We Just Breached the 410 Parts Per Million Threshold

on 18/4/17 the Mauna Loa Observatory recorded its first-ever carbon dioxide reading in excess of 410 parts per million (it was 410.28 ppm in case you want the full deal).

In what’s become a spring tradition like Passover and Easter, carbon dioxide has set a record high each year since measurements began. It stood at 280 ppm when record keeping began at Mauna Loa in 1958. In 2013, it passed 400 ppm. Just four years later, the 400 ppm mark is no longer a novelty. It’s the norm.

— source climatecentral.org

Electricity’s Carbon Footprint in U.S. Shrinks

For two years in a row, carbon emissions from electric power plants in the U.S. fell by about 5 percent each year — the first time in more than 40 years of recordkeeping that emissions have fallen so dramatically over two consecutive years, according to U.S. Department of Energy data. Overall, carbon dioxide emissions from energy use by Americans fell 1.7 percent last year, part of a decade-long slide in the carbon footprint of energy in the U.S.

The main reason is that Americans are using more renewable energy than ever before, and power plants, buildings and appliances have become more energy efficient, according to the DOE.

— source climatecentral.org

Carbon Dioxide Is Rising at Record Rates

For the second year in a row, carbon dioxide concentrations as measured at Mauna Loa Observatory rose at a record-fast clip, according to new data released by the Environmental System Research Laboratory (ESRL). The annual growth of 3 parts per million in 2016 is the slightest shade below the jump in 2015 of 3.03 ppm. Both years mark the first time carbon dioxide has risen more than 3 ppm in a single year in ESRL’s 59 years of monitoring.

The annual growth rate has increased since record keeping began in 1960 from just under 1 ppm in the 1960s to more than 2.4 ppm through the first half of the 2010s. The past two years have set a record for the fastest annual growth rate on record. Prior to the Industrial Revolution, carbon dioxide stood at roughly 280 ppm. Since then, human activities have committed a massive amount of carbon pollution to the atmosphere. This year scientists expect carbon dioxide to briefly reach 410 ppm this spring.

— source climatecentral.org

Soils Could Release Much More Carbon Than Expected as Climate Warms

Soils could release much more CO2 than expected into the atmosphere as the climate warms, according to new research by scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).

Their findings are based on a field experiment that, for the first time, explored what happens to organic carbon trapped in soil when all soil layers are warmed, which in this case extend to a depth of 100 centimeters. The scientists discovered that warming both the surface and deeper soil layers at three experimental plots increased the plots’ annual release of CO2 by 34 to 37 percent over non-warmed soil. Much of the CO2 originated from deeper layers, indicating that deeper stores of carbon are more sensitive to warming than previously thought.

They report their work online March 9 in the journal Science.

— source newscenter.lbl.gov

Carbon Dioxide Passed Critical Threshold in 2015

the World Meteorological Organization released another reminder of the planetary predicament we’re in: The earth’s atmosphere permanently passed the 400 parts per million (ppm) threshold last year. It’s the first year in human history where carbon dioxide levels have reached the symbolic milestone for an entire year. But it certainly won’t be the last as humans continue to treat the atmosphere as a waste dump for carbon pollution.

— source climatecentral.org

Here’s How Much CO2 Will Make the Arctic Ice-Free

For every round-trip transatlantic flight or just two months of a home’s electricity use, 30 square feet of Arctic sea ice is lost, according to a new study that lays out in the simplest possible terms the relationship between heat-trapping greenhouse gas emissions and the precipitous decline of sea ice.

The further accumulation of 1,000 gigatons of carbon dioxide — about the limit that would keep global temperature rise under 2°C — would leave the Arctic Ocean effectively ice-free in the summer, the study, detailed in the journal Science, found. But keeping emissions in line with just 1.5°C of warming would allow ice to hang on in at least some parts of the Arctic.

“Our study now allows people for the first time to grasp intuitively how each of us affects the global climate system,” study co-author Dirk Notz, of the Max-Planck-Institute for Meteorology in Germany, said in an email. He and other sea ice researchers hope this clearer connection will help inform policy decisions to limit warming.
Summer Sea Ice Decline

The area of sea ice covering the frigid recesses of the Arctic naturally waxes and wanes with the seasons, reaching a peak at the end of winter and a low at the end of the summer melt season. But because of the excess heat trapped in the atmosphere by ever-rising levels of carbon dioxide and other greenhouse gases, that area has been steadily shrinking.

The largest losses have come at the summer minimum, which has declined by 13.7 percent per decade since satellite records began in 1979.

The summer minimum today is now about half of what it was just 30 years ago. This year saw the second lowest sea ice minimum on record and the lowest winter maximum.

“Things have already changed dramatically in the Arctic,” Walt Meier, a NASA sea ice researcher who wasn’t involved with the study, said.

This stark decline is of major concern because the loss of reflective sea ice causes more heat to be absorbed by dark ocean water, leading to even further warming at high latitudes. Sea ice also serves as a critical part of the habitats of Arctic species and protects coastal communities from storm-whipped waves.

After the shocking record low reached at the end of summer in 2007 (a record later bested in 2012), researchers were concerned about sea ice reaching a tipping point beyond which it would decline exponentially and irreversibly.

But the rebounding of ice between these record-setting years suggested this wouldn’t be the case, and the new study is the latest to suggest that over the long-term, sea ice decline is more directly related to carbon dioxide emissions.

Using both observations and computer models, Notz and colleague Julienne Stroeve, of the U.S. National Snow & Ice Data Center and University College, London, found that when looking at averages over 30 years, every metric ton of carbon dioxide emitted results in the loss of 30 square feet of sea ice. That amount of CO2 is what is emitted per person on a round-trip flight from New York to London, or by a car driving 2,500 miles.

“It is a useful, if simplified way of conceptualizing” sea ice loss, Meier said.

Notz and Stroeve’s explanation for the linear relationship between emissions and sea ice decline is that the ice is adjusting to a heat imbalance: As more heat is trapped by greenhouse gases, the ice retreats further north, where there is less sunlight. This year, open water reached up to 85 degrees north latitude, the furthest north it’s ever been noted.

Both Meier and Bruno Tremblay, of McGill University in Montreal, thought that explanation was likely too simplistic and that other factors, like ocean heat, played a key role. But, in general, the relationship the study lays out “brings [sea ice decline] into more concrete terms,” Tremblay said.
Ice-Free Arctic

The straightforward link between CO2 emissions and sea ice loss makes it easy to calculate just how much more CO2 can be emitted before the Arctic becomes ice-free, which researchers have defined as there being less than 1 million square kilometers (or about 390,000 square miles) of ice.

By their reckoning, emitting another 1,000 gigatons of carbon dioxide would cause the ice to reach that threshold. At the current rate of annual emissions — about 35 gigatons per year — that point would be hit sometime mid-century. A spate of exceptionally warm summers could mean it is hit earlier, while a stretch of cooler ones could delay it.

That amount of carbon dioxide would push global temperature to about 2°C above pre-industrial levels, “so reaching the 2°C global warming target means that sea ice is gone in summer,” Notz said.

But if emissions are significantly reduced, to only an additional 400 gigatons — or roughly in line with only 1.5°C of warming — ice could hang on in several spots.

Notz and Stroeve said they hope their findings will help inform the decisions being made at the national and international levels, including at the upcoming international climate negotiations in Morocco.

“We for the first time provide very concrete guidance on how policy decisions regarding total future emissions affect Arctic summer sea ice,” Notz said. “This has not been possible before.”

— source climatecentral.org By Andrea Thompson

The World Passes 400 PPM Threshold. Permanently

In the centuries to come, history books will likely look back on September 2016 as a major milestone for the world’s climate. At a time when atmospheric carbon dioxide is usually at its minimum, the monthly value failed to drop below 400 parts per million.

That all but ensures that 2016 will be the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes, according to scientists.

Because carbon pollution has been increasing since the start of the Industrial Revolution and has shown no signs of abating, it was more a question of “when” rather than “if” we would cross this threshold. The inevitability doesn’t make it any less significant, though.

September is usually the month when carbon dioxide is at its lowest after a summer of plants growing and sucking it up in the northern hemisphere. As fall wears on, those plants lose their leaves, which in turn decompose, releasing the stored carbon dioxide back into the atmosphere. At Mauna Loa Observatory, the world’s marquee site for monitoring carbon dioxide, there are signs that the process has begun but levels have remained above 400 ppm.

Since the industrial revolution, humans have been altering this process by adding more carbon dioxide to the atmosphere than plants can take up. That’s driven carbon dioxide levels higher and with it, global temperatures, along with a host of other climate change impacts.

“Is it possible that October 2016 will yield a lower monthly value than September and dip below 400 ppm? Almost impossible,” Ralph Keeling, the scientist who runs the Scripps Institute for Oceanography’s carbon dioxide monitoring program, wrote in a blog post. “Brief excursions toward lower values are still possible, but it already seems safe to conclude that we won’t be seeing a monthly value below 400 ppm this year – or ever again for the indefinite future.”

We may get a day or two reprieve in the next month, similar to August when Tropical Storm Madeline blew by Hawaii and knocked carbon dioxide below 400 ppm for a day. But otherwise, we’re living in a 400 ppm world. Even if the world stopped emitting carbon dioxide tomorrow, what has already put in the atmosphere will linger for many decades to come.

“At best (in that scenario), one might expect a balance in the near term and so CO2 levels probably wouldn’t change much — but would start to fall off in a decade or so,” Gavin Schmidt, NASA’s chief climate scientist, said in an email. “In my opinion, we won’t ever see a month below 400 ppm.”

The carbon dioxide we’ve already committed to the atmosphere has warmed the world about 1.8°F since the start of the industrial revolution. This year, in addition to marking the start of our new 400 ppm world, is also set to be the hottest year on record. The planet has edged right up against the 1.5°C (2.7°F) warming threshold, a key metric in last year’s Paris climate agreement.

Even though there are some hopeful signs that world leaders will take actions to reduce emissions, those actions will have to happen on an accelerating timetable in order to avoid 2°C (3.6°F) of warming. That’s the level outlined by policymakers as a safe threshold for climate change. And even if the world limits warming to that benchmark, it will still likely spell doom for low-lying small island states and have serious repercussions around the world, from more extreme heat waves to droughts, coastal flooding and the extinction of many coral reefs.

It’s against this backdrop that the measurements on top of Mauna Loa take on added importance. They’re a reminder that with each passing day, we’re moving further from the climate humans have known and thrived in and closer to a more unstable future.

— source climatecentral.org