Abrupt Climate Change
Other online resources
The past climate change heats up PNAS 2000 research paper
Steven M. Stanley
Research  has provided a shocking new assessment of the speed with which major climate changes can sweep across our planet.

​​The most precise evidence of rapid climate change comes from cores extracted from mountain glaciers and from the larger ice sheets of Greenland and Antarctica. Annual layers in the glacial ice provide the chronology and key data on snowfall, temperature, influx of dust, and trace gases from the ancient atmosphere trapped in air bubbles.

​​There is ominous evidence that, during the past few thousand years, Earth's climate has been anomalously tranquil compared to its behavior during the preceding hundred thousand years. 

Ice-core evidence of abrupt climate changes
Richard B. Alley
Ice-core records show that climate changes in the past have been large, rapid, and synchronous over broad areas extending into low latitudes, with less variability over historical times. These ice-core records come from high mountain glaciers and the polar regions, including small ice caps and the large ice sheets of Greenland and Antarctica.

As the world slid into and out of the last ice age, the general cooling and warming trends were punctuated by abrupt changes. Climate shifts up to half as large as the entire difference between ice age and modern conditions occurred over hemispheric or broader regions in mere years to decades. Such abrupt changes have been absent during the few key millennia when agriculture and industry have arisen. ​​​


The IPCC 2007 AR4 ​ Arctic Ch 15  warned of feedback abrupt change. '​​​​The possibility of abrupt climate change and/or abrupt changes ​ in the earth system triggered by climate change, with potentially catastrophic consequences, cannot be ruled out.
​Positive feedback from warming may cause the release ​of carbon or methane from the terrestrial biosphere and ​oceans which would add to the mitigation required

​​IPCC 2014 AR5 included abrupt references but in unclear language
Within this century, magnitudes and rates of climate change associated with medium- to high-emission ​scenarios (RCP4.5, 6.0, and 8.5) I.e. ALL BUST BEST CASE pose high risk to abrupt and  regional-scale change in composition structure,.... Examples that could lead to substantial impact on ​climate are the ​boreal-tundra Arctic system  and the Amazon forest. Carbon stored in the terrestrial biosphere  (e.g., in ​peatlands, permafrost, and forests) is susceptible to loss to the atmosphere as a result of climate change, deforestation, and ecosystem degradation (high confidence). Increased tree mortality ​and associated forest dieback is projected to occur in many regions over the 21st century, due to increased ​temperatures and drought. Forest dieback poses risks for carbon storage

IPCC 2007 AR4 Arctic abrupt refs

​​Climate models cannot predict abrupt or sudden change because  by design their If the projections
​have to be smooth.

In 2002 the national research council of published a comprehensive ​report on abrupt climate change inevitable surprises. A 2004 short report followed. The NRC published another  ​comprehensive report in 2013 Abrupt Impacts of Climate Change ​Anticipating Surprises.

Today's ocean heating is abrupt (sudden) and accelerating.

Abrupt Arctic change The Arctic is now heating up over 2x the global average, which is abrupt and causing adverse abrupt Arctic changes, making Arctic climate change abrupt by any definition for policy.

​​​The real question is do today's record high atmospheric GHGs have the world committed (locked in) to actual abrupt catastrophic impacts to the planet. There is evidence from amplifying feedback science that this is the case.

The most recent and dramatic example is the Younger Dryas ​​13,000 years ago, of abrupt cooling terminated by an abrupt warming of 10C in a only a few decades. The sudden warming is attributed to methane and CO2 from wetlands and thawing permafrost. 

The ​​IPCC AR5 : a large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems. There is information on potential consequences of some abrupt changes
  • ​​Examples of components susceptible to such abrupt change are the strength of the Atlantic Meridional Overturning Circulation (AMOC), 
  • ​clathrate methane release,
  • ​tropical and boreal forest dieback, 
  • ​disappearance of summer sea ice in the Arctic Ocean,
  • ​long-term drought and 
  • ​monsoonal circulation
​​The planetary catastrophic risk of abrupt climate change has been recognized for many years
​ In 2002 the us National  Academy published
Abrupt Climate Changes: Inevitable Surprises
In 2013 an update report (extracts below) from the US National Academies was published Abrupt Impacts of Climate Change
12 Oct 20​15 Catalogue of abrupt shifts in Intergovernmental Panel on Climate Change climate models. 'Eighteen out of 37 events occur for global warming levels of less than 2°'

​The US under the Department of Energy has a special research project called the Investigation of the Magnitudes and Probabilities of Abrupt Climate TransitionS (IMPACTS) Project. It addresses four abrupt situations. 
  • ​Dynamics of ice shelf — ocean interaction and  marine ice sheet instability;
  • Boreal/Arctic-climate positive feedbacks and ACC;
  • Rapid destabilization of methane hydrates in Arctic Ocean sediments;
  • Mega droughts in North America, including the role of biosphere-atmosphere feedbacks.
 The Health and Human Rights Approach to Climate Chnage
July 2020 Current abrupt Arctic warming risks abrupt global heating. The most recent and dramatic example of abrupt (as sudden)climate change is at the end of the abrupt 'Younger Dryas' cooling ​​13,000 years ago. Greenland ice cores showed  this was followed by a Northern hemisphere sudden huge warming of 10C in o​nly a few decades. The sudden warming is attributed to methane and CO2 from wetlands and thawing permafrost, but nitrous oxide is also linked (IPCC AR4)That makes today a global planetary emergency situation.

​​Today's sudden decline in Arctic summer sea ice cooling is expected to cause abrupt climate changes outside of the Arctic (Holocene warming marked by abrupt onset of longer summers ..., P. A. Mayewski, 2013). 

End Younger Dryas Abrupt Warming: 10C in a few decades!
We know abrupt warming and cooling can happen because they show up in the ice cores. A particularly recent (in climate history​ terms 11,500 years ago) and extreme example is the Younger ​ Dryas abrupt cooling and abrupt warming event. Research finds​ the warming was 10C over just a few decades. The cause was methane emissions. Research by Prof Nisbet has shown that ​NH wetland methane was involved and also methane hydrate​ may have played a role.​​The Greenland and temperature increased from about -50C to -35C. More than Greenland average temperature is -18.5 (from 1850-2015). A 2012 study Younger Dryas cooling and the Greenland climate response to CO2, ​Zhengyu Liu, 'suggests that climate sensitivity as assessed from ice core records may underestimate the severity of rapid regional warming over Greenland in response to present and future anthropogenic greenhouse gas emissions.'

​​The atmospheric increases of all three main greenhouses are clearly abrupt. In particular atmospheric CO2 is accelerating faster than ever (2017) at a rate without past precedent (WMO 2017).

​There is no question that today's abrupt atmospheric greenhouse gas levels have led to a dramatic obvious sustained abrupt accelerating radiative forcing (heating) of the biosphere (see: dramatic graphs from the2007 IPCC asessment). This is a most policy relevant definition of abrupt climate system change.

The IPCC AR5 2014 assessment defined abrupt climate change as a large-scale change in the climate system that takes place over ​a few decades or less, persists (or is anticipated to persist) for at ​least a few decades, and causes substantial disruptions in​
​human and natural systems. That should have said and risks substantial disruptions in​ ​human and natural systems 
Our agriculture based civilizations are only a go back about 5000 years and the earliest very small scale agriculture about 10,000 years, which is the Holocene. Agriculture is totally dependent on a stable climate. Today's global warming of a couple of hundred years is extremely sudden. ​​

​The sudden temperature spike now is up to 1.1°C is abrupt, and is above the global temperature limit of the Holocene.

Today's global warming over the past 50 years is sudden in terms of the past 2000 years. ​​