If you boil water in a covered pot, you will see the water turn to steam and then condense on the inside of the pot lid. This illustrates the “water cycle” that encircles the Earth. Liquid water from lakes and oceans evaporates by warm air and sunlight into a gas of water vapour. The amount of water vapour in the air can be measured and becomes what we call the “relative humidity.” There is a limit on the amount of water that any given air can hold as vapour. When the humidity reaches near 100 per cent, the water vapour cannot be absorbed and it starts to condense back into liquid. The temperature of the air mass also affects the amount of water vapour that it can hold. Generally, warmer air can hold a greater amount of water vapour. Hot summer nights can be extremely humid and feel wet and sticky due to the warm air holding its maximum water vapour.  If the local climate pushes that humid air mass up the side of a mountain, the air cools as it rises in the atmosphere and the water vapour condenses into cloud formations. But clouds have a limit as well and if you watch them develop you can see the colour of clouds gradually darken as they struggle to keep that water vapour in the air. Finally, the vapour will turn back into liquid and fall as rain onto the ground below.

Many areas which have available water, and hot daytime temperatures will experience daily rainfall as the local cycle evaporates water in the morning and condenses that vapour into rain in the afternoon.  While some cycles can feel like they are local, the same water cycle operates globally.  The sun is the energy that, as the earth turns, heats up one side then the other side of the earth every twenty-four hours.  The swirling atmosphere heats and rises, it absorbs tonnes of water vapour as it does, lifting it high above the ground.  Cooler air sweeps in to replace the warm rising air. The earth is turning under both air masses and as the warm air cools it spins clockwise in the northern hemisphere as a high pressure dome and wind is created in the air mass. This occurs multiple times every day all around the earth and our local weather is made up of these spinning high and low pressure systems.

But this is just “weather,” it is not climate, or climate change which is measured over a longer period. 

What humanity has done is to “mess” with the normal composition of the atmosphere.  Using fossil fuels to pollute the air with excess carbon dioxide allows the envelope of air around the earth to retain more heat.  More heat allows the air to evaporate more moisture and retain it as water vapour.  This heat leads to melting of glaciers and permafrost, as well as droughts, and to arid land with reduced ability to support life.  Meanwhile the turning earth and swirling air masses can travel around the earth and drop that much larger amount of water as torrents of sudden rainfall which can result in flooding.  The water cycle is no longer a regular cycle that can be predicted.  Droughts and floods have been warned about for the last seventy years.  Only now are people worldwide beginning to understand firsthand the effects of human made climate change.

The 2017 CRD report “Climate Projections for the Capital Regional District” shows clearly the effect of human made climate change on our south island region.  By 2050: no snow pack on the hills, at least two “tropical nights” per year when the temperature stays above 20 degrees Celsius, an increase in rainfall over a shorter winter season as the water cycle pushes water laden air off the Pacific Ocean, dry summers or drought until at least mid-September and no frost days. All of these predictions are coming true.

Chris Moss is a resident of Otter Point