Wednesday, November 27, 2019

Accelerating greenhouse gas levels

The United Nations Environment Programme (UNEP) just released its annual Emissions Gap Report, warning that even if all current unconditional commitments under the Paris Agreement are implemented, temperatures are expected to rise by 3.2°C, bringing even wider-ranging and more destructive climate impacts.

The report adds that a continuation of current policies would lead to a global mean temperature rise of 3.5°C by 2100 (range of 3.4–3.9°C, 66% probability) and concludes that current policies will clearly not keep the temperature rise below 3°C and that temperatures may rise by much more than that.

Below is the UNEP video On the brink: Emissions Gap Report findings in 60 seconds.


[ image from earlier post ]
Indeed, the rise in greenhouse gas levels appears to be accelerating, despite pledges made under the Paris Agreement to holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels.

The World Meteorological Organization (WMO) recently reported carbon dioxide (CO₂) concentrations for 2018 of 407.8 ppm (parts per million), as illustrated by the image on the right. The WMO adds that CO₂ levels, as well as methane and nitrous oxide levels, had all surged by higher amounts than during the past decade.

In energy, fossil fuel consumption for heating and transport increased. While renewables grew strongly in 2018, an even larger part of the growth in electricity was generated by fossil fuel, particularly by coal and natural gas. 

As the image below shows, a trend based on NOAA March 1958 through October 2019 monthly mean CO₂ data at Mauna Loa points at CO₂ levels crossing the 415 ppm mark in 2020, when an El Niño is forecast to come, as discussed in an earlier post.


The added trend in the image points at CO₂ levels crossing 1200 ppm before the end of the century, triggering the cloud feedback tipping point that by itself could push up global temperatures by 8°C, within a few years. Importantly, the clouds feedback starts at 1200 ppm CO₂-equivalent. Besides a CO₂ rise, further elements could contribute to the 1200 ppm CO₂e tipping point getting reached, such as albedo changes due to disappearing Arctic sea ice and seafloor methane releases from a rapidly-warming Arctic Ocean.

In conclusion, a huge temperature rise could eventuate much earlier than by the end of the century. The image below illustrates the potential for a rise of 18°C or 32.4°F by 2026.

[ from an earlier post ]
As discussed in a recent post, a 2020 El Niño could be the catalyst triggering huge methane releases from the Arctic Ocean seafloor starting in 2020 and resulting in such a 18°C (or 32.4°F) temperature rise within a few years time. To put this into perspective, an earlier post concluded that humans will likely go extinct at a 3°C rise, as such an abrupt rise will make habitat for humans (and many other species) disappear.

In the video below, John Davis describes some of the extreme weather events that he experienced recently. “Disasters like this are man-made now”, John says, “they're not natural disasters. This is caused by climate change.”



Meanwhile, a recent study found that the consensus among research scientists on anthropogenic global warming has grown to 100%, based on a review of 11,602 peer-reviewed articles on “climate change” and “global warming” published in the first 7 months of 2019.

This further confirms the probability or likelihood that emissions by people are causing global warming, from a likely danger to certain danger. Furthermore, as discussed in many earlier posts, there are two additional dimensions to the danger of climate change; the severity of the impact makes it not merely a catastrophic danger, it is an existential threat; finally, regarding timescale, the danger is not just near, the danger is imminent and in many respects we're already too late.


Above image expresses this visually, with the red area depicting where we are now. There were readability problems with the text on the sides of the cube, reason why a version without text and the color on the sides was posted in an earlier post.

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


Links

• UN news release
https://www.unenvironment.org/news-and-stories/press-release/cut-global-emissions-76-percent-every-year-next-decade-meet-15degc

• Paris Agreement
https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement

• United Nations Environment Programme (UNEP) - Emissions Gap Report
https://www.unenvironment.org/resources/emissions-gap-report-2019

• UNEP video: On the brink: Emissions Gap Report findings in 60 seconds
https://www.unenvironment.org/news-and-stories/video/brink-emissions-gap-report-findings-60-seconds

• WMO - Greenhouse gas concentrations in atmosphere reach yet another high
https://public.wmo.int/en/media/press-release/greenhouse-gas-concentrations-atmosphere-reach-yet-another-high

• NOAA Trends in Atmospheric Carbon Dioxide
https://www.esrl.noaa.gov/gmd/ccgg/trends/data.html

• Most Important Message Ever
https://arctic-news.blogspot.com/2019/07/most-important-message-ever.html

• 2020 El Nino could start 18°C temperature rise
https://arctic-news.blogspot.com/2019/11/2020-el-nino-could-start-18-degree-temperature-rise.html

• Scientists Reach 100% Consensus on Anthropogenic Global Warming
https://journals.sagepub.com/doi/full/10.1177/0270467619886266

• The Threat Of Arctic Albedo Change
https://arctic-news.blogspot.com/2016/09/the-threat-of-arctic-albedo-change.html

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




Sunday, November 24, 2019

The breach of the Paris Agreement

By Andrew Glikson
Earth and climate scientist
Australian National University



Since its inception the Paris Agreement has been in question due to, among other:
  • its broad definition, specifically holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels;
  • its non-binding nature; and 
  • accounting tricks by vested interests.
The goal assumes pre-determined limits can be placed on greenhouse gas levels and temperatures beyond which they would not continue to rise. Unfortunately these targets do not appear to take account of the amplifying positive feedback effects from land and oceans under the high cumulative greenhouse gas levels and their warming effects. Thus unfortunately the current high CO₂ levels of about 408 ppm and near-500ppm CO₂-equivalent (CO₂+methane+nitrous oxide) would likely continue to push temperatures upwards.

Significant climate science evidence appears to have been left out of the equation. The accord hinges on the need to reduce emissions, which is essential, but it does not indicate how further temperature rise can be avoided under the conditions of a high-CO₂ atmosphere, which triggers carbon release, unless massive efforts at sequestration (drawdown) of greenhouse gases are undertaken. Inherent in global warming are amplifying positive feedbacks, including albedo (reflection) decline due to the melting of ice and the opening of dark water surfaces, increased water vapor contents of the atmosphere in tropical regions which enhances the greenhouse effect, reduced sequestration of CO₂ by the warming oceans, desiccation of vegetation, fires, release of methane from permafrost and other processes. This means that even abrupt reductions in emissions may not be sufficient to stem global warming, unless accompanied by sequestration of greenhouse gases from the atmosphere to a lower level, recommended as below 350 ppm CO₂ by James Hansen, the leading climate scientist.

The world is on track to produce 50% more fossil fuels than can be burned before reaching the limit prescribed by the Paris Agreement, with currently planned coal, oil and gas outputs making the Paris Agreement goal impossible. Projected fossil fuel production in 2030 being more than is consistent with 2°C, and 120% more than that for 1.5°C.

Unbelievably, according to the International Monetary Fund, “In 2017 the world subsidized fossil fuels by $5.2 trillion, equal to roughly 6.5% of global GDP”, which is more than the total the world spends on human health. Such subsidies cannot possibly be consistent with the Paris Agreement. The pledge to end fossil fuel subsidies by 2025 by the G7 nations, with exceptions by the UK and Japan, may come too late as global CO₂ concentrations, already intersecting the stability limits of the Greenland and Antarctic ice sheets, are rising at a rate of 2 to 3 ppm per year, the highest in many millions of years.

Despite the scientific consensus regarding the anthropogenic origin of global warming, the world’s biggest fossil fuel corporations are taking a defiant stance against warnings that reserves of coal, oil and gas are already several times larger than can be burned if the world’s governments are to meet their pledge to tackle climate change. ExxonMobil said new reserves in the Arctic and Canadian tar sands must be exploited. Peabody Energy, the world’s largest private coal company, said global warming was “an environmental crisis predicted by flawed computer models”. Glencore Xstrata said that governments would fail to implement measures to cut carbon emissions. The World Bank and Bank of England have already warned of the “serious risk” climate action poses to trillions of dollars of fossil fuel assets.

Not to mention the risks to the living Earth and its billions of inhabitants!

The apparent neglect of scientific advice is not an isolated instance. It is not uncommon that climate reports are dominated by the views of economists, lawyers, bureaucrats and politicians, often overlooking the evidence presented by some of the world’s highest climate science authorities. Whereas the IPCC reports include excellent and comprehensive summaries of the peer-reviewed literature, the summaries for policy makers only partly represent the evidence and views of scientific authorities in the field, including those who have identified global warming in the first place.
Figure 2. from: James Hansen, data through June 2019

There exists a tendency in the media to report averages, such as average global temperature values, rather than the increasingly-common high zonal, regional and local anomalies.

For example, the annual mean global temperature rise of for 2018 is about one third the Arctic mean temperature rise (Fig. 2). Given that developments in the Arctic bear major consequences for climate change, the global mean  does not represent the seriousness of the climate crisis.

Another example is the way extremes weather events are reported as isolated instances, neglecting the rising frequency and intensity of hurricanes, storms, fires and droughts, indicated in frequency plots (Fig 3.).

Figure 3. Rise in geophysical, meteorological, hydrologocal and climatological events. Munich RE
It is not until international and national institutions take full account of what climate science is indicating that a true picture of the climate crisis will be communicated to the public.


Andrew Glikson
Dr Andrew Glikson
Earth and climate scientist
Australian National University


Books:
- The Archaean: Geological and Geochemical Windows into the Early Earth
- The Asteroid Impact Connection of Planetary Evolution
- Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
- Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
- The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
- Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
- From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence



Sunday, November 17, 2019

Arctic Ocean November 2019


On November 16, 2019, there was little sea ice between Greenland and Svalbard. For reference, the image below has been added, showing coastlines for the same area.


The image on the right shows that the average air temperature (2 m) on November 15, 2019, was 4°C higher over the Arctic than during 1979-2000.
Ocean heat is rising up from the Arctic Ocean, while a wavy jet stream enables cold air to leave the Arctic and descend over North America and Eurasia. On November 13, 2019, it was warmer in Alaska than in Alabama.

The image below shows temperatures north of 80°N. The red line on the image shows the 2019 daily mean temperature up to November 16, 2019. The temperature is now well above the 1958-2002 mean (green line). The image also shows the freezing point of fresh water (273.15K, 0°C or 32°F, blue line).

The freezing point for salt water is lower, at around -2°C, or 28.4°F, or 271.2°K. In other words, a rise in the salt content of the water alone can make ice melt, i.e. even when the temperature of the water doesn't rise.


The image below shows that Arctic sea ice volume has been at record low levels for the time of year for some time.


As the image below shows, Arctic sea ice extent in the Chukchi Sea is currently very low.

[ image by Zack Labe, uploaded November 13, 2019 ]
Oceans are absorbing more than 90% of global heating, as illustrated by the image below.


Arctic sea ice used to absorb 0.8% of global heating (in 1993 to 2003). Ocean heat keeps flowing into the Arctic Ocean, carried by ocean currents, as illustrated by the image below.


As peak heat arrives in the Arctic Ocean, it melts sea ice from below. In Summer 2019, a critical tipping point was crossed; ocean heat could no longer find further sea ice to melt, as the thick sea ice that hangs underneath the surface had disappeared. A thin layer of sea ice at the surface was all that remained, as air temperatures remained low enough to prevent it from melting from above.


This indicates that the buffer has gone that has until now been consuming ocean heat as part of the melting process. As long as there is sea ice in the water, this sea ice will keep absorbing heat as it melts, so the temperature will not rise at the sea surface. The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C.


The images above and below shows very high sea surface temperature anomalies on the Northern Hemisphere for October 2015 and October 2019. In both cases, anomalies of 1.09°C or 1.96°F above the 20th century average were recorded.

The October 2015 anomaly occurred under El Niño conditions, whereas the equally-high anomaly in October 2019 occurred under El Niño/La Niña-neutral conditions, while another El Niño is likely to come in 2020. In other words, the threat is that even more ocean heat is likely to arrive in the Arctic Ocean in 2020.


The danger is particularly high in October, as Arctic sea ice starts growing in extent at the end of September, thus sealing off the water, meaning that less ocean heat will be able to escape to the atmosphere. This increases the danger that hot water will reach sediments at the Arctic Ocean seafloor and trigger massive methane eruptions.


Concentrations of carbon dioxide (CO₂, 407.8 ppm), methane (CH₄, 1869 ppb) and nitrous oxide (N₂O, 331.1 ppb) in 2018 surged by higher amounts than during the past decade, the WMO said in a recent news release and as illustrated by the image on the right, which shows that CH₄, CO₂ and N₂O levels in the atmosphere in 2018 were, respectively, 259%, 147% and 123% of their pre-industrial (before 1750) levels.

“There is no sign of a slowdown, let alone a decline, in greenhouse gases concentration in the atmosphere despite all the commitments under the Paris Agreement on Climate Change,” said WMO Secretary-General Petteri Taalas.

“It is worth recalling that the last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago. Back then, the temperature was 2-3°C warmer, sea level was 10-20 meters higher than now,” said Mr Taalas.

Global methane levels are very high. Mean global methane levels were as high as 1914 parts per billion on September 3, 2019, as discussed in a recent post. Peak methane levels as high as 2961 parts per billion were recorded by the MetOp-2 satellite on October 24, 2019, in the afternoon at 469 mb.

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

In the video below, Paul Beckwith discusses Arctic sea ice.



Links

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

• It’s warmer in Alaska than in Alabama today
https://www.al.com/news/2019/11/its-warmer-in-alaska-than-in-alabama-today.html

• 100 weather observing stations across the U.S. are forecast to tie or break their record low temperatures
https://twitter.com/NWS/status/1194381679483375616

• NOAA - Global Heat Content
https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT

• Where is global warming going? | by John Cook (2010)
https://skepticalscience.com/Where-is-global-warming-going.html

• Danish Meteorological Institute - Daily mean temperatures for the Arctic area north of the 80th northern parallel
http://ocean.dmi.dk/arctic/meant80n.uk.php

• Polar portal - Sea Ice Thickness and Volumehttp://polarportal.dk/en/sea-ice-and-icebergs/sea-ice-thickness-and-volume

• WMO - Greenhouse gas concentrations in atmosphere reach yet another high
https://public.wmo.int/en/media/press-release/greenhouse-gas-concentrations-atmosphere-reach-yet-another-high

• 2020 El Nino could start 18°C temperature rise
https://arctic-news.blogspot.com/2019/11/2020-el-nino-could-start-18-degree-temperature-rise.html

• Critical Tipping Point Crossed In July 2019
https://arctic-news.blogspot.com/2019/09/critical-tipping-point-crossed-in-july-2019.html

• IPCC Report Ocean and Cryosphere in a Changing Climate
https://arctic-news.blogspot.com/2019/09/ipcc-report-ocean-and-cryosphere-in-a-changing-climate.html

• Most Important Message Ever
https://arctic-news.blogspot.com/2019/07/most-important-message-ever.html

• When will we die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Arctic Ocean overheating
https://arctic-news.blogspot.com/2019/09/arctic-ocean-overheating.html

• How extreme will it get?
https://arctic-news.blogspot.com/2012/07/how-extreme-will-it-get.html

• Warning Signs
https://arctic-news.blogspot.com/2018/03/warning-signs.html





Saturday, November 16, 2019

2020 El Nino could start 18°C temperature rise

[ click on image to enlarge ]
Above image shows a blue long-term trend, based on NASA LOTI 1880-Oct.2019 data, 0.78°C adjusted to reflect ocean air temperatures (as opposed to sea surface temperatures), to reflect a higher polar anomaly (as opposed to leaving out 'missing' data) and to reflect a 1750 baseline (as opposed to a 1951-1980 baseline).

The image also shows a red short-term trend, based on NASA LOTI 2012-Oct.2019 data, similarly adjusted and added to illustrate El Niño/La Niña variability and how El Niño could be the catalyst to trigger huge methane releases from the Arctic Ocean seafloor starting in 2020 and resulting in an 18°C (or 32.4°F) temperature rise within a few years time.

To put such a temperature rise in perspective, humans will likely go extinct with a 3°C rise, while most if not all life on Earth will go extinct at 5°C rise, as discussed in an earlier post.

The image below, from a recent study, indicates that El Niño is likely to come in 2020. 

An international team of scientists are forecasting an El Niño for 2020. "The probability of 'El Niño' coming in 2020 is around 80%", says Hans Joachim Schellnhuber, Director Emeritus of the Potsdam Institute for Climate Impact Research.


Above image shows NOAA's monthly global temperature anomaly from the 20th century average, colored by the El Niño - Southern Oscillation (ENSO) phenomenon.

A recent study found that El Niño‐Southern Oscillation (ENSO) variability over the last five decades is ~25% stronger than during the preindustrial.

As the NASA map below shows, heating in October 2019 was particularly pronounced over the Arctic Ocean.


Note that the above NASA map shows anomalies from a 1951-1980 baseline.

As the image below shows, just the existing carbon dioxide and methane, plus seafloor methane releases, would suffice to trigger the clouds feedback tipping point to be crossed that by itself could push up global temperatures by 8°C, within a few years.


As described in this post and in an earlier post, a rapid temperature rise could result from a combination of elements, including albedo changes, loss of sulfate cooling, and methane released from destabilizing hydrates contained in sediments at the seafloor of oceans.

[ from an earlier post ]
The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.


Links

• Early warning: Physicists from Giessen, Potsdam and Tel Aviv forecast "El Niño" for 2020 — PIK Research Portal
https://www.pik-potsdam.de/news/press-releases/early-warning-physicists-from-giessen-potsdam-and-tel-aviv-forecast-el-nino-for-2020

• Very early warning signal for El Niño in 2020 with a 4 in 5 likelihood, by Josef Ludescher et al.
https://arxiv.org/abs/1910.14642

• NOAA - Monthly temperature anomalies versus El Niño
https://www.ncdc.noaa.gov/sotc/global/201909/supplemental/page-3

• Enhanced El Niño‐Southern Oscillation variability in recent decades, by Pamela Grothe et al.
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083906

• NASA - GISS Surface Temperature Analysis (GISTEMP v4)

Thursday, November 14, 2019

Portents of continental-scale fires as the Earth warms

Andrew Glikson
Earth and climate scientist
Australian National University
15.11.2019

The effects of encroaching deserts and of fire storms on terrestrial forests originally developed under moderate conditions distinct from those emerging under rapid global warming and extreme weather events may have been underestimated. Average global temperatures do not tell the story — it is the increasingly frequent weather anomalies which do. Powerful psychological factors prevent many scientists from expressing their worst fears, a phenomenon dubbed as “scientific reticence”.

As the tropical climate zones expand toward the poles, moderate climate zones shift polar-ward and are contracting where they clash with polar-derived cold air and ice melt water flow through weakened jet stream boundaries. As climate zones are shifting at a rate of 56-111 km per decade and ecosystems have only a short time to adapt, arid zones expand and droughts and fires consume the moderate-climate forests and formerly fertile habitats. Allen et al. (2012) suggest the increase in black carbon aerosols and tropospheric ozone constitute significant factors generating a polar-ward shift of moderate climate zones.

Global fire maps by NASA document the progression of wildfires since about 2000, including major fires in Siberia, northwest Europe, southern Europe, Russia, Southeast Asia, Australia, central and southern America, California and elsewhere (Fig. 1).

Figure 1. The Moderate Resolution Imaging Spectro-radiometer (MODIS) on NASA's Terra satellite showing fires around the world. Credit: NASA
Some of the global patterns that appear in the fire maps are the result of natural cycles of rainfall, dryness, and lightning. For example, naturally-occurring fires are common in the boreal forests of Canada in the summer. In other parts of the world, the patterns are the result of human activity. For example, the intense burning in the heart of South America from August-October is a result of human-triggered fires, both intentional and accidental.

Many scientists and the IPCC have underestimated the scale and rate of global warming and its consequences. With exceptions, the need for excessive caution and absolute certainty in science is often manifested in reticence from the mainstream science (‘Down to Earth’ 2019). However, the available evidence suggests that scientists have in fact been conservative in their projections of the impacts of climate change and at least some of the key attributes of global warming from increased atmospheric greenhouse gases have been underpredicted, particularly in IPCC assessments of the physical science by Working Group I.

By contrast, at a speed hardly anticipated about 20 years ago, wildfires have been spreading around the globe over large parts of the continents.

Nor do average global land-ocean temperatures tell the whole story. It is the increasingly frequent anomalies which underlie extreme weather events (Fig. 2), including rapid Arctic melt, heatwaves, fires, storms and cyclones, which underpin the fundamental shift in the state of the terrestrial climate.

Figure 2. Temperature anomaly distribution: The frequency of occurrence (vertical axis) of local temperature anomalies (relative to 1951-1980 mean) in units of local standard deviation (horizontal axis). Area under each curve is unity. Image credit: NASA/GISS.
It has been stated “What happens in the Arctic doesn't stay in the Arctic”. Temperatures in the Arctic have reached 34°C in July 2019, affecting melting over 700,000 km² in Greenland late May 2019. The weakening of the circum-Arctic jet stream ensues in its undulation and intersection by warm air masses moving north and by cold air masses moving south, along with ice melt from the Greenland ice sheet forming cold regions in the North Atlantic Ocean.

Figure 3. Weather systems driven by the 
strong westerly winds of the Antarctic 
polar vortex curl over the southern 
continents (NASA, Galileo).
According to the Australian Climate Council, climate change has contributed to a southward shift in weather systems that typically bring cool season rainfall to southern Australia. As the cold humid spirals of the Antarctic vortex (Fig. 3) recede to the south, since the 1970s late autumn and early winter rainfall has decreased by 15% in southeast Australia, and Western Australia’s southwest region. Current drought conditions come after a 2016/2017 and 2018 Summer characterized by record-breaking temperatures, followed by a record dry winter. Rainfall over southern Australia during autumn 2018 was the second lowest on record (Fig. 4). The drought has reached extreme level, accompanied by wildfires. Australia, like other parts of the world, is paying the price of climate change in terms of growing damage to its agriculture, communities and way of life.

Figure 4. Australia: Current effects of global warming. 
A. 2018 annual mean temperatures compared to historical temperature observations. 
B. 2018 annual rainfall compared to historical rainfall observations.
The global rise rate in CO₂ has reached 2 to 3 ppm/year, the fastest rate since 66 million years ago, and a level of CO₂-equivalent (a value including the radiative forcing of methane and nitrous oxide) near 500 ppm. According to the IMF (2017), the world is subsidizing fossil fuels by $5.2 trillion, equal to roughly 6.5% of global GDP. By contrast, the loss of wealth due to reduced agricultural productivity due to climate change is projected to exceed $19 billion by 2030, $211 billion by 2050 and a projected $4 trillion by 2100.

Figure 5. Fires in Australia, November 8, 2019, NASA Worldview 
As stated by Hansen et al. (2012): “Burning all fossil fuels would create a different planet than the one that humanity knows. The palaeoclimate 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”.


Andrew Glikson
Dr Andrew Glikson
Earth and climate scientist
Australian National University



Books:
The Archaean: Geological and Geochemical Windows into the Early Earth
The Asteroid Impact Connection of Planetary Evolution
The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence



Tuesday, November 5, 2019

A record CO2 rise rate since the KT dinosaur extinction 66 million years ago

By Andrew Glikson
Earth and climate scientist
Australian National University

As the concentration of atmospheric CO₂ has risen to 408 ppm and the total greenhouse gas level, including methane and nitrous oxide, combine to near 500 parts per million CO₂-equivalent, the stability threshold of the Greenland and Antarctic ice sheets, currently melting at an accelerated rate, has been exceeded. The consequent expansion of tropics and the shift of climate zones toward the shrinking poles lead to increasingly warm and dry conditions under which fire storms, currently engulfing large parts of South America (Fig. 1), California, Alaska, Siberia, Sweden, Spain, Portugal, Greece, Angola, Australia and elsewhere have become a dominant factor in the destruction of terrestrial habitats.

Figure 1. Sensors on NASA satellites Terra and Aqua captured a record of thousands of points
of fire in Brazil in late August. Credit: NASA Earth Observatory
Since the 18th century, combustion of fossil fuels has led to the release of more than 910 billion tons of carbon dioxide (GtCO₂) by human activity, raising CO₂ to about 408.5 ppm (Fig. 2), as compared to the 280-300 ppm range prior to the onset of the industrial age. By the early-21st century the current CO₂ rise rate has reached of 2 to 3 ppm/year.

Figure 2. Global temperature and carbon dioxide - Climate Central
Allowing for the transient albedo enhancing effects of sulphur dioxide and other aerosols, mean global temperature has potentially reached ~2.0 degrees Celsius above pre-industrial temperatures. Current greenhouse gas forcing and global mean temperatures are approaching Miocene-like (5.3-23 million years-ago) composition.

The current carbon dioxide rise rate exceeds the fastest rates estimated for the K-T asteroid impact (66.4 million years-ago) and the PETM (Paleocene-Eocene Temperature Maximum) hyperthermal event (55.9 million years ago) by an order of magnitude (Fig. 3). The current growth rate of atmospheric greenhouse gases, in particular over the last 70 years or so, may appear gradual in our lifetime, but it constitutes an extreme event in the recorded history of Earth.
Figure 3. Cenozoic CO₂ and temperature rise rates. Current rise rates of CO₂ (2.86 ppm CO2/year) and temperature (0.15-0.20°C per decade since 1975) associated with extreme weather events raise doubt regarding gradual linear climate projections. Instead, chaotic climate conditions may arise from the clash between northward-shifting warm air masses which intersect the weakened undulating Arctic jet stream boundary and freezing polar air fronts penetrating Siberia, North America and Europe.
The definition of a “tipping point” in the climate system is a threshold which, once exceeded, can lead to large changes in the state of the system, or where the confluence of individual factors combines into a single stream. The term “tipping element” describes subcontinental-scale subsystems of the Earth system that are susceptible to being forced into a new irreversible state by small perturbations. In so far as a tipping point can be identified in current developments of the climate system, the weakening of the Arctic boundary, indicated by slowing down and increased disturbance of the jet stream heralds a likely tipping point, an example being the recent ‘Beast from the East” freeze in northern Europe and North America (Fig. 4).

Figure 4. The cold fronts penetrating Europe from Siberia and the North Atlantic and North America from the Arctic, 2018. UK Met Office.
A report by the National Academy Press 2011 states: “As the planet continues to warm, it may be approaching a critical climate threshold beyond which rapid (decadal-scale) and potentially catastrophic changes may occur that are not anticipated.”

Direct evidence for changing climate patterns is provided by the expansion of the tropics and migration of climate zones toward the poles, estimated at a rate of approximately 56-111 km per decade. As the dry subtropical zones shift toward the poles, droughts worsen and overall less rain falls in temperate regions. Poleward shifts in the average tracks of tropical and extratropical cyclones are already happening. This is likely to continue as the tropics expand further. As extratropical cyclones move, they shift rain away from temperate regions that historically rely on winter rainfalls for their agriculture and water supply. Australia is highly vulnerable to expanding tropics as about 60 percent of the continent lies north of 30°S.

Low-lying land areas, including coral islands, delta and low coastal and river valleys would be flooded due to sea level rise to Miocene-like (5.3-23 million years ago) sea levels of approximately 40±15 meters above pre-industrial levels. Accelerated flow of ice melt water flow from ice sheets into the oceans is reducing temperatures over tracts in the North Atlantic and circum-Antarctic oceans. Strong temperature contrasts between cold polar-derived fronts and warm tropical-derived air masses lead to extreme weather events, retarding habitats, in particular over coastal regions. As partial melting of the large ice sheets proceeds the Earth’s climate zones continue to shift polar-ward (Environmental Migration Portal, 2015). This results in an expansion of tropical regions such as existed in the Miocene, reducing the size of polar ice sheets and temperate climate zones.

According to Berger and Loutre (2002) the effect of high atmospheric greenhouse gas levels would delay the next ice age by tens of thousands of years, during which chaotic tropical to hyper-tropical conditions including extreme weather events would persist over much of the Earth, until atmospheric CO₂ and insolation subside. Humans are likely to survive in relatively favorable parts of Earth, such as sub-polar regions and sheltered mountain valleys, where cooler conditions would allow flora and fauna to persist.

To try and avoid a global calamity, abrupt reduction in carbon emissions is essential, but since the high level of CO₂-equivalent is activating amplifying feedbacks from land and ocean, global attempts to down-draw about of 50 to 100 ppm of CO₂ from the atmosphere, using every effective negative emissions, is essential. Such efforts would include streaming air through basalt and serpentine, biochar cultivation, sea weed sequestration, reforestation, sodium hydroxide pipe systems and other methods.

But while $trillions continue to be poured into preparation of future wars, currently no government is involved in any serious attempt at the defense of life on Earth.


Andrew Glikson
Dr Andrew Glikson
Earth and climate scientist
Australian National University

Books:

- The Archaean: Geological and Geochemical Windows into the Early Earth
- The Asteroid Impact Connection of Planetary Evolution
- Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
- Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
- The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
- Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
- From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence