Imagine cutting down a tree. Initially, you chop and chop … but not much seems to change. Then suddenly, one stroke of the hatchet frees the trunk from its base and the once distant leaves come crashing down.
It’s an apt metaphor for one of the most alarming aspects of climate change – the existence of “tipping points.”
These elements are components of the climate that may pass a critical threshold, or “tipping point,” after which a tiny change can completely alter the state of the system. Moving past tipping points may incite catastrophes ranging from widespread drought to overwhelming sea level rise.
Some of the Threats:
Disappearance of Arctic Summer Sea Ice
- As the Arctic warms, sea ice melts and exposes dark ocean waters that reflect sunlight much less efficiently.
- This decreased reflectivity causes a reinforcement of Arctic warming, meaning that the transition to a sea-ice free state can occur on the rapid scale of a few decades.
- Some scientists have suggested that we have already passed this tipping point.
Melting of the Greenland Ice Sheet
- Arctic warming feedback described above may one day render Greenland ice-free.
- Research predicts that the tipping point for complete melt can occur at a global temperature rise of less than two degrees Celsius.
Disintegration of the West Antarctic Ice Sheet
- The bottom of this ice sheet lies beneath sea level, allowing warming ocean waters to slowly eat away at the ice.
- There is evidence that this tipping point has already been surpassed – possibly as early as 2014.
Collapse of Coral Reefs
- Healthy corals maintain a symbiotic relationship with the algae that provide their primary food source.
- As oceans warm and become more acidic, these algae are expelled from the corals in an often fatal process called coral bleaching.
- Research predicts that most of our remaining coral systems will collapse even before a global temperature rise of two degrees Celsius.
Disruption of Ocean Circulation Patterns
- The Thermohaline Circulation is driven by heavy saltwater sinking in the North Atlantic, but this water is becoming fresher and lighter as glaciers melt in a warming climate.
- The change in water density may prevent sinking and result in a permanent shutdown of the circulation.
- Research suggests that weakening of the Thermohaline Circulation is already in progress.
- Some models suggest that these changes may prompt a secondary tipping element in which the subpolar gyre currently located in the Labrador Sea shuts off.
- As global temperatures rise and the high latitudes experience amplified warming, melting permafrost gradually releases carbon dioxide and methane into the atmosphere and creates a feedback for even more warming.
Release of Marine Methane Hydrates
- Large reservoirs of methane located on the ocean floor are stable thanks to their current high pressure-low temperature environment.
- Warming ocean temperatures threaten the stability of these greenhouse gas reservoirs
Melting of the Himalayan Glaciers
- Several warming feedbacks render the Himalayan glaciers vulnerable to dramatic melt within this century.
- Dust accumulation on the mountainous glaciers and the continual melt of snow and ice within the region both prompt a decrease in sunlight reflectivity and amplify regional warming.
Extracted from Everything you need to know about climate tipping points, written by Casey Ivanovich, 1 November 2017. http://blogs.edf.org/climate411/2017/11/01/everything-you-need-to-know-about-climate-tipping-points/
Dangerous Climate Change is Here
‘Climate change is here, it is dangerous,’ Johan Rockström, executive director of the Stockholm Resilience Centre, tells COP23 delegates.
As global temperatures climb higher, the earth is approaching tipping points that threaten human security, leading scientists – including social scientists – have warned during the UN climate summit in Bonn.
The warning comes as global greenhouse gases (GHG) emissions are projected to rise after three stable years. GHG emissions – mainly carbon dioxide – are warming the earth’s atmosphere, leading to more frequent and more severe floods, storms and droughts, and rising sea levels.
“There is no room for complacency. Climate change is here. It is dangerous. And it is about to get much worse,” said Johan Rockström, executive director of the Stockholm Resilience Centre and Chair of the Earth League – an international network of scientists. “In the last two years, evidence has accumulated that we are now on a collision course with tipping points in the earth system.”
Much evidence suggests that the planet has entered a new geologic epoch — called the Anthropocene. The rate of change of the earth system is accelerating as a result of humans’ impact on the planet’s biology, chemistry and physics. The Earth’s climate has been remarkably stable since before the dawn of civilisation, but is now at risk
Earth is approaching critical “tipping points”. By crossing these thresholds, the planet may see abrupt – and possibly irreversible – shifts in the workings of the Arctic, Amazon and other parts of the globe
The record-breaking Atlantic hurricane season this year provides a glimpse at the increased risks of extreme weather events that the planet may experience in the future. These events include severe flooding, heat waves and droughts
Changes are occurring quickly in the ocean, with accelerating sea-level rise and ocean acidification
The economic costs of climate change are already being felt, and some of the world’s poorest nations are bearing the heaviest burden
Climate change will have a profound impact on human health by placing new pressures on food and water security in nations around the world.
Climate change is likely to exacerbate migration, civil unrest and even conflict. In 2015, more than 19 million people worldwide were displaced by natural disasters and extreme weather events. Climate change will likely cause that number to grow.
Extracted from Earth approaching tipping point, warn scientists by Joydeep Gupta, 17 November 2017. https://www.thethirdpole.net/2017/11/17/earth-approaching-tipping-point-warn-scientists/
Anyone who does not know what Latent Heat is will have a false sense of security. It is not hard to understand.
Place on a hot stove a pot of cold water containing 1 kg of ice cubes. Stir the ice water with a long thermometer and take temperature readings. The question is: When will the thermometer begin to show a rise in temperature? Answer: After all the ice has melted.
In other words, all the heat from the stove would first all go into melting the ice, without raising the water temperature. The amount of heat entering a system without raising the temperature of the system is called Latent Heat.
It takes 80 calories of heat to melt one gram of ice. So in this case, the first 80,000 calories of heat from the stove went into melting the 1 kg of ice first. Only when the ice is all gone will the water temperature rise, and it will do so until it reaches 100C, when the water will begin to boil.
Once again, Latent Heat comes into play, and the water temperature will stabilize at the boiling point – until all the water have changed from liquid to vapour, at which point the temperature of the dry pot will rise to the temperature of the flame itself.
So how does this apply to Earth’s climate? Consider the Arctic Ocean to be a gigantic pot of ice water, and the sun as the stove. For as long as there is still sea ice to melt, the Arctic Ocean will remain relatively cool, in spite of the ever increasing solar heat entering the Arctic ocean due to ever decreasing ice cover. When the sea ice is gone in the summer, as early as the latter part of this decade, the Arctic Ocean’s temperature will steeply rise, and when it does, so will the global mean temperature, and all hell will break lose.
Extracted from The Role of Latent Heat of Fusion in Global Warming, by Anthony Marr – http://www.occupyforanimals.net/how-the-climate-will-change–the-role-of-latent-heat-of-fusion-in-global-warming.html