Key Heat Trapping Gas Crosses 410 Parts Per Million Threshold — Highest Level in Past 5-20 Million Years

This past week, atmospheric carbon dioxide levels passed a new ominous milestone.

Clocking in at 410.7 parts per million at the Mauna Loa Observatory, this key heat trapping gas hit a range not seen on Earth for many millions of years.

(The world crossed the 410 part per million milestone in the daily measure this week. Image source: The Keeling Curve.)

These levels now correspond with the Miocene Climate Epoch when seas were 120 to 190 feet higher than today and when global temperatures ranged from 3 to 5 degrees Celsius hotter than preindustrial averages.

Record Rates of Accumulation

These new records come following two years of record rates of atmospheric CO2 accumulation. According to NOAA, carbon dioxide accumulated by 3.03 parts per million during 2015 and by 3.00 parts per million during 2016. These now represent the two fastest rates of carbon dioxide accumulation in the climate record to date. By comparison, the substantial warming at the end of the last ice age was accompanied by an approximate 0.01 part per million per year rate of CO2 increase averaged over 10,000 years.

2017 rates of atmospheric CO2 accumulation, according to NOAA, appear to have backed off somewhat in the first quarter. Comparative gains from Q1 2016 to Q1 2017 are about 2.8 parts per million. A weak La Nina in the Pacific during late 2016 probably helped ocean surfaces to cool and to draw down a bit more CO2. However, the rate of increase is still disturbingly rapid. A 2.8 ppm increase in 2017, should it emerge, would be the 4th highest annual rate of increase in the record and would be substantially above past decadal averages. Hopefully, this still-disturbingly-rapid rate of increase will continue to tail off a bit through the year. But it is increasingly clear that the time for urgent action to reduce carbon emissions and this very harmful related rate of accumulation is now upon us.

(The CO2 growth rate has recently been ramping higher due to record carbon emissions during the present decade. Rates of carbon emission will need to fall away from record high rates in order to tamp down the presently high rate of accumulation which will tend to trend higher even if such emissions remain at plateau due to various faltering carbon sinks and leaking natural carbon stores. Image source: NOAA.)

The total CO2 increase since major fossil fuel burning began in the 19th Century is now in the range of 130 parts per million from 280 (ppm) to today’s high of 410 (ppm). By comparison, during the end of the last ice age, levels of this heat trapping gas jumped by about 100 (ppm) from around 180 (ppm) to 280 (ppm). Atmospheric averages for 2017 should range about 3-4 ppm lower than the April-May high mark (which might still hit daily highs of 411 ppm or more). But at present rates of increase, we’ll be leaving the 410 ppm threshold level in even the lower average months behind in just a handful of years.

Depending on How You Look at it, We’re 5 to 30 Million Years Out of the Holocene Context

The primary driver of the present extreme rate of CO2 increase is global carbon emissions (primarily from fossil fuel burning) in a record range near 11 billion tons per year (or nearly 50 billion tons of CO2 equivalent gas each year). Though 2014 through 2016 saw a plateau in the rate of global carbon emission, the decadal average accumulation of this emission is still at record highs. Meanwhile, it appears that warming oceans, lands more susceptible to deluges and wildfires, increasingly deforested regions like the Amazon, and thawing Arctic permafrost are less able to take in this record excess. As a result of these factors, human fossil fuel emissions will need to fall for a number of years before we are likely to see an impact on the average annual rate of atmospheric accumulation of this potent heat-trapping gas.

(Past paleoclimate proxy records show that we are millions of years out of the Holocene context when it comes to present levels of atmospheric CO2 accumulation. Image source: Skeptical Science.)

Paleoclimate studies of past epochs are unable to provide 100 percent accuracy for past atmospheric CO2 levels. However, proxy data provides a good range of estimates. Based on these measures, it appears that the most recent likely time when atmospheric CO2 levels were comparable to those we now see today occurred around 5 million years ago. Meanwhile, it appears possible that the last time CO2 levels were so high extended as far back as 20 to 25 million years ago.

Unfortunately, carbon dioxide is not the only heat trapping gas humans have emitted into the atmosphere. Add in methane and other greenhouse gasses and you end up with a heat forcing roughly equivalent to 493 parts per million of CO2 (CO2e) during 2017 at present rates of increase. This level is very close to the maximum Miocene boundary level of 500 parts per million — a total amount of heat forcing that likely hasn’t been seen in 20-30 million years.

Serious, Concerted Action Required to Avoid Worsening Disasters

The only safe and reliable way to halt the rapid rise of heat trapping gasses and concurrent warming is to cease emitting carbon to the atmosphere. Such an undertaking would primarily involve a major shift away from fossil fuel burning machines and infrastructure. Present low-cost renewable energy provides a powerful option for just such a transition. In addition, various forms of atmospheric carbon capture from changes to land use, to biofuel-based carbon capture, to materials-based carbon capture will be necessary to draw down the extraordinarily high level of carbon overburden that has already been emitted. Failing such an undertaking, however ambitious, would consign the world to increasingly harmful temperature increases and related damaging geophysical changes for the foreseeable future.

Links:

The Keeling Curve

NOAA

Skeptical Science

Entering the Middle Miocene

Renewable Energy Technology is Now Powerful Enough to Significantly Soften the Climate Crisis

Hat tip to Ryan in New England

Hat tip to Wili

Hat tip to Erik Frederickson

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2016 on Track for Record Rate of Atmospheric CO2 Increase

During 2016, the annual rate of atmospheric carbon dioxide increase will have hit a record 3.2 to 3.55 parts per million (ppm). By 2017, the amount of carbon dioxide in the Earth’s atmosphere will be roughly equivalent to concentrations last seen during the Middle Miocene climate epoch (404 to 410 ppm average). In other words, atmospheric CO2 is rising at a record rate and we are hitting levels of this heat-trapping gas that have not been seen in about 15 million years.

Record Rates of CO2 Increase

The world is struggling to make the necessary turn toward reducing fossil fuel-based carbon emissions. Global emissions have plateaued at or near new record highs during the past three years. Conflicts over fossil fuel cuts and transitioning to renewable energy embroil numerous countries. Climate change deniers hold significant power in places like the United States, the United Kingdom, Canada, and Australia. And facing off against those who would defend the harmful interests of what could well be called the most destructive industry to ever inhabit the planet, are a broad group of environmentalists, scientists, concerned citizens, and renewable energy advocates.

carbon-dioxide-october-2016-global

(Global carbon dioxide is approaching a level not seen since the Middle Miocene period around 15 million years ago when atmospheric concentrations typically averaged above 405 ppm and global temperatures were 3-4 degrees Celsius hotter than 19th-century averages. Record annual rates of CO2 increase in excess of 3 ppm each year for 2015 and 2016 are swiftly propelling us into a climate state that is more similar to this ancient epoch — a shift that is producing increasingly harmful global consequences. Image source: The Copernicus Observatory.)

As the political turmoil ramps up, it appears that the Earth’s oceans and biosphere are straining to draw in the massive volumes of these gasses that we’ve been pumping out. Annual atmospheric CO2 growth rates for 2015 were a record 3.05 ppm. 2016 appears to be on track to beat that high mark, being likely to see a new annual increase of between 3.2 and 3.55 ppm.

Hot Lands and Oceans Tend to Produce a Carbon Feedback

The previous most rapid annual rate of atmospheric CO2 increase was 2.93 ppm during the strong El Niño year of 1998. Back then, high ocean surface temperatures combined with warming-related wildfires and droughts which spanned the globe to reduce the Earth’s capacity to take in carbon. More carbon was squeezed out of hot soils, burning forests, and warming oceans. Less was drawn down. New record rates of atmospheric CO2 increase were breached.

the-keeling-curve-2-years

(Except for a couple of days, all of 2016 saw atmospheric CO2 levels above 400 ppm. Peak values as measured at the Mauna Loa Observatory in May were 407.7 ppm. By May 2017, atmospheric CO2 levels are likely to hit near 410 ppm — a level not seen in about 15 million years. Image source: The Keeling Curve/Scripps Institution of Oceanography.)

Even during the period of heightened heat stress that occurred in 1998, we did not see a year in which annual rates of CO2 increase exceeded 3 ppm. We have never, until 2015-2016, seen a time when there were two back-to-back years of such rapid rates of increase. Similar but worsening heat stress impacts have likely flagged what at first appeared to be an increased rate of carbon uptake from the biosphere during the late 2000s. Ocean heat content is now dramatically greater than during 1998 and this significant warming is likely having at least a periodic impact on the ocean’s rate of carbon uptake. Wildfires are now far more prolific, generating more atmospheric carbon. Droughts are more widespread and these tend to squeeze carbon from the soil. The Arctic is the warmest it’s been in 115,000 years and, as a result, some new Earth system carbon sources are starting to pop up.

Record High Rates of Fossil Fuel Emissions Hitting a Plateau

In the intervening years since 1998, global carbon emissions from fossil fuels have also jumped dramatically. During 1998, yearly CO2 emissions were in the range of 26 billion tons per year. By 2014-2015, these greenhouse gas releases had soared to around 35.8 billion tons per year. Through this period, average annual rates of CO2 increase continued to climb during the 2000s and 2010s.

global-carbon-project-emissions-2015

(Global carbon emission increases stalled during 2013, 2014, and 2015 according to The Global Carbon Project. But despite this recent pause, atmospheric rates of carbon dioxide increase have continued to ramp up. Due to a number of factors, including atmospheric and ocean inertia as well as temperature and saturation stress to global carbon stores, it is likely that significant reductions in carbon emissions from fossil fuels will be necessary to have a marked impact on annual rates of atmospheric CO2 increase.)

According to NOAA, the 1980s and 1990s saw yearly jumps in CO2 at the rate of about 1.5 ppm each year. By the 2000s, this average rate of increase had leaped to about 2 ppm per year. For the first six years of the 2010s, the average rate will likely be around 2.5 ppm per year.

New Records Provide Urgency For Rapid Emissions Cuts

This rate of increase roughly matches the overall rate of increase in emissions. As yet, there is no major global trend sign in the atmospheric CO2 data showing that carbon uptake from the oceans and the biosphere has been significantly curtailed, at least not to the point that it has shown up in the long term global trend. There are, however, widespread signs of stress to the Earth’s carbon storage system, and two years of 3 ppm-plus increase back-to-back is a warning blip on the climate radar.

In other words, these new record rates of CO2 increase are disturbing. If the annual increases do not fall back into the low 2-ppm per year range in 2017 and 2018, it will be an indication that some of the Earth’s ability to draw down carbon has been significantly hampered. If that is the case, then the urgency to draw down emissions is considerably greater.

Links:

NOAA ESRL

Middle Miocene

The Global Carbon Project

The Copernicus Observatory

The Keeling Curve

Doubling Down on Our Faustian Bargain

Hat tip to SmallblueMike

(Note: This post focuses primarily on CO2 as an indicator. Overall CO2e levels will be covered in a separate exploration.)

Tottering Totten and the Coming Multi-Meter Sea Level Rise

A new scientific study has found that the Totten Glacier is fundamentally unstable and could significantly contribute to a possible multi-meter sea level rise this Century under mid-range and worst case warming scenarios.

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408 Parts per million CO2. 490 parts per million CO2e. This is the amount of heat-trapping CO2 and total CO2 equivalent for all heat-trapping gasses now in the Earth’s atmosphere. Two measures representing numerous grave potential consequences.

We’re Locking in 120-190 Feet of Sea Level Rise Long Term

Looking at the first number — 408 parts per million CO2 — we find that the last time global levels of this potent heat-trapping gas were so high was during the Middle Miocene Climate Optimum of 15-17 million years ago. During this time, the Greenland Ice Sheet did not exist. East Antarctic glacial ice was similarly scarce. And the towering glaciers of West Antarctica were greatly reduced. Overall, global sea levels were 120 to 190 feet higher than they are today. Meanwhile, atmospheric temperatures were between 3 and 5 degrees Celsius hotter than those experienced during the late 19th Century.

Antarctica Below Sea Level

(Large sections of Antarctica rest below sea level. A physical feature that renders substantial portions of Antarctica’s glaciers very vulnerable to rising ocean temperatures. Since the latent heat content of water is substantially higher than that of air, even comparatively small ocean temperature increases can cause significant melt in sea-facing glaciers and in below sea level glacial basins. Image source: Potential Antarctic Ice Sheet Retreat Driven by Hydrofracturing and Ice Cliff Failure.)

Hitting the 408 ppm CO2 threshold this year catapults the current push for global climate transitions outside of the Pliocene context of 3 to 5 million years ago (topping out at 405 parts per million CO2) and places it in the bottom to mid-range of the Middle Miocene context (300 to 500 parts per million CO2). The 490 ppm CO2e number — due to added atmospheric heating contributions from human-emitted gasses like methane, chlorofluorocarbons, NOx compounds, and others — is enough to catapult our current climate context into the upper Middle Miocene range.

If global greenhouse gasses were to stabilize in this range long-term (for a period of hundreds of years), we would expect the Earth’s climate and ocean states to become more and more like those experienced 15-17 million years ago. Unfortunately, atmospheric concentrations of heat trapping gasses are still rapidly rising due to an increasingly dangerous emission coming from global fossil fuel burning. In addition, risks are rising that the Earth System will begin to contribute its own substantial amounts of carbon — possibly enough to raise the CO2e number by around 50 to 150 ppm over the next few centuries. Two contributions — one we control and another we do not — that risk swiftly pushing the global climate context into a 550 to 650 ppm CO2e range that is enough to eventually melt all the glacial ice on the planet.

Glacial Inertia vs Lightning Rates of Warming

It’s a tough climate state. A context that many scientists are still having difficulty coming to grips with. First, the global glacier research community is still looking at the world’s potential future ice melt in Pliocene and Eemian contexts. This makes some sense given the fact that current atmospheric warming in the range of 0.9 to 1.3 C above 1880s values is more in line with those two climate epochs (the Eemian saw seas 10-20 feet higher than today and the Pliocene saw seas at 25-75 feet higher). But it doesn’t take into account the underlying heat forcing and the likely climate end-state.

Second, we don’t really have a good grasp on how fast or slow glaciers will respond to the added heat we’re putting into the Earth System. We do know that at the end of the last ice age, melting glaciers contributed as much as 10 feet of sea level rise per Century. But this was during a time of comparatively slow global temperature increase at the rate of about 0.05 C per Century — not the current rate in the range of 1.5 to 2 C per Century, which is 30 to 40 times faster.

10 Feet of Sea Level Rise South Florida

(What 10 feet of sea level rise would do to South Florida. Given the increasing vulnerability of glaciers around the world to human-forced warming, there’s a rising risk that seas could rise by 10 feet before the end of this Century. Image source: Climate Central.)

In early studies, much weight has been given to glacial inertia. And older climate models did not include dynamic ice sheet vulnerabilities — like high latent-heat ocean water coming into contact with the submerged faces of sea-fronting glaciers, the ability of surface melt water to break up glaciers by pooling into cracks and forcing them apart (hydrofracturing), or the innate rigidity and frailty of steep ice cliffs which render them susceptible to rapid toppling. But now, new studies are starting to take these physical melt-amplifying processes into account and the emerging picture is one in which glacial melt and sea level rise may end up coming on at rates far more rapid than previously feared.

Overall, when taking a look at these newly realized ice-sheet weaknesses, it’s worth noting that the total heat forcing impacting the world’s ocean, air, and glacial systems is now rising into a range that is much more in line with Middle Miocene values. And that global temperatures are now increasing at a lightning rate that appears to be unprecedented in at least the past 60 million years.

Tottering Totten

It’s in this dynamic, rapidly changing, and arguably quite dangerous climate context that new revelations about the stability of one of East Antarctica’s largest glaciers have begun to emerge. In size, the Totten Glacier is immense — covering an area the size of California in mountains of ice stretching as high as two and a half miles. If all of Totten were to melt, it would be enough to raise seas by around 11 to 13 feet — or about as much as if half of the entire Greenland Ice Sheet went down.

Edge of the Totten Glacier

(The Totten Glacier, at lower edge of frame, faces a warming Southern Ocean. How rapidly this great mass of ice melts will, along with the destabilization of numerous other glaciers around the world due to a human-forced warming, determine the fates of numerous coastal cities and island nations during this Century and on into the future. Image source: LANCE-MODIS.)

Last year, a study found that warm, deep circumpolar water was beginning to approach ice faces of the Totten Glacier plunging 1 mile below the surface of the Southern Ocean. The study observed a rapid thinning that appeared to have been driven by this new influx of warmer ocean water near the glacier base:

Totten Glacier… has the largest thinning rate in East Antarctica. Thinning may be driven by enhanced basal meltingWarm modified Circumpolar Deep Water, which has been linked to glacier retreat in West Antarctica, has been observed in summer and winter on the nearby continental shelf beneath 400 to 500 m of cool Antarctic Surface Water…We identify entrances to the ice-shelf cavity below depths of 400 to 500 m that could allow intrusions of warm water if the vertical structure of inflow is similar to nearby observations. Radar sounding reveals a previously unknown inland trough that connects the main ice-shelf cavity to the ocean. If thinning trends continue, a larger water body over the trough could potentially allow more warm water into the cavity, which may, eventually, lead to destabilization of the low-lying region between Totten Glacier and the similarly deep glacier flowing into the Reynolds Trough (emphasis added).

Observed increasing melt rates for such a huge slab of ice in Eastern Antarctica was generally seen as a pretty big deal among glacial scientists and a flurry of additional research soon followed. By last week, a model study had found that Totten alone could produce nearly a meter of sea level rise before the end of this Century if global warming forces ocean waters to heat up by 2 C or more near the Totten Glacier. The study also found that 5 C worth of local ocean warming would be enough to force nearly 3 meters worth of sea level rise from this single large glacier over a relatively short time-frame.

Donald D. Blankenship, lead principal investigator for the new ICECAP study noted:

“Totten Glacier’s catchment is covered by nearly 2½ miles of ice, filling a California-sized sub-ice basin that reaches depths of over one mile below sea level. This study shows that this system could have a large impact on sea level in a short period of time.”

Like many large glaciers around the world, a huge portion of Totten’s ice sits below sea level. This feature makes the glacier very vulnerable to ocean warming. Water carries far more latent heat than air and just a slight rise in local ocean water temperature can contribute to rapid ice loss. Totten itself rests in three large below sea level basins. And study authors found that 2 C to 5 C warming of local ocean waters with somewhat greater local air temperature increases was capable of flooding these basins in stages — forcing Totten’s glacial ice to flow out into the Southern Ocean and provide significant contributions to sea level rise.

Unfortunately, Totten is just one of many large glacial systems that are now destabilizing across Antarctica. And researchers are now beginning to identify significant potential sea level rise contributions from Antarctica alone (ranging from two feet to nearly two meters) before the end of this Century. In New Scientist, during March, Antarctic researcher Rob Deconto notes:

“Today we’re measuring global sea level rise in millimetres per year. We’re talking about the potential for centimetres per year just from [ice loss in] Antarctica.”

Centimeters per year sea level rise is about ten times faster than current rates and implies 100 year increases — once it gets going — in the range of 2 to 3 meters. Such increased melt does not include Greenland’s own potential sea level rise contribution. Nor does it include sea level rise from other glacial melt and ocean thermal expansion. As such, it appears that multi-meter sea level rise is becoming a more and more distinct possibility this Century. Furthermore, the paleoclimate context is now pointing toward catastrophic levels of overall melt and sea level rise if global greenhouse gasses aren’t somehow stabilized and then swiftly reduced.

Links:

Repeated Large-Scale Retreat and Advance of Totten Glacier Indicated by Inland Bed Erosion

The Totten Glacier

The Human-Warmed Southern Ocean Threatens Major Melt for East Antarctica

Fundamentally Unstable — Scientists Confirm Their Fears About East Antarctica’s Biggest Glacier

Potential Antarctic Ice Sheet Retreat Driven by Hydrofracturing and Ice Cliff Failure

Unstable East Antarctic Glacier Has Contributed to Sea Level Rise in the Past

Sea Levels Set to Rise Far More Rapidly Than Expected

Unexpected Antarctic Melt Could Trigger 2 Meter Sea Level Rise

Entering the Middle Miocene

The Middle Miocene

LANCE MODIS

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