Knowing the future has long been a quest for man and the desire to understand how things works, the quest to know cause and effect, has been one of the driving forces of civilisation.
Our success at understanding cause and effect has been outstanding in every aspect of science and engineering. Today we can build higher and bigger structures than ever before; we can travel further and faster than pretty much any time in our history, we understand more about our bodies and health than we have ever done allowing us to conquer disease and extend life spans for many. But, along with all that success, there has been a discovery that throws the whole world into uncertainty, that of global warming and the resultant climate change.
It comes as a surprise to many that the knowledge of global warming is not new.
As long ago as 1824 a scientist called Joseph Fourier discovered that the Earth’s atmosphere kept the planet warmer than would otherwise have been expected and this became know as the “greenhouse effect” The knowledge that that carbon dioxide or CO2 in shorthand, is an active gas that allows the visible (sunlight) radiation from the sun into the climate system but slows that same energy down on its way out as heat (infrared) radiation came more than 100 ago and was described in 1859 by a scientist called John Tyndall. Another called Svante Arrhenius made the first calculations of the impact of adding more CO2 from human activities (principally through the use of fossil fuels) to raise the average temperature of the earth’s surface before the end of the 19th century. Pretty much since then, scientists have been improving our knowledge and watching closely for generations now.
In recent years, scientists have recorded many activities that demonstrate that global warming is a real and continuing phenomenon such as:
Global temperature rise
Although accurate instruments measuring temperature in a wide number of areas is fairly recent, scientists have other ways to calculate past temperatures from other observations such as tree ring growth. There are three major methods for approximating global surface temperature and all three show that Earth has warmed since 1880. Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years.
With higher surface temperatures has come warmer oceans. In the top 700 meters of the oceans a small but measurable increase in temperature has been recorded.
Whether it is the Greenland and Antarctic ice sheets, the extent of Arctic ice cover or the size of glaciers, all of the world’s stocks of ice are melting. This and the fact that the oceans are warmer has also led to sea level increases.
Extreme Weather Events
Across the globe the number of extreme record high temperatures has been increasing and the number of record low levels has been decreasing. The frequency and intensity of storms and flooding is also increasing.
The big question facing global society is what to do about global warming and the resultant climate change. On one side, funded primarily by fossil fuel companies, is a lobby that says “don’t do anything”. Their argument is that science is “uncertain” about what the effects will be of further global warming and that the cost of switching from fossil sourced energy to clean energy would be unaffordable. Better, they say, to wait and see how we can adapt to whatever changes come along. The implication is that science doesn’t know what or when the impacts will be so don’t worry until there is clearly something that needs to be reacted to.
“Uncertain” has a special meaning when used in science and scientists seldom claim to be “certain” of anything: after all according to the most advanced thinking in physics there will be occasions when somebody could walk through a wall. What matters most is the likelihood of something happening and for that science talks about “confidence levels”. This is actually a term from the field of statistics and means the likelihood that something you’ve seen happen being caused by the thing you expect to have caused it rather than it just being a “chance” observation. Let me give you an example using coins. Pretty much everybody is comfortable with the thought that if you flip a coin, it can land as a head or a tail so the chance of a head or a tail coming up is 50/50. If you toss again, the chances are still 50/50 because each throw is independent of the last: there is no “law of averages” that says if you have just tossed 4 or 5 head in a row, the next toss must be tail: each toss has just as much chance of being either a head or tail as the last one. However it is quite unusual to toss many heads or tails in a row and how unusual it is can be calculated by probability.
Let’s say we want to know how likely it is to get ten heads in a row. Each time you toss a coin it has two possible outcomes, head or tail so if you toss a coin twice you have four possible outcomes Heads then Heads, Head then Tails, Tails then Heads, Tails then Tails. Each additional toss adds two possible outcomes to each of the possible past outcomes so three tosses gives 8 possibilities, four 16 and so on. Ten tosses gives 1024 possible outcomes of which, only 1 is ten heads in a row. In scientific terms, if you sat down and tossed a coin 1024 times they would be “confident” that at some point during that session you would get ten heads in a row.
In the case of global warming and the resultant climate change, scientist are “confident” that the future is bleak in that crop yields will be affected, more people will get sick from excessive heat and that people, buildings and bridges will be disrupted by flooding. Where the “uncertainty” sits is whether the worst effects will be being felt by 2030 or 2050: either way it is not far away.
Throughout the quest to be able to foretell the future, one thing has become apparent: what will happen in the future will largely be determined by what we do today. It is still possible to change the course of the future by the simple act of reducing the amount of carbon dioxide we put into the atmosphere. You can help bring that about by your own actions through reduced energy use by better insulating your home, using shared or naturally powered transport and reducing the amount of red meat in your diet. But individual action is not enough. You also need to tell your political representatives and the businesses that you deal with that you think this is a big issue and you want action taken on it.
We can never be certain of the future but we do understand cause and effect: it is time to cause change for the better. It is time to implement the solutions to climate change.