Armageddon Science (15 page)

Of course, prediction isn’t an exact science. We can’t forecast the weather accurately for more than a few days out, so it seems optimistic to assume that we can know how the world’s climate will change over tens of years. But while there will always be varying interpretations as long as there are different scientists analyzing the data, the consensus is now hugely in favor of global warming being a real, growing threat.

Some skeptics still point out that the changes so far have been relatively slight, and may not have a huge impact before the end of the century, but they are missing two significant points. First, the impact has begun. If you doubt this, speak to a citizen who has lost his home to unprecedented wildfires or coastal floods. Second, it’s a mistake to assume that the change we see now will continue at such a relatively slow pace.

According to the Australian climate change expert Will Steffen, the world is not usually a place of gentle, slow drift. “Abrupt change seems to be the norm, not the exception,” says Steffen. On twenty-three occasions during the last ice age, for instance, air temperatures went through massive climbs, pushing temperatures up by as much as 15 degrees Celsius (28 degrees Fahrenheit) in around forty years. Around half of the entire warming between the ice ages and interglacial periods that followed—again, changes on the order of a huge 15 degrees Celsius—took place in just ten years.

When the Earth undergoes major change it tends to be in sudden, large steps—this is something that is a relatively recent discovery. Richard Alley, in a report for the U.S. National Academy of Sciences, concluded, “Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed…. This new thinking is little known and scarcely appreciated in the wider community of natural and social scientists and policymakers.” We might be predicting a half meter (1.6-foot) rise in ocean level by 2100 (plus up to another 3 feet of storm surges) based on current, slow, steady rise, but we have to prepare for the possibility of a precipitate increase in temperature that will result in much faster rises in sea level.

Even without such a change, there is a real possibility that current predictions are underanticipating the impact because positive feedback may accelerate the process.

Sometimes, even our attempts to make the environment better can have an ironic and unexpected effect. Aerosols, the scientific term for suspensions of fine particles in the air, typical of much airborne pollution from smog to black smoke, are something that has been cut back significantly as we manage to clean up the air. But aerosols have a helpful effect where global warming is concerned. Unlike greenhouse gases, they stop the Sun’s energy on the way in, and so have a cooling effect on the ground below. (This is reversed if soot particles, for instance, land from the aerosol on snow, darkening it and reducing reflection.) At the moment aerosols could be reducing the global-warming impact of greenhouse gases by up to half—but this contribution is liable to seep away as we achieve cleaner air.

Everyone from the most adamant denier of human-caused global warming to the greenest of scientists agrees that there’s a lot of uncertainty in the predictions of just how much the effect will be. That’s inevitable because they are dealing with a very complex and only partly understood system. Clouds, for example, have a big impact on the climate. Low clouds have a cooling effect; high clouds trap infrared radiation and warm us up. Different types of clouds make dramatically different contributions to heating or cooling. Attempting to include the feedback produced by clouds into climate models produces a huge range of variation.

This means that though the most likely predictions are still for a one or two degrees Celsius temperature rise within a century, it certainly isn’t impossible to be looking forward to a rise of 8 to 12 degrees Celsius (15 to 20 degrees Fahrenheit)—plenty to make the most dire predictions of the impact of climate change a reality in our lifetimes. The knowledge that there’s uncertainty doesn’t mean we can just cross our fingers and hope the threat goes away. It’s all the more reason to be ready, in case things head for the unpleasant end of the prediction range. And something we know for certain is that even if the predicted averages are true, we will experience worse, because as we have already seen, we don’t experience averages; we live through the peaks and troughs. The damage is caused by the worst the weather can throw at us.

Is total devastation of society as we now know it inevitable from climate change? Thankfully, no. There are three possibilities that could save us.

The first is that it could all be a big mistake. Only twenty-five years ago some scientists were forecasting a return to ice age conditions rather than global warming. The Earth’s weather system is immensely complex. We can’t make detailed weather predictions more than a few days ahead. Beyond that, chaos reigns, as very small changes now can make a big difference to weather in the future. While the urban myth that a butterfly beating its wings on one continent can cause a hurricane on another is not true, chaos theory assures as that we will never be able to give a 100 percent accurate weather forecast over as short a period as a fortnight.

The models used to predict climate change are immensely complex, and subject to a lot of doubt. However, what we can do is take the best picture from a range of forecasts; this is how regular weather forecasts have been improved vastly over the last ten years. And doing that, the prognosis is not good. We can also compare the predictions of the models from a few years ago with what has happened since. So far, practically every model has been too optimistic. Things seem to be getting worse faster than the models predict.

The theory could still be wrong, and that could still save us. We may find that the world’s climate surprises us and takes a whole different turn—but there is no good reason to assume that this is going to happen, and it’s a pretty weak basis to plan the future of the world on.

The second possibility to mitigate the impact of climate change is that we make enough changes to the way we act, reducing greenhouse gas emissions and improving the way we soak up carbon dioxide, methane, and other such gases, to be able to hold off the kind of temperature rises that are currently predicted.

The global financial difficulties of 2008–9 could help a little with this, as there was a slowing down at least of the rate of rise of emissions, though some initiatives to try to overcome the recession, like those encouraging consumers to buy more new cars, would have had a negative effect on the environment.

Perhaps most encouraging are changes to both power generation and transport. On the power-generation side we have seen attempts to clean up power station exhaust gases, an increasing use of “renewable” resources like wind and wave power, and carbon cap-and-trade schemes to encourage organizations and governments to reduce emissions. For cars and trucks we have seen the May 2009 initiative, which promises leaner, greener automobiles in the future, reducing emissions by about one-third by 2016, with the equivalent impact on emissions of taking over 100 million cars off the road.

However, great though these actions are, most climate scientists tell us it’s not enough to cut back on emissions. We need to get to a state where we’re actively taking greenhouse gases out of the atmosphere. This is one of the possibilities for the third wave of fixes for climate change—where science is used to reduce greenhouse gas levels in an active fashion.

The most straightforward approach is to get hold of greenhouse gases and lock them away. This is what trees do—but unfortunately, they’re much too slow at it for a tree-planting program to help with our short- to medium-term climate change problems. (And trees also have the problem that eventually they will die and rot, sending much of the carbon back into the atmosphere.)

We can already scrub the carbon out of the output of power stations, and with time could be able to do this with smaller emitters, like car engines. The carbon dioxide is captured, often by pushing it through solvents that latch onto it, then taken somewhere it can be stored long term. In theory this could just involve pumping CO
₂
into the deep oceans; but it would gradually escape, and doing this would also contribute to increased acidification of seawater, putting corals and other marine life at risk.

More practical is pumping the gas into underground fissures and disused oil fields. Carbon dioxide is heavier than air, and with appropriate capping, such stores could keep the greenhouse gas locked away for thousands of years.

The trouble with much carbon capture, whether it’s operating on car exhausts, your domestic boiler, or a power station, is that the processes involved can be energy intensive. The exhaust gases are bubbled through a liquid solvent that reacts with the CO
₂
, pulling it into the liquid. You then have to either wastefully and dangerously dispose of the solvent, or use a considerable amount of energy getting the carbon dioxide back out of solution so it can be stored away.

At the University of California, Los Angeles, a location all too familiar with car exhaust gases, scientists have been developing new carbon-capture materials. These zeolitic imidazolate frameworks are collections of tiny crystals that are like traps for CO
₂
. The crystals have pores in them that the carbon dioxide molecules can slip into, but find it difficult to get out of. Because the CO
₂
has not undergone a chemical reaction, it can be extracted from the crystals by simply dropping the air pressure, leaving the crystals fresh to be reused. The team at UCLA hope that they will be able to test the crystals live in a power station within a year or two.

Others are looking at ways to recycle the carbon from the atmosphere, actively reducing levels of greenhouse gases. There is a technique that can use solar energy to process carbon dioxide and hydrogen to produce hydrocarbons—the basic components of fuel oil and gas. Such carbon recycling could be used to actively reduce carbon levels, or simply to prevent them rising any higher by reusing the hydrocarbons produced this way, rather than burning fossil fuels.

These are the straightforward approaches that science can take, but others are more surprising, or more extreme. There are many suggestions; Here are three samples. One is to move from farming cattle and sheep to raising kangaroos. The reasoning here is that ruminants, grass-feeding mammals, are a major contributor to global warming. As an animal like a cow eats it burps up considerable amounts of methane. Although we don’t hear as much about methane as we do about carbon dioxide, it is a powerful greenhouse gas, as we’ve seen, with around twenty-three times as strong an effect as carbon dioxide. The output of such livestock worldwide contributes 18 percent of all greenhouse gas emissions (in terms of impact)—more than all forms of transport combined. But kangaroos are different. They don’t burp methane.

One possibility is to convert ranches to farming kangaroos, but a more likely approach is to look at what makes kangaroos different from cows and sheep. The kangaroos have a unique kind of bacterium breaking down plant matter in their stomachs. While the bacteria in cow and sheep stomachs pump out the greenhouse gas, the kangaroo equivalent doesn’t. It has been known for some time that a diet rich in clover will partially suppress production of methane, but efforts are also being made to vaccinate against the offending bacterium, or even to try switching cows’ stomachs over to the kangaroo bacteria.

A second idea that has been tried on a small scale is seeding the ocean with iron filings. These encourage the growth of algae, which take carbon dioxide from the atmosphere to build their cells, but (hopefully) don’t release it back when they die, as they sink to the bottom of the ocean. On a large-enough scale an increase in algae levels would have a noticeable impact on greenhouse gas levels, but we just don’t know what the result of dumping so much iron in the sea would have on other organisms, what the effect of a massive increase in algae populations would have on the marine ecology, or even how much the iron would really benefit the algae.

A final idea that is taken seriously in some quarters, despite seeming like a science-fiction fantasy, is to accept that there’s nothing we can do about the level of greenhouse gases, and instead to reduce the level of natural heating of the Earth to compensate for the global warming coming from the greenhouse gases. The Earth’s main source of heat is the Sun. So why not stop some of the sunlight from ever reaching the Earth?

The idea here would be to put an enormous screen in space that would cast a shadow over part of the Earth. This would have the immediate effect of reducing the Sun’s heating power, it’s true, but the cost and complexity of the idea are staggering. Ken Caldeira of the Carnegie Institution for Science of Washington, who has modeled the effects of a solar shield, has said, “We would need to be confident that we would not be creating bigger problems than we are solving. Therefore, it is important both to understand the mess we are in today—how close are we to making irreversible changes, how fast can we alter our energy system—and to understand what might happen should we try to avoid some of the worst outcomes by engineering our climate.”

Scientists approach ideas to tweak the environment back the other way, away from global warming, with real trepidation. We have already demonstrated how good we are at messing up the environment, and we are all too aware of other situations where attempts to play nature at its own game have failed. Often, for instance, when a predator from a different country has been introduced to control a pest it has resulted in an out-of-control population of the predators, lacking the situations that normally keep them in check. The burgeoning population of predators then takes on prey they were never intended to attack, and throws the whole ecosystem out of balance.

Similarly, but on a much larger scale, there is a concern that taking action to reverse the effects of climate change could either produce unwanted side effects, or could go too far the other way, resulting in equally undesirable climate change involving global cooling. There’s another, more subtle danger, too. If we give too much attention at this stage to possible future scientific solutions, we might be tempted not to do anything about cutting our emissions of greenhouse gases, assuming “we can just fix it”—when we have no evidence as yet that such a fix will ever be feasible.