Everything on Earth, underground, and in the atmosphere interacts in complex ways: this is sometimes called the Earth system . When greenhouse gases make the atmosphere warmer, this has a range of effects on the Earth system . In the last few posts we have delved into how this can cause “positive feedback loops”, whereby a response by the Earth system to a change in temperature leads to even more temperature rise [3,4].
But the opposite can also happen! In some cases, an increase in temperature causes a response in the Earth system that triggers a decrease in temperature, stabilising the climate [3,8,9]. Unsurprisingly, this is an example of a “negative feedback loop” [3,4]! You can think of them like human sweat: when you get too hot, sweating cools your skin because evaporation of water take energy from your body, making you less likely to overheat .
One of the most important negative feedbacks for climate change is “lapse rate” feedback : there is a temperature gradient linked to height which means the Earth’s atmosphere gets cooler the higher you go . This gradient (or lapse rate ) is changing due to climate change . In the tropics, the top of the atmosphere is warming more than the lower part . This allows more infrared radiation to escape into space , cooling the atmosphere – it’s negative feedback [6,7,13].
Near the poles, the opposite is the case: the lower atmosphere is warming faster, leading to less efficient radiation loss into space. This is a positive feedback [6,7,13], but it is thought to be outweighed by the negative feedback occurring in the tropics .
Unfortunately, the stabilising effect of negative feedbacks is outweighed by the destabilising effect of positive feedbacks [8,9,10]. Overall, the Earth System amplifies the warming effect of greenhouse gases [8,9], but we can be grateful to negative feedback for slowing the rate of warming !
 https://www.ipcc.ch/site/assets/uploads/2018/03/TAR-07.pdf See: 7.1 Introduction
 https://www.soas.ac.uk/cedep-demos/000_P500_ESM_K3736-Demo/unit1/page_14.htm See: Feedback loops and equilibrium
 https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_TS_FINAL.pdf See: TS.3.7 Climate Feedbacks
 https://www.nature.com/articles/s41467-018-04173-0 See: Feedbacks in polar regions, Radiative feedbacks
 https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_TS_FINAL.pdf See: TFE.6 Climate Sensitivity Feedbacks
 https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINAL_full.pdf See: 2.2.4 “Based on Earth System Models…”
 https://www.grc.nasa.gov/www/k-12/airplane/atmos.html See: Paragraph 2
 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5953926/ See: Radiative feedbacks
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