Few people these days deny that the climate is changing - over the past 30-50 years we've seen a variety of record-breaking events, which seem to be getting more and more frequent, especially the last 25 years. There are also many worrying trends of coastal erosion, natural disasters and melting ice caps which are causing concern. But I would like to talk about the confusion in what it all means and how we should interpret it. Without getting too deeply into the science, there seem to be some trends which should concern us principally and they are as follows. Let me know if I have missed anything out or got anything wrong:
Long-term trends in geoclimatology: this is a favourite of climate change denialists. The Milankovitch cycles, combined with tectonic shifts in the position of the continents (and corresponding paths of ocean currents) seem to be largely responsible for the phenomenon of 'Ice Ages', one of which we are currently in, specifically an interglacial period between two nadirs of glacial activity. The trajectory over the course of the next 25-50,000 years is towards a glacial maximum which would replicate conditions when most of modern North Europe and Canada were covered in thick ice sheets and mammoths roamed the tundra. However, this is in large part dependent on us having polar ice caps in place (due to the feedback loop created by the Albedo effect which means massive-scale glaciation reflecting the sun's energy) and atmospheric carbon levels remaining largely stable. As such,
1. We weren't scheduled to descend into another glacial maximum for quite some millenia yet, so the idea that we will be 'saved' from global warming by the ice age is for the birds, considering the next 250 years will bring unprecedented catastrophes even with conservative estimates of current warming trajectory.
2. Most climatologists now agree that we will likely avoid the next glacial maximum altogether unless drastic changes are made to greenhouse gas emissions.
Volcanism and oceanic emissions - Volcanism has caused massive extinction events in the past, including global warming on a terrifying scale. The Paleocene-Eocene thermal maximum was thought to have been caused by undersea volcanic greenhouse gas emissions. This means such drastic changes are entirely a natural part of earth's geological history, and so manmade global warming would not 'destroy the planet' as some alarmists claim, in the sense of making the planet uninhabitable by all mammalian species. However, the P-E thermal maximum is theorised to have increased temperatures by around 7 degrees. This is actually within the worst-case scenario estimates of manmade climate change, if carbon emissions in the developing world increase to match those of the developed world. And so while volcanism is not under human control, we risk seeing a climactic change of a magnitude comparable to some of geological history's worst climate disasters unfold during the next dozen generations. This means:
- If there were ever a massive volcanism event, we might see entirely natural global warming on a devastating scale. However this might not happen for millions of years and, while it should be of concern to the survival of the human race on planet earth in the long term, it's actually a threat of a magnitude not disimilar to what we may see in the very near future due to manmade action.
Manmade C02 emissions This needs no further explanation, I think! Unless anyone wants to seriously claim that C02 emissions don't have a track record of leading to climate change, or that we aren't producing large quantities of greenhouse gases. If so, go ahead, I'm game.
Solar energy output - sunspot cycles are thought to cause changes in climate. They are sometimes thought to be largely responsible for the Roman Warm period, the Migration period dip, the Medieval Warm period, and the Little Ice Age. Some scientists predict a weaker cycle coming in the next decades, leading to a slightly colder climate. Climate change denialists claim that this will counteract global warming. However, the science behind all of this is HIGHLY questionable, and even if it were true, it would be a temporary respite which wouldn't have much of an impact on the baseline warming which carbon emissions seem to be producing, over the span of the next couple of centuries. I found a great article on this which you can read here.
Unpredictable climactic feedback loops and counterloops - perhaps the best known of these is the disruption of El Nino and the Gulf Stream through melting ice, which are hypothesised to be leading to colder weather in localised areas. This has also been put forward by some as a 'saviour' from global warming. It is of course nothing of the sort - it will lead to more extreme weather which, even if not always 'warming', will still cause havoc and make some parts of the world more disaster-prone without helping other parts of the world much.
Other environmental challenges which put society at risk - some things which have little directly to do with climate are nevertheless linked with manmade climate change through the 'manmade' part of the term. The felling of forests and other vegetation not only increases carbon emissions but also leads to degradation of habitats, leading to species loss (most notably the bee-pocalypse which poses a huge threat to agriculture) as well as the degradation of soil, leading to poor agricultural yields and desertification as well as flooding, landslides and other localised disaster risks. This feeds into climate change through exacerbating and complementing many of its effects. Urbanisation, poorly though-out engineering projects such as dams, and last but not least human population increase are environmental challenges which put huge localised pressure on things like water resources, again exacerbated by the warming climate.
- The environmental challenges will be felt most keenly in developing countries where agriculture is key to the economy and political stability. If agriculture, most notably the ability to provide livelihoods and food for citizens, suffers a collapse, we will see huge increases in the type of civil wars and mass migration which are already happening and already causing huge upheavals in the developed world.
In conclusion, the pace of changing climate is quite simply not compatible with claims that long-term geoclimactic trends will somehow 'save' us, or that we are in the midst of hysteria surrounding short-term data being misunderstood and separated from the long-term context - there is clearly an acute crisis which will unfold over the course of the lifetimes of people currently alive, and which can only easily be stopped by reducing the amount of carbon going into the atmosphere as well as making drastic changes to how we use land and water. Combatting this will require, as far as I can see, coalescence around organisations like the UN and EU, or some kind of equivalent global cooperation, as ways of instituting global coordinated policy aimed at reducing the impact of all of the abiove. Next year will see a summit in my home city of Glasgow, and it will be among our last chances to avert a period of intense regress in living standards and wealth which will touch all of us. This is the reality of climate change.