By Lin Smith

The Safe Limit of CO2 for Humanity

January 20, 2014-–The science of 350: Scientists say that 350 parts per million of CO2 in our atmosphere is the safe limit, and unless we rapidly return to below 350 ppm this century, we risk reaching tipping points and irreversible impacts, such as the continued melting of the Greenland ice sheet and major methane releases from increased permafrost melt.

Up until about 200 years ago our atmosphere contained about 275 parts per million of carbon dioxide, which gave human beings the environment necessary to exist. It provided us with just enough warmth on Earth–not too hot, not too cold! Parts per million (ppm) is  a way of measuring the concentration of different gases. It means the ratio of the number of carbon dioxide molecules to all of the molecules in the atmosphere.

Atmospheric CO2 and the Industrial Revolution

Beginning in 18th century, people began to burn coal, gas, and oil to produce energy and goods. This was the Industrial Revolution of Britain, Europe, and the U.S. During this time period, CO2 began to rise in our atmosphere. The production of goods transitioned from hand made to machine made. The transition also included changing from wood and other biofuels to coal.

What is a Biofuel?

A biofuel means a fuel derived directly from living matter, such as wood, corn, ect. The CO2 released from wood and other biofuels has minimal impact on greenhouse gases. When we burn wood and other biofuels, the energy the biofuels took from the sun for photosynthesis, (remember your science classes?) is released back into the atmosphere. It takes and gives back about the same amount, thus maintaining the 275 ppm of carbon dioxide in our atmosphere-just enough for us to exist –comfortably, up until now! When we burn fossil fuels, such as coal and oil, we put more CO2 in the atmosphere than is used by earth’s vegetation. The earth then warms and that warmth is absorbed by the CO2, which does not allow it to escape into space. When CO2 is too high, climate change occurs, as it is doing today.

Reliance on Fossil Fuels

Many activities we do every day, like turning the lights on, cooking food, or heating and cooling our homes, rely on these fossil fuel energy sources that emit carbon dioxide, trapping gasses into the atmosphere. We’re taking millions of years worth of carbon, stored beneath the earth as fossil fuels, and releasing it into the atmosphere. The planet now has above 400 parts per million of CO2, and the number is rising every year. That is more than this planet has seen in its history! Scientists say the highest safe level of CO2 is 350 parts per million. This is the safety zone for planet earth!

Preserving Our Planet

James Hansen, of NASA, says if we wish to preserve a planet similar to that we are inhabiting, we need to reduce the CO2 above 400ppm to, at most, 350ppm. We need to stop taking carbon (coal) out of the ground and putting it in the air. We need to start using solar and wind and other sources of renewable energy. If we do this, then the earth’s soils and forests will slowly cycle some of the extra carbon out of the atmosphere and eventually CO2 concentrations will return to a safe level. By doing this we could go back to the 350 by 2050. But the longer we remain in the danger zone, above 350, the more likely that we will see disastrous and irreversible climate impacts!

Cutting Fossil Fuels

1. Recycle your waste. Many household wastes, including most plastics, are made from fossil fuels. Most prepackaged foods and goods use fossil fuels for their production and disposal. Try to reduce your overall consumption of things you don’t really need, and recycle everything!
2. Drive less, walk, cycle, take public transportation, or drive a hybrid vehicle. I know hybrid vehicles aren’t an economic choice  for many people, but there are a growing number of older hybrids on the market, and if you weigh the cost of purchasing one with the amount you could save in gas, it may be a good choice, for you and the environment. An older Prius may get 60 mpg, and, no, the batteries aren’t wearing out like predicted.
3. Cut your household power consumption, turn off lights when not in use. Most of the electricity in your house is likely to come from coal-fired power stations, not renewables. Insulate your home, use a ceiling fan instead of air conditioning, hang your clothes instead of tumble dry. I know–who has clothes lines anymore?? BUT they can be inexpensively installed in the back yard–just like the old days! Just put ‘em back!
4. Install a solar panel. They are getting less expensive to install and will save you money in the long run.

The Science of 350 states we must lower the CO2 in our atmosphere, even doing something small will be a start towards saving our planet for future generations!