Discussions of climate change often involved the concept of tipping points. This concept breaks climate change into a series of components, each of which represents a major controlling factor. The tipping point is defined as a threshold point, that when passed, will lead to an irreversible change. An example of a tipping point could be Arctic sea ice. Recent years have seen a significant reduction of Arctic sea ice in both volume and areal coverage. Some studies claim a decrease in sea ice of about 40% over the past 40 years. The cause, at the simplest level, is that more ice melts each summer than forms each winter.
Understanding where a tipping point may exist for Arctic sea ice involves some knowledge of thermodynamics controlling sea ice formation. Sea ice forms at the interface between the ocean and the atmosphere, and it develops as part of a heat exchange mechanism. Because the Arctic Ocean is warmer than the atmosphere in the winter, the heat transfers from the warmer water to the colder air. Cooling at the ocean surface then lets ice form. As ice forms, it inhibits this heat transfer and acts as an insulator. When the ice is thick enough to impede any transfer of heat (about 3 meters), it stops growing. At this point, the sea ice has reached its thermodynamic equilibrium thickness. When the atmosphere warms in the summer, the sea ice will melt and thin. If the atmosphere warms enough, the ice will disappear and expose the open ocean waters below.
Large continuous sheets of sea ice are called floes. Single floes can be thousands of meters wide, and they can drift as individual units or weld together to form a continuous ocean cover. A critical aspect of sea ice is its high albedo (sunlight reflectivity). The darker ocean water is not nearly reflective as the ice and absorbs heat more quickly. If ice thins, but remains as an insulating cover, during the summer, then significant amounts of solar radiation will be reflected back into the atmosphere or space. However, if the ice completely melts, then the ocean waters will efficiently absorb the sun’s energy and heat up. The warmer water makes it harder for ice to form the next winter. This process leads to thinner ice floes and even more exposed Arctic ocean water the following summer.
It’s not difficult to imagine there is a point where temperatures escalate, the Arctic Ocean heats up, and sea ice cannot form in the wintertime. The point where enough ice melts to create conditions where the winter ice floes don’t form would be a tipping point. A threshold that once passed renders the Arctic climatic system incapable of forming enough winter ice to reverse the changes.
Climate change
Is it fair to think that politics is a tipping point for climate change? The answer is an indisputable yes. The basis for this is that there is zero evidence that any factor other than human activity since the industrial revolution has caused global temperatures to rise significantly faster today than in all previous interglacial periods. Studies from various disciplines all point to interglacial warming periods with rates of temperature change of up to 0.1 degrees C per 100 years. We have managed to increase global temperatures by 0.8 degrees C in the last 100 years. Solar and volcanic activity cannot account for the magnitude of this change.
Of course, it is not all just about temperature. Rapid acidification of our oceans has been a side effect of increased CO2 since about 25 percent of all CO2 put into the atmosphere is absorbed by ocean waters. Substantial reductions in the size of the Amazon rain forest change the rate of heat exchange between the earth and air and affect weather patterns. Species reduction and extinction is occurring at an unprecedented rate, only seen in geologic history during mass extinction events.
It’s not all bad news. The rise in renewable and sustainable energy production is reducing the rate at which we consume fossil fuels. Ecologically friendly farming technology is producing more efficient and sustainable farming practices. Efforts in developed nations over the past 50 years to clean up waterways have been largely successful. Much of this has been due to government policy that provides a level playing field so individual enterprises cannot degrade the public environment in order to achieve short term profits. With a level playing field, we have seen companies embrace conservation and environmentally sustainable practices.
Politics
Politics can work to move climate and environmental issues forward. Politics, however, is subject to the whims of those in power, and it is just as easy to move forward as backward. When science ceases to be a basis for policymaking and becomes a partisan political tool, then poor long-term decision making will be the rule of the day. The will of governments to address climate change, or not, is a tipping point. The only question is which way will it tip scales.
There are reasons that the younger generation is leading the way in demanding changes in our treatment of the climate. It is the same reason a whole generation in the 1960s exploded in protest over the Vietnam War: Survival. The draft was in full force and the blind persistence of the government to fight a war that couldn’t be won, was a death sentence to many. Blind political persistence to take wealth now at the expense of the environment, and let future generations pay the price, probably does not seem like a great deal to them. Just as those politicians who start wars don’t die in them, those who make poor environmental decisions today will not be the ones to suffer the consequences.
When we trade critical thinking for a bag of magical beans, then we know we are approaching a negative tipping point.
Sources:
Arctic sea ice reduction: the evidence, models and impacts. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4455716/
