of human survivability. In those conditions, the human body can’t cool itself down with perspiration enough, and death happens within a few hours.

All of these factors would lead to a lot of so-called “climate refugees” around the world.

Why It’s Important to Act Now

There’s a reason why climate scientists stress the need to limit warming to less than 1.5 °C (2.7 °F) above pre-industrial levels. When global temperatures exceed that, irreversible damage (at least for the next few decades to millennia) becomes much more likely. That includes the release of methane and carbon dioxide from permafrost (which normally locks a lot away) and a partial collapse of the West Antarctic ice shelf (which would cause a rapid rise in sea level and reduction in local ocean salinity). If we stay at our current emission levels, it’s estimated that the carbon “budget” left for meeting this goal would be exhausted by 2028. If nothing’s done, we’re on track to reach about 3 °C (5.4 °F) above pre-industrial levels by the end of the century.

Many of these events are spurred on by positive feedback cycles that become more potent as the temperature rises. These are cycles that reinforce themselves and can lead to runaway effects. One such feedback cycle is the ice-albedo feedback cycle. As I mentioned before, ice reflects a lot of the sunlight that hits it. As it gets hotter, ice melts and reveals more sun-absorbing land or ocean, which further increases the temperature.

Another feedback cycle is the water vapor feedback cycle. Warm air can hold more water vapor, which is a greenhouse gas. So as the Earth warms, more water vapor ends up in the atmosphere from increased evaporation. The extra water vapor then traps even more heat, increasing the temperature.

The strength of these feedback cycles isn’t fully known, which accounts for some of the variability in how much warming climate models predict. But it’s certain that as the temperature increases, so does the chance of any of these feedback cycles getting out of hand or even triggering other feedback cycles, sending the Earth past an irreversible tipping point. It’s absolutely not worth the risk.