Preventing a climate calamity is still possible.

 This is an informative video from Climate Adam.  He uses an analogy I've used before: a bathtub.  Virtually every year since 1850, the CO2 we push out into the atmosphere has risen.  Because the outflow from the atmosphere (natural carbon sinks) is less than what we're pumping into the air, the level of CO2 has risen.  Emissions have flatlined over the last 10 years, but they're still more than the removal of CO2 from the atmosphere via carbon sinks.  Using the analogy, the level of water (CO2) in the tub (atmosphere) is continuing to rise, just more slowly.  And thus temperatures continue to rise.  But if we could cut emissions so that they are the same as outflows, the level of water (CO2) would stop rising, and so would temperatures.

Adam makes the point that carbon sinks (where CO2 gets sucked out of the atmosphere) take up around 50% of emissions.  This is only a temporary help, because the carbon sinks (the sea, forests and marshes) are taking less and less out of the atmosphere.  They're filling up.  But it does mean that if we could cut emissions by 50%, the level of CO2 in the atmosphere, and therefore temperatures, would stop rising (or at least, rise more slowly), though we would still need to cut emissions over time to near zero.  It used to be thought that temperatures would go on rising for decades even after we achieved zero emissions, but this is no longer the scientific consensus.

Now, the good news is that together, emissions from electricity generation and land transport, on average across the world, are roughly 50% of total CO2 emissions.  If we could replace coal and gas in electricity generation, and convert the global car, lorry and bus fleets to electricity, we would have cut emissions by 50%.  In other words, stopping temperatures rising is achievable, and achievable over the next decade.  We would still have to achieve zero emissions, because with the oceans, the carbon sink reduction (the oceans offset and bury CO2) is offset by their thermal inertia — they will continue to release heat into the atmosphere as long as they are cooler than the atmosphere.   But switching to renewables and EVs would give us time to cut emissions from all the other more difficult sectors like cement, steel, air and sea transport and agriculture.

The other climate-warming gas Adam talks about is methane.  Methane comes from gas leaks, rubbish dumps, and cattle and sheep.  Methane has been rising fast, and shows no signs of peaking.  Over a ten-year time frame, methane is 80 times as potent a greenhouse gas as CO2.  But it quickly decays into CO2, so if we could cut methane emissions, the effects would be rapid.  One third of the rise in temperatures since pre-industrial times is from methane.  So, as we replace gas in electricity generation (and we will for now still need 5 - 10% gas generation to cover dunkelflaute events, because we don't have workable long-term storage), gas leaks will fall.  There are super emitters of methane from rubbish dumps.  And that's easy to stop: just cover your rubbish dumps with a thick layer of earth.  Finally, each of us can avoid beef, mutton and milk.  That's something we can directly do to cut emissions.  Turning vegetarian could be your single biggest step to cutting emissions!  (Buying an EV is another.)

The moral of all this is that we are far from helpless.  CO2 emissions have peaked.  Our task is to bend that curve down, until the level of CO2 in the atmosphere also peaks.  We have to turn the CO2 and methane taps off, and then we will actually be able to avoid a catastrophic climate future.

(One really scary factor driving increasing emissions is AI datacentres.  We need to stop their construction.  Now.)

Nature's carbon sinks start to fail

Firefighters battling the Tsah Creek wildfire in British Columbia. Last year’s wildfires in Canada released as much carbon as six months of US fossil-fuel emissions. Photograph: J Winter/Guardian

From The Guardian

It begins each day at nightfall. As the light disappears, billions of zooplankton, crustaceans and other marine organisms rise to the ocean surface to feed on microscopic algae, returning to the depths at sunrise. The waste from this frenzy – Earth’s largest migration of creatures – sinks to the ocean floor, removing millions of tonnes of carbon from the atmosphere each year.

This activity is one of thousands of natural processes that regulate the Earth’s climate. Together, the planet’s oceans, forests, soils and other natural carbon sinks absorb about half of all human emissions.

But as the Earth heats up, scientists are increasingly concerned that those crucial processes are breaking down.

In 2023, the hottest year ever recorded, preliminary findings by an international team of researchers show the amount of carbon absorbed by land has temporarily collapsed. The final result was that forest, plants and soil – as a net category – absorbed almost no carbon.

There are warning signs at sea, too. Greenland’s glaciers and Arctic ice sheets are melting faster than expected, which is disrupting the Gulf Stream ocean current and slows the rate at which oceans absorb carbon. For the algae-eating zooplankton, melting sea ice is exposing them to more sunlight – a shift scientists say could keep them in the depths for longer, disrupting the vertical migration that stores carbon on the ocean floor.

“We’re seeing cracks in the resilience of the Earth’s systems. We’re seeing massive cracks on land – terrestrial ecosystems are losing their carbon store and carbon uptake capacity, but the oceans are also showing signs of instability,” Johan Rockström, director of the Potsdam Institute for Climate Impact Research, told an event at New York Climate Week in September.

“Nature has so far balanced our abuse. This is coming to an end,” he said.

The 2023 breakdown of the land carbon sink could be temporary: without the pressures of drought or wildfires, land would return to absorbing carbon again. But it demonstrates the fragility of these ecosystems, with massive implications for the climate crisis.

Reaching net zero is impossible without nature. In the absence of technology that can remove atmospheric carbon on a large scale, the Earth’s vast forests, grasslands, peat bogs and oceans are the only option for absorbing human carbon pollution, which reached a record 37.4bn tonnes in 2023.

At least 118 countries are relying on the land to meet national climate targets. But rising temperatures, increased extreme weather and droughts are pushing the ecosystems into uncharted territory.

The kind of rapid land sink collapse seen in 2023 has not been factored into most climate models. If it continues, it raises the prospect of rapid global heating beyond what those models have predicted.

For the past 12,000 years, the Earth’s climate has existed in a fragile equilibrium. Its stable weather patterns allowed the development of modern agriculture, which now supports a population of more than 8 billion people.

As human emissions rose, the amount absorbed by nature increased too: higher carbon dioxide can mean plants grow faster, storing more carbon. But this balance is beginning to shift, driven by rising heat.

“This stressed planet has been silently helping us and allowing us to shove our debt under the carpet thanks to biodiversity,” says Rockström. “We are lulled into a comfort zone – we cannot really see the crisis.”

Only one major tropical rainforest – the Congo basin – remains a strong carbon sink that removes more than it releases into the atmosphere. Exacerbated by El Niño weather patterns, deforestation and global heating, the Amazon basin is experiencing a record-breaking drought, with rivers at an all-time low. Expansion of agriculture has turned tropical rainforests in south-east Asia into a net source of emissions in recent years.

Emissions from soil – which is the second-largest active carbon store after the oceans – are expected to increase by as much as 40% by the end of the century if they continue at the current rate, as soils become drier and microbes break them down faster.

Tim Lenton, professor of climate change and Earth system science at Exeter University, says: “We are seeing in the biosphere some surprising responses that are not what got predicted, just as we are in the climate.

“You have to question: to what degree can we rely on them as carbon sinks or carbon stores?” he says.

A paper published in July found that while the total amount of carbon absorbed by forests between 1990 and 2019 was steady, it varied substantially by region. The boreal forests – home to about a third of all carbon found on land, which stretch across Russia, Scandinavia, Canada and Alaska – have seen a sharp fall in the amount of carbon they absorb, down more than a third due to climate crisis-related beetle outbreaks, fire and clearing for timber.

Combined with the declining resilience of the Amazon and drought conditions in parts of the tropics, the hot conditions in the northern forests helped drive the collapse of the land sink in 2023 – causing a spike in the rate of atmospheric carbon.

“In 2023 the accumulation of CO2 in the atmosphere is very high and this translates into a very, very low absorption by the terrestrial biosphere,” says Philippe Ciais, a researcher at the French Laboratory of Climate and Environmental Sciences, who was an author of the most recent paper.

“In the northern hemisphere, where you have more than half of CO2 uptake, we have seen a decline trend in absorption for eight years,” he says. “There is no good reason to believe it will bounce back.”

The oceans – nature’s largest absorber of CO2 – have soaked up 90% of the warming from fossil fuels in recent decades, driving a rise in sea temperatures. Studies have also found signs that this is weakening the ocean carbon sink.

“Overall, models agreed that both the land sink and the ocean sink are going to decrease in the future as a result of climate change. But there’s a question of how quickly that will happen. The models tend to show this happening rather slowly over the next 100 years or so,” says Prof Andrew Watson, head of Exeter University’s marine and atmospheric science group.

“This might happen a lot quicker,” he says. “Climate scientists [are] worried about climate change not because of the things that are in the models but the knowledge that the models are missing certain things.”

Many of the latest Earth systems models used by scientists include some of the effects of global heating on nature, factoring in impacts such as the dieback of the Amazon or slowing ocean currents. But events that have become major sources of emissions in recent years have not been incorporated, say scientists.

“None of these models have factored in losses like extreme factors which have been observed, such as the wildfires in Canada last year that amounted to six months of US fossil emissions. Two years before, we wrote a paper that found that Siberia also lost the same amount of carbon,” says Ciais.

Mankind has been spewing CO2 into the atmosphere for more than a century, confident that Nature would deal with it.  But this is no longer happening.  We need to accelerate our efforts to slash carbon emissions.  Meanwhile at the COP29, the latest climate gabfest, lobbyists from oil and gas companies continue to try to stop moves away from carbon fuels, and governements pretend to care.

The carbon offset scam

This very interesting video from Deutsche Welle, Germany's equivalent of the BBC (don't worry, it's in English) explains what carbon offsets are, and how many of them are scams.  For example, you buy a carbon offset which funds protection of a natural forest.  And 10 years later the forest has been cleared.   Does the offset scheme get its money back?  Fat chance.  Or a planted forest gets burnt down, and all the embedded carbon is re-released into the atmosphere.   Or offset money is used to build new wind and solar farms, but they were going to be built anyway.  Something like 85-90% of offsets actually do not reduce emissions at all.

But some are good.  The rewilding of marshland that the video starts off with is a real offset.  The scheme in Iceland for turning carbon into rock is real:  carbon dioxide is permanently removed from the atmosphere.  But most are fake.

The video concludes with 3 useful points.  First, if it's a real carbon offset, it'll prolly be expensive.  Second, we will need real carbon offsets in the future to keep temperatures from rising past 1.5 degrees above pre-industrial levels.  Third, we can't offset our way to zero emissions.  We have to actually cut emissions, by replacing petrol/diesel cars and light trucks with EVs; by switching to renewables electricity generation; and by using green hydrogen or methane in industrial processes. 

Rewilding two UK fields

 From ZME Science:

With no special equipment, no fences, and no watering, two abandoned agricultural fields in the UK have been rewilded, in large parts due to the efforts of jays, which virtually “engineered” these new woodlands. Researchers now hope that rewilding projects can take a more natural and hands-off approach — and that jays can shed some of their bad rep.

The two fields, which researchers have dubbed the New Wilderness and the Old Wilderness, had been abandoned in 1996 and 1961 respectively. The former was a barley field, while the latter was grassland — both were adjacent to ancient woodland. Researchers had suspected that the fields would gradually return to wilderness, but it was impressive to see just how quickly this happened, and how much of it was owed to birds.

Using aerial data, the researchers monitored the two sites. After just 24 years, the New Wilderness had grown into a young, healthy wood with 132 live trees per hectare, over half of which (57%) were oaks. Meanwhile, the Old Wilderness resembled a mature woodland after 39 years, with 390 trees per hectare.

“This native woodland restoration was approaching the structure (but not the species composition) of long-established woodlands within six decades,” the researchers explain in the study.

Part of this reforestation was done by wind, and researchers suspect that previous ground disturbance may have aided the woodland establishment — which is good news, as it would suggest that agricultural areas may be reforested faster than anticipated. However, animals — and in particular Eurasian jays, thrushes, wood mice, and squirrels — were also essential in helping the forests take shape. This handful of species provided much of the natural regeneration needed for the forest to develop. Jays, in particular, seem to have done a lot of heavy lifting.

Eurasian Jay (Garrulus glandarius). Image credits: Luc Viatour.

But just because land can rewild itself in time doesn't mean that a bit of help wouldn't make the process faster.  In my own experience, planting a copse on bare land where the topsoil had been removed,  spreading grass clippings on the subsoil transformed the soil, with grass (which stops the soil drying out and washing away) covering the bare earth in 2 seasons.

We will need to plant billions of trees to soak up CO2.  This story suggests that that nature will help us if she is given a chance.  Plus....hooray for jays.

Global heating lag

 Just as with the lag between the midday peak of insolation and the afternoon peak in temperatures, and the summer solstice peak in June/December (depending on hemisphere) and the temperature peak one or two months later, so it has been believed that even if  we cut emissions to zero, global temperatures will continue rising for several more decades because of lags built into the system.

Recent research suggests that this might not be the case, which is good news, if true.  Not, note, because there aren't lags, but because 'carbon sinks' (like the sea) will absorb some of the CO2 from the atmosphere.  And anyway, temperatures will continue to rise "for a couple of decades."   

From The Guardian:

For many years it was assumed that further global heating would be locked in for generations even if emissions were rapidly cut. Climate models run by scientists on future temperatures were based on a certain carbon dioxide concentration in the atmosphere. If this remained at the current high level there would be runaway climate disaster, with temperatures continuing to rise even if emissions were reduced because of a lag time before greenhouse gases accumulate in the atmosphere.

But more recent understanding of the implications of getting to net zero emissions is giving hope that the warming could be more swiftly curtailed.

Should this be achieved globally, “surface temperatures stop warming and warming stabilizes within a couple decades,” said Michael Mann, a climate scientist at Pennsylvania State University. “What this really means is that our actions have a direct and immediate impact on surface warming. It grants us agency, which is part of why it is so important to communicate this current best scientific understanding.”

Scientists have now factored in the dynamism of the Earth’s natural systems, whereby stopping emissions would actually see atmospheric CO2 content go down due to the huge carbon absorption capacity of oceans, wetlands and forests. Mann likens it to filling up a sink with water with the drain partially open – the water level will still rise due to the incoming water but if you reduce the water flow it will drop due to the drain remaining open.

“This falling atmospheric CO2 causes enough cooling to balance out the warming ‘in the pipeline’ due to slow ocean heat uptake, and global temperatures remain relatively flat after net-zero emissions are reached,” said Zeke Hausfather, a climate expert at the Breakthrough Institute. “The main takeaway for me is that this is good news, because it means that how much warming happens this century and beyond is up to us.”

This would give civilization time to adapt to the changes or come up with technological fixes. “At the moment we are changing the temperature a hundred times faster than what happened in the last ice age,” said Andrew Dessler, a climate scientist at Texas A&M University and co-author of the paper, published in Nature Climate Change. “An extra degree in a few hundred years is far less damaging than a degree in a few decades. The timescale is important.”

[Read more here]

Source: The BBC

Oceans likely to belch CO2 as they warm

This is another of those tipping points.  So far, a quarter of the CO2 we've generated each year has dissolved into the ocean, and the scary rise in temperatures we've seen comes from the small proportion which has remained in the atmosphere.  But what if the oceans start to release their stores of CO2 as they heat up?   

From ZME Science:

As oceans warm up due to climate change, they’ll likely start generating a lot of CO2.

Despite being the largest carbon sink active today, oceans might become net emitters under warmer climates, a new study reports. The paper reports that warmer oceans lose some of their ability to store carbon, which will accelerate the rate of CO2 regeneration in many areas of the world. This will further reduce the ocean’s ability to store carbon, the authors explain.  

“The results are telling us that warming will cause faster recycling of carbon in many areas, and that means less carbon will reach the deep ocean and get stored there,” said study coauthor Robert Anderson, an oceanographer at Columbia University’s Lamont-Doherty Earth Observatory.

Ocean water soaks up roughly 25% of our carbon dioxide emissions year after year. While this process also involves abiotic chemical and physical processes, the lion’s share of that CO2 is gobbled up by plankton through photosynthesis. But, all plankton must die eventually, and when they do, these tiny marine plants sink to the bottom of the ocean — and the carbon they ‘ate’ goes down with them. It’s estimated that plankton produces around 40 to 50 billion tons of dry, solid organic carbon each year.

Some of this organic matter (and the carbon therein) gets locked into the depths for centuries at a time, but part of it gets consumed by aerobic bacteria before sinking into oxygen-free waters, the team writes. Those bacteria then expel it as carbon dioxide, pushing it back into the atmosphere. Only about 15% of plankton-derived carbon sinks to the bottom of the sea, the authors estimate. They further report that the environmental conditions that allow bacteria to recycle carbon are spreading as water temperatures rise.

The team used data from a 2013 research cruise from Peru to Tahiti. They focused on two distinct regions: nutrient-rich, highly productive waters off South America, and the largely infertile bodies of water that form the South Pacific Gyre. Instead of using traditional sampling methods — simple devices that trap particles as they sink — the team pumped large amounts of water from different depths and isolated particles and thorium isotopes. This approach allowed them to calculate the quantity of carbon sinking at different depth intervals, they explain, and much more reliably so — the technique yielded far more data than the traditional traps.

In the oxygenated upper waters layers off South America, the team reports, oxygen gets used up very quickly. It is consumed completely at about 150 meters of depth, halting aerobic activity. Organic matter that reaches this layer (called the oxygen minimum zone, OMZ) will sink to the bottom of the ocean. In the depths, oxygen levels do increase again, and aerobic bacteria start breaking down organic matter. However, any CO2 produced down that far will take centuries to get back into the air via upwelling currents.

The OMZ thus forms a sort of protective cap over any organic matter that sinks past it, according to the team. The common wisdom of today, held that organic matter produced near the surface makes it through the OMZ, and that most CO2 regeneration takes place in the deep ocean. However, only about 15% of this matter sinks past the OMZ, the team shows.

“People did not think that much regeneration was taking place in the shallower zone,” said the study’s lead author, Frank Pavia, a graduate student at Lamont-Doherty. “The fact that it’s happening at all shows that the model totally doesn’t work in the way we thought it did.”

As mean water temperatures in the ocean increase, OMZs will spread both horizontally and vertically, covering larger areas of ocean at shallower depths, the team estimates. At the same time, higher temperatures will drive bacterial activity above the OMZs. On one hand, this would allow more organic matter to sink undegraded into the deep. However, the increased rate of CO2 regeneration near the surface will counteract this increased trapping, the team says. Whether near surface regeneration or the cap provided by the OMZ might have a stronger effect is still something we need to look into, they explain. However, this shift in OMZs is definitely not good news, as they are not at all suitable for most marine life — and this shift will affect a lot of today’s key fishing areas.

In the South Pacific Gyre, the results were less ambiguous. There is far more regeneration near the warmer surface than previously estimated in this area. The South Pacific Gyre and similar current systems in other parts of the oceans are projected to grow as the oceans warm. The gyres will divide waters into warmer layers (on the surface) and colder ones (deeper down). Because much of the CO2 regeneration will take place in the warm, shallower waters, CO2 regeneration will pick up over wide spans of ocean, the team explains. And, unlike below the nearer-shore OMZs, “there is no counterbalancing effect in the gyres,” said Anderson.

“The story with the gyres is that over wide areas of the ocean, carbon storage is going to get less efficient.” (There are four other major gyres: the north Pacific, the south and north Atlantic, and the Indian Ocean.)