Response to the New York Times primer on climate change: ‘Short Answers to Hard Questions About Climate Change’

Guest essay by Lance Wallace

For several months, the New York Times has been running a permanent feature on climate change. They direct their readers to this feature with the promise that it will answer their questions.

Will it really? Let’s see. My responses are in italic below each item.

Short Answers to Hard Questions About Climate Change

By JUSTIN GILLIS

NOV. 28, 2015

The issue can be overwhelming. The science is complicated. Predictions about the fate of the planet carry endless caveats and asterisks.

We get it.

So we’ve put together a list of quick answers to often-asked questions about climate change. This should give you a running start on understanding the problem.

1. How much is the planet heating up?

1.7 degrees is actually a significant amount.

As of October 2015, the Earth had warmed by about 1.7 degrees Fahrenheit since 1880, when records begin at a global scale. That figure includes the surface of the ocean. The warming is greater over land, and greater still in the Arctic and parts of Antarctica.

Richard Muller’s Berkeley group (BEST) has pushed the starting point back to 1800. What that shows is a similar rise in temperature (land only) of about 0.5 degrees C (0.9 degrees F) from 1800-1880. Isn’t that interesting? Long before the rise of CO2, we have the earth emerging from the depths of the Little Ice Age, temperatures rising for more than 200 years now. http://www.woodfortrees.org/plot/best/from:1850/to:1880/trend/plot/best/from:1800/to:1850/trend

The number may sound low, but as an average over the surface of an entire planet, it is actually high, which explains why much of the world’s land ice is starting to melt and the oceans are rising at an accelerating pace. The heat accumulating in the Earth because of human emissions is roughly equal to the heat that would be released by 400,000 Hiroshima atomic bombs exploding across the planet every day.

The temperature has been higher in the past. During the Holocene Optimum, for example (Shakun et al, 2013). From 10,000 to 6,000 years before present, the temperatures were perhaps 0.7 degrees C above the low reached at the end of the Little Ice Age. See Fig. 1 in http://science.sciencemag.org/content/339/6124/1198/tab-pdf

Marcott, S.A., Shakun, J.D., Clark, P.U., Mix, A.C. A Reconstruction of Regional and Global Temperature for the Past 11,300 Years Science 08 Mar 2013: Vol. 339, Issue 6124, pp. 1198-1201 DOI: 10.1126/science.1228026.

The authors conclude: Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history.

(Note: It is unfortunate that Marcott, whose Ph.D. thesis led to the above article in Science, was persuaded to publish a later article in which the high-resolution temperature measurements of the last few decades were appended to his low-resolution (100 year average) estimates in an attempt to show that present temperatures were “unprecedented”. Of course, if it were possible to increase his resolution, there could well have been periods in which short-term (decadal) averages reached quite high levels.)

[oceans rising at an accelerated pace] Arguable. Church and White (2006) find an acceleration of 0.013 + 0.006 mm per year per year. If the acceleration is constant until 2100, the rise would be 31 cm (one foot). But the tide gauges, the glacial isostatic adjustments, the land subsidence or rise due to continental drift are so uncertain that it seems extremely difficult to use our limited short-term measurements to reliably extract an acceleration signal.

[400,000 atomic bombs] Fear-mongering.

Scientists believe most and probably all of the warming since 1950 was caused by the human release of greenhouse gases. If emissions continue unchecked, they say the global warming could ultimately exceed 8 degrees Fahrenheit, which would transform the planet and undermine its capacity to support a large human population.

Some scientists, most dependent on Federal funds for their research. What would happen to them if their research showed something different?

Human emissions are about 5% of the total carbon flux. If they were the cause of increasing temperatures after 1950, what caused the increase between 1910 and 1940, which was nearly identical to that between 1975 and 1998? What caused the pause between 1998 and 2015? What caused the increased temperatures around 1000-1300, when the Vikings were growing grapes in Greenland? CO₂ emissions cannot account for these variations. Please ask your climate scientists for the explanation for these earlier temperature changes. If they cannot supply the reason, why could not the present-day reason be related to these earlier increases?

2. How much trouble are we in?

For future generations, big trouble.

The risks are much greater over the long run than over the next few decades, but the emissions that create those risks are happening now. Over the coming 25 or 30 years, scientists say, the climate is likely to resemble that of today, although gradually getting warmer. Rainfall will be heavier in many parts of the world, but the periods between rains will most likely grow hotter and therefore drier. The number of hurricanes and typhoons may actually fall, but the ones that do occur will draw energy from a hotter ocean surface, and therefore may be more intense, on average, than those of the past. Coastal flooding will grow more frequent and damaging.

Maybe. But if the destructive potential is due to the collision of hot and cold air masses, as some have shown, then the colder air masses will be warmer and the difference no longer so great. By the way, we have now gone 4000 days (a new record) with no hurricanes of level 3 or higher making landfall in the US.

Longer term, if emissions continue to rise unchecked, the risks are profound. Scientists fear climate effects so severe that they might destabilize governments, produce waves of refugees, precipitate the sixth mass extinction of plants and animals in Earth’s history, and melt the polar ice caps, causing the seas to rise high enough to flood most of the world’s coastal cities.

This all depends on the unvalidated predictions of global climate models. For the last 20 years, these models have run hot by a factor of at least two compared to satellite and weather balloon measurements. The models have an average sensitivity of 3.2 degrees C per doubling of CO₂. But most recent estimates are in the neighborhood of 1.6 degrees C per doubling. (Otto et al, 2013, Lewis 2014, Lewis and Curry 2016). The models have inadequate resolution to deal with actual important climate-affecting processes, such as thunderstorms and cloud formation. They have to be smeared over their smallest possible cell of one square degree (3600 square miles) so evolution from any initial conditions rapidly approach chaos within a few years of model time. See Lorenz about 1963 for the first demonstration of chaos in weather prediction.

All of this could take hundreds or even thousands of years to play out, conceivably providing a cushion of time for civilization to adjust, but experts cannot rule out abrupt changes, such as a collapse of agriculture, that would throw society into chaos much sooner. Bolder efforts to limit emissions would reduce these risks, or at least slow the effects, but it is already too late to eliminate the risks entirely.

[collapse in agriculture]. Increased CO₂ has been associated with increases in food production, perhaps accounting for 15-25% of the observed increase. 50% of the earth’s surface has greened due to CO₂ rise compared to 4% that has browned. This alone makes the social cost of carbon negative, (i.e., a benefit to plant growth, as all greenhouse operators know).

The “too late” comment depends on the Bern model of CO₂ residence time in the atmosphere. The Bern model includes a portion of the emissions that are assumed just to persist in the atmosphere for basically forever. But the nuclear tests in the atmosphere provided a natural experiment, raising the level of C14 while they were occurring and then with their abrupt end, providing a direct measurement of the residence time in the atmosphere, which is in the neighborhood of 10-15 years.

3. Is there anything I can do?

Fly less, drive less, waste less.

You can reduce your own carbon footprint in lots of simple ways, and most of them will save you money. You can plug leaks in your home insulation to save power, install a smart thermostat, switch to more efficient light bulbs, turn off the lights in any room where you are not using them, drive fewer miles by consolidating trips or taking public transit, waste less food, and eat less meat.

Perhaps the biggest single thing individuals can do on their own is to take fewer airplane trips; just one or two fewer plane rides per year can save as much in emissions as all the other actions combined. If you want to be at the cutting edge, you can look at buying an electric or hybrid car, putting solar panels on your roof, or both.

If you want to offset your emissions, you can buy certificates, with the money going to projects that protect forests, capture greenhouse gases and so forth. Some airlines sell these to offset emissions from their flights, and after some scandals in the early days, they started to scrutinize the projects closely, so the offsets can now be bought in good conscience. You can also buy offset certificates in a private marketplace, from companies such as TerraPass in San Francisco that follow strict rules set up by the state of California; some people even give these as holiday gifts. Yet another way: In states that allow you to choose your own electricity supplier, you can often elect to buy green electricity; you pay slightly more, with the money going into a fund that helps finance projects like wind farms.

In the end, though, experts do not believe the needed transformation in the energy system can happen without strong state and national policies. So speaking up and exercising your rights as a citizen matters as much as anything else you can do.

“Fly less, drive less, waste less”. Please pass this message on to the 20,000 people who attend conferences to save the Earth in Rio, Bali, Cancun, and Paris. Electric cars and solar panels cannot compete on their own, so rich people get subsidies and poor people pay higher prices for electricity.

4. What’s the optimistic scenario?

Several things have to break our way.

In the best case that scientists can imagine, several things happen: Earth turns out to be less sensitive to greenhouse gases than currently believed; plants and animals manage to adapt to the changes that have already become inevitable; human society develops much greater political will to bring emissions under control; and major technological breakthroughs occur that help society both to limit emissions and to adjust to climate change.

The two human-influenced variables are not entirely independent, of course: Technological breakthroughs that make clean energy cheaper than fossil fuels would also make it easier to develop the political will for rapid action.

Scientists say the odds of all these things breaking our way are not very high, unfortunately. The Earth could just as easily turn out to be more sensitive to greenhouse gases than less. Global warming seems to be causing chaos in parts of the natural world already, and that seems likely to get worse, not better. So in the view of the experts, simply banking on a rosy scenario without any real plan would be dangerous. They believe the only way to limit the risks is to limit emissions.

“less sensitive to greenhouse gases” Already shown in multiple new estimates of climate sensitivity mentioned above leading to halving the predictions of global warming.

“Global warming … causing chaos… already” Hard statistics on tornadoes, hurricanes, drought, floods, etc. do not support this statement. You point out another important factor below (item 13), where you state that “The Internet has made us all more aware of weather disasters in distant places. On social media, people have a tendency to attribute virtually any disaster to climate change, but in many cases there is no scientific support for doing so.”

5. Will reducing meat in my diet help the climate?

Yes, beef especially.

Agriculture of all types produces greenhouse gases that warm the planet, but meat production is especially harmful – and beef is the most environmentally damaging form of meat. Some methods of cattle production demand a lot of land, contributing to destruction of forests; the trees are typically burned, releasing carbon dioxide into the atmosphere. Other methods require huge amounts of water and fertilizer to grow food for the cows.

The cows themselves produce emissions of methane, a potent greenhouse gas that causes short-term warming. Meat consumption is rising worldwide as the population grows, and as economic development makes people richer and better able to afford meat.

This is worrisome: Studies have found that if the whole world were to start eating beef at the rate Americans eat it, produced by the methods typically used in the United States, that alone might erase any chance of staying below an internationally agreed-upon limit on global warming. Pork production creates somewhat lower emissions than beef production, and chicken is lower still. So reducing your meat consumption, or switching from beef and pork to chicken in your diet, are both moves in the right direction. Of course, as with any kind of behavioral change meant to benefit the climate, this will only make a difference if lots of other people do it, too, reducing the overall demand for meat products.

Good luck with this suggestion. It might make you feel better—a noble cause. But so unlikely to happen!

6. What’s the worst-case scenario?

There are many.

That is actually hard to say, which is one reason scientists are urging that emissions be cut; they want to limit the possibility of any worst-case scenario coming to pass. Perhaps the greatest fear is a collapse of food production, accompanied by escalating prices and mass starvation. Even with runaway emissions growth, it is unclear how likely this would be, as farmers are able to adjust their crops and farming techniques, to a degree, to adapt to climatic changes. Another possibility would be a disintegration of the polar ice sheets, leading to fast-rising seas that would force people to abandon many of the world’s great cities and would lead to the loss of trillions of dollars worth of property and other assets. Scientists also worry about other wild-card scenarios like the predictable cycles of Asian monsoons’ becoming less reliable. Billions of people depend on monsoons to provide water for crops, so any disruptions could be catastrophic.

If this is the greatest fear, then we are certainly saved! Because the 15-25% effect on increased food production already observed can only increase as the great wheat-growing areas in Canada and Russia will come into play.

[Disintegration of polar ice sheets]This disintegration would take millennia.

7. Will a tech breakthrough help us?

Even Bill Gates says don’t count on it, unless we commit the cash.

As more companies, governments and researchers devote themselves to the problem, the chances of big technological advances are improving. But even many experts who are optimistic about technological solutions warn that current efforts are not enough. For instance, spending on basic energy research is only a quarter to a third of the level that several in-depth reports have recommended. And public spending on agricultural research has stagnated even though climate change poses growing risks to the food supply. People like Bill Gates have argued that crossing our fingers and hoping for technological miracles is not a strategy — we have to spend the money that would make these things more likely to happen.

[growing risks to the food supply] Why do you keep saying this without mentioning the already-observed beneficial changes?

8. How much will the seas rise?

The real question is not how high, but how fast.

The ocean is rising at a rate of about a foot per century. That causes severe effects on coastlines, forcing governments and property owners to spend tens of billions of dollars fighting erosion. But if that rate continued, it would probably be manageable, experts say.

The risk is that the rate will accelerate markedly. If emissions continue unchecked, then the temperature at the Earth’s surface could soon resemble a past epoch called the Pliocene, when a great deal of ice melted and the ocean rose by something like 80 feet compared to today. A recent study found that burning all the fossil fuels in the ground would fully melt the polar ice sheets, raising the sea level by more than 160 feet over an unknown period.

With all of that said, the crucial issue is probably not how much the oceans are going to rise, but how fast. And on that point, scientists are pretty much flying blind. Their best information comes from studying Earth’s history, and it suggests that the rate can on occasion hit a foot per decade, which can probably be thought of as the worst-case scenario. A rate even half that would force rapid retreat from the coasts and, some experts think, throw human society into crisis. Even if the rise is much slower, many of the world’s great cities will flood eventually. Studies suggest that big cuts in emissions could slow the rise, buying crucial time for society to adapt to an altered coastline.

[soon resemble the Pliocene]. How soon? Multiple centuries?

9. Are the predictions reliable?

They’re not perfect, but they’re grounded in solid science.

The idea that Earth is sensitive to greenhouse gases is confirmed by many lines of scientific evidence. For instance, the basic physics suggesting that an increase of carbon dioxide traps more heat was discovered in the 19th century, and has been verified in thousands of laboratory experiments.

Climate science does contain uncertainties, of course. The biggest is the degree to which global warming sets off feedback loops, such as a melting of sea ice that will darken the surface and cause more heat to be absorbed, melting more ice, and so forth. It is not clear exactly how much the feedbacks will intensify the warming; some of them could even partially offset it. This uncertainty means that computer forecasts can give only a range of future climate possibilities, not absolute predictions.

But even if those computer forecasts did not exist, a huge amount of evidence suggests that scientists have the basic story right. The most important evidence comes from the study of past climate conditions, a field known as paleoclimate research. The amount of carbon dioxide in the air has fluctuated naturally in the past, and every time it rises, the Earth warms up, ice melts, and the ocean rises. A hundred miles inland from today’s East Coast, seashells can be dug from ancient beaches that are three million years old, a blink of an eye in geologic time. These past conditions are not a perfect guide to the future, either, because humans are pumping carbon dioxide into the air far faster than nature has ever done.

There is also important evidence suggesting the basic story is wrong. All greenhouse gases work by affecting the lapse rate in the tropics. They thus create a “hot spot” in the tropical troposphere. This is admitted even by Gavin Schmidt. The theorized “hot spot” is shown in the early IPCC publications. Yet it has never been seen. Some millions of radiosondes, weather balloons, and satellite measurements (since 1979) have been unable to locate the “hot spot.” As my Caltech physics professor used to say “Doesn’t matter who made the theory, doesn’t matter how many people believe it, if the observations are not there, it is wrong.” (R.P. Feynman).

[The amount of carbon dioxide in the air has fluctuated naturally in the past, and every time it rises, the Earth warms up, ice melts, and the ocean rises.]

This is the most completely false and misleading statement in the whole sidebar. Yes, temperature and CO2 move together, as shown by the Greenland and Antarctica ice cores. But not quite together—for the last four interglacials (last 400,000 years) the temperature rises or falls first—CO₂ follows about 600 (+ 400) years later (Fischer et al., 1999). So CO₂ cannot be a cause of the observed temperature rise. Temperature could be a cause of the CO2 rise, for example, if as the oceans heat up they emit more CO2 to the atmosphere (Henry’s Law). Some estimates of the ocean overturning time to complete mixing are in the neighborhood of 1000 years, so this is a plausible cause of the CO2 increase. But there may also be something else (e.g., solar insolation) causing the temperature and then the CO2 to increase.

Perhaps you are not aware that Al Gore’s movie An Inconvenient Truth used this very argument to show CO2 causes temperature rise. A British court found that this was one of the 9 errors of fact that appear in the movie. The court ruled that any theater showing the movie would need to inform the audience of these 9 errors. http://www.telegraph.co.uk/news/earth/earthnews/3310137/Al-Gores-nine-Inconvenient-Untruths.html

Fischer, H., Wahlen, M., Smith, J., Mastroianni, D., and

Deck, B.: Ice core records of atmospheric CO2 around

the last three glacial terminations, Science, 283, 1712–1714,

doi:10.1126/science.283.5408.1712, 1999.

10. Why do people question climate change?

Hint: ideology.

Most of the attacks on climate science are coming from libertarians and other political conservatives who do not like the policies that have been proposed to fight global warming. Instead of negotiating over those policies and trying to make them more subject to free-market principles, they have taken the approach of blocking them by trying to undermine the science.

This ideological position has been propped up by money from fossil-fuel interests, which have paid to create organizations, fund conferences and the like. The scientific arguments made by these groups usually involve cherry-picking data, such as focusing on short-term blips in the temperature record or in sea ice, while ignoring the long-term trends.

The most extreme version of climate denialism is to claim that scientists are engaged in a worldwide hoax to fool the public so that the government can gain greater control over people’s lives. As the arguments have become more strained, many oil and coal companies have begun to distance themselves publicly from climate denialism, but some are still helping to finance the campaigns of politicians who espouse such views.

But in fact conservative politicians and economists are “trying to make [climate change policies] more subject to free-market principles.” The government provides thousands of dollars to rich homeowners to put solar panels on their homes, or to buy electric cars. The government then forces electric utilities to buy solar or wind power as a priority over fossil fuel power and at a higher price. This is of course the opposite of a free-market approach. President Obama has been quoted as saying this will cause electricity rates to “skyrocket” (direct quote). Does he not realize that this is a war on the poor, who spend a much higher percentage of their incomes on electricity? Well, he does realize it, but the noble cause means that some must pay the price. If solar and wind were not subsidized by the government, which makes very bad choices (Solyndra) when it meddles, then they would depend on technological change to bring their prices down to compete with fossil fuels. Once the technology is there, they might then naturally complement the fossil fuels. The present force-feeding before they are ready causes pain. In Germany, over 300,000 homes have been thrown into energy poverty by the Energiewende.

The “ideological position” is that taken by the IPCC, which has convinced various countries, which have spent far more, in the hundreds of billions of dollars, to prop up the war on demon CO₂. Consider that there are about 40 separate global climate models, each of which requires millions of dollars to run on supercomputers. Why 40? 39 of them must be wrong.

The main cherry-picking was famously carried out by Michael Mann, who erased the Medieval Warming Period as well as the Little Ice Age from history, at least for a few years until his work was debunked (The Hockey Stick Illusion, by Andrew Montford). The IPCC ran his graph about six times in one of their earlier reports just to make the point that present conditions are unprecedented. After the debunking, his graph has completely disappeared from subsequent reports.

Virtually the entire attention of the IPCC is to the short period from 1950 on. If they went back any further, they would see inconvenient truths, such as the sharp increase in temperature from 1910-1940, which even Phil Jones is on record as saying was undistinguishable from the 1975-1998 increase, the latter of which is supposed to be from CO₂.

11. Is crazy weather tied to climate change?

In some cases, yes.

Scientists have published strong evidence that the warming climate is making heat waves more frequent and intense. It is also causing heavier rainstorms, and coastal flooding is getting worse as the oceans rise because of human emissions. Global warming has intensified droughts in regions like the Middle East, and it may have strengthened the drought in California.

In many other cases, though, the linkage to global warming for particular trends is uncertain or disputed. That is partly from a lack of good historical weather data, but it is also scientifically unclear how certain types of events may be influenced by the changing climate.

Another factor: While the climate is changing, people’s perceptions may be changing faster. The Internet has made us all more aware of weather disasters in distant places. On social media, people have a tendency to attribute virtually any disaster to climate change, but in many cases there is no scientific support for doing so.

Tornadoes, hurricanes, and floods are not increasing. See Pielke, Jr., an advisor to insurance companies, for the data.

12. Will anyone benefit from global warming?

In certain ways, yes.

Countries with huge, frozen hinterlands, including Canada and Russia, could see some economic benefits as global warming makes agriculture, mining and the like more possible in those places. It is perhaps no accident that the Russians have always been reluctant to make ambitious climate commitments, and President Vladimir V. Putin has publicly questioned the science of climate change.

However, both of those countries could suffer enormous damage to their natural resources; escalating fires in Russia are already killing millions of acres of forests per year. These countries may think differently, once they are swamped by millions of refugees from less fortunate lands.

Present-day refugees are fleeing violence and poverty, mainly. This statement is more fear-mongering, sounding almost as if the NYT is hoping this will happen.

13. Is there any reason for hope?

If you share this with 50 friends, maybe

Is this a newspaper or an activist Green NGO?

Scientists have been warning since the 1980s that strong policies were needed to limit emissions. Those warnings were ignored, and greenhouse gases in the atmosphere have since built up to potentially dangerous levels. So the hour is late.

But after 20 years of largely fruitless diplomacy, the governments of the world are finally starting to take the problem seriously. A deal reached in Paris in December commits nearly every country to some kind of action.

Purely voluntary, no enforcement, China gets a free pass until 2030, Indian premier says no way will he do anything that would slow down his country’s emergence from energy poverty. Meanwhile the developed countries are supposed to cut back on their already small contribution to total emissions and hurt their economies and their people with taxes and higher energy costs. What a great deal!

Religious leaders like Pope Francis are speaking out. Low-emission technologies, such as electric cars, are improving. Leading corporations are making bold promises to switch to renewable power and stop forest destruction. Around the world, many states and cities are pledging to go far beyond the goals set by their national governments.

What is still largely missing in all this are the voices of ordinary citizens.

You just heard the voices of ordinary citizens in the recent election. These ordinary citizens care about jobs and electrical bills, not future uncertain catastrophes. The longer the NYT does not listen to ordinary citizens, the farther from relevance you recede.

Because politicians have a hard time thinking beyond the next election, they tend to tackle hard problems only when the public rises up and demands it.

Except when they get a chance to tax the air you breathe, you will find many who are willing, throughout the EU, Canada, Australia, etc.

14. How does agriculture affect climate change?

It’s a big contributor, but there are signs of progress.

The environmental pressures from global agriculture are indeed enormous.

The demand for food is rising, in large part because of population growth and rising incomes that give millions of once-low income people the means to eat richer diets. Global demand for beef and for animal feed, for instance, has led farmers to cut down huge chunks of the Amazon rain forest.

Efforts are being made to tackle the problems. The biggest success has arguably been in Brazil, which adopted tough oversight and managed to cut deforestation in the Amazon by 80 percent in a decade. But the gains there are fragile, and severe problems continue in other parts of the world, such as aggressive forest clearing in Indonesia.

Scores of companies and organizations, including major manufacturers of consumer products, signed a declaration in New York in 2014 pledging to cut deforestation in half by 2020, and to cut it out completely by 2030. The companies that signed the pact are now struggling to figure out how to deliver on that promise.

Many forest experts at the Paris climate talks in late 2015 considered the pledge as ambitious, but possible. And they said it was crucial that consumers keep up the pressure on companies from whom they buy products, from soap to ice cream.

But as we speak, climate policy in the UK is causing a main energy provider (Drax) to stop using local peat and coal and use instead wood pellets gained from cutting thousands of trees in the Carolinas. These are then transported across the ocean on diesel-powered ships. How’s that for a sensible solution?

15. Will the seas rise evenly across the planet?

Think lumpy.

Many people imagine the ocean to be like a bathtub, where the water level is consistent all the way around. In fact, the sea is rather lumpy – strong winds and other factors can cause water to pile up in some spots, and to be lower in others.

Also, the huge ice sheets in Greenland and Antarctica exert a gravitational pull on the sea, drawing water toward them. As they melt, sea levels in their vicinity will fall as the water gets redistributed to distant areas.

How the rising ocean affects particular parts of the world will therefore depend on which ice sheet melts fastest, how winds and currents shift, and other related factors. On top of all that, some coastal areas are sinking as the sea rises, so they get a double whammy.

This argues for infrastructure work at the threatened areas. But a King Canute command to the oceans to stop rising will not get the job done.

16. Is it really all about carbon?

Here’s a quick explainer.

The greenhouse gases being released by human activity are often called “carbon emissions,” just for shorthand. That is because the two most important of the gases, carbon dioxide and methane, contain carbon. Many other gases also trap heat near the Earth’s surface, and many human activities cause the release of such gases to the atmosphere. Not all of these actually contain carbon, but they have all come to be referred to by the same shorthand.

By far the biggest factor causing global warming is the burning of fossil fuels for electricity and transportation. That process takes carbon that has been underground for millions of years and moves it into the atmosphere, as carbon dioxide, where it will influence the climate for many centuries into the future. Methane is even more potent at trapping heat than carbon dioxide, but it breaks down more quickly in the air. Methane comes from swamps, from the decay of food in landfills, from cattle and dairy farming, and from leaks from natural gas wells and pipelines.

While fossil-fuel emissions are the major issue, another major creator of emissions is the destruction of forests, particularly in the tropics. Billions of tons of carbon are stored in trees, and when forests are cleared, much of the vegetation is burned, sending that carbon into the air as carbon dioxide.

When you hear about carbon taxes, carbon trading and so on, these are just shorthand descriptions of methods designed to limit greenhouse emissions or to make them more expensive so that people will be encouraged to conserve fuel.

Let’s not forget that politicians and governments are always on the lookout for new revenue streams. What better to tax than the air we breathe?