Frequently asked questions: So what is this global warming thing all about anyway?

Greenhouse gases are heat-trapping gases in our atmosphere that act as a sort of blanket around the Earth, preventing the sun’s warmth from radiating back into space. Greenhouse gases are a naturally occurring phenomenon. Without them, the Earth would be too cold to support life.

There are six primary greenhouse gases. They vary greatly in their warming effects. Carbon dioxide (CO2) is the most important one from the perspective of manmade global warming.

In the industrial era, humans have added significantly to the amount of greenhouse gases in the atmosphere by burning fossil fuels. As levels increase, the average temperature of the planet also rises. Because the climate system is complex, local effects of this increased temperature vary greatly with geography. Some places will become hotter and some colder; some wetter and some drier; etc. In general, the effects will be highly disruptive for both humans and for other species accustomed to the old weather patterns.

The greenhouse effect is the warming of the earth by heat-trapping gases. Think of the way that a gardener’s greenhouse lets in sunlight and traps warmth to maintain a nice temperature for growing plants. The greenhouse effect is similar, but it operates on a planetary scale.

Without the greenhouse effect, the planet would be too cold to live on — about 18° C below zero!

Global warming — sometimes referred to more accurately as manmade global warming — is the rise in the earth’s temperature as a result of the creation of greenhouse gases through human activities. The principal greenhouse gas is carbon dioxide, created when we burn oil, coal, natural gas, or other fossil fuels. Other greenhouse gases, such as methane, are a byproduct of industrial and agricultural practices.

Carbon dioxide is a naturally occurring gas. Indeed, it’s an important part of the natural life cycle of plants and animals. The problem is that, as a result of fossil fuel use, we now have too much of it. Over the past several decades, carbon dioxide levels in the atmosphere have built up to levels not seen in the last 650,000 years.

Scientists don’t know exactly how much the planet will warm as a result of the fossil fuels we’ve burned so far, but most estimates range from 2 - 4° C. This might not sound like a lot, but remember that it represents an average across the entire planet. In specific regions, the effects will be much more dramatic.

The effects will vary across regions. The global climate system is incredibly complex. Many areas will experience drought, but others will experience flooding as a result of increased rainfall. Agricultural patterns will shift. Sea levels will rise as a result of both increased water temperatures and melting of the polar ice caps. Many species will be pushed into extinction as their ecosystems undergo rapid change. Hurricanes may become more frequent and more intense, although the science of storms is still far from settled.

The exact results of climate change are difficult to predict. One of the biggest dangers is that we may inadvertently cross a “tipping point” that causes runaway effects.

In the long term, the primary solution to climate change is to switch our energy production to low-carbon sources such as wind and solar energy. Such sources are really the only viable long-term way to address climate change. The world’s population is rapidly growing both bigger and wealthier, which means it will continue to consume more and more energy over time. As long as this energy comes from clean sources, the planet’s wealth will be sustainable.

In the nearer term, energy efficiency is our best hope for controlling greenhouse gas emissions. Energy has always been cheap, and as a consequence, we use it wastefully. For example, simply by switching to compact fluorescent light bulbs, we get energy savings for free. Energy efficiency is important because we can implement efficiency measures quickly — much more quickly than we can change over our energy infrastructure to clean sources of power.

Finally, conservation has a vital role to play, particularly in the near term. Simple changes such as riding a bike instead of driving your car can make a big difference. Like efficiency measures, conservation measures can be implemented quickly.