Climate lag
Climate lag refers to the delay in the observable effects of climate change resulting from specific factors, such as greenhouse gas emissions. When carbon dioxide (CO2) is released into the atmosphere, its full impact is not immediately felt due to various processes, including natural absorption by oceans. This delay can range from two to three decades, meaning that even if emissions stopped entirely, warming would still continue for years due to ongoing climate processes. The phenomenon illustrates the complexity of Earth's climate system, where changes in climate forcings take time to manifest.
The concept of climate lag is significant because it highlights the potential for climate feedback effects—such as increased heat absorption by dark ocean waters or methane emissions from thawing permafrost—during this lag period, which could exacerbate warming. Given these concerns, responses to climate lag typically include prevention, mitigation, and remediation strategies. Prevention focuses on reducing greenhouse gas emissions to minimize future warming, while mitigation recognizes the inevitability of some climate impacts and seeks to lessen their severity. Remediation involves altering geophysical processes to address the consequences of climate change rather than just its causes. Understanding climate lag is crucial for informing effective climate policy and action.
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Climate lag
Definition
Climate lag denotes a delay in the climate change prompted by a particular factor. This can occur when the system is influenced by another, slower-acting, factor. For example, when carbon dioxide (CO2) is released into the atmosphere, its full effect may not be recognized immediately, because some of the CO2 may be partially absorbed, and much later released, by the oceans. The considerable amount of lag in geophysical systems can be seen in the delay between actions that increase or decrease climate forcings (changes that affect the energy balance of Earth) and their consequent impacts on the climate. Lag can be accounted for in several ways: Some occurs because of the length of time it takes for certain chemicals to cycle out of the atmosphere, some results from the effects of warming upon natural cycles, and some comes from the slow pace of oceanic temperature change. Many climate scientists estimate climate lag to be between twenty and thirty years; thus, even if all additional carbon emissions were to cease, Earth would still experience two to three decades of warming before the cessation took effect.
Significance for Climate Change
If, during a two- to three-decade lag, rising temperatures begin to trigger climate feedback effects—such as a reduction of the polar ice cap, allowing more heat to be absorbed by the dark water, or large emissions of methane from melting permafrost—the lag time could be extended. The longer some kinds of climate disruption are delayed, and the more climate commitment is built up, the more likely it is that feedback effects will be seen. “Climate commitment” refers to the fact that climate reacts with a delay to influencing factors. For example, an increase in the concentration of will influence Earth’s climate over time, rather than all at once. There are at least three responses to this situation: prevention, mitigation, and remediation. The potential for dangerous feedback effects drives a prevention response, that is, action that reduces the global warming risk. Since it is not yet known how damaging to the environment feedback effects could be, it seems prudent to do everything possible to start eliminating the sources of GHGs and thereby keep the level of committed warming to a minimum. A mitigation response takes a practical approach: Climate disaster is already imminent, and the best prevention efforts may be too little, too late, but there is still the need to reduce the worst of the threats. A remediation approach would not look at ways to change greenhouse emissions and their consequences; instead, efforts would be made to use geoengineering, that is, to alter the core geophysical processes that relate to global warming.
Hersher, Rebecca. "Carbon Emissions Could Plummet. The Atmosphere Will Lag Behind." NPR, 14 Apr. 2021, www.npr.org/2021/04/14/981333730/carbon-emissions-could-plummet-the-atmosphere-will-lag-behind. Accessed 16 Dec. 2024.
Huasfather, Zeke. "Explainer: How the Rise and Fall of CO2 Levels Influenced the Ice Ages." CarbonBrief, 2 July 2020, www.carbonbrief.org/explainer-how-the-rise-and-fall-of-co2-levels-influenced-the-ice-ages/. Accessed 16 Dec. 2024.
Peake, Tracey. "Time Lag Between Intervention and Actual CO2 Decrease Could Still Lead to Climate Tipping Point." NC State University, 15 Dec. 2021, news.ncsu.edu/2021/12/time-lag-could-still-lead-to-climate-tipping-point/. Accessed 16 Dec. 2024.