The Science of Climate Change
(or "Oops, My Scientist Warned Me This Day Might Come...")
Climate change is a well-established scientific fact which, if left unchecked, will cause dire consequences for most species on earth.
Scientists have already measured a 0.6C rise over the last 50 years, and the temperature is climbing faster and faster as time goes on.
A 0.6C temperature rise is one that the planet can cope with. Yes, we have storms, droughts, melting glaciers, sea level rises and significant shifts in plant and animal habitats, but life goes on.
To understand what the temperature will do in the next 50 years we have to look at the underlying causes of global warming.
The earth's atmosphere plays a really important role in keeping the earth's surface warm. Two key gases in the atmosphere, water vapour and carbon dioxide, help trap the sun's heat near the earth's surface so warming the planet from what would be an icy -18C to the balmy +14.6C average global temperature we enjoy today.
However, burning of coal, oil and natural gas (i.e. fossil fuels) that were previously safely stored in the earth's crust has added more carbon dioxide to the earth's atmosphere. This has increased the amount of heat trapped by the atmosphere, raising the earth's temperature. So the earth is warming, and has warmed 0.6C SO FAR.
Before humans started increasing the carbon dioxide content of the atmosphere the planet radiated heat off to space at the same rate it was absorbing heat from the sun.
The important thing is not to stop questioning.
Einstein But now the earth is trapping extra heat. The longer this trapping goes on, the warmer the earth will become. At some point, the warmer earth will be able to radiate more heat to space, and the heat flow in and heat flow out will be back in balance. But we are not there yet; so we are still warming. The critical question in all this is how much the extra carbon dioxide in the earth's atmosphere will raise the temperature before a balance is re-established.
This question is one that can be answered by the laws of science, but it isn't a simple calculation that you or I can do, as many changes will happen as the earth warms; these changes will affect the amount of carbon dioxide in the earth's atmosphere. These are called 'feedback' mechanisms and the major ones are listed below, pretty much in the order they will happen if the warming continues:
Water Vapour
As the land and oceans warm, more water is evaporated from them. Water vapour traps the suns rays, so add an extra boost to the earth's temperature.
Snow and Ice
Snow, being white, reflects 90% of the suns rays directly back to space. However, as the earth warms, snow becomes water which absorbs 90% of the sun's energy. Thus, a little warming becomes a major warming where there was once snow on the ground, such as in the Arctic.
Amazon Rainforest (and others)
Should we continue to emit carbon dioxide in large quantities, in another 50 years or so the Amazon rainfall pattern will change and the forest will be replaced by a desert surrounded by a savannah. All the carbon locked up in the trees and soils will change to carbon dioxide and thus cause further warming planet wide.
Let’s Clear Up the
Greenhouse Gas versus Smog Confusion
There appears to be a lot of confusion and disinformation about smog and
greenhouse gases. While both are bad, it is for different reasons and, in fact, their components are entirely different. Smog is visible and composed of tiny droplets of stuff, usually nasty stuff, while greenhouse gases are exactly that…. gases, the most troublesome at this stage being C02.
The very sad but little known problem is that we must reduce our greenhouse gases before we deal with the smog. While this thought horrifies most people, the fact is the smog is acting like an umbrella, reflecting the sun’s rays out of the atmosphere into space (no one out there seems to mind). Without the smog, temperature increases on Earth would be twice as great! Not a cheery situation, is it? But there you have it. For a detailed explanation, check out Science & Nature, BBC.
Polar Ice Sheets
The north pole, sound pole and Greenland ice sheets will eventually melt, leading to greatly increased sunlight absorption and more heating.
Permafrost
A huge amount of frozen plant material is persevered near the arctic circle. As the world warms, this material thaws and rots. The ultimate by-product is carbon dioxide which causes more warming.
Ocean Warming
Oceans are big, and haven't warmed much yet. But they will. As they warm, carbon dioxide that is currently dissolved in the oceans will start to return to the atmosphere (gases dissolve better in cold water than warm water - as Salmon dying from oxygen shortage in BC's warmed rivers can attest). This will cause more warming. The mechanism is the major mechanism in the past that has swung the earth out of ice ages.
Recent calculations by NASA scientist James Hansen (NASA, January 2008) have shown that when humans raise the concentration of carbon dioxide from 280 ppm (parts per million) from the beginning of the industrial revolution to 350 ppm, the earth's temperature will eventually climb by 2C. The series of feedbacks outlined above will begin to warm the earth further even if we humans were to stop emitting carbon dioxide at that point. As the planet passes 2C and the warming is out of our hands, we say that 2C is a tipping point. Passing the tipping points causes a runaway.
The runaway will lead to the extinction of most species on earth and certainly to the end of human civilization. It isn't clear whether humans could survive or not; we are fairly adaptive creatures.
It would appear obvious then we must keep the level of carbon dioxide well below the 350 parts per million mark. This should be our planetary goal.
Unfortunately, we have already raised the level of carbon dioxide to almost 390 ppm.
This does not mean a runaway has started because the earth has not yet reached 2C. However, we must reduce our emissions to well below what the biosphere and oceans can currently absorb so that the levels of carbon dioxide will drop below the critical 350 parts per million before it is too late. This is why scientists are strongly promoting an 80% reduction in our emissions by 2030 and 90% by 2050.
Please go to our Carbon Tax page to see how this could be done (and for other information to shock and awe you).
... ordinary people entering extraordinary times
