Sunday, October 6, 2013

A summary of why we need to globally reduce the emission of carbon dioxide into the atmosphere

What do coral reefs off of the coast of Australia, computer chip factories in Thailand, ski&snowboarding resort on the US east coast, and islands in the South Pacific all have in common? The answer is that all of these places are already feeling the negative impact of human-induced increases in the concentration of CO2 into the atmosphere.
The goal of this post is explain the science behind the effects of higher CO2 levels in the atmosphere, such as global warming, ocean acidification, and sea level rises. My hope is to explain in a somewhat less-technical manner the effects of higher CO2 concentrations in the atmosphere compared with the recent publication by the IPCC. There's nothing wrong with how the IPCC presents this information; it's just that I think that it's help for the information to be presented by the eyes of somebody who has no connection to those people who wrote the report or the papers cited in the report.
Unfortunately, the topic of CO2 emissions has become so politicized that the actual facts are easily swept under the rug of political ideology. Part of the problem is that environmental groups rarely discuss the actual science (and are quick to bash people who aren't alarmists), and the other part of the problem is clearly that there are people who refuse to accept that humans can affect the global climate, the ocean pH, or the sea level.  I consider myself a fairly moderate person and my goal here is to tell it as it is, regardless of how difficult it may or may not be to solve the problem of preventing major changes to Earth's climate, to Earth's average sea/ocean level, and Earth's average pH level in the seas/oceans.
So, before I get into the science, I'd like to state simply what the actual problem is that we face:
The problem:  Our global society is on pace to cause the temperature in Arctic and Antarctic to raise to the point at which we will likely see at least a 3 meter increase in sea levels. In addition, the higher concentration of CO2 in the atmosphere will cause lower pH levels in the ocean, which is harmful to major shell forming species, such as coral reefs. These are the straight-forward and indisbutable effects of higher concenrtations of CO2 in the atmosphere. There are also a number of other effects, of varying levels of certainty.

The Solution: The only realistic way to prevent major climate change, sea level change and pH change is to globally limit the emission of CO2 into the atmosphere. We can't "geo-engineer" our way out of this problem by throwing particulates into the atmosphere to scatter light from hitting the surface because this "solution" doesn't solve the fact that the pH of the ocean will continue to decrease if we were to continue to emit large amounts of CO2 into the atmosphere.

As mentioned earlier, the goal of this post is to summarize the science behind each of the effects listed above (higher temperatures, higher sea levels, and lower pH.)

First Questions
How do we know that humans are causing the increase of CO2 in the atmosphere? Why are humans to blame if we only emit a small fraction of the CO2 into the atmosphere compared with emissions from other species?
Answer:  The emission and consumption of CO2 by living species on Earth was nearly in balance for thousands of years until the advent of the industrial revolution in "Western Civilization." [Note: this doesn't mean that the "Industrial Revolution" was a bad thing. It's just that we still need to figure out how save the good aspects of the "Industrial Revolution" and get rid of the bad aspects...such as emission of large quantities of CO2, clear cutting of forests, and disposal of waste in landfills or bodies of water.] Since the ~1880s, the concentration of CO2 has increased from roughly 280 ppm (the concentration from 1000 to 1800) to 400 ppm (the concentration in 2013.) The concentration of CO2 has not been above 300 ppm in the last 400,000 years.
 As seen in the figure below, as the concentration of CO2 has been increasing, there has been a subsequent decrease in the concentration of oxygen in the atmosphere. The fact that oxygen levels are decreasing exactly by how much is expected by the consumption of fossil fuels in our global society is proof that the increase in CO2 is not due to volcanoes or other natural sources of buried CO2.
In addition to monitoring the oxygen levels, we can also monitor the type of carbon dioxide in the atmosphere. For example, since the 1980s, scientists have been monitoring the ratio of Carbon13 to Carbon12 in the atmosphere. The Carbon13 to Carbon12 ratio has been decreasing since the Industrial revolution, which suggests that the source of the CO2 is from the burning of plants (either burning of fossil fuels or clear cutting of forests.)
The problem is that humans are emitting CO2 into the atmosphere faster than nature can pull it out of the atmosphere.

Second Questions:
How does CO2 cause global warming? Doesn't water vapor cause more global warming than CO2? Aren't we headed for an ice age?

First, let me present a table with the approximate composition of the Earth's atmosphere.
Composition Dry
0.04% (400ppm)
Ne, He, Kr
18, 5, 1 ppm
2 ppm

In order to cause global warming, a gas in the atmosphere has to be able to absorb in the infrared, i.e. the range of frequencies of light that the Earth emits into outer space. Only certain types of gas species can absorb in the infrared (IR). In order to absorb in the IR, the gas species must have a mode of vibration that causes a net change in the dipole of the molecule. Since N2 and O2 are symmetric diatomic species, these species can't have a net dipole and hence can't absorb in the IR. The major species in the Earth's atmosphere  that can absorb in the IR are H2O, CO2, CH4 and O3.
The figure immediately below shows the relative amount and frequency of light emitted from the Sun that reaches the Earth's surface (left) and the relative amount and frequency of light emitted by the Earth that escapes into outer space. The second plot below shows the change in the amount of radiation leaving the Earth's atmosphere between 1970 and 1996 as a function of frequency of the IR light. The brightness temperature equates with the equivalent blackbody temperature (Harries 2001), and the graph shows that there has been an increase in the absorption of IR radiation at those frequencies at which CO2 and CH4 can absorb. The third plot show the data from 2003 to 2012.  Note that the plots below show an average across the Earth. Locally, the graphs can be greatly influenced by the amount of water vapor in the atmosphere.
The major greenhouse gas is H2O because it absorbs significant amount of infrared radiation. However, the concentration of H2O in the atmosphere is extremely variable. It can be as high as 4% near the equator; however, it's nearly 0% in the Arctic during the winter at night. Since there is some overlap between where CO2 absorbs and where H2O absorbs, the effect of CO2 in the atmosphere is much more pronounced in the Arctic or Antarctic than it is near the equator. This is why the average temperatures in the Arctic have increased significantly more than temperatures near the equator. This can be easily seen in recent data that shows the trend in surface temperatures at different locations across the globe.

As seen above, the temperatures have increase in the Arctic faster than the rest of the globe and even faster than the Antarctic. The temperatures in the Arctic has been increasing fairly rapidly over the last few years and are a major source of the overall increase in global temperatures (see graphs below and the dark lines in the second figure are the most recent estimates of global average surface temperatures over the last 33 years.)

The roughly 3oC increase in temperature in the Arctic over the last century is particularly worrisome because the majority of land-based ice is located at the poles: Greenland and Antarctica. Even more worrisome is the fact that the melting of the ice at the poles has many positive feedback mechanics. First, as the ice melts, the surface reflectivity decreases, which means that more solar energy from the Sun is absorbed. Second, as the ice melts and the temperatures increase, some of the naturally occurring methane in the soil will be released into the atmosphere. Since methane is also a greenhouse gas, this means that there is another positive feedback mechanism that can cause the temperatures to increase even more. Third, as the temperatures increase, there will be more water vapor in the atmosphere, which will cause even more warming. The only negative feedback mechanism at the poles is if there were cloud formation, but this would already mean that there had been a significant change in the temperature and climate in the region.
To put it another way, we do not have to worry about another ice age because humans have already over-powered the effects from small oscillations in the Earth's axis/distance that have caused ice ages in the past. We have essentially prevented future ice ages from occurring. So, yes, there is some good to have come from out emitting CO2 into the atmosphere (No more Ice Ages!). The problem is that our current rate of emissions of CO2 will cause the temperature to increase, sea levels to increase, and pH to decrease with major effects on nearly all living species. Not all change is necessarily good. This leads us to the next topic: Increases in global ocean/sea level. But before leaving this topic, I want to point out that increases in winter temperatures are not necessarily bad things (unless you enjoy skiing and snowboarding.) The ultimate question we have to ask ourselves is:  is it fair for us to emit CO2 into atmosphere and to negatively impact large numbers of people and animal species? Personally, I do not thing that it's fair or just for me or others to emit large amounts of CO2 into the atmosphere, and I look forward to the day in which CO2 emissions are capped or taxed in all of the countries with significant emissions of CO2 (i.e. China, U.S., E.U., Russia, India, Canada, and Brazil.)

Third Questions:
How does global warming cause higher sea levels? What is the effects of higher sea levels?
Answer: As discussed above, as ice melts that was on land and enters the oceans/sea, there is an increase in the level of the ocean/seas. It's only ice that was on land that effects the ocean/sea level because when icebergs melts, there's virtually no change in the ocean level. The increase in sea level has been particularly rapid  over the last 20 years.

If this trend of ~3 to 4 mm/yr rise in sea level continues for a century, then we can expect a 3-4 meter rise in sea/ocean levels. This site will show you which locations on the globe will be permanently under water if there is an increase in the ocean/sea level. (Note that, from the site, you can vary the value of the ocean/sea level increase.) It should be noted that if Greenland's ice were to melt, we could see a ~7 meter increase in sea levels, and if all of Antarctica's ice were to melt, we could see a ~61 meter increase in sea levels. This is very worrisome, and must be prevented from occurring. Also, there are other ways for the sea level to increase. For example, water expands with higher temperature, and water expands when CO2 is added. This means there are three different ways for higher CO2 concentrations in the atmosphere to cause ocean/sea levels to increase.
There are likely no positive benefits from higher sea levels and there will be large costs associated with adapting to the higher sea levels. Is it fair for the 7 billion people on the globe to continue to emit CO2 into the atmosphere if it causes millions of people to lose their property on the ocean/sea shore? My answer to this question is a firm "No." It's not fair, and we must act globally to prevent millions of people from losing their property along the coasts. Even if you don't live on the coast, you will be effected by this. For example, the higher sea levels and the cyclical flooding in Thailand in 2011 caused major computer chip manufacturing factories to be destroyed. This ended up having a large effect on the prices of computer equipment in 2011.
There is simply no avoiding the fact that CO2 emissions will cause the Arctic to melt, and the melting Arctic will cause higher global ocean/sea levels. The net effect is a significant amount of damage to the global economy. Quantifying this damage is one of the main thrusts of research in the field of climate change and in the field of insurance. Studies by economists on average estimate that the negative impact of higher sea levels is more negative than is the positive benefits of high concentrations of CO2, such as warmer winters and a navigable Arctic. So while there will likely be some benefits to people in cold weather climates (who happen to not like skiing or snowboarding), this doesn't change the fact that it's not fair for us to emit CO2 into the atmosphere and cause people to lose their homes or businesses that live near the coast.

Fourth Questions:
What does CO2 have to does with ocean pH?  How does increasing CO2 decrease the ability of animals to form shells? Don't the shells need CO2?
Answers:  In addition to causing higher ocean/sea levels, more CO2 in the atmosphere will cause the pH level of the ocean/sea to decrease. CO2 is a weak acid gas. While it's much less of an acid gas than SOx or NOx, if there's a lot of it in the atmosphere, then it can be an acid gas with significant impact on the pH level. Many biological processes in nature rely on there being a narrow range of pH levels. One of these processes is shell formation, in which Ca+2 and CO3-2 combine to form a limestone shell. This process is strongly dependent on the concentration of Ca+2 , CO3-2, as well as the temperature. While slightly non-intuitive, more CO2 in the atmosphere actually means less CO3-2 because the increase in CO2 causes the following sequence of reactions to occur:
CO2(g) → CO2(aq) → H2CO3(aq)
H2CO3(aq) +   CO3-2(aq) → 2 HCO3-1(aq)
This means that there is a decrease of CO3-2(aq)  and an increase of HCO3-1(aq). This set of reactions, when combined with higher temperatures, makes it more difficult for animals to form limestone shells. The net effect is that large numbers of coral species will die due to the emission of CO2 into the atmosphere. There are no known positive effects from lower pH, only negative impacts. In addition, it's the pH aspect of CO2 emissions that rule out "geo-engineering" techniques that address the higher temperatures but don't address the ocean pH.

The decrease of the ocean pH is quite worrisome because we may only learn about all of the negative effects of lower ocean pH after we start noticing 'strange' things happening to populations of ocean species. I personally thing that it will be nearly impossible to predict all of the effects of lower pH, and therefore, it just makes more sense to stop emitting CO2 into the atmosphere.

Fifth Questions:
So, what do we do to prevent higher temperature, higher sea levels and lower pH levels?
Answer: We globally implement laws that limit the amount of CO2 that can be emitted into the atmosphere. These laws will force companies and people into using fuels and electricity that is CO2-neutral. This means that power plants will have to capture and sequester CO2 or else they will have be CO2 neutral. It also means that cars&trucks will need to operate on electricity or hydrogen (or on a liquid fuel that is somehow CO2-neutral.) These laws will also mean that lime calcinations plants and steel mills will have to capture any CO2 emitted into the atmosphere.
Such a transition will not be easy, but it is absolutely crucial to do this. One way to speed up the transition is to compensate those people who will be negatively impacted by the transition. For example, perhaps we can compensate people who work in the fossil fuel industry and will be harmed by the laws that limit CO2 emissions into the atmosphere. (Right now, it appears that the strongest opposition to climate change legislation is so-called "free-market" libertarians who work in the fossil fuel industry. However, with that having been said, I am a "free-market, libertarian" who works in the fossil fuel industry. But many of my co-workers, bosses and family members are extremely against the idea of CO2 legislation, either because they don't like government, they don't want to lose their job, or they don't want to destroy the economy.)
But I'm starting to get tired of the same old paranoia from so-called free-market libertarians. Either you believe in free-markets or you don't. Our current market is not a free-market because we don't pay for the negative externalities of higher temperatures, higher sea levels, and lower pH levels. In addition, we have all of the technology required to transition to a CO2-neutral economy because scientists and engineers have been preparing for this for decades. We are just waiting for politicians in countries like the U.S., China, Canada and India to implement laws that limit or tax CO2. The technical problems have largely been solved now that we are mass-producing solar PV cells / wind turbines, have solved the "platinum problem" in fuel cell vehicles and hydrogen electrolyzers, and have demonstrated large-scale capture and sequestration of CO2 from fossil fuel power plants.

All we have left is the political will to change our destiny and the destiny of the Earth's environment. I hope that you help me in getting our politicians to enact global laws that limit the concentration of CO2 into the atmosphere. These laws should not pick winners or losers. The laws should apply to all major human sources of CO2 emissions. The key is to enact laws that do not increase the role of government in business, but that help us limit the concentration of CO2 in the atmosphere to less than ~600 ppm. If we do this correctly, we could actually lower government's role in the economy (by ending subsidies to renewable energy companies) while also protecting the Earth from higher temperatures, higher sea levels, and lower pH levels. That is my hope. I see this as a viable path forward for the Libertarian party in the U.S.

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