There was a provocative headline, in the Science Times section of The New York Times on February 13, 2007, “A Cool $25 Million for a Climate Backup Plan,” above a story by John Tierney. British entrepreneur and Virgin Enterprises founder Richard Branson had just made the cash offer in his Virgin Earth Challenge (VEC) to “…anyone who figures out how to remove a billion tons of carbon dioxide per year from the atmosphere.”
But four years later another New York Times story, “Cash Prize for Environmental Help Goes Unawarded,” told a very different tale. Branson and his team had reviewed more than 2,600 challenge submissions and found none of them worthy. Climate change is a hard (but not impossible) problem.
In the intervening years, Branson and company discovered how squeamish people are about geoengineering, which many submissions advocated, and for good reasons. Done right geoengineering strategies can be part of a solution to climate change; done poorly they can cause major problems.
Geoengineering is an approach that attempts to change some large features of the environment to achieve a desirable result, such as reducing global temperature increases. Some proposals in the VEC included seeding the atmosphere with chemical aerosols to reflect solar radiation back into space; others called for fertilizing the oceans with dilute iron solutions that would stimulate plankton growth resulting in carbon capture. But Branson later notedin a blog, “Changing the chemistry of the oceans to promote plankton growth however feels very risky, seeding clouds likewise.”
The VEC’s rules might have had a role in the decision to exclude geoengineered solutions. In addition to pulling a billion tons of CO2 from the atmosphere, the winning solution(s) would have to be provable in nature and able to scale up. You might think a billion tons is already at scale, but the atmosphere has on the order of 7 trillion tons of CO2 in it and close to one of those trillions would, ideally need removal. A rate of a billion tons per year, big as it is, would take 1,000 years to remove one trillion tons and we don’t have that much time. Also, for comparison, civilization is significantly less than ten thousand years old.
We also need to deal with the reality that humankind is generating 40 billion tons of CO2 pollution per year.
The albedo and other impediments
A few years ago, The Guardian published a storyon geoengineering that included brief descriptions of some popular ideas. Each of the ideas has some promise but on closer inspection most have fatal flaws. There are two basic approaches to geoengineering including reducing the amount of sunlight that reaches the earth’s surface, thus reducing its temperature; and various schemes to remove CO2 from the atmosphere. This article deals with reducing the amount of sunlight reaching earth, the next in this series will deal with carbon absorption.
Earth already reflects some solar radiation. Cloud cover, glaciers, and similar things reflect solar radiation back into space. It’s called the albedo and this kind of proposal is really about increasing the albedo or reflectiveness of the planet. The question boils down to starting with less sunlight for everything that requires it, like growing food, and whether or not that’s a good idea.
Perhaps the most controversial idea for limiting global warming is reducing the amount of sunlight that reaches earth’s surface. In principal this sounds like a no-brainer but nature has already performed numerous natural experiments around that idea and the results are scary.
Earth’s ecosystem has evolved over billions of years to use solar energy for photosynthesis and this process captures all of the energy used by living things. Even the term fossil fuels is a nod to the key role photosynthesis performed millions of years ago to support life because some of that living mass fossilized into the energy sources we use today.
So throttling the amount of sunlight reaching earth would be an incredibly delicate operation and there is absolutely no certainty we could get it right. How much light is reflected and where introduces the prospect of winners and losers based on their geography.
Volcanic winter, a natural experiment
We can observe natural experiments in climate cooling with every volcanic eruption. Severe examples are referred to by geologists as volcanic winter. When volcanoes erupt, they spew many tons of ash and rock into the atmosphere. They also release significant amounts of Sulphur that reaches the stratosphere. Each reflects sunlight and causes some amount of cooling. Here are some examples from history.
1991 The explosion of Mount Pinatubo in the Philippines reduced global temperatures for 2–3 years.
1883 Krakatoa in Indonesia erupted and for four years after the eruption earth experienced unusually cold weather and the winter of 1887–1888 saw powerful blizzards and record snowfall.
1815 Mount Tambora another big volcano in Indonesia erupted and caused what Europeans on the other side of the planet called the year without a summer in 1816.
It goes on like that and the further back in history you go, the less reliable the data except for what can be eye-witnessed. For instance, the eruption of Mount Tarawera in New Zealand, is thought to have caused the Great Famine of 1315–1317 in Europe.
The impact of volcanoes on biological activity is a big unknown, not in the sense that we don’t know what happens when there isn’t enough food to go around because volcanic activity curtails crop growth. But the unknowns are secondary or even tertiary effects like great famines. In an era like the Middle Ages there was no way to know what was happening half way around the world or to understand global weather.
Even earlier, scientists suggest that the eruption of Lake Toba on Sumatra island in Indonesia might have caused a volcanic winter 71,000 to 73,000 years ago that was severe enough to reduce the human population to between 15,000 and 40,000 world-wide. It is also suspected of massive deforestation in Southeast Asia and of lowering global temperature by 1 oC.
This is known as a population bottleneck because it kills off many members of a species and significantly lowers the diversity of a species’ gene pool. A bottleneck in our pre-history may be responsible for enhanced evolutionary activity among the survivors but no one can say how it affected our species. A catastrophe big enough could simply wipe out the species. Consider what happened to the dinosaurs.
This is the first of a two-part series looking primarily at geoengineering from the perspective of lowering earth’s temperature and we noted some of the possible side effects. We should also acknowledge that cooling earth’s temperature is only one facet of solving the global warming problem. Reduced temperature or not, CO2dissolved in sea water continues rising in this scenario, causing acidification that kills coral reefs and makes it difficult for fish larva to survive. So at best, manipulating earth’s albedo through artificial means is potentially just one part of a larger solution.
I have said in other places that solving climate change is like solving a Rubik’s Cube (see the video). You have to solve all sides at once or you end up with one side that’s perfect while the others are chaotic. So we need to keep looking for a more comprehensive solution. Adjusting the albedo might be one of those facets but there might be solutions out there that do more to lower temperature as well as reduce carbon concentrations.