Most climate models do not yet account for a new UC Riverside discovery: methane traps a significant amount of heat in the Earth's atmosphere while also producing cooling clouds that offset 30% of the heat.
Greenhouse gases, such as methane, form a blanket in the atmosphere, trapping heat from the Earth's surface, known as longwave energy, and preventing it from radiating into space. This raises the temperature of the planet.
Methane Cools Even As It Heats
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"You feel warm because the blanket inhibits your body's ability to send heat into the air, which is the same concept as a blanket," explained Robert Allen, UCR assistant professor of Earth sciences, as per ScienceDaily.
In addition to absorbing longwave energy, methane absorbs incoming solar energy, also known as shortwave energy.
"This should warm the planet," said Allen,
However, contrary to popular belief, shortwave absorption encourages changes in clouds that have a slight cooling effect.
This effect is described in the journal Nature Geoscience, along with a second discovery that the research team did not anticipate.
Though methane generally increases precipitation, accounting for shortwave energy absorption reduces that increase by 60%.
Longwave (from Earth) and shortwave (from the sun) energy both escape from the atmosphere more than they are absorbed.
The atmosphere requires compensation for escaped energy, which it obtains from heat generated when water vapor condenses into rain, snow, sleet, or hail.
According to study co-author Ryan Kramer, a researcher at NASA Goddard Space Flight Center and the University of Maryland, Baltimore County, precipitation essentially acts as a heat source, ensuring the atmosphere maintains an energy balance.
This equation is altered by methane. By retaining solar energy, methane introduces heat that the atmosphere no longer requires from precipitation.
Furthermore, methane shortwave absorption reduces the amount of solar radiation that reaches the Earth's surface.
As a result, the amount of water that evaporates is reduced. Because precipitation and evaporation are generally equal, a decrease in evaporation results in a decrease in precipitation.
This has implications for a better understanding of how methane and possibly other greenhouse gases affect the climate system, according to Allen.
Shortwave absorption mitigates the overall warming and rain-increasing effects but does not completely eliminate them.
The findings were discovered by developing detailed computer models that simulated both longwave and shortwave methane effects.
They intend to conduct additional experiments in the future to learn how different methane concentrations affect the climate.
Methane has sparked increased scientific interest in recent years as emissions levels have risen.
Much of it comes from industrial sources, as well as agricultural and landfill activities. Methane emissions are also expected to rise as the frozen ground beneath the Arctic thaws.
Methane exposure, especially at high concentrations, can result in methane gas poisoning. While it is considered relatively non-toxic, its primary threat is that it acts as an asphyxiant, much like carbon monoxide exposure, as per NevadaNano.
When inhaled, it displaces surrounding air, depriving the body of the oxygen it requires to breathe.
While low concentrations are generally not harmful, higher concentrations result in decreased oxygen availability and a variety of symptoms.
As the concentration of methane rises and the period of exposure lengthens, the symptoms will worsen.
Mild exposure over days or weeks can often result in few physical symptoms but have a significant impact on overall mental health.
Methane gas poisoning can cause long-term cardiovascular, respiratory, and neurological problems.
Those who have been exposed are also more likely to suffer from memory loss, depression, epilepsy, claustrophobia, and heart problems.
Symptoms also appear and worsen more quickly as physical exertion increases (due to the increased oxygen needs of the body during physical activity).
Prolonged oxygen deprivation caused by methane gas poisoning can also cause permanent brain and heart damage.
Aside from the serious consequences of methane gas exposure displacing oxygen, methane poses few other health risks to those who come into contact with it.
Although it is not irritating, direct contact with liquified gas can cause frostbite and tissue death to exposed skin. It is not known to be carcinogenic.
