Climate change is a huge subject, but its importance is related to how it will affect our lives, so this article is aimed at people who are young adults today and will live till almost the end of the century.

Most people are aware that the planet has had ice ages and warm periods in the past, and these are well researched and recorded. They were caused by changes in the level of CO2 in the atmosphere, which varied between 180 parts per million in an ice age to 280ppm in a warm period. In the last warm period, 125,000 years ago, CO2 reached 300ppm and sea levels were seven metres higher than today. There are shelves where the sea cut into the shoreline all round the Bay of Islands.

Currently CO2 is at 410ppm, and rising quickly, due to our burning of coal and oil, and for this reason governments and people are very concerned. There are two bench marks we should keep an eye on; one is a temperature increase of three degrees Celsius, when food production will be extremely difficult, and many, or most, of the trees will die. We have raised the temperature one degree already, and are trying to limit the increase to 1.5 or two degrees.

The second bench mark is a sea level rise of one metre, where 11 of the 15 largest cities in the world will be flooded and about 400 million people will be on the move, looking for safer homes for their families. At one metre Auckland airport goes under water, and in Northland we have many coastal towns that have vulnerable waterfronts.

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Changes to the weather are already happening in that there has been an 18 per cent increase in westerly winds, resulting in more, and much heavier, rain on the west coast and less rain and more drought on the east coast. Another change is that for every degree increase in temperature the atmosphere will hold 7 per cent more moisture. This brings heavier rainfall and the wind is denser, so that in a gale the wind has more power to knock trees over.

The oceans have been absorbing the majority of heat and CO2 from the atmosphere, and this is having a greater, but slower, effect. Warmer water makes fish stocks move to regions better suited to them, disrupting the fishing industry. Warmer water can energise cyclones that come down from the Pacific and can devastate Northland, and bring rain storms of 300mm in a single event.

The increase in CO2 in the oceans increases the acidity of the water, which will kill our shellfish such as mussels, oysters and crayfish. The acidity levels are already increasing.

There are already dozens of satellites monitoring the planet, and thousands of scientists examining the results, so we know what is happening. The timing is still not accurate, but most will be in your lifetime.

There are solutions, and I will outline how we can achieve them later.