Greenhouse emissions today linger in the atmosphere for decades or even centuries. David McNew/Getty Images Julien Emile-Geay, USC Dornsife College of Letters, Arts and Sciences
By now, few people think that we have a hand in influencing the climate of Earth. But the real issue is: How quickly can we stop, or even reverse the harm?
Part of the answer to this question is in the notion of ” committed warming,” also known as “pipeline warming.”
This refers to the future rises of global temperatures which will originate from greenhouse gases which have already been released. In other words, if the transition to cleaner energy took place in a short time, what amount of warming will still occur?
The energy budget of Earth is not in equilibrium
Humans contribute to global warming because their activities release greenhouse gases. They hold heat within the air, and block it from escaping out to space.
Before people began burning fossil fuels to power machinery and automobiles, as well as raising methane-releasing cattle in almost every region of arable, earth’s energy resources were in balance. About the same amount of energy was coming from the Sun that was being released.
Today, rising carbon dioxide concentrations within the atmosphere are more than 50% more than at the dawn of the industrial age, and they’re trapping more of that energy.
Earth’s delicate energy balance. California Academy of Sciences.
Those carbon dioxide emissions, along with greenhouse gases like methane, as well as partially offset by aerosol air pollution, have the capacity to trap energy comparable to the detonation of five Hiroshima-style atomic bombs every second.
With more energy coming in than leaving, Earth’s thermal energy grows, elevating the temperature of the earth, oceans and air and melting ice.
The pipeline is warming
The results of playing with Earth’s balance of energy take time to show up. Take a look at what happens when you turn the hot water tap fully on an unseasonably cold winter day. The pipes are full of cold water. It takes time for the warm water to reach you , hence the name “pipeline warming.” The warming isn’t yet felt however, it’s already present in the pipeline.
There are three main causes for Earth’s climate to continue warming when emissions cease.
The leading contributing factors for global warming are carbon dioxide and methane – stay in the atmosphere for an extended period of time: around 10 years, on average in the case of methane, and a whopping 400 years for carbon dioxide, with some molecules remaining around for as long as millennia. So, turning off emissions won’t result in instant reductions in the amount of heat-trapping gasses in the atmosphere.
Second, part of this warming has been offset with pollution from man made sources of another kind of pollutioncalled sulfate sulfate aerosols. They are tiny particles produced in the combustion of fossil fuels, which reflect light into space. Since the beginning of the century this worldwide dimming has been masking the warming effect from greenhouse gases. Yet, other, human-made aerosols can also be harmful to our health and ecological balance. Removing those and short-lived greenhouse gases translates to just a couple of tenths of one degree of warming more over about a decade, before attaining a new equilibrium.
In the end, the Earth’s climate needs some time to adapt to any change in energy balance. Around two-thirds of the Earth’s surface is comprised of water, sometimes very deep waters, that are slow to take up the extra carbon and heat. As of now, over 91% of the added heat from human activity along with about a quarter of the excess carbon has gone to the oceans. Although land dwellers might be thankful for this protection, the added heat can contribute to rising sea levels through the expansion of thermal energy and sea heat waves, while the extra carbon can make the ocean hostile to shelled animals that can cause disruption to the ecosystem of marine food chains.
Temperature of the earth’s surface is influenced by the imbalance in radiant energy at the top of the atmosphere, as well as modulated by the enormous thermal inertia of its oceans it is playing catch-up on its largest control knob the concentration of carbon dioxide.
How much warming?
How much committed warming are we in for? We don’t have a definitive answer.
The earth has already warmed more than 1.1 degree Celsius (2 F) compared with pre-industrial levels. World leaders agreed in the year 2015 to work towards preventing the temperature of the world average from rising over 1.5degC (2.7 F) to minimize the harm, however, the world is in a slow reaction.
How to determine the degree of warming ahead can be a bit difficult. Numerous recent studies make use of climate models to forecast future temperatures. A examination of 18 Earth system models discovered that once emissions were cut off certain regions continued to warm for several decades, or hundreds of years, while others began cooling quickly. Another study, which was published in June 2022, showed an 42% chance that the planet is determined to 1.5 degree Celsius.
The amount of warming matters since the harmful effects from global warming aren’t just grow in relation to global temperature; they typically accelerate, with a particular focus on the production of food at risk from heat, drought and storms.
Furthermore, Earth has tipping spots that can trigger irreparable alteration to vulnerable parts of the Earth system, such as ecosystems or glaciers. It isn’t always clear immediately when our planet has crossed a tipping mark since these modifications tend to take a long time to show up. These and similar climate-related systems serve as the foundation for the precautionary principle that helps limit warming below 2degC (3.6 F), and preferably, 1.5degC.
The core of the climate challenge, as reflected in this concept of committed heating, is the long gaps between human behavior and changes in the climate. Although the exact amount of climate change that has been committed is subject to debate but evidence suggests that the best route forward is to urgently switch to a carbon-free and more fair economy that releases lesser greenhouse gas emissions.
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