Heads in the clouds while Earth is burning

Changes in clouds 

The high impact that changes in clouds have on the global temperature is becoming more and more clear as more scientific studies appear. Nonetheless, many people keep their heads in the clouds and act as if nothing is changing. 

[ James Hasen et al. Earth’s albedo (reflectivity, in percent), seasonality removed ]

[ James Hansen: Inferred contributions
to reduced Earth albedo ]

There are many reasons for this apathy. Loss of albedo due to loss of lower clouds, loss of sea ice and loss of the aerosol masking effect are all concepts that can be hard to grasp. As an example, the aerosol masking effect is getting progressively reduced, e.g. due to tightening shipping emissions regulations. The image above and on the right are by Hansen et al. 

For the average person, many effects of the temperature rise are also hard to notice, such as stronger ocean stratification and stronger wind. 

Feedbacks can be complex, e.g. decline of Arctic snow and ice comes with albedo loss as well as loss of the latent heat buffer, while Arctic amplification of the temperature rise can lead to changes in ocean currents and deformation of the Jet Stream. Compound impacts threaten to occur, such as formation of a lid at the surface of the North Atlantic Ocean enabling more heat to move to the Arctic Ocean, in turn causing huge amounts of methane to erupt from the seafloor, thus further contributing to the danger that the 1,200 ppm CO₂e cloud tipping point will get crossed that causes an extra 8°C rise, which this 2019 post warned about.

It is hard to reduce greenhouse gas emissions and to remove greenhouse gases from the atmosphere, while there also is a lag between carbon dioxide (CO₂) emissions and their maximum impact and a “lag time” between climate action and an actual decrease in CO₂ levels, due to transient growth as a result of delayed feedback. “It’s like trying to slow down an enormous train – you can’t stop it all at once, there will be a delay between applying the brakes and the train coming to a halt. And in talking about CO₂ levels, this could have catastrophic consequences,” explains Mahommad Farazmand, warning that even if CO₂ emissions decreased, transient growth would still push the climate into a tipping point, resulting in a temperature increase of 6°C.

One of the biggest causes why climate action is delayed, if not sabotaged, is the way climate change is or rather isn't reported in the media. In the video below, Paul Beckwith discusses the analysis by Hansen et al.

Further below, this post looks at two conditions that enable loss of lower clouds, i.e. high concentrations of greenhouse gases that result in higher temperatures and loss of sea ice. 

High concentrations of greenhouse gases

Daily CO₂ concentrations have been below 430 parts per million (ppm) only once over the past 31 days at Mauna Loa, Hawaii, as illustrated by the image below, which shows CO₂ through May 20, 2025. The image also shows one recent hourly measurement approaching 440 ppm (arrow).

A daily CO₂ concentration of 431.25 ppm was recorded on May 10, 2025, at Mauna Loa, Hawaii, the highest daily average on record. One has to go back millions of years in time to find CO₂ concentrations this high, while the impact of high CO₂ concentrations back in history was lower due to lower solar output and while the rate of change was also much slower, as also discussed in an earlier post.

The image below shows monthly CO₂ concentrations at Mauna Loa, Hawaii. 

High concentrations of greenhouse gases lead to high temperatures and the temperature rise itself comes with many feedbacks including more water vapor in the atmosphere, loss of sea ice and loss of lower clouds. 

In the image below, a value of 430 ppm CO₂ has been manually added as a potential value for 2025 (blue circle), but this value is not included in the calculation of the trend, which is based only on 2019 through 2024 data (red circles). The trend points at the clouds tipping point at 1200 ppm CO₂ getting crossed in 2030. Crossing this tipping point could - on its own - push temperatures up by 8°C globally, in addition to the temperature rise caused by the extra CO₂ to reach the tipping point.

Moreover, the clouds tipping point is actually at 1200 ppm CO₂e (carbon dioxide equivalent), so when taking into account the impact of growth of other greenhouse gases and further mechanisms, the tipping point could be crossed much earlier than in 2030. The clouds tipping point is also discussed in the section at the end of this post. 

Temperature

The image below illustrates that air temperatures in the Northern Hemisphere have been very high for the past few months, at times reaching record high temperatures for the time of year, e.g. the temperature in the Northern Hemisphere was 10.08°C on May 14, 2025, the highest temperature on record for that day.

These record high temperatures are the more significant as they were reached under ENSO-neutral conditions, as illustrated by the image below. On May 20, 2025, the sea surface temperature was 27.65°C, 0.19°C below 1991-2020, in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño. 

Loss of sea ice

One feedback of high temperatures and high concentrations of greenhouse gases is loss of sea ice. Polar amplification of the temperature rise is hitting the Arctic hard, and is also causing dramatic loss of Antarctic sea ice. Global sea ice area has been very low for the past few years, as illustrated by the image below. This has caused a lot of sunlight that was previously reflected back into space, to instead get absorbed by the sea surface. On May 20, 2025, global sea ice area was 17.6 million km², lowest on record for the day. 

Over the past few days, Arctic sea ice area has been second lowest for the time of year, Arctic sea ice area was only lower around this time of year in 2016, a strong El Niño year, as illustrated by the image below.

The above image also shows that Arctic sea ice area around this time of year was much lower than it was in 2012, the year when Arctic sea ice would reach a record low later that year (2.24 million km² on September 12, 2012). 

[ click on images to enlarge ]

The image on the right is adapted from NASA and shows anomalies versus 1951-1980 of up to almost 4°C. The image also shows that the Arctic is heating up much faster than the rest of the world, a phenomenon also known as accelerated Arctic temperature rise.

The next image on the right illustrates how two of these feedbacks contribute to the accelerated Arctic temperature rise:

[ Two out of numerous feedbacks ]

Feedback #1: albedo loss as sea ice melts away and as it gets covered by soot, dust, algae, meltpools and rainwater pools;

Feedback #19: distortion of the Jet Stream as the temperature difference narrows between the Arctic and the Tropics, in turn causing further feedbacks to kick in stronger, such as hot air moving into the Arctic and cold air moving out, and more extreme weather events bringing heavier rain and more intense heatwaves, droughts and forest fires that cause black carbon to settle on the sea ice.

Arctic sea ice volume has been at a record low for more than a year, as illustrated by the image below.

Loss of sea ice and loss of lower clouds are self-amplifying feedbacks, i.e. as temperatures rise, there is loss that accelerates the temperature rise, which in turn causes even more loss, etc. Due to this self-amplification, the temperature rise can accelerate. For more, also have a look at the Feedback section of this 2024 post, the Feedbacks page, and the section below. 

Loss of lower clouds

A 2024 study led by Norman Loeb finds that large decreases in stratocumulus and middle clouds over the sub-tropics and decreases in low and middle clouds at mid-latitudes are the primary reasons for increasing absorbed solar radiation trends in the northern hemisphere.

For years studies have pointed at the danger that, as temperatures rise, the rise itself can cause a reduction in lower clouds. Since lower clouds reflect a lot of sunlight back into space, their decrease is in turn pushing up and accelerating the temperature rise.

Earlier studies include this 2015 study, this 2017 study and this 2022 study. The image below is from a 2021 study led by Goode that warns that warming oceans cause fewer bright clouds to reflect sunlight back into space, resulting in the Earth's surface absorbing more energy instead. 

The image below shows the Pattern Effect, illustrating the danger that oceans are becoming less able to take up heat, thus leaving more heat in the atmosphere, which will in turn result in loss of lower clouds. 

The white band around -60° (South) indicates that the Southern Ocean has not yet caught up with global warming, featuring low-level clouds that reflect a lot of sunlight back into space. Over time, these low clouds will decrease, resulting in more sunlight getting absorbed by the Earth's surface and causing  additional global warming. A 2021 study led by Zhou finds that, after this 'pattern effect' is accounted for, committed global warming at present-day forcing rises by 0.7°C.

The combination image below is from a 2022 study led by Barkhordarian. Forcing by elevated well-mixed GHG levels has virtually certainly caused the multiyear persistent 2019–2021 marine heatwave. The warming pool is marked by concurrent and pronounced increase in annual mean, and variance of SSTs (Figure below left) and decrease in cold-season low-cloud’s cooling effect. EUMETSAT satellite data shows a 5% decade⁻¹ decreasing trend in cold-season cloud cover during 1995–2018 (Figure below right). Low-cloud cover reduction is the major contribution to the observed decline in total cloud fraction, resulting in decreases of winter-time low-cloud’s cooling effect.

What makes loss of lower clouds so dangerous is that it can continue, even if emissions remain constant. So, where loss of sea ice continues while emissions remain constant, the temperature can keep rising, and as the temperature rise results in further loss of lower clouds, this will accelerating the temperature rise.

[ the temperature in the atmosphere can keep rising, even in the absence of further emissions ]

The above image also illustrates how the temperature of the atmosphere can keep rising, even in the absence of further emissions, due to shrinking of heat sinks, such as loss of sea ice thickness or oceans taking up less heat, or as certain thresholds or tipping points get crossed.  

Clouds Tipping Point

The clouds tipping point refers to abrupt disappearance of lower clouds, more specifically the stratocumulus decks. Stratus cloud decks cover about 20% of subtropical oceans and are prevalent in the eastern portions of those oceans—for example, off the coasts of California or Peru. The clouds cool and shade Earth as they reflect the sunlight that hits them back into space. Tapio Schneider et al. (2019) calculate that these clouds begin to break up when carbon dioxide equivalent (CO₂e) levels rise above the tipping point of 1,200 ppm.

Disappearance of these clouds will make the temperatures go up strongly and rather abruptly. By the time CO₂e levels will have risen to this clouds tipping point of 1,200 ppm CO₂e, temperatures will already have gone up a lot in line with the warming from rising CO₂e levels and feedbacks. On top of this, the clouds feedback itself triggers an additional surface warming of some 8°C globally, which is a tipping point and once crossed, it's very hard to revert, i.e. CO₂e would have to fall by a huge amount for lower clouds to reappear. 

Climate Emergency Declaration

The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as also discussed at this group.

Links

• Global warming in the pipeline - by James Hansen et al. (2023)

https://academic.oup.com/oocc/article/3/1/kgad008/7335889

• Large Cloud Feedback Confirms High Climate Sensitivity - by James Hansen et al. (2025)

https://www.columbia.edu/~jeh1/mailings/2025/CloudFeedback.13May2025.pdf

• Maximum warming occurs about one decade after a carbon dioxide emission - by Katharine Ricke et al. (2014) 
https://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002

• News release: Time Lag Between Intervention and Actual CO2 Decrease Could Still Lead to Climate Tipping Point (2021)
https://news.ncsu.edu/2021/12/time-lag-could-still-lead-to-climate-tipping-point
• Study: Investigating climate tipping points under various emission reduction and carbon capture scenarios with a stochastic climate model - by Alexander Mendez et al. (2021)
https://royalsocietypublishing.org/doi/10.1098/rspa.2021.0697
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10159745007124679

• NOAA - Daily Average Mauna Loa CO2
https://gml.noaa.gov/ccgg/trends/monthly.html

• NOAA - Mauna Loa - Carbon Cycle Gases 

https://gml.noaa.gov/dv/iadv/graph.php?code=MLO&program=ccgg&type=ts

• Kevin Pluck - seaice.visuals.earth
https://seaice.visuals.earth

• Observational Assessment of Changes in Earth’s Energy Imbalance Since 2000 - by Norman Loeb et al. (2024) 
https://link.springer.com/article/10.1007/s10712-024-09838-8

discussed on facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10161449934634679

• Positive tropical marine low-cloud cover feedback inferred from cloud-controlling factors - by Xin Qu et al. (2015)
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2015GL065627

• Interpretation of Factors Controlling Low Cloud Cover and Low Cloud Feedback Using a Unified Predictive Index - by Hideaki Kawai et al. (2017)
https://journals.ametsoc.org/view/journals/clim/30/22/jcli-d-16-0825.1.xml

• Estimated cloud-top entrainment index explains positive low-cloud-cover feedback - by Tsuyoshi Koshiro et al. (2022)
https://www.pnas.org/doi/10.1073/pnas.2200635119

• News release: Earth is dimming due to climate change 
Warming oceans cause fewer bright clouds to reflect sunlight into space, admitting even more energy into earth's climate system
https://news.agu.org/press-release/earth-is-dimming-due-to-climate-change
• Study: Earth's Albedo 1998–2017 as Measured From Earthshine - by Philip Goode et al. (2021)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL094888
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10159604016414679

• NASA - zonal means
https://data.giss.nasa.gov/gistemp/zonal_means

• News release: Paying for emissions we’ve already released
https://www.llnl.gov/news/paying-emissions-weve-already-released
• Study: Greater committed warming after accounting for the pattern effect - by Chen Zhou et al. (2021)
https://www.nature.com/articles/s41558-020-00955-x
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10159009753799679
and at:
https://www.facebook.com/SamCarana/posts/10164808484750161
and in the post at:
https://arctic-news.blogspot.com/2021/01/2020-hottest-year-on-record.html

• News release: Systematic warming pool discovered in the Pacific due to human activities
https://www.cliccs.uni-hamburg.de/about-cliccs/news/2022-news/2022-06-21-pm-marine-heat-waves.html
• Study: Recent marine heatwaves in the North Pacific warming pool can be attributed to rising atmospheric levels of greenhouse gases - by Armineh Barkhordarian et al. (2022)
https://www.nature.com/articles/s43247-022-00461-2
discussed on facebook at:
https://www.facebook.com/groups/arcticnews/posts/10160085259739679

and in the post at: 
https://arctic-news.blogspot.com/2023/05/will-there-be-arctic-sea-ice-left-in-september-2023.html

Possible climate transitions from breakup of stratocumulus decks under greenhouse warming - by Tapio Schneider et al. (2019)
https://www.nature.com/articles/s41561-019-0310-1

• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html

Crossing 1.5C - On track toward an uninhabitable Earth

by Andrew Glikson

“… but they can be sure that they won't be recorded for their crimes in history -- because there won't be any history” (Noam Chomsky, 2023)

The macabre criminality of world’s so-called leaders, coupled with the ignorant compliance of a majority of the victims of global heating and potential nuclear annihilation, belong to the inconceivable. It is not clear whether any climate scientists are left to whom governments are listening, for if they did, they would learn that the intensification of extreme weather events currently and later in the century is bound to render large parts of the planet uninhabitable. In particular of islands ravaged by cyclones and sea level rise, extensive tropical and subtropical coastal zones and lands subjected to storms, floods, draughts and fires, in Africa, Australia and India. Polar-sourced cold fronts crossing the weakening jet stream boundary are already disrupting North America, Siberia and Europe, as are warm air masses penetrating the Arctic circle.

Distracted by a series of horrific bloodsheds induced by toxic masculinity of alpha males around the world, propagated by the “media”, the multitudes are only dimly aware of the oncoming climate carnage, orders of magnitude bigger than currently forecast.

According to leading climate scientists like James Hansen and his colleagues: “Without major action to reduce emissions, global temperature is on track to rise by 2.5°C to 4.5°C by 2100” (NASA 2023). It is far from clear whether anything can be done to arrest or reverse global heating, for as temperatures rise so is the production of fossil fuels enhanced by science-ignorant hordes of politicians and economists oblivious to the basic laws of physics. Alternative clean energy without sharp cuts in fossil fuel combustion can hardly stem global heating.

[ Figure. 1. Daily surface temperature analysis from the ECMWF reanalysis version 5 (ERA5). ]

December was the 7th consecutive month of record-shattering global temperature (Figure 1.), driven by the combination of a moderately strong El Nino and a large decrease of Earth’s albedo. Hansen et al. (2024) expect record monthly temperatures to continue into mid-2024, due to the present large planetary energy imbalance, with the 12- month running-mean global temperature reaching +1.6-1.7°C relative to 1880-1920. It will be clear that the 1.5°C ceiling has been passed for all practical purposes, and that the mean global temperature is currently accelerating toward 2.0°C above pre-industrial temperature by the middle of the decade (Figure 2), while the Arctic has been warming nearly four times faster than the rest of the world over the last 43 years, on average around 3℃ warmer than it was in 1980. Over the past 30 years Antarctica has been one of the fastest-changing places on Earth, warming more than 3 times than the rest of the world.

[ Figure. 2. Global temperature relative to 1880-1920 based on the GISS analysis
(Goddard Institute of Space Studies) analysis - by James Hansen et al., 2024. ]

A projection by NOAA states: “While we cannot stop global warming overnight, we can slow the rate and limit the amount of global warming by reducing human emissions of heat-trapping gases and soot (“black carbon”). Unfortunately, this projection takes neither the amplifying feedback, i.e. from warming oceans, melting ice sheets, migrating climate zones and melting of methane, nor the time factor into account.

A factor rarely taken into account emerges from Hansen et al. (1996)'s paper “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modelling, and modern observations that 2°C global warming could be dangerous” (Figure 3). Here the flow of cold ice melt water results in formation of large cold-water pools of in the Atlantic and Southern oceans, inducing a contraction of the tropical climate zone and an overall decline in mean global temperatures. The collision between the cold air and water fronts and the tropical warm air mass would lead to severe storms over large tracts of Earth.

Likely transient respites in global warming (stadials) may take place over the next few centuries or longer, when the flow of cold ice-melt water from the Greenland and Antarctica ice sheets (Bronselaer et al., 2018; Glikson, 2019) reduces the mean rate of warming, although this may occur too late for civilization (Figure 3).

[ Figure 3. Surface air temperature (°C) relative to 1880-1920 for several scenarios - by James Hansen et al. 2016.
Future model transient cooling periods consequent on flow of ice meltwater from Greenland and Antarctica into oceans ]

The criminal insanity of political, military, strategic, economic leaders, matched by the blindness of billions, supports what has been referred to as Fermi’s Paradox ─ where the apparent absence of signals from technological civilizations in the Milky Way, may be explained in terms of a self-destruction of such civilizations.

Having ignored climate science, dismissed or fired climate scientists and repeatedly confected lies, while global heating accelerates with deleterious consequences, Homo “sapiens” is finding itself on track toward carbon poisoning of the atmosphere, the lungs of the inhabitable Earth, acidification of the hydrosphere and coating of the land with carbon and plastics.

A/Prof. Andrew Y Glikson
Earth and Paleo-climate scientist

Andrew Glikson

Books:

The Asteroid Impact Connection of Planetary Evolution
https://www.springer.com/gp/book/9789400763272
The Archaean: Geological and Geochemical Windows into the Early Earth
https://www.springer.com/gp/book/9783319079073
The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
https://www.springer.com/gp/book/9783319572369
The Event Horizon: Homo Prometheus and the Climate Catastrophe
https://www.springer.com/gp/book/9783030547332
Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
https://www.springer.com/gp/book/9783319225111
Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
https://www.springer.com/gp/book/9789400773318
From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence
https://www.springer.com/us/book/9783030106027
Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
https://www.springer.com/us/book/9783319745442
The Fatal Species: From Warlike Primates to Planetary Mass Extinction
https://www.springer.com/gp/book/9783030754679
The Trials of Gaia. Milestones in the evolution of Earth with reference to the Antropocene
https://www.amazon.com.au/Trials-Gaia-Milestones-Evolution-Anthropocene/dp/3031237080

A climate of Insanity

by Andrew Glikson

As the emission of greenhouse gases continues, new fossil fuel projects are subsidized, global warming accelerates, bushfires and floods engulf the planet, climate science is ignored, climate change projections are kept away from the public eye, nations invest in killer submarines rather than water spraying aircraft and other fire-fighting equipment, politicians talk about clean coal, radioactive waters are spilled into the ocean, nuclear weapons are readied for a MAD scenario, the media reports sugar-coated semi or untruths, politicians routinely betray their original pledges and playboy billionaires fire rockets at space with plans to settle on Mars.

Inherent in the nature of insanity is the fact that those inflicted by it are unaware of their mental state, nor are crowds of people or for that matter political parties, and business elites, leading populations to catastrophe, from the scale of Jonestown all the way to Auschwitz and Berlin to Vietnam, Iraq and Afghanistan.

Which has now reached a planet-wide scale. According to NASA former chief climate scientist James Hansen, the global temperature in the current El Niño is exceeding the previous El-Niño (2015-16) temperature rise rate of 0.18°C per decade, reflecting the current increase of the Earth Energy Imbalance (EEI) and accelerated heating. The change is in part due to reductions of the cooling effect of human-emitted aerosols (Figure 1). 

Figure 1. Global temperature (relative to 1880-1920 mean for each month) during the El Niño origin year for the 1997-98, 2015-16 and 2023-24 El Niños. The impact of El Niño on global temperature usually peaks early in the year following the year when the El Niño originated. Hansen et al., 2023.

Despite consequent acidification of the oceans, atmospheric geoengineering using sulphur aerosols, reflecting solar radiation, is touted as a last defence from extreme temperature rise. To date, no effective method has been applied to a drawdown of greenhouse gases on a scale required to compensate for the emissions and rise in atmospheric CO₂ (Figure 2). 

Figure 2. Source: https://ourworldindata.org/fossil-fuels#global-fossil-fuel-consumption

Energy-related greenhouse gas emissions have started to grow again, following minor Covid lockdown-related reductions in 2020 (Figure 3).

Figure 3. Global energy-related greenhouse gas emissions 2000-2022, adapted from EIA.

A rise to a mean global temperature to 3°C and 4°C this century is projected by the IPCC. Possibly even before such temperatures are reached, the flow of cold ice melt water from Greenland and Antarctica could lead to transient regional to global temperature reversals (Hansen et al., 1998; Bronselaer et al. 2018). These authors state: “Meltwater from the Antarctic Ice Sheet is projected to cause up to one metre of sea-level rise by 2100 under the highest greenhouse gas concentration trajectory (RCP8.5) considered by the Intergovernmental Panel on Climate Change (IPCC). However, the effects of meltwater from the ice sheets and ice shelves of Antarctica are not included in the widely used CMIP5 climate models, which introduces bias into IPCC climate projections.” (Figure 4)

Figure 4. (a) Model surface air temperature (°C) change in 2055–2060 relative to 1880–1920 for modified
             forcings representint the rise of temperatures in the tropics and decline in subpolar latitudes.
           (b) Surface air temperature (°C) relative to 1880-1920 for several ice melt scenarios, representing stadial
        (cooling) episodes related to the effects of ice melt (Hansen et al., 2016) and associated changes.

According to Hansen et al. (2012) “Burning all fossil fuels would create a different planet than the one that humanity knows. The paleoclimate record and ongoing climate change make it clear that the climate system would be pushed beyond tipping points, setting in motion irreversible changes, including ice sheet disintegration with a continually adjusting shoreline, extermination of a substantial fraction of species on the planet, and increasingly devastating regional climate extremes”.

The habitability of Earth and the future of life are issues that are to a large extent avoided by the largely privately-owned corporate media and even by state media, occupied as they are by advertisements, sports contests, fashion parades, cooking shows and popular frenzies such as recently generated by the kissing of a football cup winner.

Is there a way out for humanity and much of nature?

If the multiple $trillions spent by Sapiens on the military and war were directed to environmental defence, including drawdown of atmospheric greenhouse gases, the possibility exists?

A/Prof. Andrew Y Glikson
Earth and Paleo-climate scientist

Andrew Glikson

Books:
The Asteroid Impact Connection of Planetary Evolution
https://www.springer.com/gp/book/9789400763272
The Archaean: Geological and Geochemical Windows into the Early Earth
https://www.springer.com/gp/book/9783319079073
The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
https://www.springer.com/gp/book/9783319572369
The Event Horizon: Homo Prometheus and the Climate Catastrophe
https://www.springer.com/gp/book/9783030547332
Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
https://www.springer.com/gp/book/9783319225111
Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
https://www.springer.com/gp/book/9789400773318
From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence
https://www.springer.com/us/book/9783030106027
Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
https://www.springer.com/us/book/9783319745442
The Fatal Species: From Warlike Primates to Planetary Mass Extinction
https://www.springer.com/gp/book/9783030754679
The Trials of Gaia. Milestones in the evolution of Earth with reference to the Antropocene
https://www.amazon.com.au/Trials-Gaia-Milestones-Evolution-Anthropocene/dp/3031237080

Accelerating loss of global snow and ice cover

Ocean heat is at record levels. As a result, global sea ice extent was only 16.23 million km² on February 9, 2022, the third lowest extent on record. What makes this even more worrying is that we're currently in the depth of a persistent La Niña.

Antarctic sea ice at lowest extent on record since start satellite measurements

Ocean heat is a huge threat for Antarctica at the moment. The image below shows that Antarctic sea ice extent was only 2.091 million km² on February 16, 2022, the lowest on record since the start of satellite measurements.

Ocean heat is reducing the sea ice around Antarctica and is getting underneath floating sea ice. 

The Thwaites Glacier, which is on a retrograde slope, is especially vulnerable to collapse. 

The Thwaites Glacier contains enough ice to raise global sea levels by 65 cm (25.59 inches) if it were to completely collapse.

The animation on the right, created with images from Climate Reanalyzer, shows the retreat of the Antarctic snow and ice cover from January 5 to February 18, 2021. 

The animation underneath, by navy.mil, shows sea ice thickness over 30 days up to February 17, 2022 (with 8 days of forecasts added).

Another danger of a rapid loss of the snow and ice cover on Antarctica is release of methane. Jemma Wadham warned about this in a 2012 study, as discussed at the post methane hydrates. More recently, Jemma Wadham said: “We are sleepwalking into a catastrophe for humanity.”

The Thwaites Glacier is often called the Doomsday Glacier because if it collapses it would lead to vast sea level rise, and scientists believe it is likely to fail within a few years, says Cliff Seruntine (the Naturalist) in the video below. 

A recent study concludes that mountain glaciers may hold less ice than previously thought. Their disappearance means less water for drinking and agriculture, and faster temperature rises due to albedo loss. While the study found that the Himalayas contain more water than thought, another recent study, Mt. Everest’s highest glacier is a sentinel for accelerating ice loss, describes how human-induced climate change has a huge impact on the highest reaches of the planet.

The outlook for the Arctic is most threatening, as the post methane hydrates also concluded back in 2013, as described in numerous post here at Arctic-news and as discussed in the video below by Jim Massa.

A huge temperature rise threatens to unfold soon

Above image indicates that the difference between the top of El Niño and the bottom of La Niña could be more than half a degree Celsius.

As said, we're currently in the depth of a persistent La Niña, which suppresses temperatures. As the temperature keeps rising, ever more frequent strong El Niño events are likely to occur, as discussed in an earlier post. 

A 2019 study analyzes how tipping the ENSO into a permanent El Niño can trigger state transitions in global terrestrial ecosystems.

Currently, the temperature rise is additionally suppressed by low sunspots. Within a few years time, sunspots can be expected to reach the peak of their current cycle and observed sunspots are looking stronger than predicted. 

In the image below on the right, adapted from NOAA, the solar cycle is represented as the number of sunspots (top) and F10.7cm radio flux (bottom). 

In a recent communication, James Hansen repeats that, as reductions take place in the sulfate aerosols that are currently co-emitted by traffic, transport and industry, this is causing the current temperature rise to accelerate and could cause further rapid global warming, referred to in a 2021 presentation as a termination shock.

Furthermore, in addition to a huge temperature rise resulting from sulfate aerosols falling away, there could be a further rise in temperature as a result of releases of other aerosols with a net warming impact, such as black and brown carbon, which can increase dramatically as more wood burning and forest fires take place.

In summary, while the temperatures are accelerating, we'll soon be moving into the next El Niño, with sunspots moving toward a peak, with sulfate aerosols causing a termination shock and with other aerosols further driving up the temperature rise. 

Stop the deception!

In a giant scheme of deception, the temperature rise is all too often presented with images of people playing on the beach on a 'warm' day, as if 'global warming' was making life more 'comfortable'. 

Forest fires are called 'wildfires', biomass burning and associated deforestation is referred to as 'renewable biofuel', fracking-induced earthquakes are called 'natural' disasters and methane eruptions are called seeps and bubbles of 'natural' gas from 'natural' sources such as wetlands. 

This gives the false impression that this was somehow 'natural' as if human activities had nothing to do with it, and as if owning beach-front property was becoming ever more attractive.

Let's stop this deception! In reality, human-caused emissions have a huge short-term impact on temperature and their combination with genuinely natural variability such as El Niño and sunspots can act as a catalyst, causing numerous feedbacks to kick in with ever greater ferocity. 

This can result in collapse of global sea ice and permafrost, resulting in albedo loss and eruption of huge quantities of carbon dioxide, methane and nitrous oxide, further driving up the temperature rise abruptly, as described at the extinction page. Further feedbacks are also described at the feedbacks page. 

Conclusion

The situation is dire and calls for the most comprehensive and effective action, as described at the Climate Plan.

Links

• Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions - by Lijing Cheng et al. 
https://link.springer.com/article/10.1007%2Fs00376-022-1461-3

• Ocean heat is at record levels, with major consequences - by Kevin Trenberth

https://theconversation.com/ocean-heat-is-at-record-levels-with-major-consequences-174760

• Arctic Data archive System - Vishop extent

https://ads.nipr.ac.jp/vishop/#/extent

• NSIDC: Charctic Interactive Sea Ice Graph

https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph

• IPCC: Marine Ice Sheet Instability

https://www.ipcc.ch/srocc/chapter/chapter-3-2/3-1-introduction-polar-regions-people-and-the-planet/ipcc-srocc-cb_8_1

• Climate Reanalyzer

https://climatereanalyzer.org/wx/DailySummary/#seaice-snowc-topo

• Antarctica CICE ice thickness

https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/antarc.html

• Antarctica’s ‘doomsday’ glacier: how its collapse could trigger global floods and swallow islands 

https://theconversation.com/antarcticas-doomsday-glacier-how-its-collapse-could-trigger-global-floods-and-swallow-islands-173940

• Methane hydrates (2013)

https://methane-hydrates.blogspot.com/2013/04/methane-hydrates.html

• Potential methane reservoirs beneath Antarctica - by Jemma Wadham et al. (2012) 
https://www.nature.com/articles/nature11374

• A new frontier in climate change science: connections between ice sheets, carbon and food webs (2021) 

https://cage.uit.no/2021/05/19/a-new-frontier-for-climate-science-the-evidence-for-glaciers-as-methane-producers-has-exploded-in-recent-years

• Ice velocity and thickness of the world’s glaciers - by Romain Millan et al. 

https://www.nature.com/articles/s41561-021-00885-z

• Mountain glaciers may hold less ice than previously thought – here’s what that means for 2 billion downstream water users and sea level rise 
https://theconversation.com/mountain-glaciers-may-hold-less-ice-than-previously-thought-heres-what-that-means-for-2-billion-downstream-water-users-and-sea-level-rise-176514

• Mt. Everest’s highest glacier is a sentinel for accelerating ice loss - by Mariusz Potocki et al. 

https://www.nature.com/articles/s41612-022-00230-0

• Human-induced climate change impacts the highest reaches of the planet — Mount Everest

https://umaine.edu/news/blog/2022/02/03/human-induced-climate-change-impacts-the-highest-reaches-of-the-planet-mount-everest

• Ocean Heat Content Update 1 - 2022 - Science Talk with Jim Massa
https://www.youtube.com/watch?v=pctkg_LDqcU

• NOAA - ENSO: Recent Evolution, Current Status and Predictions

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

• NOAA - Monthly Temperature Anomalies Versus El Niño 

https://www.ncdc.noaa.gov/sotc/global/202201/supplemental/page-4

• Human Extinction by 2022? 

https://arctic-news.blogspot.com/2021/11/human-extinction-by-2022.html

• Tipping the ENSO into a permanent El Niño can trigger state transitions in global terrestrial ecosystems - by Mateo Duque-Villegas et al. (2019) 

https://esd.copernicus.org/articles/10/631/2019

• James Hansen - The New Horse Race

https://www.columbia.edu/~jeh1/mailings/2022/JanuaryTempUpdate.14February2022.pdf

• Climate Impact of Decreasing Atmospheric Sulphate Aerosols and the Risk of a Termination Shock - by Leon Simons, James Hansen and Yann duFournet (2021) 

https://www.researchgate.net/publication/356378673_Climate_Impact_of_Decreasing_Atmospheric_Sulphate_Aerosols_and_the_Risk_of_a_Termination_Shock

• NOAA - Solar Cycle Progression

https://www.swpc.noaa.gov/products/solar-cycle-progression

• Aerosols

https://arctic-news.blogspot.com/p/aerosols.html

• Feedbacks

https://arctic-news.blogspot.com/p/feedbacks.html

• Extinction

https://arctic-news.blogspot.com/p/extinction.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

Two degrees of warming closer than you may think

by David Spratt

It has taken a hundred years of human-caused greenhouse emissions to push the global temperature up almost one degree Celsius (1C°), so another degree is still some time away. Right? And there seems to have been a "pause" in warming over the last two decades, so getting to 2C° is going to take a good while, and we may have more time that we thought. Yes?

Wrong on both counts.

The world could be 2C° warmer in as little as two decades, according to the leading US climate scientist and "hockey stick" author, Dr Michael E. Mann. Writing in Scientific American in March 2014 (with the maths explained here), Mann says that new calculations "indicate that if the world continues to burn fossil fuels at the current rate, global warming will rise to 2C° by 2036" and to avoid that threshold "nations will have to keep carbon dioxide levels below 405 parts per million", a level we have just about reached already. Mann says the notion of a warming "pause" is false.

Global temperature over the last 1000 years: the "hockey stick"

Here's why 2C° could be just 20 years away.

Record heat

2014 was the hottest year in the instrumental record. The US government agencies NASA and NOAA announced the 2014 record on 16 January, noting that "the 10 warmest years in the instrumental record, with the exception of 1998, have now occurred since 2000".

NASA's Goddard Institute for Space Studies (GISS) says that since 1880, "Earth’s average surface temperature has warmed by about 1.4 degrees Fahrenheit (0.8C°), a trend that is largely driven by the increase in carbon dioxide (CO2) and other human emissions into the planet’s atmosphere. The majority of that warming has occurred in the past three decades."

GISS Director Gavin Schmidt says that this is “the latest in a series of warm years, in a series of warm decades. While the ranking of individual years can be affected by chaotic weather patterns, the long-term trends are attributable to drivers of climate change that right now are dominated by human emissions of greenhouse gases".

2014 was also Australia’s third-hottest year on record, according to the Bureau of Meteorology: "Overall, 2014 was Australia's third-warmest year on record: the annual national mean temperature was +0.91 °C above average… All States, except the Northern Territory, ranked in the four warmest years on record."

The 2014 record was achieved in neutral ENSO conditions

Fluctuations in the ENSO cycle affect global temperature, with El Niño conditions (a mobile blister of Pacific Ocean heat that affects wind patterns and currents and reduces rainfall in eastern Australia) correlating with warmer global temperatures. Former NASA climate science chief Dr James Hansen and colleagues note that the record global temperature in 2014 "was achieved with little assistance from the tropical ENSO cycle, confirms continuing global warming... and with the help of even a mild El Niño 2015 may be significantly warmer than 2014."

And El Niño conditions are likely to became more frequent with more warming. Last year, Wenju Cai, a climate researcher for Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), warned that the frequency of extreme El Niño events could double with climate change, in a paper that presented "evidence for a doubling in the occurrences in the future in response to greenhouse warming".

There is no "pause" in warming

In releasing the data on 2014's record warmth, NASA charted warming since 1970 and demonstrated that there has been no "pause" or slowing in warming, contrary to the million-times-repeated claims of the climate warming denial industry.

Joe Romm of Climate Progress says this chart (below) shows that: "The human-caused rise in surface air temperatures never paused, never even slowed significantly. And that means we are likely headed toward a period of rapid surface temperature warming. "

A year ago, Prof Matthew England of University of NSW suggested that temperatures were likely to rise quickly:

Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures, but the mechanism behind the hiatus remained unclear…. But the heat uptake is by no means permanent: when the trade wind strength returns to normal –- as it inevitably will –- our research suggests heat will quickly accumulate in the atmosphere. So global [surface] temperatures look set to rise rapidly….

The oceans are warming very rapidly

Of all the additional heat trapped by higher levels of greenhouse gases, more than 90 per cent goes to warming the oceans, and thus ocean heat content (OHC) is by far the most significant and reliable indicator of global warming. By contrast only two per cent goes to warming the atmosphere, so small heat exchanges between oceans and the atmosphere (caused by changing sea surface, ocean circulation and wind conditions) can have a significant impact on atmospheric temperature, but not on ocean temperature.

The NOAA's State of the Climate for 2014 reports:

During 2014, the globally-averaged sea surface temperature was 1.03°F (0.57°C) above the 20th century average. This was the highest among all years in the 1880-2014 record, surpassing the previous records of 1998 and 2003 by 0.09°F (0.05°C).

The rate of OHC incease appears to be accelerating, with Romm noting that:

... ocean warming has sped up, and sea level rise has accelerated more than we thought, and Arctic sea ice has melted much faster than the models expected, as have the great ice sheets in Greenland and Antarctica.

And as Matthew England has told us, when the trade wind strength returns to normal, some ocean heat will quickly accumulate in the atmosphere.

You can check all the NOAA ocean heat content charts here.

Human greenhouse gas emissions are not slowing

Data from the Global Carbon Project shows annual carbon dioxide emissions are continuing to increase, and that the rate of increase since 2000 is at least double that of the 1990-99 decade. Emissions are projected to continue on the current growth path till 2020.

Fossil fuel emissions 1990-2014 and projected to 2019

To summarise the story so far: 2014 was a record hot year (without El Nino conditions); there has been no pause in warming; ocean heat content is rising at an increasing rate; global annual carbon dioxide emissions are continuing to grow; and more frequent El Nino conditions and a return to more normal trade wind strength will release some ocean heat to the atmosphere; so we are likely headed for a period of rapid surface temperature warming.

But there is more to the story.

A reservoir of heat already in the system

Increased levels of atmospheric greenhouse gases create an energy imbalance between incoming and outgoing radiation, which is resolved by elements of the earth system (land and oceans) absorbing the additional heat until the system reaches a new balance (equilibrium) at a higher temperature. But that process takes time, due to thermal inertia (as with an electric oven: once energy is applied, it takes time for all the structure to heat up and is not instantaneous). As a rule of thumb, about one-third of the heating potential of an increase in atmospheric carbon dioxide will be felt straight away, another third take around 30 years, and the last third is not fully realised for a century.

Thus there is more warming to come for the carbon dioxide already emitted, amounting to about another 0.6°C of warming. And because the rate of emissions is increasing, that figure is also increasing.

From this we can conclude that around 1.5°C of warming is locked into the system for current CO2 levels, though very large-scale carbon drawdown could reduce levels slowly over decadal time frames.

As well as long-lived CO2, there are other greenhouse gases with shorter lifetimes, particularly methane (lifetime approx. 10 years) and nitrous oxide (lifetime approx. 100 years). Because emissions of these gases are also continuing unabated, they also contribute to warming temperatures on decadal time frames.

In fact, the current level of greenhouse gases if maintained is already more than enough to produce 2°C of warming over time: in 2008 two scientists, Ramanathan and Feng, in On avoiding dangerous anthropogenic interference with the climate system: Formidable challenges ahead found that if greenhouse gases were maintained at their 2005 levels, the inferred warming is 2.4˚C (range 1.4˚C to 4.3˚C).

The current level of greenhouse gases is around 400 parts per million (ppm) CO2, and 470 ppm CO2 equivalent (CO2e) when other greenhouse gases are included. The last time CO2 levels were as high as they are today, humans didn't exist, and over the last 20 million years such levels are associated with major climate transitions. Tripati, Roberts et al. found that, big changes in significant climate system elements such as ice sheets, sea levels and carbon stores are likely to occur for the current level of CO2:

During mid-Miocene climatic optimum [16-14 million years ago] CO2 levels were similar to today, but temperatures were ~3–6°C warmer and sea levels 25 to 40 metres higher than at present… When CO2 levels were last similar to modern values (greater than 350 ppmv to 400 pmv), there was little glacial ice on land, or sea ice in the Arctic, and a marine-based ice mass on Antarctica was not viable…

But the question remains as to how quickly this warming will occur, and for that we need to look at two further factors: climate sensitivity and the role of aerosols.

Climate sensitivity

The measure of how much warming occurs for an increase in greenhouse gases is known as climate sensitivity, and is expressed as the temperature rise resulting from a doubling of greenhouse gas levels.

As Michael E. Mann explains:

Although the earth has experienced exceptional warming over the past century, to estimate how much more will occur we need to know how temperature will respond to the ongoing human-caused rise in atmospheric greenhouse gases, primarily carbon dioxide. Scientists call this responsiveness “equilibrium climate sensitivity” (ECS). ECS is a common measure of the heating effect of greenhouse gases. It represents the warming at the earth's surface that is expected after the concentration of CO2 in the atmosphere doubles and the climate subsequently stabilizes (reaches equilibrium)… The more sensitive the atmosphere is to a rise in CO2, the higher the ECS, and the faster the temperature will rise. ECS is shorthand for the amount of warming expected, given a particular fossil-fuel emissions scenario.

As discussed previously here, some elements of the climate system respond quickly to temperature change, including the amount of water vapour in the air and hence level of cloud cover, sea-level changes due to ocean temperature change, and the extent of sea-ice that floats on the ocean in the polar regions. These changes amplify (increase) the temperature change and are known as short-term or “fast” feedbacks, and it is on this basis that (short-term) ECS is well established as being around 3°C for a doubling of greenhouse gas levels (see, for example, Climate sensitivity, sea level, and atmospheric carbon dioxide).

But there are also longer-term or “slow” feedbacks, which generally take much longer (centuries to thousands of years) to occur. These include changes in large, polar, land-based ice sheets, changes in the carbon cycle (changed efficiency of carbon sinks such as permafrost and methane clathrate stores, as well as biosphere stores such as peat lands and forests), and changes in vegetation coverage and reflectivity (albedo). When these are taken into account, the sensitivity is significantly higher at 4.5°C or more, dependent on the state of the poles and carbon stores. Importantly, the rate of change at present is so fast that some of these long-term feedbacks are being triggered now on short-term timeframes (see Carbon budgets, climate sensitivity and the myth of "burnable carbon").

Mann says uncertainty about ECS can arise from questions of the role of clouds and water vapour, with the most recent IPCC report simply giving a range of 1.5–4.5°C but no "best-fit" figure. Factors such as changing rates of heat flux between oceans and atmosphere (including the El Nino/La Nina cycle), and volcanic eruptions, can cloud the short-term picture, as has the focus on the non-existent "pause".

What would happen if ECS is a bit lower that the "best-fit" value of 3°C of warming for doubling of greenhouse gas levels? Mann explains:

I recently calculated hypothetical future temperatures by plugging different ECS values into a so-called energy balance model, which scientists use to investigate possible climate scenarios. The computer model determines how the average surface temperature responds to changing natural factors, such as volcanoes and the sun, and human factors—greenhouse gases, aerosol pollutants, and so on. (Although climate models have critics, they reflect our best ability to describe how the climate system works, based on physics, chemistry and biology. And they have a proved track record: for example, the actual warming in recent years was accurately predicted by the models decades ago.)

I then instructed the model to project forward under the assumption of business-as-usual greenhouse gas emissions. I ran the model again and again, for ECS values ranging from the IPCC's lower bound (1.5°C) to its upper bound (4.5°C). The curves for an ECS of 2.5 degrees and 3°C fit the instrument readings most closely. The curves for a substantially lower ECS did not fit the recent instrumental record at all, reinforcing the notion that they are not realistic.

To my wonder, I found that for an ECS of 3°C, our planet would cross the dangerous warming threshold of 2°C in 2036, only 22 years from now. When I considered the lower ECS value of 2.5°C, the world would cross the threshold in 2046, just 10 years later.

This is charted as:

Michael E. Mann's graph of future temperature for different climate sensitivities. Click to enlarge.

Mann concludes that "even if we accept a lower ECS value, it hardly signals the end of global warming or even a pause. Instead it simply buys us a little bit of time—potentially valuable time—to prevent our planet from crossing the threshold."

As I have explained repeatedly, including in Dangerous climate warming: Myth and reality, 2°C is far from a safe level of warming. In fact, a strong case is made that climate change is already dangerous at less than 1°C of warming and, in James Hansen's analysis, “goals of limiting human made warming to 2°C and CO2 to 450 ppm are prescriptions for disaster” because significant tipping points – where significant elements of the climate system move from one discrete state to another – will be crossed.

Aerosol's Faustian bargain

Mann also indicated what level of CO2 would be consistent with 2°C of warming:

These findings have implications for what we all must do to prevent disaster. An ECS of 3°C means that if we are to limit global warming to below 2°C forever, we need to keep CO2 concentrations far below twice pre-industrial levels, closer to 450 ppm. Ironically, if the world burns significantly less coal, that would lessen CO2 emissions but also reduce aerosols in the atmosphere that block the sun (such as sulfate particulates), so we would have to limit CO2 to below roughly 405 ppm.

The aerosol question is central but often not well understood. Human activities also influence the greenhouse effect by releasing non-gaseous substances such as aerosols (small particles) into the atmosphere. Aerosols include black-carbon soot, organic carbon, sulphates, nitrates, as well as dust from smoke, manufacturing, windstorms, and other sources.

Aerosols have a net cooling effect because they reduce the amount of sunlight that reaches the ground, and they increase cloud cover. This effect is popularly referred to as ‘global dimming’, because the overall aerosol impact is to reduce, or dim, the sun’s radiation, thus masking some of the effect of the increased greenhouse gas levels. This is of little comfort, however, because aerosols last only about ten days before being washed out of the atmosphere by rain; so we have to keep putting more and more into the air to maintain the temporary cooling effect.

Unfortunately, the principal source of aerosols is the burning of fossil fuels, which causes a rise in CO2 levels and global warming that lasts for many centuries. The dilemma is that if you cut the aerosols, the globe will experience a pulse of warming as their dimming effect is lost; but if you keep pouring aerosols together with CO2 into the air, you cook the planet even more in the long run. A Faustian bargain.

There has been an effort to reduce emissions from some aerosols because they cause acid rain and other forms of pollution. However, in the short term, this is warming the air as well as making it cleaner. As Mann notes above, likely reductions in coal burning in coming decades will reduce aerosol levels and boost warming

Some recent research suggest aerosol cooling is in the range of 0.5–1.2°C over the long run:

• Leon Rotstayn in The Conversation explains that "results from CSIRO climate modelling suggest that the extra warming effect from a decline in aerosols could be about 1°C by the end of the century". 
• Present-day aerosol cooling effect will be strongly reduced by 2030 as more stringent air pollution controls are implemented in Europe and worldwide, and as advanced environmental technologies come on stream. These actions are projected to increase the global temperature by 1°C and temperatures over Europe by up to 2–4°C, depending on the severity of the action. This is one of the main research outcomes of the European Integrated project on Aerosol Cloud Climate and Air Quality Interaction project. 
• In 2011, NASA climate science chief James Hansen and co-authors warned that the cooling impact of aerosols appears to have been underestimated in many climate models and inferred that: "Aerosol climate forcing today is inferred to be −1.6±0.3Wm−2," which is equivalent to a cooling of about 1.2°C. In that case, they wrote, "humanity has made itself a Faustian bargain more dangerous than commonly supposed". 

Conclusion

Michael E. Mann's analysis is sobering, especially when aerosols are accounted for.

The world is already hitting 400 ppm CO2 (the daily average at the measuring station at Mauna Loa first exceeded 400 ppm on 10 May 2013 and currently rising at a rate of approximately 2 ppm/year and accelerating), so the message is very clear that today we have circumstances that can drive us to 2°C of warming, and that emissions from now on are adding to warming above 2°C and towards 3°C or more. This reinforces my conclusion last year that there is no carbon budget left for 2°C of warming, and claims to the contrary are a dangerous illusion.

Mann concludes in not dis-similar terms:

The conclusion that limiting CO2 below 450 ppm will prevent warming beyond 2°C is based on a conservative definition of climate sensitivity that considers only the so-called fast feedbacks in the climate system, such as changes in clouds, water vapor and melting sea ice. Some climate scientists, including James E. Hansen… say we must also consider slower feedbacks such as changes in the continental ice sheets. When these are taken into account, Hansen and others maintain, we need to get back down to the lower level of CO2 that existed during the mid-20th century — about 350 ppm. That would require widespread deployment of expensive “air capture” technology that actively removes CO2 from the atmosphere.

Furthermore, the notion that 2°C of warming is a “safe” limit is subjective. It is based on when most of the globe will be exposed to potentially irreversible climate changes. Yet destructive change has already arrived in some regions. In the Arctic, loss of sea ice and thawing permafrost are wreaking havoc on indigenous peoples and ecosystems. In low-lying island nations, land and freshwater are disappearing because of rising sea levels and erosion. For these regions, current warming, and the further warming (at least 0.5°C) guaranteed by CO2 already emitted, constitutes damaging climate change today.

[Originally posted at Climate Code Red]