Warming or cooling

Adventures on Earth for August 11, 2010
By George E. Beetham Jr.
Climate change has been in the news now for several decades. It has been an issue on the planet for roughly 4.6 billion years.
At various times in Earth’s past, the climate has ranged from glacial to tropical. In addition, as continental land masses move around the globe their path takes them through a range of climatic conditions.
As they say, the one constant in the history of Earth has been change.
Change can occur over hundreds of millions of years or it can occur in an instant. The building and erosion of mountains is a slow process that transcends the lives of humans. In contrast, a flood can scour a valley in a matter of hours or an explosive eruption can blow the top off a volcano is mere minutes.
Climate change occurs for many reasons, not all of which are understood. Areas that were once tropical rain forest have become desert and vice-versa. Old seafloor was lifted to form the backbone of Antarctica.
In decades, ocean currents can shut down and plunge a continent into an ice age. In mere seconds, an asteroid can impact Earth and cause widespread extinction.
Recent climate change, though, can be traced to us – humans. Investigators noticed that warming began to increase about the time the industrial revolution and burning fossil fuels began.
As time went by burning of fossil fuels increased. So did planetary warming.
Scientists singled out fossil fuels because the process gives off what are known as greenhouse gases: carbon dioxide, water vapor, nitrous oxide, methane, and ozone are the best known.
These gases tend to seal in heat that otherwise would escape into space, making the Earth warmer just as the glass of a greenhouse seals in heat and creates a rainforest atmosphere in the depth of winter.
At the same time, emission of greenhouse gases under natural conditions, notably volcanic eruptions, has remained fairly constant.
So, while the planet has been in a warming phase since the retreat of the last glaciation some 11,000 years ago, the warming trend made an upward curve in the past 200 years. And remarkably, it was about 200 years ago that anthracite became the fuel of choice in American industry.
Then came the discovery of oil and the dawn of the automotive and air age. Internal combustion engines brought another jump in global warming.
The question we face now is whether we have already reached a tipping point where rapid warming is inevitable or whether there is still time to slow it down.
Regardless of what we do, the fact is that warming will continue. Whether we can rein in warming in time for our children to enjoy the lifestyle we now have is the question.
On the other hand, warming melts glaciers, injecting fresh water into the saline sea. Scientists think that could shut down the ocean currents that now moderate temperatures and bring on a new ice age.
And that change, should it come, could come rapidly.