Tipping Points

With Speed and Violence: Why Scientists Fear Tipping Points in Climate Change by Fred Pearce is not reassuring or comfortable. It is a scientifically-grounded explanation of climate change/global warming/freaky world changes.

It probably could only have been written by Mr. Pearce. He's been following the global-warming story as a journalist since about 1990 and because of that he was able to interview many of the principal researchers in the ongoing struggle to understand the process.

He presents four topics of interest. First, he explains the mechanics of climate change. If you're a little fuzzy on the ocean conveyor or methane clathrates he'll bring you up to speed. Second, he lays out the limits of knowledge. The parameters cover large ranges and he keeps clear the distinction between what is known and what isn't. Third, he covers the slipperiest part of the whole topic: tipping points; how they work and what happens when we reach them. He also discusses what the consequences of climate change are likely to be, bearing in mind the limits of certainty. We're going to say a little here about tipping points, based on the author's remarks.

Skeptics dismiss the concept of tipping points. You can't prove them, they say. Actually, you can prove some of them but it's not clear what will activate them. Some others aren't understood to the point they can be considered certain. It goes the other way too, though. There's no justification for traveling up the Keeling curve with insouciance. Before we jump into a pot of hot tar, common sense tells us we ought to find out how hot the tar is.

I'll go through the main tipping points the author describes.

* Shrinking ice caps. This one is maybe the most basic. As the ice caps shrink the world is absorbing more energy from the sun. Furthermore, the water released lubricates the glaciers' movements, causing the process to accelerate.

* Clearing of rain forests lowers the amount of rainfall downwind from them, whether it's done on purpose or by natural fires that result from drying out. As the vegetation burns and exposes the soil to sunlight, large amounts of CO2 are released.

* As frozen bogs thaw in the extreme north, rotting tundra releases methane, a terribly effective greenhouse gas.

* CO2 dissolved in the oceans is removed by marine organisms that use it to build structural body parts. If the CO2 level rises too high, ocean water becomes too acidic for the organisms to live and this CO2-removal mechanism disappears.

* Clathrates are layers of methane lying in deep ocean trenches where the pressure and temperature are extreme enough to keep them frozen. If ocean temperatures rise enough to thaw some of the methane then inevitably it will enter the atmosphere. But it could be worse: there are layers of methane gas under the clathrates, kept unfrozen by warmth from the earth. If the ocean melts through spots in the clathrates, large amounts of methane will escape.

* Clouds are a subject of considerable uncertainty. As water evaporates we expect to see more white, fluffy clouds that reflect solar energy. That may be why the world hasn't warmed more than it has. But if the atmosphere gets hot enough we'll see fewer fluffy clouds and more high, thin clouds. They admit more solar energy and intercept energy that otherwise would escape.

* The ocean conveyor is a superlong ocean current; one of the things it does is carry heat from the tropics to the north Atlantic, warming the US coast before it swings over and does the same for northern Europe. As it moves north to the Arctic region it cools and drops down to return under the north-moving stream. What if Greenland's ice melts? If it happens fast enough, a real possibility, the fresh water would cause the saltier and heavier water of the current to short-circuit; it would drop down to the return stream prematurely. Northern Europe would see severely cold conditions. Meanwhile, the tropics would warm up because of losing the Arctic cooling.

The author makes the point that this issue is different from the issues we're used to. Usually, when you learn more about a concern you find that it's not as alarming as you thought before. With global warming, the more you learn the more there is to worry about.

Solutions to Global Warming: Part 2

3) Renewable Energy Sources

In this article we'll look at alternative energy sources and appraise their effectiveness in minimizing global warming. The numbers apply to the US; nationals of other countries will have to figure this out for themselves.

Residential Energy Sources

Some important savings can be made by making greater use of natural energy sources. Home heating and residential water heating could be switched almost entirely to solar and solar-heat-pump systems. Passive solar heating techniques can be built into homes. The remaining residential applications would mainly be cooking, which could almost entirely be converted to electricity. These changes would reduce CO2 emissions by 367 million metric tons, or 6.1% of the total.[source]

Wind Power

Wind power is already providing some electricity at a price which is only a little higher than electricity from fossil-fired power plants.[source] What limits wind power is the need for storage, since neither homes nor businesses can stop functioning when the wind power is unavailable. Currently, only one form of bulk storage is available for energy: existing hydroelectric dams, which account for 6.6% of total US electrical capacity.[source] There are limits to how much storage can be used, since dam operators have to maintain minimum water flows and also have commitments to irrigators, but it's conceivable that wind power could provide a few per cent of the country's energy.

If some sort of bulk energy storage could be developed, that could make wind energy practical. The storage method closest to practicality is pumped storage. In fact, there is a small amount of pumped storage in use now. A rough calculation shows, however, that there aren't enough places to install pumped storage for wind power to become the main electricity source.

A different strategy would be to have fossil-fired power plants standing by to back up wind power. Since wind turbines have a load factor of 25 to 35%, that would seriously hamper the effort to reduce greenhouse-gas emissions because the fossil-fired plants would have to operate a large portion of the time.[source] But the existing fossil-fired plants will be around for some decades while replacement capacity is built. In the meantime, they can be used as backup for wind turbines and other renewable sources. So, in the short term, wind power can be a major power source until replacement sources are constructed and the wind turbines wear out.

Solar Energy

Solar photovoltaic systems are presently too expensive to compete with other energy sources, but over the years can be expected to become cheaper.[source] They already are becoming popular in remote locations where connecting to the electrical grid is impractical. If costs continue to fall, solar energy can complement wind power but the unavailability of bulk storage will apply to solar energy as well.

Geothermal energy

Geothermal energy presently supplies 0.34% of the energy used in the US.[source] There are two types of geothermal energy: wet and dry. The wet type is being exploited about as much as it can be. There is a lot more available in dry form; unfortunately, there aren't any practical ways of extracting it.

Biofuels

Biofuels represent a possibility. To use them unblended as motor fuels would require new engine designs, but that will be unavoidable with any change from petroleum-based fuels. Currently, the best estimate is that it takes 0.75 gallons of fuel to produce the energy-equivalent of 1 gallon of conventional fuel. That's only true if credit is given for the value of the leftover material as animal feed; once the demand for animal feed is satisfied, the payoff ratio won't be as good. It is believed that the fuel input could be reduced to as little as 0.4 gallons with advanced technology that allows agricultural waste to be used as the raw material.[source] Agricultural waste is what gardeners call mulch; it hasn't been determined what would be the adverse consequences of diverting mulch away from fields. Research is being done on different biomass plants and chemical processes that could give better results.

The International Energy Agency estimates[source] fossil-fuel use at 388 exajoules per year worldwide, which may be expected to double or triple in this century. It also estimates that to supply 300 exajoules/year, a goal attainable with moderate effort, would require 7% of Earth's landmass, requiring forest clearing and insecticides and synthetic fertilizers. In comparison, 13.3% of the landmass is arable, including 4.7% already under cultivation.[source] The IEA concludes that biofuels can be an important means of reducing greenhouse-gas emissions on a global scale. For the US and Europe, though, given their limited free agricultural land and their high dependence on liquid fuels, the main effect would be switching from oil-rich suppliers to land-rich ones. Presumably, the benefit of reducing global warming would justify the higher cost.

Silver Bullets

Many other systems have been proposed: wave engines, tidal engines, and ocean-thermal-gradient engines, to mention only a few. People have suggested micro-hydroelectric power, installing small turbines on thousands of creeks and streams, but never have addressed the legal obstacles to extinguishing hundreds of species. Fusion research continues apace, but no projections are made regarding when it could become practical. Schemes have been suggested for energy storage, such as compressing air in caves, or building mammoth flywheels. All of these ideas are exactly where they were over thirty years ago: nowhere.

Hydrogen

But one idea has real potential: hydrogen. Presently, hydrogen use is hampered mainly by the low energy efficiency (around 30%) of converting water to hydrogen at ordinary temperatures.[source] There are more efficient processes, but they require high temperatures and are poorly suited to renewable energy sources. Alternatively, research is going on to improve the efficiency of photosynthetic production, currently around 2%.[source] If the efficiency could be improved, then there is a real future for hydrogen. Storage technology is ahead of production technology, and fuel cells are already proven. Hydrogen could be a fuel substitute and could well be the main element in future energy delivery.

However, there is a trap in something this attractive. For over thirty years, Americans have chosen to stay with fossil fuels based on the promise that something new and better was almost ready to displace the use of fossil fuels. The new and better something never materialized, with the result that fossil-fuel use now is threatening the planet's climate. Is it safe to continue this way, or should we look for other solutions that are available now?

Summary

There are two time-frames to consider. With present technology, renewable energy can displace a big part of fossil-fired electric power, but will lose that capability as the backup fossil-fired plants wear out. In the long run, the world must focus on non-fossil energy sources. Unless some form of bulk energy storage is invented, renewable sources will only be able to provide about ten per cent of the energy the US uses. Conservation, if pursued aggressively, could hold energy consumption to its current level.

The next few articles will take a look at nuclear energy.

Skepticism about Global Warming

The world is facing some tough decisions on how to deal with the oncoming effects of global warming, so it's right and reasonable that people are looking at the subject closely to make sure we don't dislocate people's lives inappropriately.

In the past, this has led to some unfortunate situations. A few people claiming to have scientific qualifications have made arguments that are demonstrably false. It also led to an embarrassing TV presentation in the UK which claimed that global warming was a conspiracy authored by Prime Minister Thatcher in which scientists lied for pay. The presentation showed falsified solar data, claiming that it matched global temperature history, and warned that Africans would suffer severe deprivation if they were denied fossil-fueled electricity.

Among the skeptics, one of the most important is United States Senator James Inhofe, the ranking Republican member of the U.S. Senate Environment and Public Works Committee. One would predict that Senator Inhofe would examine the subject carefully. Representing an oil-producing state, and being a strong conservative with investments in aviation, the Senator also flies personal aircraft as an avocation. He and his staff have compiled an extraordinary treatise which must include just about every criticism aimed at the process by which the consensus on global warming was formed.

As we look through the arguments, some patterns emerge. The most substantive of the arguments assume that there can only be one cause of global temperature change; since solar activity was clearly the driving force before 1850, they conclude that it still is the sole driving force. This and the other scientific arguments repeat the false arguments mentioned before.

Of the remaining arguments, many contend simply that too much emphasis is put on dubious methodologies: proxy data and computer models. That's reasonable enough, but the compilation leaves out the fact that the proof of climate change doesn't depend on either of these, as shown in our last article.

Some of the critics don't challenge the science but complain about the management of the UN's Intergovernmental Panel on Climate Change. That's important to conspiracy believers but not to people more interested in the actualities.

The last group of critics don't challenge either the science or the politics, but warn that excessive alarmism could lead to mistaken decisions. Implicit in this argument is the contention that CO2's effects on the environment couldn't be very great.

The question here is, what is very great? We've only seen a temperature rise of 0.7°C (1.2°F) in over 150 years. Who cares? You can't even feel that! But mountain glaciers get a little less snow in the winter and melt a little faster in the summer. In time, the glaciers disappear and farmers who depend on snowmelt in the summer don't get it. Semi-arid parts of Africa that got just enough rain to grow some grass for cattle get less and tens of millions of people watch their livelihoods die. Beetles that never could get up a big population before because of winter-kill now can survive and increase gradually in numbers so they can destroy a forest. Cold-water fish don't tolerate temperature change and move to a different part of the ocean, disrupting their reproduction cycles. That's what we're seeing now: small temperature changes have big effects. What will happen as the temperature rises another degree? Or two degrees?

Maybe this is alarmism. If so, then alarmism isn't necessarily a bad thing.

Now that we've covered the evidence for global warming and the arguments against it, the next articles should cover our options for minimizing it.

Is Global Warming Real?

We'll get this one out of the way quick. Global warming is real indeed. Not only is the news replete with evidence of it (melting arctic ice, shrinking glaciers), the measured data show it.

First, let's look at the temperature data we have. One set of data comes from NASA [source] and the other is provided by Met Office Hadley Centre for Climate Change in the UK.[source]



The data don't agree exactly because (1) the NASA data shows the deviation from the 1951-1980 average and the Hadley Centre data shows the deviation from the 1961-1990 average and (2) the calculations were done independently so small differences are expected. We should bear in mind that the older data comes from spottier readings and is less reliable. The Hadley Centre data is shown both raw and smoothed. Now we'll look at the different factors that affect global average temperature, comparing them with the smoothed data.

Solar Variations

Sunspots receive plenty of mention in the popular literature and we have more data to look at.[source]

This is promising. Notice that the sunspots are lower in number, almost zero, in the period 1650-1700. There is anecdotal evidence that Europe and China were cooler then.[source] There also is anecdotal evidence of the same thing happening in the early 19th Century[source], although the Tambora volcano could have contributed.

Looking more closely, we see that the low number of sunspots around 1900 fits the lower temperature then, and temperature and sunspot-count both rise thereafter. There was more activity around 1960 that shows up as a temperature bump, and also around 1980-1990, that fits with a slight, stretched-out bump. So it seems clear that sunspot activity affects global temperature. Or, possibly, sunspots affect the irradiance and it's the combination that affects global average temperature. A suggestion under review is that solar activity diminishes cloud formation by influencing the intensity of cosmic rays, as shown in this figure:[source]

On the other hand, the temperature bumps are small compared with the upward temperature trend since 1900. Furthermore, if solar activity was the main driving force, then average temperature should drop after 1990 but instead it keeps going up. That means something else has become a stronger driving force since 1900.

Solar irradiance is the intensity of solar energy striking the earth and its atmosphere in watts/sq meter. It seems to follow sunspot activity, which seems reasonable. But it only matches the temperature changes about as well. [source]

Natural Greenhouse Gases and Atmospheric Dust

The gas emissions from natural vegetation are an important part of the atmosphere's loading, but the amount of land devoted to it hasn't increased. It's possible that emissions have risen as a result of global warming. Either way, natural vegetation can't be blamed for the temperature rise since 1900.

Volcanoes emit gases, too. We can do a quick calculation that shows volcanoes could never affect the atmosphere's CO2 concentration.

Volcanoes also emit particulates and aerosols, which reflect heat away from the earth and cause more clouds to form, causing further cooling. Data from the Mauna Loa Observatory shows the effects of volcanos since 1958.[source]

We can see that volcanoes reduced solar transmission in 1982 and 1991, but they don't affect the global-average temperature rise by much. The conclusion is that volcanoes don't affect global warming either way.

Heat Transfer from the Earth's Core to the Oceans

One way the Earth's core could heat the oceans is by undersea volcanoes. We can do a quick calculation that it would take around a half-million undersea volcanoes equal in size to the one at Mount Saint Helens in 1980 every year to account for the warming the oceans have seen since 1955. Even if the calculations are off by a factor of ten, it would take around five thousand such volcanoes every year just to account for ten per cent of the warming. And, there would have to have been no volcanoes before 1910. So undersea volcanoes aren't a major factor.

Another possibility is the extrusion of magma into the oceans at the edges of separating tectonic plates. But the USGS has found that the rate tectonic plates have been moving hasn't changed in the last thirty years from what it's always been.[source] So magma doesn't explain the recent warmup.

Artificial Atmospheric Dust

As is the case for natural particulates and aerosols, artificial particulates and aerosols have a cooling effect by reflecting sunlight and by causing clouds to form. The temperature graph shows a sharp drop around 1940 until almost 1950, then a slow rise until 1980 or so, and after that a sharp rise. That fits with our expectations: industrial production increased radically during the war. Virtually no attention was paid to the resulting pollution. The postwar period experienced some relaxation in both production and pollution. About 1970, serious efforts were started to control particulate emissions from fossil-burning power plants, and the temperature graph clearly shows that global warming accelerated.

Artificial Greenhouse Gases

There are a lot of these that can be important: carbon dioxide, methane, and nitrous oxide are the most dominant. We need to consider their emission rates in order to compare their relative importance in the changing of the global average temperature.

The US Department of Energy has estimated their yearly emission rates and ranks them this way (2005 data [source]). Global data comes from IPCC's report for 2001[source]. All the rates are in million metric tons per year. These numbers are calculated, but show more precision than they should. Nonetheless, they show relative magnitudes.

		US	US (CO2 Equiv)	World	World (CO2 Equiv)
	Carbon dioxide	6009	6009	29223	29223
	Methane	26.6	612	323	7429
	Nitrous oxide	1.2	367	7	2072

Clearly, CO2 is the most important artificial greenhouse gas in respect to changing temperature. The present CO2 content of the atmosphere is 3,036,000 MMT, so the emissions amount to almost 1% of what's presently in the atmosphere. The CO2 concentration is rising roughly 0.5% per year, so about half is staying in the atmosphere and the other half is going somewhere else, mostly into the ocean. We have some measured CO2 concentration data taken from ice cores.[source]

This is our smoking gun. The CO2 concentration has risen from less than 300 parts per million all the way up to 383 ppm in 2007. Of all the factors affecting global average temperature, it's the only one that's been increasing since 1980, so it's the only one that can explain the temperature rise during that time.

What is especially troubling is that, before 1850, CO2 concentration has not exceeded 290 ppm in over 400,000 years.[source]

That's not to say that we can ignore the other greenhouse gases, but controlling CO2 emissions is essential to limiting global warming.

The Culprit

The evidence shows that solar activity and aerosols can influence global temperature. Before 1900, when greenhouse-gas concentrations were below 300 ppm, solar activity seems to have been the main driving force. Since then, greenhouse gases have become the main driving force.

The Skeptics: There are individuals who argue against these conclusions. Their claims been refuted many times but still get a lot of attention from media outlets. Read about their arguments.