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If the effect of increase CO2 in the air has a negative effect, why doesn't decreased CO2 have a positive effect?

If the effect of increase CO2 in the air has a negative effect, why doesn't decreased CO2 have a positive effect?


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I recently asked a question about whether there were studies on the effects of reduced CO2 level air and got what sounds like a good answer:

Are there studies on the effect of reduced CO2 levels on human cognition?

The answer posted to the above question states that there is no reason to expect low inhaled CO2 levels to even make a difference in the relative levels of CO2 in the lungs, with are ~100x higher than in the ambiant air. This seems like a rational argument.

But with further thought that argument seems inconsistent. If average CO2 levels in the air are around ~400ppm, just 3x that number, ~1200ppm, is known to be associated with drowsiness and complaints of poor air quality (if my research is correct).

If the argument above holds, that reducing CO2 levels in the air from ~400ppm to ~0ppm, isn't going to significantly affect the ratio of CO2 in the lungs, then why doesn't that argument hold also with a seemingly small increase of 3x CO2 levels in the air (as compared to the 100x levels in the lung already)?


3X atmospheric CO2 does not have appreciable cognitive impact.

Indoor air typically is already much higher in CO2, especially in a room full of people, because they are all breathing out CO2. It would not be unusual to find 2-3X atmospheric CO2 inside.

In the answer to your previous question, I referred to much higher concentrations that do have appreciable impact. For example, at 100X normal atmospheric concentration, the concentration in the air is similar to the normal concentration in the lungs, such that CO2 builds in the lungs and dissolved levels increase in the bloodstream.


Does Wearing a Face Mask Reduce Oxygen&mdashand Can It Increase CO2 Levels? Here's What Experts Say

Why carbon dioxide toxicity is making headlines right now.

Now that we&aposve all been wearing face masks to help prevent the spread of the coronavirus, some people say that wearing a mask is reducing their intake of oxygen—or forcing them to breathe in their own carbon dioxide. This leaves them feeling faint, light-headed, or "smothered." They&aposre also concerned about how dangerous this is, and how less oxygen and more carbon dioxide might affect their health.

One driver who crashed his SUV into a pole in Lincoln Park, New Jersey, on April 23 actually blamed his collision on his mask. He told police he passed out because he𠆝 been wearing an N95 mask for too long. Initially, the investigating officers believed him, writing in a Facebook post that he was the only person in the car and passed out due to “insufficient oxygen intake/excessive carbon dioxide intake.” 

The post was shared more than 2,700 times and received hundreds of comments, with a few sharing their own experiences of feeling smothered by this type of mask. The police department later updated their post, stating that they didn’t know “with 100% certainty” that 𠇎xcessive wearing” of an N95 mask was a contributing factor to the accident. They added that “it is certainly possible that some other medical reason could’ve contributed to the driver passing out.”  

So is it possible that wearing a face mask as part of social distancing can cause someone to build up so much carbon dioxide and get so little oxygen that they pass out, or worse? Carbon dioxide is a natural by-product of the body’s respiration process, something we all breathe in and out every day. How harmful can it be?

In rare cases, it can actually be pretty dangerous, according to the National Institutes of Health (NIH). They say that inhaling high levels of carbon dioxide (CO2) may be life-threatening. Hypercapnia (carbon dioxide toxicity) can also cause headache, vertigo, double vision, inability to concentrate, tinnitus (hearing a noise, like a ringing or buzzing, that’s not caused by an outside source), seizures, or suffocation due to displacement of air.  

But the emphasis here should be on high levels. “It has to be a pretty high concentration to be capable of causing harm,” Bill Carroll, PhD, an adjunct professor of chemistry at Indiana University, Bloomington, tells Health. 𠇌O2 is present in the atmosphere at a level of about 0.04%. It is dangerous in an atmosphere when it is greater than about 10%.” 

It’s also possible to have too little CO2. “This is when you exhale too fast or too often,” Dr. Carroll says. “If you hold your breath, you wind up with too much CO2. The core issue is that CO2 regulates the pH of the blood—too much CO2 and the blood becomes too acidic too little and it becomes too basic (alkaline). In either case, your body detects the change in acidity and you pass out, which is the body’s way of saying, ‘please stop fooling with me and breathe normally.’” 

When it comes to face masks, we know they’re not all made equally. The extent to which a mask could affect CO2 levels depends on what it’s made of, and how tightly it fits.

“If you put a plastic bag over your head and tie it tight around your neck, no coronavirus could get in, but neither could any oxygen and you would suffocate, so we obviously don’t recommend that,” says Carroll. “I think it’s highly unlikely that you would pass out from a lack of oxygen with a cloth mask, which generally doesn’t fit tightly to your face. When you exhale or inhale, air can go around the mask as well through the pores in the material. This is why a cloth mask does not absolutely protect you from inhaling the virus, but by disturbing your exhalation flow it tends to protect those around you from aerosols in your breath.”

Carroll doubts that any cloth face covering would ever fit against the face so tight that someone would pass out from a lack of oxygen. “You𠆝 take it off because it’s uncomfortable well before that happens,” he says. 

But what about the guy in the New Jersey car crash? He was wearing an N95 mask, after all, not just a regular cloth mask.  

“Someone wearing an N95 mask for a prolonged period of time may have alterations in their blood chemistry that could lead to changes in level of consciousness if severe,” infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health. But it’s most likely to happen to those who are already predisposed to breathing difficulties, such as smoker, obese people, or individuals with COPD or emphysema.

Kelli Randell, MD, an internist and medical advisor at Aeroflow Healthcare, tells Health that prolonged use of any face mask, including the N95 respirator, has not been shown to cause carbon dioxide toxicity in healthy people. �use breathing is slightly harder with a mask, I do recommend that people who suffer from severe COPD or other lung diseases that make breathing difficult carefully consider the use of face masks,” says Dr. Randell

Dr. Adalja adds that there’s absolutely no need for any member of the general public to be wearing an N95 respirator, which is a type of personal protective equipment (PPE) designed to protect health care workers and the patients they care for. “It’s uncomfortable to wear, and it does restrict your breathing,” he says. “When I wear one to take care of patients I try to keep it on only for as long as I have to.” 

The bottom line? The N95 might be uncomfortable and restrictive to the point where it affects your oxygen and carbon dioxide levels. but you really shouldn’t be wearing that anyway. As for cloth face coverings (either store-bought or homemade), there’s even less of a chance of breathing issues, and it’s definitely not an excuse for going out without one. Make sure your mask covers your nose and mouth but feels loose, rather than so tight you really can&apost breathe. If you continue to feel like your airways are cut off, consider other possible causes, such as a panic attack, which can trigger sudden feelings of suffocation and breathlessness. 

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it&aposs possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the򠳜, WHO, and their local public health department as resources.

To get our top stories delivered to your inbox, sign up for the Healthy Living newsletter


Whenever I post something here at ImaGeo involving climate change, it’s a good bet that I’ll get a spectrum of critical responses in the comments section. These range from skepticism about the urgency of the problem to outright dismissal of humankind’s influence on climate through our emissions of greenhouse gases.

A recent post here about thawing permafrost releasing climate-warming carbon dioxide into the atmosphere was no exception. For the story, I reviewed dozens scientific research papers, and used information and quotations from two interviews. Based on that reporting, here’s what I wrote at the top of the story:

The coldest reaches of the Arctic on land were once thought to be at least temporarily shielded from a major — and worrisome — effect of a warming climate: widespread melting of permafrost. But a recent study suggests these northernmost Arctic areas are likely to thaw much sooner than expected. That’s concerning because melting permafrost releases climate-warming greenhouse gases.

As always, I expected skeptical pushback — but nothing as extreme as this:

As CO2 has had no noticeable effect on climate in 600 million years, until 15- 20 years ago, when carbon tax was invented, any alleged climatic effects can be ignored.

I took this to mean that a liberal scientific establishment invented the idea that carbon dioxide plays a role in Earth’s climate system to support raising taxes.

Never mind that relatively simple physics worked out in the 1800s, and since corroborated by experiments and observations, show that adding CO2 to the atmosphere should raise Earth’s average temperature.

I ordinarily ignore comments like the one I quote above. Discover is a science magazine, not a platform for political grandstanding. And it is especially not a platform for ideas that run counter to basic physics and more than a century of hard scientific work by generations of researchers.

This is not to say that I and the other writers and editors here at Discover view science as being infallible. Far from it. We recognize that as a human endeavor, science is prone to error born of vanity, preconceived notions, confirmation bias, a herd mentality, etc. Scientists know this better than anyone, so skepticism is one of their cardinal values. So is the recognition that even today’s most widely accepted theories may have to be modified or even replaced tomorrow if new evidence requires it.

Journalists are also supposed to be skeptical and self-critical. We should frequently ask ourselves things like, “How do I know this? Am I sure? Maybe I should check because I could be deceived by my preconceived notions.”

And so in this case, I thought it would be useful to delve deeper into what scientists know of the link between carbon dioxide and climate over the geologic timescale, and CO2’s overall role as a kind of thermostat for the planet.

I don’t pretend that what follows is a definitive primer on these issues. Not even close. But I thought it might be useful to share what I learned — if for no other reason that it might arm readers with some useful scientific information when they encounter people peddling politics in the name of science.

So, back to that original claim that “CO2 has had no noticeable effect on climate in 600 million years,” the commenter wrote this to support it:

My evidence for my comment, is climate history over 600 million years, during which time, when CO2 increased, global temperature decreased, for several million years, and when CO2 decreased, global temperature increased, also for several millions of years.

He also used a graph originally posted online by someone named Monte Hieb at this website . Hieb has changed the graph a number of times over the years. The following version is one that has been frequently picked up by people who deny the science on humankind’s impact on climate, including such well known figures as Christopher Monckton :

It purports to show that CO2 and climate really aren’t well linked.

When I sought more information about this graph, I landed first on a post at RealClimate by Gavin Schmidt, who heads NASA’s Goddard Institute for Space Studies. From his article, titled “Can we make better graphs of global temperature history?,” I learned that Hieb had hand drawn his temperature record based on the work of a scientist named Chris Scotese. And as Schmidt puts it:

Scotese is an expert in reconstructions of continental positions through time and in creating his ‘temperature reconstruction’ he is basically following an old-fashioned idea . that the planet has two long-term stable equilibria (‘warm’ or ‘cool’) which it has oscillated between over geologic history. This kind of heuristic reconstruction comes from the qualitative geological record which gives indications of glaciations and hothouses, but is not really adequate for quantitative reconstructions of global mean temperatures. Over the last few decades, much better geochemical proxy compilations with better dating have appeared . and the idea that there are only two long-term climate states has long fallen by the wayside

The “proxy” records Schmidt references are preserved physical characteristics of the environment that stand in for direct measurements — in this case, chemical fingerprints in the geological record of changing climatic conditions. (For more on proxy records, see this explainer .)

Based on Schmidt’s post, here is part of my response to the commenter claiming no link between CO2 and climate:

You are deluded by hubris — the idea that by reading one graph of suspect origin you know better than an entire scientific community consisting of literally thousands of researchers, operating over many decades and doing the actual hard work of science — and holding up their findings to rigorous review by expert peers.

. your alleged “evidence” is a graph, in part hand-drawn, posted to a website that hasn’t been updated in six years by an obscure person with no discernible expertise in this area, and based on the work of a scientist who is not an expert in paleo temperature reconstructions and whose ideas were long ago supplanted by better work based on actual physical proxy records.

I then pointed him toward an example of real researchers doing the truly complex and hard work of science — a peer-reviewed paper titled “CO2 as a primary driver of Phanerozoic climate” .

In their paper, the team of five scientists analyzed a wealth of different data to examine the role of CO2 in climate over the past 540 million years. Their conclusions are nuanced — which is to be expected for a system as complex as global climate, and especially when looking at it over such long time periods. But here is the most relevant fundamental finding:

Here we review the geologic records of CO2 and glaciations and find that CO2 was low (<500 ppm) during periods of long-lived and widespread continental glaciations and high (>1000 ppm) during other, warmer periods.

Other scientists have addressed particular details of the geologic record. These include a period of glaciation that occurred during late Ordovician Period. Climate change dismissives say it happened despite sky high concentrations of climate-warming carbon dioxide in the atmosphere 440 million years ago. This, they claim, is proof that CO2 plays less of a role, or even no role, in determining Earth’s climate.

In supporting this claim they use a geochemical model called “ GEOCARB ” that provides estimates of CO2 concentrations through geologic time. But the critics fail to mention that the data included in the GEOCARB model come in very long time steps of 10 million years. With this in mind, the creators of GEOCARB explicitly warned that their model cannot discern changes in CO2 occurring over periods less than 10 million years long — including shorter-term drops of the kind that scientists have shown likely occurred during the late Ordovician glaciation.

“Thus, exact values of CO2 . should not be taken literally and are always susceptible to modification,” GEOCARB’s creators said.

Yet climate dismissives do just that. And they ignore copious evidence gathered by scientists supporting lower CO2 levels in the atmosphere during that period. For example, a 2009 paper in the journal Geology came to the following conclusion, as described by Phil Berardelli in a story in Science :

The rise of the Appalachians plunged Earth into an ice age so severe that it drove nearly two-thirds of all living species extinct. That’s the conclusion of a new study, which finds that the mountains’ rocks absorbed enough greenhouse gas to freeze the planet.

For more details about the Ordovician glaciation and related issues, the website Skeptical Science has an excellent overview .

Commenters on my blog also often claim that since the concentration of CO2 in the atmosphere is so low compared to that of water vapor, also a greenhouse gas, it could not possibly play the role of a thermostat. But here, too, rigorous research shows otherwise.

For example, a team of four NASA scientists led by Andrew Lacis and including Gavin Schmidt, found this: “Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere.”

Yes, water vapor and clouds are the major contributors to Earth’s overall greenhouse effect. And, in fact, a companion study led by Schmidt showed that water vapor and clouds together account for 75 percent, with CO2 coming in at 20 percent, and other non-condensing greenhouse gases making up the rest.

So given that CO2 accounts for just a fifth of Earth’s overall greenhouse effect, what supports the claim that it nevertheless is the most important greenhouse gas?

The answer involves different characteristics of greenhouse gases. When the atmosphere cools enough, water vapor condenses and rains out. By contrast, carbon dioxide, methane and other greenhouse gases do not — they are non-condensing.

The researchers found that without these non-condensing greenhouse gases — CO2 foremost among them — there would be nothing to prevent the atmosphere from cooling enough to cause water vapor to rain out. And since it is such a potent greenhouse gas, if water vapor were to rain out, the result would be very dramatic cooling. In this way, CO2 may not be as potent a greenhouse gas as water vapor, but it is actually more important.

“Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state,” the authors of the first study concluded.

Just how much does carbon dioxide contribute? The second study led by Gavin Schmidt concluded that the CO2 in our atmosphere is itself is responsible for 80 percent of the radiative forcing that sustains Earth’s greenhouse effect.

This brings me to another claim made by some commenters here at ImaGeo. Climate records show that global temperatures drop before CO2 does as Earth enters an ice age, and visa versa too: Temperatures rise before CO2 as we come out of an ice age. So once again, CO2 cannot be the most important factor.

Scientists have actually long known that something something other than CO2 sets things in motion when Earth enters and emerges from ice ages: shifts in solar radiation reaching Earth due to variations in the Earth’s orientation to the Sun. (These are known as Milankovitch cycles ). Then other natural feedbacks kick in — most especially changes in carbon dioxide.

Scientists haven’t fully teased out all of the details yet. But in general, the picture looks like this:

As Earth starts to warm at the end of an ice age due to increased solar radiation reaching Earth, ice sheets and snow begin to contract. These surfaces are very reflective. So as they shrink, less sunlight is reflected back into space. This helps to enhance the warming. The warming causes ocean waters to give up CO2 — because CO2 is less soluble in warmer water. This strongly enhances the warming, which reduces the ice and snow, which causes more warming, which increases the CO2, leading to even more warming.

The bottom line is that a change in the amount of solar energy reaching Earth may get things going, but it’s CO2 that plays the dominant role.

This general picture leaves out some important details, such as the role of fresh water flowing into the oceans as ice sheets melt. A 2012 study led by Jeremy Shakun, now a Boston College climatologist, examined some of these details. Skeptical Science posted an excellent explainer about the results here . But the upshot of the study was this: “While the orbital cycles triggered the initial warming, overall, more than 90% of the glacial-interglacial warming occured after that atmospheric CO2 increase.”

I’ll finish with one recent piece of research in which a team of five scientists examined the role of greenhouse gases in temperature anomalies, including the overall warming trend, since the onset of the industrial revolution.

Here, too, commenters on this blog often claim that since recent periods in Earth’s past were almost as warm as it is now, we can’t know for sure that the CO2 we’ve added to the atmosphere is responsible for the observed recent warming.

But in their paper , published in the journal Scientific Reports, the scientists confirmed that our emissions of greenhouse gases, “especially CO2, are the main causal drivers of the recent warming.”

Earth’s climate is clearly an incredibly complex system. And climate scientists have never contended that they’ve understood all the details, or that their current understanding isn’t subject to revision when new evidence comes along. This is why they continue to do their research – to improve our understanding of how one of Earth’s key life support systems works.

They’ve also never contended that CO2 is the sole factor driving climate changes over geologic history. As we’ve seen, however, it plays a key role: Without the CO2 thermostat, Earth would likely be a proverbial snowball.

And now, we humans have turned the thermostat up, with predictable results that we’re already observing — such as changes to permafrost in the Arctic that got me going on this post to begin with.


Potential Health Risks of Low CO2 Levels

As discussed so far, low CO2 levels may indicate problems with acid-base balance in the blood, which may require urgent medical attention. In the section below, we&rsquoll discuss the health risks of chronically low CO2 levels, according to research.

However, low CO2 levels do not always indicate that there is a problem. Always talk with your doctor to learn more about your test results.

1) Association With Higher Death Rates

There is some evidence that low bicarbonate (HCO3-) levels may be associated with the risk of death. Bicarbonate is the most common form that CO2 takes in the body.

One observational study of 31,590 adults suggests that HCO3- levels less than 26 mEq/L are associated with about 1.5 times more deaths from any cause compared to levels above 31 mEq/L [8].

Another study of 15,836 adults with chronic kidney disease found that HCO3- levels below 22 mEq/L are linked to 2.6 times more deaths compared to levels above 31 mEq/L [9].

2) Worse Asthma Symptoms

Low CO2 levels may trigger several changes in the lungs, such as narrowing of the airways, otherwise known as bronchoconstriction. These effects on the lungs may negatively impact health, especially those with asthma [10].

There is some evidence that lower CO2 levels may reduce lung function, worsen asthma symptoms, and lower quality of life in asthma patients [10].

3) Connections to Anxiety and Panic Disorder

Hyperventilation often goes hand in hand with anxiety and panic attacks. There is evidence that CO2 levels in the blood also may play an important role [10].

For example, research suggests that baseline CO2 levels in people with panic disorder and PTSD are lower compared to the general population. Some researchers theorize that this lower baseline CO2 level is a natural coping mechanism of the body since sudden increases in CO2 are known to trigger panic attacks [10].


Are the Effects of Global Warming Really that Bad?

Eight degrees Fahrenheit. It may not sound like much—perhaps the difference between wearing a sweater and not wearing one on an early-spring day. But for the world in which we live, which climate experts project will be at least eight degrees warmer by 2100 should global emissions continue on their current path, this small rise will have grave consequences, ones that are already becoming apparent, for every ecosystem and living thing—including us.

According to the National Climate Assessment, human influences are the number one cause of global warming, especially the carbon pollution we cause by burning fossil fuels and the pollution-capturing we prevent by destroying forests. The carbon dioxide, methane, soot, and other pollutants we release into the atmosphere act like a blanket, trapping the sun's heat and causing the planet to warm. Evidence shows that 2000 to 2009 was hotter than any other decade in at least the past 1,300 years. This warming is altering the earth's climate system, including its land, atmosphere, oceans, and ice, in far-reaching ways.

More frequent and severe weather

Higher temperatures are worsening many types of disasters, including storms, heat waves, floods, and droughts. A warmer climate creates an atmosphere that can collect, retain, and drop more water, changing weather patterns in such a way that wet areas become wetter and dry areas drier. "Extreme weather events are costing more and more," says Aliya Haq, deputy director of NRDC's Clean Power Plan initiative. "The number of billion-dollar weather disasters is expected to rise."

According to the National Oceanic and Atmospheric Administration, in 2015 there were 10 weather and climate disaster events in the United States—including severe storms, floods, drought, and wildfires—that caused at least $1 billion in losses. For context, each year from 1980 to 2015 averaged $5.2 billion in disasters (adjusted for inflation). If you zero in on the years between 2011 and 2015, you see an annual average cost of $10.8 billion.

The increasing number of droughts, intense storms, and floods we're seeing as our warming atmosphere holds—and then dumps—more moisture poses risks to public health and safety, too. Prolonged dry spells mean more than just scorched lawns. Drought conditions jeopardize access to clean drinking water, fuel out-of-control wildfires, and result in dust storms, extreme heat events, and flash flooding in the States. Elsewhere around the world, lack of water is a leading cause of death and serious disease. At the opposite end of the spectrum, heavier rains cause streams, rivers, and lakes to overflow, which damages life and property, contaminates drinking water, creates hazardous-material spills, and promotes mold infestation and unhealthy air. A warmer, wetter world is also a boon for food-borne and waterborne illnesses and disease-carrying insects such as mosquitoes, fleas, and ticks.

Higher death rates

Today's scientists point to climate change as "the biggest global health threat of the 21st century." It's a threat that impacts all of us—especially children, the elderly, low-income communities, and minorities—and in a variety of direct and indirect ways. As temperatures spike, so does the incidence of illness, emergency room visits, and death.

"There are more hot days in places where people aren't used to it," Haq says. "They don't have air-conditioning or can't afford it. One or two days isn't a big deal. But four days straight where temperatures don't go down, even at night, leads to severe health consequences." In the United States, hundreds of heat-related deaths occur each year due to direct impacts and the indirect effects of heat-exacerbated, life-threatening illnesses, such as heat exhaustion, heatstroke, and cardiovascular and kidney diseases. Indeed, extreme heat kills more Americans each year, on average, than hurricanes, tornadoes, floods, and lightning combined.

Dirtier air

Rising temperatures also worsen air pollution by increasing ground level ozone, which is created when pollution from cars, factories, and other sources react to sunlight and heat. Ground-level ozone is the main component of smog, and the hotter things get, the more of it we have. Dirtier air is linked to higher hospital admission rates and higher death rates for asthmatics. It worsens the health of people suffering from cardiac or pulmonary disease. And warmer temperatures also significantly increase airborne pollen, which is bad news for those who suffer from hay fever and other allergies.

Higher wildlife extinction rates

As humans, we face a host of challenges, but we're certainly not the only ones catching heat. As land and sea undergo rapid changes, the animals that inhabit them are doomed to disappear if they don't adapt quickly enough. Some will make it, and some won't. According to the Intergovernmental Panel on Climate Change's 2014 assessment, many land, freshwater, and ocean species are shifting their geographic ranges to cooler climes or higher altitudes, in an attempt to escape warming. They're changing seasonal behaviors and traditional migration patterns, too. And yet many still face "increased extinction risk due to climate change." Indeed, a 2015 study showed that vertebrate species—animals with backbones, like fish, birds, mammals, amphibians, and reptiles—are disappearing 114 times faster than they should be, a phenomenon that has been linked to climate change, pollution, and deforestation.

More acidic oceans

The earth's marine ecosystems are under pressure as a result of climate change. Oceans are becoming more acidic, due in large part to their absorption of some of our excess emissions. As this acidification accelerates, it poses a serious threat to underwater life, particularly creatures with calcium carbonate shells or skeletons, including mollusks, crabs, and corals. This can have a huge impact on shellfisheries. Indeed, as of 2015, acidification is believed to have cost the Pacific Northwest oyster industry nearly $110 million. Coastal communities in 15 states that depend on the $1 billion nationwide annual harvest of oysters, clams, and other shelled mollusks face similar long-term economic risks.

Higher sea levels

The polar regions are particularly vulnerable to a warming atmosphere. Average temperatures in the Arctic are rising twice as fast as they are elsewhere on earth, and the world's ice sheets are melting fast. This not only has grave consequences for the region's people, wildlife, and plants its most serious impact may be on rising sea levels. By 2100, it's estimated our oceans will be one to four feet higher, threatening coastal systems and low-lying areas, including entire island nations and the world's largest cities, including New York, Los Angeles, and Miami as well as Mumbai, Sydney, and Rio de Janeiro.

There's no question: Climate change promises a frightening future, and it's too late to turn back the clock. We've already taken care of that by pumping a century's worth of pollution into the air nearly unchecked. "Even if we stopped all carbon dioxide emissions tomorrow, we'd still see some effects," Haq says. That, of course, is the bad news. But there's also good news. By aggressively reducing our global emissions now, "we can avoid a lot of the severe consequences that climate change would otherwise bring," says Haq.


Disadvantages of the Greenhouse Effect

The Endowment for Medical Research cites university studies that show increasing the level of CO2 to 550 parts per million (ppm) speeds up plant growth as much as 40 percent in a controlled greenhouse environment. The CO2 levels in the average greenhouse, with a closed ventilation system, decreases to 150 ppm to 200 ppm. During the summer, opening the ventilation system allows fresh air into the greenhouse, which increases the CO2 level. However, during the winter, in northern regions, the circulation of cold outside air into heated greenhouses could kill plants.

  • The Endowment for Medical Research cites university studies that show increasing the level of CO2 to 550 parts per million (ppm) speeds up plant growth as much as 40 percent in a controlled greenhouse environment.
  • The CO2 levels in the average greenhouse, with a closed ventilation system, decreases to 150 ppm to 200 ppm.

Other indirect effects of air pollution on animals

Ocean acidification

Ocean acidification occurs when the increasing amount of CO2 from air pollution is absorbed by the oceans. The absorption of CO2 changes the pH of the seawater i.e makes it more acidic.

As with climate change if this change occurred slowly, like it might have done before humans arrived, then animals could potentially adapt to the different conditions. However, these changes are happening rapidly thanks to all the air pollution we are causing and animals just can’t adapt quickly enough.

This more acidic water makes it difficult for animals to create shells, and has actually been found to start dissolving the shells of existing ones (5).

Acid rain

Acid rain is formed when sulphur dioxide and nitrogen oxide air pollution combines with water in the atmosphere causing it to become acidic. When this water falls as rain it can then have some bad consequences for wildlife.

The clearest effects of this are on aquatic animals in streams, lakes, swamps and marshes. The acid rain has been found to react with soils to release aluminium which washes into waterways. This aluminium causes acidification and has effects on the survival of fish eggs for example.

The more acidic water also causes more mucus buildup on the gills of adult fish. This affects their ability to absorb oxygen and they can suffocate. This has lead to some pretty apocalyptic scenes of dead fish floating on the surface of ponds and lakes.

More acidic conditions have also lead to impacts on frogs, snails and other species. Frogs are slightly more resilient to acidic conditions than fish, but the shallow ponds they use to breed can be more rapidly affected by acid rain which quickly makes it impossible for frogs and other amphibians to breed in them.

Ozone layer depletion

Ozone (O3) is a molecule in the atmosphere that occurs naturally and forms a layer, known as the ozone layer, that acts to absorb potentially harmful UVB rays from the sun. Those rays that cause us to tan (or burn) although too many of which would cause us to be covered in skin cancer.

Chlorofluorocarbons (CFCs) are an air pollutant released by refrigerators and aerosols. These are broken down in the atmosphere to form, among other things, chlorine. The chlorine reacts with the ozone and this converts it to oxygen which no longer provides the protection from those UVB rays.

So what does this mean for wildlife?

Well it has been shown to affect the development of plants, which you now know will consequently affect many animal species too. It has also been shown to have effects on marine life (6).

More recent findings of the effects of air pollution on animals include:

Some air pollutants (such as ozone) have been found to interact with and break down the scent molecules produced by plants that bees use to find their food. This increases the amount of time they have to spend foraging and therefore causes a decrease in average lifespan (7).

Another study showed that plants in urban areas with high levels of nitrogen dioxide produced more chemicals to help defend themselves against insects that want to eat them. (8)


Effects of increased greenhouse gas emissions

The main effect of increased greenhouse gas emissions is global warming. Carbon dioxide, methane, nitrous oxide and fluorinated gases all help trap heat in the Earth's atmosphere as a part of the greenhouse effect. The Earth's natural greenhouse effect makes life as we know it possible. However, human activities, primarily the burning of fossil fuels and deforestation, have intensified the greenhouse effect, causing global warming.1

Effects of increased greenhouse gas emissions

Increases in the different greenhouse gases have other effects apart from global warming including ocean acidification, smog pollution, ozone depletion as well as changes to plant growth and nutrition levels.

Global warming

Greenhouse gas levels have been increasing since the start of the Industrial Revolution, but over the last few decades growth has been particularly fast. Total greenhouse gas emissions have increased by about 80% since 1970,2 creating a radiative forcing of 2838 mW/m^2 equivalent to an atmospheric concentration of 473 ppm CO2e.3

With increasing levels of greenhouse gases being added daily, the greenhouse effect is now enhanced to the point where too much heat is being kept in the Earth's atmosphere. The heat trapped by carbon dioxide and other greenhouse gases has increased surface temperatures by 0.75°C (1.4°F) over the last 100 years.4

Global warming is harming the environment in several ways including:

  • Desertification
  • Increased melting of snow and ice
  • Sea level rise
  • Stronger storms and extreme events

Ocean Acidification

Increases in carbon dioxide levels have made the world's oceans 30% more acidic since the Industrial Revolution.5 The ocean serves as a sink for this gas and absorbs about a quarter of human carbon dioxide emissions,6 which then goes on to react with seawater to form carbonic acid.7 So as the level of carbon dioxide in the atmosphere rises, the acidification of the oceans increases.

Changes to plant growth and nutrition levels

Since plants need carbon dioxide to grow, if there are higher amounts in the air, plant growth can increase. Experiments where carbon dioxide concentrations were raised by around 50% increased crop growth by around 15%.8 Higher levels of carbon dioxide makes carbon more available, but plants also need other nutrients (like nitrogen, phosphorus, etc.) to grow and survive. Without increases in those nutrients as well, the nutritional quality of many plants will decrease. In different experiments with elevated carbon dioxide levels, protein concentrations in wheat, rice, barley, and potato tubers, decreased by 5-14%.9

Smog and ozone pollution

Over the last century, global background ozone concentrations have become 2 times larger due mainly to increases in methane and nitrogen oxides caused by human emissions.10 At ground level, ozone is an air pollutant that is a major component of smog which is dangerous for both humans and plants.11

Long-term ozone exposure has also been shown to reduce life expectancy. 362000-700000 of annual premature cardiopulmonary deaths worldwide are attributable to ozone.12 13 Recent studies estimate that the global yields of key staple crops, like soybean, maize (corn), and wheat, are being reduced by 2-15% due to present-day ozone exposure.14

Ozone layer depletion

Nitrous oxide damages the ozone layer and is now the most important ozone depleting substance and the largest cause of ozone layer depletion.15 This is because CFCs and many other gases that are harmful for the ozone layer were banned by the Montreal Protocol (MP) which has reduced their atmospheric concentration. Nitrous oxide is not restricted by the MP, so while the levels of other ozone depleting substances are declining, nitrous oxide levels are continuing to grow.


Carbon dioxide has an unexpected effect in Antarctica

Rising CO2 levels are causing temperatures to climb across most of the planet. But above central Antarctica (home to the Kohnen Station, a German research facility, shown), those excess greenhouse gases cause cooling, not warming, new data show.

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December 10, 2015 at 7:00 am

At the bottom of the world, carbon dioxide is doing something surprising. Rising levels of this gas normally cause warming. But over central Antarctica, they produce a cooling. That’s the finding of a new study.

This discovery does not undermine climate science, the researchers note. Rising levels of greenhouse gases, such as carbon dioxide, do raise temperatures elsewhere. The effect is instead a sign of how extreme and unique the conditions are in Antarctica.

“We’re not saying the greenhouse effect is rubbish,” says Justus Notholt. He is an atmospheric physicist at the University of Bremen in Germany. It’s just that “in Antarctica, the situation is different.”

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Explainer: Global warming and the greenhouse effect

Except central Antarctica.

This is the only place on Earth where surface temperatures are regularly colder than those some 8 to 50 kilometers (5 to 31 miles) above the surface. This second layer of the planet’s atmosphere is known as the stratosphere. And over central Antarctica, excess carbon dioxide actually boosts the amount of heat escaping into space. This is the opposite of what happens everywhere else.

The surprising finding will appear in Geophysical Research Letters.

Antarctica is unique

Unlike the rest of Earth, the Antarctic interior has not warmed over the last few decades. It has even shown signs of cooling slightly. A chilling effect from carbon dioxide in the atmosphere might partly explain this. More research would be needed to prove that, though, Notholt says.

Explainer: How scientists know Earth is warming

Like a pinball machine, the carbon dioxide molecule fires off that energy in random directions. Sometimes the energy continues out to space. Other times it returns to the surface. And when it does that, it creates what’s known as a greenhouse warming.

Where carbon dioxide blocks some of this radiation from the surface, satellites see it as a dip in the amount of energy — heat — escaping into space. So the ground level warms. But over central Antarctica, satellites see an increase in heat escaping into space.

Notholt and colleagues now call this the “negative” greenhouse effect.

And they propose that it’s due to the region’s super-frigid temps. This is the coldest place on Earth. Surface temperatures can fall to −93.2° Celsius (−136° Fahrenheit). That’s typically colder than the stratosphere.

The surface is so cold that little infrared radiation leaves. That is true even though the Antarctic Plateau is covered by ice and snow. Those surfaces reflect sunlight. But, as in other places around the world, carbon dioxide in the stratosphere over Antarctica soaks in heat. And that sends infrared radiation pinballing in different directions. That siphons some heat into space that might otherwise remain near Earth.

Elsewhere, this effect is normally overshadowed by the trapping of heat from the ground. But in Antarctica, so little heat comes from the ground that the loss becomes significant. What results is an overall cooling.

Just because part of the atmosphere cools doesn’t mean the mechanism cools the ground below too, says Scott Rutherford. He is an environmental scientist at Roger Williams University in Bristol, R.I.

The new work does predict that other places with frigid surfaces, such as Greenland, should see a reduced — but still positive — greenhouse effect. Temperatures in Greenland, however, are rising much faster than the global average, Rutherford notes. That suggests that the effect doesn’t significantly affect surface temperatures there.

Power Words

(for more about Power Words, click here)

atmosphere The envelope of gases surrounding Earth or another planet.

carbon dioxide A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. Carbon dioxide also is released when organic matter (including fossil fuels like oil or gas) is burned. Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food. The abbreviation for carbon dioxide is CO2.

climate The weather conditions prevailing in an area in general or over a long period.

environmental science The study of ecosystems to help identify environmental problems and possible solutions. Environmental science can bring together many fields including physics, chemistry, biology and oceanography to understand how ecosystems function and how humans can coexist with them in harmony.

fossil fuel Any fuel — such as coal, petroleum (crude oil) or natural gas — that has developed in the Earth over millions of years from the decayed remains of bacteria, plants or animals.

greenhouse gas A gas that contributes to the greenhouse effect by absorbing heat. Carbon dioxide is one example of a greenhouse gas.

greenhouse effect The warming of Earth’s atmosphere due to the buildup of heat-trapping gases, such as carbon dioxide and methane. Scientists refer to these pollutants as greenhouse gases. The greenhouse effect also can occur in smaller environments. For instance, when cars are left in the sun, the incoming sunlight turns to heat, becomes trapped inside and quickly can make the indoor temperature a health risk.

infrared light A type of electromagnetic radiation invisible to the human eye. The name incorporates a Latin term and means “below red.” Infrared light has wavelengths longer than those visible to humans. Other invisible wavelengths include X rays, radio waves and microwaves. It tends to record a heat signature of an object or environment.

molecule An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

physics The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study which emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in that field is known as a physicist.

radiation (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

satellite A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.

stratosphere The second layer of the Earth’s atmosphere, just above the troposphere, or ground layer. The stratosphere stretches from 10 kilometers to 50 kilometers (about 6.2 to 31 miles) above sea level.

sun The star at the center of Earth’s solar system. It’s an average size star about 26,000 light-years from the center of the Milky Way galaxy. Or a sunlike star.

Citations

S. Oosthoek. “Concerns about Earth’s fever.” Science News for Students. November 24, 2015.

B. Brookshire. “Scientists Say: Dioxide.” Eureka! Lab. November 16, 2015.

T.S. Feldhausen. “Beliefs about global warming vary by country.” Science News for Students. August 27, 2105.

A.P. Stevens. “Mapping our carbon footprint.” Science News for Students. January 27, 2014.

S. Ornes. “The certainty of climate change.” Science News for Students. October 16, 2013.

S. Ornes. “Climate change: The long reach.” Science News for Students. August 22, 2013.

Original Journal Source: H. Schmithüsen et al. How increasing CO2 leads to an increased negative greenhouse effect in Antarctica. Geophysical Research Letters, in press, 2015. doi: 10.1002/2015GL066749.

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U.S. carbon dioxide emissions have dropped to unprecedented low during pandemic

Credit: Northern Arizona University

As the demand for transportation fuels has plummeted in the last month due to the COVID-19 pandemic, a Northern Arizona University scientist says the dramatic decrease in local air pollution and carbon dioxide (CO2) levels above cities is significant, measurable and could be historic, depending on how long commuters and other drivers stay off the road.

Professor Kevin Gurney of NAU's School of Informatics, Computing, and Cyber Systems measures greenhouse gas emissions in major U.S. cities. He says the consumption of three important fuels has made a nose-dive: gasoline, jet fuel and distillate (diesel).

"For the first three weeks of April, gasoline has declined 43.1 percent, jet fuel by 59.3 percent and diesel fuels by 16.7 percent compared to the same three weeks over the last decade," Gurney said. "If you didn't know any better, you'd think it was an error in the data. Nothing like this has ever shown up in the record. Never."

Vehicles driving on the road account for roughly 20 percent of carbon dioxide emissions each year.

"The decline in gasoline has implications for both local air quality and climate change," he said. "We never could have run an experiment in which the public stops driving. The COVID-19 virus has forced this, and it gives us a glimpse of what not driving does to our air."

Early data from both satellite and ground monitors show decreased local air pollution in a number of locations across the US, consistent with the decline in fuel consumption. Based on data gathered since mid-March, he has projected longer-term levels of climate change gases in the atmosphere should transportation fuel demands remain low.

"If one were to assume that gasoline, jet fuel and distillates persisted at the current levels until the end of June, this would result in an annual decline of 5 percent in CO2 emissions from total energy for 2020," Gurney said. "If the current levels persisted for 12 months, or until the end of February 2021, this would result in an annual decline of CO2 emissions of roughly 15 percent."

As a point of reference, Gurney compared petroleum fuel use impacts of the coronavirus pandemic with the global financial crisis of 2008, when carbon dioxide emissions decreased by 3 percent.

"This far exceeds that event in terms of fuel consumption data we can see, but we've only had a few weeks to measure the results. We don't know how this is going to show up over the long haul. Once the pandemic is over, we may go right back to our normal levels of greenhouse gas emissions. However, there may be positive outcomes for climate in the midst of this devastating social and economic event. For example, business owners may see opportunities to continue telecommuting with a portion of the workforce and thereby increase productivity and lower costs. This could lessen road traffic and increase the efficiency of commercial space."

Gurney continues to archive numerous CO2 emission datasets as part of his Vulcan and Hestia projects, which map emissions at fine scales across the U.S. landscape.

"From a climate change point-of-view, there may be some valuable insights on energy consumption that we can use as we emerge from the COVID-19 crisis," Gurney said.



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