The Connection Between Greenhouse Gases, Climate Change & Global Warming


 

WHAT IS THE DIFFERENCE BETWEEN CLIMATE CHANGE AND GLOBAL WARMING?

Climate change is the shift in long-term, global weather patterns due to human action; it’s not exclusive to warming or cooling.

Climate change includes any change resulting from different factors, like deforestation or an increase in greenhouse gases. Global warming is one type of climate change, and it refers to the increasing temperature of the surface of Earth. According to NASA, the term global warming gained popular use after geochemist Wallace Broecker published a 1975 paper titled Climatic Change: Are We on the Brink of a Pronounced Global Warming?

Since 1880, the average surface temperature of the Earth has increased by roughly 0.9 degrees Fahrenheit, but the rate it’s increasing is faster than that, depending on which region you live in. If you’re closer to the equator, temperatures are increasing more slowly. The fastest increase in temperatures in the United States is in Alaska, where average temperatures have been increases by more than 3 degrees Fahrenheit per century. For a graph of average global temperatures by year, see the NASA website here.

 

HOW GREENHOUSE GASES RELATE TO CLIMATE CHANGE

Greenhouse gases are those thought to contribute to the greenhouse effect, an overall warming of the Earth as atmospheric gases trap electromagnetic radiation from the sun that would otherwise have been reflected back out into space.

Noteworthy greenhouse gases are methane, nitrous oxide, carbon dioxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are thought to affect the climate directly and indirectly, even though they constitute only a small fraction of the blanket of gases that make up the atmosphere.

Currently, the composition of the atmosphere is mostly nitrogen and oxygen, with just 0.033 percent carbon dioxide and all other gases accounting for even less.

 

WHICH GASES CONTRIBUTE THE MOST?


According to 2010 models cited by NASA, 20 percent of the greenhouse effect is attributed directly to carbon dioxide and 5 percent to all other greenhouse gases. The remaining 75 percent of the greenhouse effect is thought to be due to water vapor and clouds, which are naturally-occurring. However, even though carbon dioxide and the other greenhouse gases are such a small percentage of the total gas in the atmosphere, they affect when, where and how clouds form, so greenhouse gases have some relevance when it comes to 100 percent of the greenhouse effect. Carbon dioxide is thought to modulate the overall climate, like a atmospheric thermostat.

Some greenhouse gases are produced in natural processes, like forest fires, animal manure and respiration, or volcanic eruptions. However, the majority of new greenhouse gases are produced from industrial processes and energy production.

The four largest human sources of U.S. greenhouse gases in 2009 were energy, non-fuel use of fossil fuels, natural gas production, and cement manufacture, in descending order. Non-fuel, greenhouse gas-producing applications of fuels include industrial production like asphalt, lubricants, waxes and other . Emissions related to cement manufacture happen when limestone (calcium carbonate) is reacted with silica to make clinker, the lumps ground to make cement. ( Emissions of Greenhouse Gases in the United States 2009: Independent Statistics & Analysis.)

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Water Depends on Energy, Or Is It The Other Way Around?

The United States took more than 400 billion gallons of water out of the ground, lakes, rivers, and reservoirs daily in 2005.  (more…)

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Groundwater, the Water Cycle, and Depletion

THE WATER CYCLE AND GROUNDWATER

Water is created and destroyed in natural chemical reactions within plants and animals. However, most water sticks around. It changes phases through the water cycle; it can become polluted with salt, toxic chemicals, or pathogenic organisms. However, it generally doesn’t go away, globally speaking.

The water, or hydrologic, cycle describes how water moves through the atmosphere, on the Earth’s surface, and underground.

As “surface water” in the lakes, streams, rivers and oceans warms from the sun’s electromagnetic radiation, some evaporates into the atmosphere.

This water vapor in the atmosphere condenses into rain and snow, called precipitation. The precipitation falls on the Earth, eventually feeding into streams, lakes, and oceans. Some of the water seeps into the ground and collects in underground aquifers as groundwater. About 20 percent of the U.S. water supply comes from groundwater.

Groundwater can resurface from springs or it can discharge into lakes, streams, rivers, and oceans. High pressures deep inside the Earth can force groundwater up through artesian wells, or groundwater can be pumped up or pulled up in old-fashioned buckets from wells. (“Artesian” means that there’s sufficient water pressure that the groundwater need not be pumped).

Briones Reservoir in Northern California

Humans use water from the surface sources (lakes, rivers, oceans), we collect rainwater and snowmelt, and we also use groundwater. Most of this water gets discharged back out into waterways or oceans. However, water used in homes and businesses is sent to municipal water treatment, after which it is discharged into waterways, returning to the water cycle.

 

 

GROUNDWATER AND DEPLETION

Groundwater isn’t as free-flowing as surface water. Predicting and modeling how it flows is wildly complex, factoring for what’s dissolved in the water and what materials it’s moving through, in three dimensions. What is easy to say is groundwater moves slower than surface water, and it gets recharged more slowly. Because modeling is complex, and tracking depletion involves drilling wells, it’s far more difficult to gauge groundwater depletion than water shortages on the surface.

When groundwater is depleted, it is still there, just lower down, as many as several hundred feet lower in extreme cases. However unseen it is, groundwater depletion – and the lowering of the water table – is very serious for several reasons.

Trees and plants rely on groundwater, and if they cannot reach water with their roots in regions where it doesn’t rain all year long, they can die, and with them all the life that depends upon them.

For people who rely on well-water, depletion can be equally disastrous. As the depth needed to reach the water increases, the amount of energy required to pump it out also increases. Lowering the water table can pollute the water, as saltwater zones can underly freshwater zones.

And even for those who depend on surface water, which is all of us, groundwater depletion can have its effect because ground water feeds surface water and vice-versa. Groundwater depletion can reduce the amount of water in streams and lakes, even if the effects take years to become obvious.

 

ARE WE SINKING?

An apartment building in Amsterdam, The Netherlands.

As the water table lowers from groundwater depletion, the materials within the ground dry out and the ground can actually collapse in on itself, either suddenly or slowly over time, a phenomenon called subsidence. The most dramatic incidents of subsidence are sinkholes, but most of the sinking is happening imperceptibly slowly. This sinking is why some regions of the Netherlands came to be below sea level; centuries of pumping water out of the peat-based soils shrank them, and the land — protected from flooding by the North Sea and Rhine River waters behind dikes — sunk lower and lower.

Today, subsidence from pumping of water has been recorded all over the United States, but the Santa Clara Valley in California was the first area in the country where land subsidence from human use of groundwater was recognized and the first place that organized remediation to stop the subsidence in 1969, according to a report by the U.S. Geological Survey.

While today the region is best known for its Silicon Valley technology, in the late nineteenth century, Santa Clara was full of fruit orchards irrigated with groundwater, much of it from artesian wells, meaning that the wells filled themselves with the pressure of the water created by confined aquifers. Constant reliance on this easy source of groundwater meant by 1930, wells that formerly filled themselves had to be pumped, and by 1964 one well in downtown San Jose had sunk well over 200 feet below the surface.  As water was permanently removed from the ground, the ground shrank, and by 1984, downtown San Jose had sunk quite substantially, to just 84 feet above sea level from 98 feet above sea level in 1910.

 

For more about water use and energy see here.

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