Monday, July 03, 2017

Carbon in Atmosphere Is Rising, Even as Emissions Stabilize - The New York Times

The Cape Grim Baseline Air Pollution Station in Tasmania. (Credit: Commonwealth Scientific and Industrial Research Organization) Click to Enlarge.
Scientists are concerned about the cause of the rapid rises because, in one of the most hopeful signs since the global climate crisis became widely understood in the 1980s, the amount of carbon dioxide that people are pumping into the air seems to have stabilized in recent years, at least judging from the data that countries compile on their own emissions.

Scientists have spent decades measuring what was happening to all of the carbon dioxide that was produced when people burned coal, oil and natural gas.  They established that less than half of the gas was remaining in the atmosphere and warming the planet.  The rest was being absorbed by the ocean and the land surface, in roughly equal amounts.

In essence, these natural sponges were doing humanity a huge service by disposing of much of its gaseous waste.  But as emissions have risen higher and higher, it has been unclear how much longer the natural sponges will be able to keep up.

Should they weaken, the result would be something akin to garbage workers going on strike, but on a grand scale:  The amount of carbon dioxide in the atmosphere would rise faster, speeding global warming even beyond its present rate. It is already fast enough to threaten the polar ice sheets.

The record increases of airborne carbon dioxide in 2015 and 2016 thus raise the question of whether this has now come to pass.  Scientists are worried, but they are not ready to draw that conclusion, saying more time is needed to get a clear picture.

Many of them suspect an El Niño climate pattern that spanned those two years, one of the strongest on record, may have caused the faster-than-usual rise in carbon dioxide, by drying out large parts of the tropics.  The drying contributed to huge fires in Indonesia in late 2015 that sent a pulse of carbon dioxide into the atmosphere.  Past El Niños have also produced rapid increases in the gas, though not as large as the recent ones.

Yet scientists are not entirely certain that the El Niño was the main culprit; the idea cannot explain why a high rate of increase in carbon dioxide has continued into 2017, even though the El Niño ended early last year.

Scientists say their inability to know for certain is a reflection not just of the scientific difficulty of the problem, but also of society’s failure to invest in an adequate monitoring system to keep up with the profound changes humans are wreaking on the planet.

“It’s really bare bones, our network, contrary to common misperceptions about the government wasting money,” said Pieter Tans, chief of a unit that monitors greenhouse gases at the National Oceanic and Atmospheric Administration.

While the recent events have made the scientific need for an improved network clear, the situation may be about to get worse, not better. President Trump’s administration has targeted American science agencies for cutbacks, with NOAA, the lead agency for tracking greenhouse gases, being one of those on the chopping block.

Australia also had a recent fight over proposed cutbacks in climate science, but so far that country’s conservative government has promised continued funds for the Cape Grim science program, Australia’s most important contribution to global climate monitoring.  The atmospheric observatory here, which receives some money from NASA, is one of the most advanced among scores of facilities around the world where greenhouse gases and other pollutants are monitored.

The network is complete enough to give a clear picture of the overall global trends in industrial gases in the air, scientists say.  But it is too sparse to give definitive information about which parts of the planet are absorbing or releasing greenhouse gases at a given moment.  Lacking such data, scientists have trouble resolving some important questions, like the reasons for the rapid increase of carbon dioxide over the past three years.

“It’s really important that people get that there’s an awful lot that’s just not known yet,” Sam Cleland, the manager of the Cape Grim station, said.
With a better monitoring network, scientists say they might be able to specify in greater detail what is causing variations in the amount of carbon dioxide staying in the air — and, perhaps, to give a timely warning if they detect a permanent shift in the ability of the natural sponges to absorb more.

Read more at Carbon in Atmosphere Is Rising, Even as Emissions Stabilize

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