A Millennium of Climate Change Predicted

That's what is in store for humanity if we don't begin to scale back our emissions of greenhouse gases soon, according to a new study being published later this week in the Proceedings of the National Academy of Sciences. According to the press release describing the report from the National Oceanic and Atmospheric Administration (NOAA):

The study examines the consequences of allowing CO2 to build up to several different peak levels beyond present-day concentrations of 385 parts per million and then completely halting the emissions after the peak. The authors found that the scientific evidence is strong enough to quantify some irreversible climate impacts, including rainfall changes in certain key regions, and global sea level rise.

If CO2 is allowed to peak at 450-600 parts per million, the results would include persistent decreases in dry-season rainfall that are comparable to the 1930s North American Dust Bowl in zones including southern Europe, northern Africa, southwestern North America, southern Africa and western Australia.

The study notes that decreases in rainfall that last not just for a few decades but over centuries are expected to have a range of impacts that differ by region. Such regional impacts include decreasing human water supplies, increased fire frequency, ecosystem change and expanded deserts. Dry-season wheat and maize agriculture in regions of rain-fed farming, such as Africa, would also be affected.

The study claims that the effects will last at least a thousand years largely because, while the ocean buffers global temperatures by absorbing heat-trapping carbon dioxide, it also soaks up extra heat which it will slowly release back into the atmosphere over the coming centuries. 

The lead researcher, Susan Solomon, from NOAA's Earth System Research Laboratory in in Boulder, Colo., told the AP news agency:

"People have imagined that if we stopped emitting carbon dioxide the climate would go back to normal in 100 years, 200 year—that's not true." 

Note: An economist buddy once told me, "There are no 100-year problems." I can imagine what he would say about a 1,000-year problem. Why did he make such a pronouncement? Because there is no way to adequately forecast the level of technological development, wealth, and competency of social institutions that far into the future. It may be possible to predict long-term climate changes, but such scientific predictions don't tell us what is the best way to make a better future. 

Whole AP article available here.