By Jonny Lupsha, Wondrium Staff Writer
The Environmental Protection Agency’s new website now has climate info. The subsite, called Climate Change Indicators in the United States, features dozens of links to information about our changing climate. The Hadley cell concept best explains climate change.
The Environmental Protection Agency has launched a comprehensive new website with information about climate change. The site is divided into six sections: Greenhouse Gases, Weather and Climate, Oceans, Snow and Ice, Health and Society, and Ecosystems. Each section features between five and a dozen pages with more detailed information about climate change. For example, the Greenhouse Gases section has a greenhouse gas summary, a page on U.S. greenhouse emissions, another on global emissions, and so on.
Climate change is a delicate subject. In his video series Earth at the Crossroads: Understanding the Ecology of a Changing Planet, Dr. Eric Strauss, Presidential Professor of Ecology at Loyola Marymount University in Los Angeles, explained the science of climate change through the Hadley cell concept.
Birds Have the Right Idea
Earth’s climate goes through cyclical patterns of warming and cooling. Throughout Earth’s history, many of these cycles have been naturally occurring.
“However, examination of the effect that humans have shows that global warming is occurring, and humans are the critical contributing factor,” Dr. Strauss said. “In order for us to understand this a little better, we need to understand how heat moves around the globe to begin with. The Hadley cell concept is a pretty helpful model to consider the movement of heat around the globe.”
The circulation of air dominates the climate on Earth. That means that heat produced in one part of the Earth will be moved around due to the global circulation of air currents. Solar heating at the equator has the most direct angle to receive heating from the Sun, and that heat makes the air expand and travel up in latitude, later diverging at the poles.
“Soaring birds use this phenomenon on a smaller scale to conserve energy while flying,” Dr. Strauss said. “The notion that warm air rises and cool air falls, this rising of warm air becomes an available energy source that animals can use.”
The Hadley Cell Concept
In the middle of the 18th century, George Hadley developed the idea of a simple, single cell of convection, with air rising and cooling in a circular fashion. The idea came from the popular comment by sailors that in lower altitudes, winds blew east to west. In 1865, meteorologist William Ferrel proposed an alternate model with three convection cells.
“So this heat driven by these cells circulates air between the tropics and subtropics—we call that the ‘Hadley cell,'” Dr. Strauss said. “Then there’s a Ferrel cell in the mid-latitudes that circulates and then, finally, there’s a Polar cell. Each consists of one belt of rising air that moves up, cools, and then sinks, and then warm air moving up again and back where it originally rose.”
These three cells work like cogs in a machine, generating one huge movement of heat around the Earth.
Localized areas of the Earth may become wetter, drier, hotter, or colder as climate change affects our planet, but overall, Dr. Strauss said, the whole system is heating up. The so-called “greenhouse gases” play a crucial role.
“Greenhouse gases occur naturally in the Earth’s atmosphere—they include water vapor, carbon dioxide, methane, and ozone. The primary physical function they have with respect to global climate is that they help absorb and emit the Sun’s infrared radiation. [We know] that over the last 150 years, the greenhouse gases have been driving significant amounts of temperature change.”
He added that one of the most important studies that help us understand the rising levels of greenhouse gases come from a 60-year uninterrupted study of carbon dioxide readings taken from Mauna Loa in Hawaii, which showed an increase of 30%. Another study by the International Plan on Climate Change showed that from 1970 to 2004, greenhouse gas levels have gone from 28.7 gigatons of carbon equivalence per year to almost 50 gigatons.
“The greenhouse effect is a model that we use to understand how our Earth remains a hospitable environment under normal circumstances, but actually heats up with the addition of this anthropogenic carbon,” Dr. Strauss said. “When we think of the blanket model of thinking about greenhouse gases, it’s less like a greenhouse and more like an electric blanket.
“An electric blanket keeps you warm in the winter not just because it traps your body heat, but because it generates additional heat as a function of an electrochemical interface.”
The more greenhouse gases there are in the atmosphere, the more heat they’ll trap from the Sun. The more heat gets trapped, the more it affects the Hadley cells and, ultimately, our climate.