Abrupt climate change can be differentiated from regular climate change behavior and patterns.
In this guide, we look at what an abrupt climate change event is, and events that may have happened in the past.
We discuss whether abrupt climate change may happen in the future.
Summary – How Fast Earth’s Climate Changed In The Past, & What To Know About Abrupt Climate Change
- Earth’s climate has varied and gone through different periods in it’s 4.5 billion year history
- When defining Abrupt climate change specifically, this is a sudden change in the climate over the course of a few years or decades, or even the span of a human lifetime
- One current admissions about abrupt climate change is that ‘Scientific understanding of abrupt climate change is generally poor’ (wikipedia.org)
- According to studies of paleoclimatic records, there has been several ‘abrupt’ climate change events throughout Earth’s history, although they are rare
- Temperatures are thought to have changed by as much as +10 °C (+18 °F) within a timescale of a few years during studied abrupt climate change events (studied from ice cores)
- Each abrupt change event in the climate was due to different specific factors
- One of the effects of abrupt climate change might be that humans and the environment have difficulty adapting to the change, or even that the change results in destructive and dire consequences
- What some scientists are saying, is that the rate of warming we are seeing today has some similarities to these abrupt climate change events of the past (increased CO2 levels, increasing temperature, events like a rising sea level and ocean acidification etc.). Additionally, some climate trends we are seeing today, such as rapid warming, may increase the probability of abrupt change happening
- They do also say though that a true abrupt climate change event is unlikely right now at least for the next century, but, increasing our emissions from fossil fuels could make one more likely (and conversely, reducing our emissions as quickly as possible might be the best way to reduce the likelihood of an abrupt or rapid climate change event happening in the future)
Firstly, What Is Classified As A True Abrupt Climate Change Event?
- The term “abrupt climate change” describes changes in climate that occur over the span of years to decades, compared to the human-caused changes in climate that are occurring over the time span of decades to centuries.
- The term is … used within the context of global warming to describe sudden climate change that is detectable over the time-scale of a human lifetime
- Timescales of events described as ‘abrupt’ may vary dramatically
- [Abrupt climate change may occur rapidly and unexpectedly]
Potential Uncertainty About Abrupt Climate Change
Interpretation of past abrupt climate change events might be taken as a general guide and not as an absolute because:
- ‘Scientific understanding of abrupt climate change is generally poor’ (wikipedia.org)
On Average, How Quickly Has Earth Climate Changed Throughout History?
Abrupt Climate Change Events In The Past (& What Caused Them)
Abrupt Climate Change Events From The Past
- Past [abrupt climate change] events include the end of the Carboniferous Rainforest Collapse, Younger Dryas, Dansgaard-Oeschger events, Heinrich events and possibly also the Paleocene–Eocene Thermal Maximum.
- Changes recorded in the climate of Greenland at the end of the Younger Dryas, as measured by ice-cores, imply a sudden warming of +10 °C (+18 °F) within a timescale of a few years. Other abrupt changes are the +4 °C (+7.2 °F) on Greenland 11,270 years ago or the abrupt +6 °C (11 °F) warming 22,000 years ago on Antarctica.
- By contrast, the Paleocene-Eocene thermal maximum may have initiated anywhere between a few decades and several thousand years.
Read more about the above events at https://en.wikipedia.org/wiki/Abrupt_climate_change
- Most past changes in global temperature occurred slowly, over tens of thousands or millions of years. However, there is also evidence that some abrupt changes occurred, at least at regional scales.
- For example, during the last ice age, temperatures in the North Atlantic region changed by 5°C or more over as little as a few decades, likely due to sudden collapses of Northern Hemisphere ice sheets or changes in ocean currents.
- An example of an abrupt climate change event is the Younger Dryas (~12,000 years ago), a period of abrupt cooling that interrupted a general warming trend as Earth emerged from the last Ice Age. During the Younger Dryas period, average summertime temperatures in New England cooled by about 5-7°F (3-4°C). This and other abrupt events have been linked to changes in an ocean circulation pattern known as thermohaline circulation.
- Indeed, during some of the abrupt events in Earth’s past climate, scientists find evidence of large catastrophic flows of fresh water into the North Atlantic from the melting of glaciers and ice caps, and due to flooding from glacier-dammed lakes. Without the large-scale sinking of salty water in the North Atlantic the influx of warm water to replace it from the tropics would not occur, effectively switching off the thermohaline circulation.
- Past changes in thermohaline circulation have occurred during periods of relatively rapid climate change, such as transitions in and out of glaciations.
- …there have been several times in Earth’s past when Earth’s temperature jumped rapidly, in much the same way as they are doing today.
- Those times were caused by large and rapid greenhouse gas emissions, just like humans are causing today.
- In Earth’s past the trigger for these greenhouse gas emissions was often unusually massive volcanic eruptions known as “Large Igneous Provinces,” with knock-on effects that included huge releases of CO2 and methane from organic-rich sediments. But there is no Large Igneous Province operating today, or anytime in the last 16 million years. Today’s volcanoes, in comparison, don’t even come close to emitting the levels of greenhouse gasses that humans do.
- …Those rapid global warming events were almost always highly destructive for life, causing mass extinctions such as at the end of the Permian, Triassic, or even mid-Cambrian periods.
- The symptoms from those events (huge and rapid carbon emissions, a big rapid jump in global temperatures, rising sea levels, ocean acidification, widespread oxygen-starved zones in the oceans) are all happening today with human-caused climate change
- … global warming 66 million years ago was due to catastrophic eruptions in India, which emitted a pulse of CO2 that sent global temperatures soaring by 7°C (13°F).
Skeptical Science explain more about what causes rapid global warming in this guide – https://skepticalscience.com/Lee-commentary-on-Burgess-et-al-PNAS-Permian-Dating.html
In addition to what is identified as causes of specific events above.
- Abrupt climate change is possibly the result of ‘feedback loops within the climate system’ … [where a] warming event causes a change that ads to further warming (wikipedia.org)
Possible Effects Of Abrupt Climate Change
It can possibly result in:
- Mass extinctions
- Loss of biodiversity
- Changes in ocean circulation
How Are Abrupt Climate Change Events From The Past Interpreted?
One way is through ice cores:
- Changes recorded in the climate of Greenland at the end of the Younger Dryas, as measured by ice-cores, imply a sudden warming
But, various forms of proxy material can be used:
- From ice cores, ocean sediments, tree rings, and other records of Earth’s past climate, scientists have found that changes in climate have occurred quickly in the past—over the course of a decade
Climate Models & Abrupt Climate Change
- Climate models are unable yet to predict abrupt climate change events, or most of the past abrupt climate shifts
Will Abrupt Climate Change Events Happen In The Future?
Abrupt climate change in the near future is only a possibility at this stage, and probably a low possibility at that [at least over the next century].
Certain factors and precursors may increase the likelihood of an abrupt climate change event happening in the future.
- Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly and warming that is sustained over longer time periods
- [A precursor to abrupt climate shifts is a sudden circulation shift]
- While abrupt climate change is not a certainty, human-caused climate change makes abrupt events more likely [Human activities may be driving the climate system toward a threshold and thus increasing the chance of abrupt climate changes occurring.]
- The possibility of an abrupt shift in the climate system is only one feature of a changing climate that is expected to become more erratic, with extreme weather events like droughts, torrential rainfall, and extreme heat becoming more common.
- We can slow down global warming and reduce the likelihood of future abrupt climate changes by reducing our emissions of heat-trapping gases.
- … the rapid warming we are currently experiencing could trigger an abrupt thermohaline shutdown and subsequent regional cooling. … [however] a shutdown of thermohaline circulation is unlikely to occur in the next century