Sunday, 10 February 2013

Disrupting Earth's climate is to awaken a sleeping beast

Fixing Climate; The Story of Climate Science and How to Stop Global Warming by eminent climate scientist Wallace Broecker and his co-writer Robert Kunzig is an informative look at the science of global warming as well as a summary of the options for solving it. Wallace Broecker is a professor of Earth and Environmental Sciences at Columbia University, and through his research first discovered one of the primary regulators of the planet's climate; namely the “thermo-haline conveyor,” the network of ocean currents which circulates hot and cold water over much of the Earth's surface.

A recurrent theme in Broecker's writing is his view of Earth's climate as a sleeping beast which we awaken at our peril. The relative stability of climate for the past ten thousand years (since the end of the last ice age) is exactly what allowed humans to develop agriculture and create civilisation. Thus, we have greatly benefited from the long sleep of the climate beast. However, the carbon dioxide emissions created by our modern society's dependence on fossil fuels like coal, oil and gas risk disrupting the climate and waking the climate beast. The consequences could be sudden and drastic.

Whereas we may think of climate change as being gradual and taking place over centuries or millennia, climate science has shown that drastic changes have happened very quickly in the past. A prime example is the end of the “Younger Dryas” ice age, a cold period which lasted from 12,800 to 11,500 years ago.

“The [ice] measurements ... had shown that the warming at the end of the Younger Dryas had been abrupt ... the ice layers were suddenly half as thick ... most of that change had taken place in just a few years” (page 141).

So the scientific evidence is that climate change of sufficient magnitude to end an ice age can occur naturally in “just a few years,” not centuries or even decades. This bodes ill for our future, as our burning of coal, oil and gas is now changing the carbon dioxide concentration in the atmosphere faster than any time in history. If a similarly quick global warming were to happen now, humanity would have little time or ability to adapt to it. The results would be catastrophic in terms of increased desertification, reduced food production and famine.

Aside from temperature rise, the biggest threat to Bangladesh in particular is from sea level rise. This is another area where research in climate science has made it clear that big changes can happen at a frightening pace.

In the 1980's a colleague of Broecker's, Richard Fairbanks, thought he could pinpoint a time when sea level rose twenty metres in a single century (page 171).

The above is indeed a stark contrast with the scientific conservatism of the Intergovernmental Panel for Climate Change (IPCC) assessment of sea likely sea level rise being 59 centimetres by 2100.

The IPCC scientists specifically did not take into account the recent observations of accelerated ice loss from Greenland and Antarctica -- essentially because they didn't know what to make of them (page 183).

The problem is that scientists are generally cautious by nature, and unwilling to talk about possible worst case scenarios until that outcome is virtually certain. Unfortunately, if we wait until the worst case global warming scenario is inevitable before we start doing anything, it will be too late; the climate will have already changed, and humanity will have to suffer the awful consequences. Scientific conservatism in this case is lulling the public and world governments into a misplaced sense of security. So what is to be done? The answer is clear.

Which brings us to the one absolute certainty; no significant solution to the [carbon dioxide] problem can emerge until governments worldwide, and especially that of the United States, follow the lead of Norway and the European Union and impose either an emissions cap or a direct tax on [carbon dioxide] (page 266).

Broecker's conclusion is shared by most climate scientists. To prevent dangerous climate change, carbon dioxide emissions must be reduced by replacing fossil fuels rapidly with nuclear, wind and solar energy. This will require huge investments, and the only way the money can be raised is through a carbon tax. Those of us who care about what the future holds for our children need to start thinking about how to bring about this colossal change in the world economy.

(First published in Bangladesh in The Daily Star on 11th February 2013.)