Archive for August, 2012

Self-inflicted Heat

Thursday, August 9th, 2012

An astonishing event has occurred. The Wall Street Journal just ran a regular column acknowledging that the climate is getting warmer, and that the warming is caused by humans.

The record-breaking and devastating heat and drought across America may be the immediate reason for this change in point of view, but a political consensus may be emerging in the US that global warming is real. Not of course on what to do about it, but it’s a start.

Another reason for the possible shift in thinking is the recent research of atmospheric scientist Richard Muller. An out-spoken climate change skeptic in the past, he has received a lot of attention this year because he has changed his mind. His own careful analysis of global temperature data has convinced him that in fact the Earth is warming after all, and that human-produced greenhouse gases are the cause.

Nothing is more convincing than a scientist who looks at the evidence and changes his mind. His impact is huge.

Muller’s analysis of temperature data (the red Berkeley line on the graph, which ignores the data that Muller has been so skeptical about, still shows the same increase in global temperature. He concludes that global warming is real, and human-caused. (ibtimes.com)

Climate change skeptics, though, have continued to argue that any increase in levels of CO2 in the atmosphere is a natural phenomenon, not caused by the increasing burning of fossil fuels.

So a more remarkable contribution is the research of a NOAA-funded a team of atmospheric scientists at the University of Colorado at Boulder led by John Miller and Scott Lehman, and published a couple of months ago.

In this study, atmospheric gases along the northeast coast of the US were sampled by aircraft every 2 weeks for 6 years. The team then analysed the CO2 in the samples for the presence of Carbon 14. While CO2 from biological sources such as plant respiration is rich in C14, CO2 from burning fossil fuels has no C14, for its half life is only 5700 years, and fossil fuels are of course many millions of years old. So the less C14 in the sample, the greater the contribution of CO2 from burning fossil fuels.

The half life of C14 is 5700 years. CO2 emitted by the burning of fossils fuels, all of which are many millions of years old, has no measurable amounts of C14 left. (yellowtang.org)

Their results: the increase of atmospheric CO2 from the 280 ppm of the early 1800s to the current level of 390 ppm can only have come from sources lacking C14, and the only sources are the fossil fuels we have burned.

So what are the facts?
– CO2 levels have risen from 280 ppm in early pre-industrial 1800s to 390 ppm currently.
– That increase is human-caused, the result of burning ever increasing amounts of fossil fuels.
– Global temperatures over the same period have been increasing, and the increase is highly correlated with increasing atmospheric CO2 levels.

For the past 400,000 years, global temperature atmospheric CO2 levels have been tightly correlated (atlas.nrcan.gc.ca)

The correlation of global temperature and atmospheric CO2 increases in the past century are also tight. (skepticalscience,com)

– The correlation between increasing global temperature and atmospheric levels of CO2 is so tight that it is almost certainly causal.
– The planet is going to continue to get warmer.
– Fossil fuel companies have proven reserves sufficient to drive CO2 levels and global temperatures to frightening levels (check out Bill McKibben’s recent essay in Rolling Stone).
– Fossil fuel companies a show no inclination to curtail exploitation. We’ll adapt, they say.

We’re screwed.

How Resilient Are Coral Reefs?

Thursday, August 2nd, 2012

On the Pacific coast of Panama, coral reefs exist in a fairly narrow band of tropics compressed between cold water currents that flow south along the California coast and north along the Peruvian coast. Not exactly the extensive coral reefs of the South Pacific, but still, they are there.

Sea surface temperatures in the tropical Pacific. That’s supposed to be Central America in the upper right, Indonesia in the lower left. Blue indicates cool water, red to yellow increasingly warm water. The ocean currents compress the tropics in the Eastern Pacific compared with the Western Pacific (pord.ussd.edu)

An elegant piece of research published last month in Science indicates that reefs may be resilient, able to cease growth during harsh times, and then regrow once conditions improve. The Pacific Panama reefs are about 7000 years old, but from 4000 years ago to about 1500 years ago, they quit growing. Then they started to grow again.

The 2500 years of no growth is correlated with a long period of intense El Nino and La Nina activity. If the greater stress of these events caused the reefs to stop growing, then the same should have occurred broadly around the tropical Pacific. This appears to be true.

How does a dormant or dying reef reef recover? In the case of the Panama reefs, it is very likely that as conditions improved, the reefs were recolonized from remnants of reefs that had survived in sites less affected by the stressful times.

Cauliflower coral, Pocillopora damicornis, dominates the coral community of the reefs off the west coast of Panama. According to cores made into several of the reefs, growth of this species ceased for 2500 years (loiczsouthasia.org)

A reasonable conclusion is that if we now just stopped – and reversed – the increase in CO2 emissions that our current coral reefs could recover.

But that’s the kicker, isn’t it? CO2 emissions continue to rise every year, and we have no reason to think they will stabilize, let alone reverse, in any political future we can see.

Earlier this summer, 2000 coral reef biologists got together for one of their regular international meetings. They produced a Consensus Statement that they are all signing, and it is a clear, concise and grim summary of the predicament that coral reefs face as ocean temperatures rise, ocean acidification continues, and other stresses of over-fishing and pollution continue relentlessly. The only hope for coral reefs is for CO2 emissions to be reduced.

This is part of the statement (and here’s the full statement)
“CO2 emissions at the current rate will warm sea surface temperatures by at least 2-3°C, raise sea-level by as much as 1.7 meters, reduce ocean pH from 8.1 to less than 7.9, and increase storm frequency and/or intensity. This combined change in temperature and ocean chemistry has not occurred since the last reef crisis 55 million years ago.”

Coral reefs will not survive what we doing to the planet.
As I and many others have written before, that is beyond sad. We have evolved in a complex, beautiful and who knows how unique world, and we are wrecking it.