Climate Change: Winners and Losers
Lesson 5: Winners and Losers
Page 1: Feedback Loops Page 2 Summary
Feedback Loops:
Our story so far: Climate change is a very complex problem, with many influences and many unpredictable effects. These lessons present only a brief introduction to the topic. One area we have not looked at yet is the role of potential feedback loops on global temperatures.
A feedback loop is a condition where a change in one thing has an effect on something else that then impacts the initial change. There are both positive and negative feedback loops.
In a positive feedback loop, the effect makes the change even greater, which makes the effect greater, which then makes the change even greater, and so on. Calling a feedback loop "positive" does not mean that the outcome is desirable. All it means is that the effects increase the amount of change.
We've already discussed one positive feedback loop that relates to climate change. As the planet heats up, ice caps melt, exposing the darker water or land under the ice. The water or land absorbs more of the Sun's energy than the ice, so the planet heats up even more. This causes more ice to melt.
Methane release is another positive feedback loop. Methane is a powerful greenhouse gas. There is a lot of methane in ocean sediments. A lot of this methane is currently trapped under polar ice. As increasing temperatures cause ice caps to melt, more methane gets released into the atmosphere, which raises temperatures even more.
There are also negative feedback loops. With a negative feedback loop, the effect reduces the amount of change. Negative feedback loops can help to reduce the increase in global temperatures.
Plants are an example of a negative feedback loop. Plants pull CO2 out of the atmosphere, using it to make starches and build cells. As the level of CO2 increases, plants grow more quickly and pull more CO2 out of the atmosphere. If the rate at which plants pull CO2 out of the atmosphere balances the rate at which we add it, worldwide CO2 levels will begin to stabilize.
There are beautiful, microscopic, plant-like plankton in the ocean called coccolithophores (kok-a-LITH-a-4s) that also rely on CO2 for their survival. As CO2 in the atmosphere increases, coccolithophore populations increase and pull more CO2 out of the atmosphere. This can also help to stabilize temperatures over time.
One of the ironies of climate change is that positive feedback loops have negative outcomes, while negative feedback loops have positive outcomes.
The difficulty in discussing the effects of feedback loops on climate change together is that it is not clear which feedback loops will have the greater impact. All we know right now is we are adding CO2 to our atmosphere at a rate that is faster than the rate that these negative feedback loops can remove it.
Over the past 70 years or so, an improving world economy has lifted hundreds of millions of people out of extreme poverty. This has helped reduce the malnutrition and infectious diseases that extreme poverty can foster. The result is that in many countries, people today can expect to have longer, healthier lives than the people who lived 70 years ago.
Yet the improving world economy that has lifted so many countries out of poverty is also the main engine driving the climate change that may well plunge many countries back into poverty in the future. Over the next 70 years, rapid climate change could start to reverse all of the positive gains of the past 70 years.
Go to Page 2