Released - IPCC Fifth Assessment Report of Working Group One
Monday, 4 November 2013
| Mick Pope
In case you haven’t heard, the climate change debate is alive and well in the media and politics in Australia. Meanwhile, the slow, investigative activities of the Intergovernmental Panel on Climate Change (IPCC) are beginning to come to fruition with the release of the fifth assessment report of Working Group One. This represents the work of 600 contributing authors, 209 lead authors and 50 review editors from 39 countries. This large tome will soon be out of date: indeed, some of its information is probably out of date now. But this is no reason to ignore it, for although it is couched in cautious, scientific terms and built upon a broad consensus, it tells an tale of concern for our world, now and into the future.
First, with so many years of observations, the authors of the Summary for Policymakers are able to say that “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.”
It is worth reading part of that again: “unprecedented over decades to millennia”! Christians understand that God is sovereign. And yet we see again and again in Scripture that God gives us over to our sins and their consequences as acts of judgment. Human beings have pursued wealth and power, growth and prosperity at a cost: and now the ‘birthpangs’ (Romans 8:22) of the creation that sustains us seem very, very real.
Some observers point to a hiatus in global warming, with a flattening trend in global temperatures, but this is too simple a picture. While global mean temperatures have slowed, many parts of the world, such as Australia, continue to break records. Australia has had its warmest year on record. Furthermore, the oceans continue to soak up most of the heat, with one recent paper noting that the warming of the oceans below a depth of 700 metres is unprecedented. It seems that the combination of the solar cycle, volcanoes and internal variability has slowed the warming. The observed slowdown in warming appears to be due to three factors. First, the sun has undergone an unusually long dip in solar activity, associated with the sunspot cycle. Second, volcanoes have emitted sunlight reflecting sulphur. Third, the El Niño-Southern Oscillation which brings alternating droughts and floods to Australia, has largely been in a La Niña phase since 1999, and this has caused cooler conditions over Europe during the winter. Short term changes can work against the longer term trend.
That said, the last three decades have been the warmest since 1850, with each decade progressively warmer than the last. More than this, Europe during 1983-2012 was likely warmer than the last 1400 years. This should give us pause for thought. Temperatures continue to rise even when natural factors militate against these rises. And what happens when these natural factors point in the other direction?
The largest contributor to all of this warming is the increase in atmospheric carbon dioxide through the burning of fossil fuels. With concentrations of gases like carbon dioxide and methane being higher than they have been for 800,000 years, human beings have become a geological force. This is a far cry from the Genesis call to “fill the Earth and subdue it”.
With the warmest recent summer on record in Australia, warmest 12 months on record and warmest September on record, it is also likely that human influence has more than doubled the number of heat waves in some places. While it is an area of debate (to say nothing of political sensitivity), The Climate Institute recently noted that the Forest Fire Danger Index has increased significantly at 16 of 38 weather stations across the country between 1973 and 2010. In south-eastern Australia, the fire season has expanded into November (arguably now October) and March. With 2-3° C of warming—something very possible if no strong action is taken—the number of extreme fire days could occur 4-5 times more often by 2050.
The carbon we emit doesn’t just go into the atmosphere to heat it up. It also goes into the oceans, making them more acidic. With high confidence, the IPCC states that since the industrial revolution, the ocean surface pH has decreased, or become more acidic by 0.1, meaning a 26% increase in hydrogen ions. Acidic oceans impact marine life.
The fifth assessment report reminds us that the world’s ice continues to melt, whether it is sea ice or continental ice sheets. Ice cools the climate by reflecting sunlight into space. Over 1979-2012, Arctic sea ice has decreased by half a million square kilometres per decade, and climate reconstructions suggest it is unprecedented in the last 1400 years! This is not a fact of which to be proud. Some sceptics claim that 2013 represents a huge recovery from last year, yet this ‘recovery’ is only to the sixth smallest area on record. Much of that recovery is thin ice, and year-to-year variations in weather can cause relatively large changes in ice cover.
Given our proximity to many Pacific nations just above sea level, and our own love of beaches and living by the sea, it is worth noting that sea level continues to rise. From 1901 to 2010, sea level has risen by 19 centimetres, and is doing so at an accelerating rate. The estimated rates are 1.7 millimetres per year for the entire period and 3.2 millimetres per year since 1993. With estimated (and conservative) sea level rise of 80 centimetres by the end of the century, some 100 million Bangladeshis will be displaced. Already, the Carteret Islanders off PNG are starting to leave their homes. What about loving our Pacific neighbours as ourselves?
In such a brief summary I can’t do justice to all the changes we’ve seen or the possible changes we will see, but hopefully you can see that none of them are good or represent the best of human beings as God’s image bearers. The IPCC is not a body to be dismissed for political or religious reasons, but is a voice crying out for God’s people to hear and respond.