Yes, CO2 is Warming the Climate (And no, Exhaling is Not the Cause)

Carbon Dioxide (CO2) concentration in the atmosphere is the primary driver of man-made climate change (often called global warming). This has been demonstrated by multiple lines of evidence and is undeniable.

"But we exhale CO2 when we breathe, right? So CO2 can't be harmful, right?"

Wrong, and let me explain.*

Those new to climate science may be confused by intentionally deceptive graphs like the following, which was recently making the rounds on Facebook and denier lobbyist blogs. Often, especially on Facebook, the graph is given with no further explanation (insinuation and innuendo are common tactics of climate deniers). People who post it claim "it comes from a reliable source," but then refuse to actually cite and/or link to that source. It's because the source is the denier lobbyist industry. The goal of the graph is to mislead the public. Here's the deceptive graph:

Let's assume the values given are at roughly accurate. The green highlighted level of 400 ppm (parts per million) is approximately the current level in the atmosphere. You wouldn't know it from the graph, but 400 ppm in the atmosphere is exceptionally high; we'll get back to that in a minute. The graph is deceptive for two reasons: 1) it suggests levels in the atmosphere aren't high because levels in other situations are okay, and 2) it assumes the toxicity level of CO2 is somehow relevant to the physical warming capacity of CO2.

Both of these points are absolutely and grossly false. It's akin to saying that because we drink, swim, bath, and are composed largely of water, we can't drown in it.

CO2, like water, has multiple properties. At very high levels it is toxic. A very low levels it is necessary for plant growth. All well known and understood.

But CO2 also acts as a greenhouse gas. CO2 in the atmosphere keeps the Earth at a relatively stable temperature. Without the CO2, Earth's surface temperature would be about 30 degrees Celsius colder and, well, none of us would be here. Adding more CO2 to the atmosphere warms the Earth. This is just basic, well-understood, physics. CO2 keeps us warm; more CO2 = more warming.


While not intended by its creator, the graph actually shows how important CO2 is to warming. According to the values given, much of the northern hemisphere was just coming out of glaciers at 190 ppm but was comfy for us at 275 ppm, only about a 45% increase in CO2 levels. We're now at 400 ppm (and growing), which is roughly another 45% increase in CO2 levels.

So we've added as much CO2 since the beginning of industrialization as was the difference between glaciers and comfortable climate. As Vice President Biden might say, that's a Big F'n Deal.

To use slightly more technical language, the fact that CO2 acts as a greenhouse gas is basic physics known for more than a century. Sunlight passes through the atmosphere and heat gets radiated back to space, but a lot of that heat gets trapped by CO2 and other greenhouse gases and sent back to the surface. This process is continuous and keeps our Earth warm. We've been in a narrow balance for hundreds of thousands of years, but since we started burning fossil fuels we've added a lot more CO2 to the atmosphere (about 45%). More CO2 means more warming. Basic physics (and math). All demonstrated over and over again.

So don't be confused by intentional acts of deception like the first graph given above. The reality is that whether CO2 is toxic at 400 ppm or not is irrelevant to CO2's warming properties in the atmosphere.

A more relevant graph is the one below from NASA (see on this page), which shows that our current CO2 levels (arrow, top right) in the atmosphere are unprecedented in the modern age (i.e., during the time us humans have made a home here):

And a result, we've caused warming of the atmosphere, as the graph below clearly shows (source here). The red dot is February 2016. New heat records were set in 2014, then broken in 2015, and are on track to be broken again in 2016. Year to year fluctuations occur because of short-term events like El Nino and La Nina, but the overall trend is absolutely clear.

Bottom Line: CO2 is warming the climate, and humans are the dominant cause of that warming.

Now that is a big deal.

*A note about the exhaling of CO2. Yes, we exhale CO2. No, breathing isn't contributing to man-made climate change. The CO2 we exhale is the same CO2 that has been cycling around for thousands of years, moving from plants to soils to air to humans to everything else and back again, just as it has always been. The amount of CO2 has been stable within a relatively narrow range (second graph above) because it cycles in and out of things but is always somewhere. But here's the kicker - CO2 from fossil fuels is not part of that cycle. It has been buried in the ground for millions of years getting turned into coal and oil and natural gas, completely out of the carbon cycle. During the last century we've dug up a lot of that "out-of-the-loop" carbon and emitted it into the atmosphere in humongous amounts where it hasn't been during human civilization. More carbon = more CO2 = more warming.

Arctic Sea Ice Continues to Decline at Record Pace

The decline of Arctic sea ice extent continues to decline at a record pace. As noted here two weeks ago, January sea ice extent was the lowest in the modern satellite record. Well guess what - February 2016 sea ice extent was the lowest February on record.

Larger here.

As the graph above shows, sea ice extent in February has been declining for many years, with the linear rate of decline at 3% per decade. [The previous post explains how to read the graphs] NASA and NOAA also note that February continued the trend of ten straight months of record-breaking high global surface temperatures, with the Arctic being especially hot (more than 4 degrees Celsius above the baseline).

It could have been even worse. Most of the month had almost no ice growth, in a time of year where it should be growing substantially (sea ice extent grows in winter, falls in summer). Only a late month burst of growth got it to where it was - and it was still a record low for the month. That's how bad it is.

Let's take a closer look:

The chart above is kind of busy even though I've only selected the most recent years. You can go here and use the interactive chart to include whatever years you want.  I highly encourage looking at all the years going back. The previous post explains what the lines and shading mean.

As you can see, sea ice extent grows in winter and shrinks in summer. This happens every year, so what you want to look for is how much it grows and shrinks compared to previous years. Keep in mind that the baseline mean (the black line and gray shaded area) was lowered recently to reflect the continuing declines. [This means if we had kept the old baseline the current sea ice extent would be even worse]

The current year is the burnt red line in the upper left corner, right at the bottom of the other lines shown. Right now it's about the same as where last year was at this time (darkish blue), but only because of that late-February bump up. We're right about the maximum now, though we won't know officially until we get a little further along. That doesn't bode well as last year was only barely above the second worst minimum extent years (see where the lines reach their most downward loop around September).

Starting the melt season in such a bad maximum doesn't mean we'll set a new record minimum. You can see that at this time in 2012 the maximum in late March (dashed green line) was higher than it was in ensuing years, yet 2012 smashed the previous record minimum year of 2007 (light blue line). Because sea ice extent is highly sensitive to local weather conditions (especially wind), we simply won't know how bad the minimum will be this year until we reach it in September. But we do know that it will be a bad year because every recent year has been a bad year. All you have to do is look at where all the lines fall compared to the baseline mean - they are all below. That means the baseline mean will again have to be lowered at some point, once again tracking the race to the bottom. At some point we're likely to see an ice-free Arctic for part of the summer.

And that is not a good thing. Not a good thing at all.

What is Happening to the Arctic? How to Read the Graphs

As 2016 starts off even hotter than the record-breaking heat of 2015 because of man-made climate change, one of the fastest warming areas of the planet is the Arctic. This year one of the key measures of Arctic "health" - sea ice extent - is showing signs of even more severe impact than normal. This fact has scientists fearful of a major speed up in climate change effects. It also has fossil fuel lobbyists scrambling to find new ways to deny the science.

So how do normal people (that is, us) know what's going on in the Arctic and elsewhere? This post gives a basic primer on how to read the graphs put out by the National Snow & Ice Data Center (NSIDC). The NSIDC collects data from a variety of sources and provides a monthly update. For this post I'll focus on Arctic sea ice extent as reported in NSIDC's Arctic Sea Ice News and Analysis page. As I write this the last update was in early February covering the status through the end of January. The next update will be in early March covering up through February.

One of the first things visitors to the see will be the "Daily Image Update" in the top right corner. As of today it shows:

See it larger here.

The graphic is fairly simple but shows a lot of important information. The bottom scale shows the months from November to March, so this represents the winter period where Arctic sea ice extent is expected to grow, which it does every year. [In the summer months it shrinks every year] The left scale shows extent in millions of square kilometers, but for now you don't need to worry about that; focus on the graph lines themselves.

See that thick black line running through the gray area? That represents the baseline sea ice extent from 1981 to 2010. It's essentially an average. One important point - that average was recently recalculated because all of the years after the end of the old averaging period were much lower than average. Therefore, the baseline has been lowered. What that means is that we should roughly see as many years over the average line as below. That hasn't been happening, even after lowering the bar. That's a bad thin. But let's not forget the gray area. That represents a range around the average. It gives you some idea of where the current year levels stand compared to the baseline years.

Which gets us to the solid blue (2015-2016) and dashed green (2011-2012), which represent the current year and the year with the record low ice extent. As you can see, the current year (blue line) is tracking well below the record low year. That's not a good thing, but we need more information so NSIDC also gives us the following graph, a bigger version of which can be seen here:

As you can see, this graph is the same as the previous one but shows several more recent years to provide context (note they changed the color of the 2011-2012 record year to purple instead of green, but it's still the only dashed line). You can see that the ice extent lines wiggle along; that's because short-term weather systems can either increase or decrease sea ice extent for any given time period, while man-made climate change is the reason for the longer trends. More on that shortly.

Want even more data? You can pick the years you want to plot on the graph with this handy Chartic Interactive Sea Ice Graph, which is also on the NSIDC page in the right hand column.

The graphs for 2015-2016 (the current winter) show that sea ice extent is dramatically lower than any other year. January was a record low and it looks like February will be too. Scientists are worried that we may have already seen the yearly maximum, which would be very early and dramatically lower than normal. It's from this point that the sea ice extent decreases until it reaches its yearly minimum (usually in September).

That doesn't necessarily mean we'll see a record low sea ice extent minimum this year. If you look at the Charctic Interactive graph you'll see that even though last year started out much lower in winter, it managed to reach only the fourth lowest minimum on record. That's not good at all, but it could have been worse. We won't know how bad this year will be until we reach the minimum, but based on where we're starting and the historic trend, we're pretty much assured it will be bad.

That gets us to the last graph I'll talk about today (larger):

This graph is for January but you can pick any other month and it will reflect exactly the same trend.
What the graph shows is the trend for that month over the years, that is, what the sea ice extent is in January each year from 1978 to 2016. Because of those short-term factors that make the lines in the first graphs wiggle, you see some years where the January extent is higher and some years lower. But look at the trend. The blue line shows how the sea ice extent has been decreasing for decades. The end of the black (and blue) line to the right of the graph is this year, the lowest ever recorded. You can see that this isn't a one-off problem, it's the continuation of a long-term decline in sea ice extent. Again, this graph shows January but every other month shows the same downward trend.

Bottom line: We're losing ice. Big time.

There are more graphics and information on the Arctic Sea Ice and Analysis page, plus information on Antarctica, Greenland, glaciers, and other snow and ice-related topics on the National Snow & Ice Data Center website. These are accurate, scientific sources of information that readers should save for future reference.

How (and Why) Professional Climate Deniers Create Deceptive Graphics

Graphics can be an extremely useful way to communicate science to the public. Simple graphs related to climate change can be used to show the increasing CO2 concentrations taken at Mauna Loa, increasing global temperatures, and how we know that it is human activity causing the warming.

But graphics can sometimes be deceiving, and professional climate deniers intentionally create deceptive graphics to mislead the public about the science of man-made climate change. For example, take one of the "most popular deceptive climate graphs" around. The following "widget" can be downloaded from one of the biggest climate denier blogs on the internet, Watts Up With That? (WUWT). The blog was founded in 2006 by a former TV weatherman with no apparent college degree and no climate research expertise. WUWT receives funding from Heartland Institute (a science denial lobbyist) and relies on posts by its founder, several non-science policy commentators, anonymous and pseudonymous bloggers, and the occasional contrarian climate scientist.

At first glance the widget above looks useful. It shows temperature, CO2 trend and concentration, and for some unexplained reason, a picture of the sun showing current sunspot activity.

But the graphic is incredibly deceptive. In fact, its goal is to misinform the unsuspecting public.

This intentional deception by the creators of the WUWT widget was recently examined by a science-based blog called Real Climate (RC). The site was created ten years ago by a group of respected climate scientists as a means to help explain the science to technically oriented readers. All of its current contributors are real climate scientists, each with hundreds of peer-reviewed climate publications to their credit.

Real Climate has annotated the WUWT graphic below to document four separate ploys used to deceive the public.

As can be seen, WUWT intentionally chose the data plotted to increase the "noise" (i.e., make it harder to understand), cherry picked a data set to create greater variability, manipulated the scales used to falsely suggest lack of corellation, and added extraneous information to "lead on" viewers to a false conclusion. See the Real Climate site for a more detailed discussion.

These intentional deceptions are obvious to actual climate scientists, so why do climate denier organizations do something that is easy to expose? The answer is because the goal of professional deniers' posts isn't to debate the science but to manipulate public opinion. WUWT and other denial sites target the generally ideologically-driven amateur deniers who are often willfully ignorant of the science. Professional deniers know that whatever they say (no matter the lack of qualifications of who is saying it) and whatever they provide as graphics (even obviously deceptive ones) will be accepted uncritically and unskeptically by amateur deniers, who then will saturate the internet, Facebook, and comment threads all over the blogosphere.

Finally, note that in my initial paragraph I linked to three science sites - NOAA, NASA, and the IPCC. It's always preferable to get data and explanations from the web pages and reports of the scientific organizations (or directly from the peer-reviewed papers if you have access and can weed through the highly technical scientific terminology). That said, in this age of blogs there are several that offer some accurate and useful explanations in more human language (e.g., Real Climate). Unfortunately, with the good also comes the bad, and there are plenty of denialist blogs out there that either intentionally misrepresent the science (e.g., WUWT) or push along the latest conspiracy claims.

To help people sort out which is which, I'll do a future post in this Exposing Climate Denialism series on Blogs - The Good, the Bad, and the Ugly.