In 2015, our average atmospheric global carbon dioxide (CO2) levels hit the milestone 400 parts per million (ppm). This means that out of every one million molecules and compounds in the air, about 400 or 0.04% of them are carbon dioxide.
According to the National Oceanic and Atmospheric Administration (NOAA), that’s a 120 ppm — roughly 43% — increase in average CO2 concentrations since the industrial age began about 250 years ago.
Carbon dioxide is a heat-trapping “greenhouse” gas. The sun sends its energy to the Earth through electromagnetic radiation, or light waves. The Earth absorbs some, and reflects the rest.
If it weren’t for CO2 (and a few other gases), energy reflected by the Earth would escape the atmosphere and our planet would be too cold to sustain life. If there were too much CO2, the planet would be too hot for life.
Think of it this way: Venus has too much CO2, and Mars has not enough. Earth’s CO2 concentrations are somewhere in the middle — a major factor for the habitability of our planet.
So what happens when our CO2 levels get too high?
By looking to Venus, we can know the effects of too much CO2. The planet’s atmosphere has about ninety times the mass of Earth’s, and it’s made up almost entirely of carbon dioxide. As a result, the surface temperature on Venus can reach higher than 800 degrees Fahrenheit, with more than a little help from the planet’s thick covering of sulfuric acid clouds.
While Venus is an extreme example of the “runaway greenhouse effect,” current CO2 levels in our atmosphere aren’t entirely innocuous, either. With a mere 0.04% atmospheric CO2, we’re already starting to see some dramatic changes to our planet’s climate.
Here’s what you need to know about how the consequences of increased CO2 are changing life on Earth:
Our ocean currents are slowing.
Way back in 2004, NASA reported on an emerging climatological prediction: the Arctic’s thawing sea ice, melting because of the region’s elevated temperatures, could have devastating effects on the Atlantic Ocean. Specifically, the excess of fresh water from melting ice could cause the ocean’s major currents to shift, or cease altogether.
This could significantly alter global temperatures.
The Atlantic’s currents are responsible for distributing massive amounts of heat to the Northern Hemisphere, and a shift in current could result in a dramatic drop in temperature for western Europe and eastern North America. Global average temperatures would thereafter be comparable to Earth’s last ice age, about 20,000 years ago.
When they published the scenario over ten years ago, NASA reported that this could take as little as twenty years to happen — but also that it might not happen at all. Well, this past March, a little more than eleven years later, the journal Nature released a study that says it’s happening right now — at least in part.
Although we haven’t yet seen a dramatic drop in temperature — except for a “conspicuous region” near Greenland (see below) — the Atlantic currents do appear to be weakening, and it does seem to be as a result of melting Arctic ice sheets.
Although we don’t know for sure whether the New Ice Age scenario will ever actualize, further melting in Greenland will almost certainly result in devastating consequences. Most notably, if the Atlantic circulatory currents significantly slow or stop, we may see a dramatic rise in sea level on North America’s east coast.
While this will certainly be inconvenient for people who live near the ocean, there are worse things that could happen. In fact, worse things are happening. Much of the carbon dioxide in our atmosphere, an estimated 26%, will dissolve into the ocean. While this process does help abate drastic changes to global temperatures, it also produces carbonic acid in our waters.
Historically our oceans have been close to neutral on the pH scale, leaning slightly toward basic — which is a good thing for life. However, in the last two centuries, ocean acidity has increased by 25%.
The trees are losing momentum.
For decades, the Amazon rainforest has majorly contributed to keeping global carbon dioxide levels in check. Over the past decade, however, it has shown a steady decline in its ability to turn excess CO2 into oxygen.
Another study published last March by Nature posits that a rise in tree mortality rates, a fall in new plant growth, and an increase in tree metabolism may be responsible for the unexpected observation.
Normally, a high level of atmospheric CO2 is great for plant growth. Not in this case.
Plants have for the most part been able to consume more carbon dioxide than they have given off, and global carbon uptake from trees has seen an overall increase. But the new data from the Amazon suggests that the increase in CO2 levels has caused trees’ metabolisms to speed up.
As with any living thing, a faster metabolism means a shorter life.
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Decreased life expectancy for trees — when combined with the high rates of deforestation, wildfires, and drought seen by the Amazon in recent years — could mean that we won’t be able to rely on Earth’s largest rainforest to save us from ever-increasing CO2 levels. If we start seeing this trend everywhere, we will almost certainly need to reconsider our long-term carbon emission reduction goals.
Animals are running out of food.
In theory, nothing should run out of food in a healthy ecosystem; the food web has historically been the major driving force for evolution on our planet. Now humans are the driving force, and — altruistically speaking — we are not doing well.
Remember how atmospheric carbon dioxide traps in heat? Well, there’s another side-effect of fossil fuel-burning you should know about…
When we burn coal, oil, and tropical forests, tiny particles enter the air — they’re called aerosols.
Aerosols create smog and haze, which block some solar radiation from entering the atmosphere, and are partly responsible for Earth’s slowed rate of temperature increase.
Despite this apparent benefit, aerosols are simply not good.
The negative health effects of breathing smog are well-documented, and the shift in our planet’s energy cycling process — caused by a decrease of incoming solar energy and an increase in temperature — results in reduced evaporation and rainfall, making Earth a hotter and dryer planet.
One long-term study, measuring protein-to-fiber ratios in ten Ugandan tropical tree species, found that a dryer climate is the likely reason for a significant drop in health benefits of tropical leaves. Species that rely on leaves for sustenance may experience drastic decreases in population if tropical leaves continue to decrease in value, if they don’t quickly adapt to eating more or better leaves.
Milder winters in Yellowstone are causing grizzly bears to wake up early from their hibernations, which means an increased demand for Yellowstone’s finite food sources, which will likely result in higher cub mortality rates.
Polar bears, who rely on Arctic ice floes for food, may not be able to survive on a land-based diet when the ice melts away.
At The Rainforest Site, we believe that dwindling food sources for animals is the worst effect of climate change.
Our planet’s ability to sustain life is the most valuable thing that we earthlings have going for us, and humanity is the only species that has the power to disrupt or preserve that. Therefore, we are responsible for the well-being of all life on Earth. So let’s act like it.
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