Very few people actually doubt that climate change is occurring. The only dissenters come from research institutions on the fringe devoted, for ideological or other reasons, to refuting the notion that human activities are altering the planet’s climate.
But all the same, for many non-scientists the discussion can seem confusing and many questions remain: Is the Arctic Ocean predicted to be ice-free by the summer of 2030? What exactly does ice-free mean? Will hurricanes become more frequent, or less frequent but more intense?
For scientists studying climate change, these questions, and their answers, are constantly being revised and refined as more information is gathered, models are fine-tuned, and feedback is better understood. But even so, scientists are finding increasing evidence of global warming happening right now, and many of these changes validate earlier predictions and, in some cases, indicate even more severe and more rapid changes than anticipated. Climate change is not just a prediction; it is already underway.
Carbon Dioxide (CO2) concentrations in the atmosphere are increasing, as we know, but why is too much CO2 in the atmosphere a bad thing? CO2 is a naturally occurring gas that is also emitted at great levels by human activity; it is one of several greenhouse gases in the atmosphere that surrounds our Earth. Other greenhouse gases include water vapour, methane, ozone, nitrous oxide and halocarbons.
To understand the impact of these gases, we first start with the sun, which sends solar radiation in the form of light to Earth. The atmosphere deflects some of this radiation back into Space, while the rest hits the surface of the planet and warms the land and oceans. The Earth then radiates its own heat back up in the form of infrared rays. Some of those rays escape the atmosphere, while others are absorbed and then re-emitted by the atmospheric Greenhouse Gases. In so doing, these greenhouses gases help to keep the planet at its normal temperature.
For millions of years, the production of greenhouses gases was regulated by the natural systems of the planet. Gases were absorbed and emitted at a fairly steady rate, and temperatures were maintained at a level that supported life around the world. It was a sort of natural balancing act.
At the arrival of the Industrial Revolution in the second half of the 1700s and all the machines that came into being, human activity altered this balancing act. Ever since that time, we have been adding greenhouse gases, primarily CO2, to the atmosphere at a steadily increasing rate, trapping that heat and warming the planet.
Although there are several greenhouse gases, and some are more potent than others, CO2 currently represents about 84% of all greenhouse gases emitted by human activities, totalling about 30 billion tons a year. Most of this comes from burning fossil fuels for electricity, transportation, industrial processes and forestry. CO2 does not only affect the atmosphere; it has also made the oceans about 30 percent more acidic affecting a wide variety of sea organisms. That percentage is also expected to rise in the coming years.
Obviously all of this carbon we have added to the atmosphere will not go away overnight. Its effects will be destructive and long-felt. But by understanding the impact of CO2, hopefully we can make steps toward reducing our emissions and, if we’re really lucky, avoid the worse effects of climate change yet to come.
By analyzing air bubbles trapped in the ice of Antarctica and Greenland, scientists have been able to determine atmospheric concentrations of CO2 over the past 650,000 years. Immediately prior to the Industrial Revolution in the mid-eighteenth century it stood at approximately 280 ppm. It is now closing in on 400. Greenhouse gases are accumulating in the Earth’s atmosphere as a result of human activities, causing surface air temperatures and sub-surface ocean temperatures to rise.
Many believe that we must stop this rise at 1.5 degrees Celsius or we will perish, and have adopted the motto “1point5tostayalive”: 1.5 to stay alive!