Wednesday, 6 November 2013

Climate Change

You may have heard publicity about the recent report issued by the Intergovernmental Panel on Climate Change (IPCC), and unfortunate comments by some politicians which showed they had not understood the science. To those of us who have followed this for debate for 30 years, there was little new, just even greater certainty. Below is a brief summary, for more details go to the IPCC's website, or look at a somewhat more digestible version e.g. from Stop Climate Chaos, The Carbon Brief,  Friends Of The Earth or the BBC video "The IPCC in 90 seconds".

Global climate change is certainly happening: anyone over 40 who has spent much time outside will know that our weather has changed, and climate is just weather summed up over 30+ years and large areas. Land surface temperatures have risen 0.85oC since 1880, and the first decade of the 21st century is the warmest since modern records began in 1850. This is not a steady trend - nothing to do with the natural world ever is - and warming has been slower between 1998 and 2012 than in surrounding decades, but this has much to do with choosing end-dates - 1998 was a very hot year globally because of an El Nino event and is also affected by short-term fluctuations in solar radiation and volcanic ash levels in the atmosphere. There is 95% confidence among climate scientists that human activity is contributing more than half of the observed rise. No natural scientist ever admits to above 95% confidence in anything - that is just the way science works!

Other signs of climate change are proceeding apace. The oceans are absorbing human-produced carbon dioxide, which is making them more acidic, with bad consequences for shelled animals (limpets, barnacles etc) as calcium carbonate dissolves more readily in acidic water. The oceans are also expanding as the water warms, and the volume of ice is decreasing markedly in Antarctica, Greenland, the Arctic and most glaciers. So sea level is rising: over the decades 1993-2012 by 3 mm a year globally (and about the same in Liverpool Bay). This does not sound much until you think of it in decades, and realise that sea level rise is likely to speed up markedly, with predictions anywhere between 26 cm and 82 cm by 2100. Think of the effect of that on low-lying coasts and you see why Wirral Borough Council is planning to spend significant money on sea defences in the next 20 years.

A warmer climate means more energy in the atmospheric system, so more extreme weather events - increased frequency and intensity of droughts, storms, floods, and the occasional cold winter. This is already showing a pattern in tropical and sub-tropical countries. We in Britain are at present having it easy - but if changes in sea temperatures lead to the North Atlantic Drift sea current slowing or stopping (as it at some point probably will), then we will get significantly colder! Global warming does not mean we all warm up.

So what do we do? Individually, continue to reduce energy use, insulate your house, reduce travel, eat local food, reduce waste, reduce water use (it takes a lot of energy to process), and put some of the money saved into supporting appropriate renewable and low-carbon energy schemes e.g. solar panels on your roof. But a lot has to be done by governments, so we need to lobby our politicians at every opportunity. We cannot now avoid a 1oC rise in temperatures above pre-industrial levels. We can avoid a rise that would be catastrophic for people and wildlife, but only if we seriously cut our carbon dioxide, methane and nitrogen oxide emissions, leaving at least two-thirds of the known fossil fuel reserves in the ground. The IPCC gives for the first time a "carbon budget"  - the figures are difficult to comprehend but, simply put, people can only afford to emit in total 800 billion tonne of Carbon, and we have already emitted 500 million. It is a challenge, but possible - see the Centre For Alternative Technology for their "Zero-carbon Britain" analysis.

So do what you can yourself, encourage any organisation you are involved in, like churches, to do their bit - and nag our politicians to get their heads out of the sand and act.

Hilary Ash

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