Note: originally published on 05/30/2010 (transferred from wordpress). 

A response I wrote to this Newsweek article.

I am a climate researcher – a PhD student looking at past climates, actually. There are so many unsourced, unreliable accusations in this article and among the comments that I had to respond in some depth.

Most importantly: climate is nothing more than the overall tendencies of weather patterns over a long period. These overall climatic tendencies mask a huge amount of short term fluctuations in weather. If our world is warming that doesn’t mean some regions of the earth – like Europe over the past few months – won’t have especially cold winters. I study a period called “the Little Ice Age,” referring to a few centuries of generally colder-than-normal weather in the early modern period. Well, some of those years – even some decades – were actually warmer than normal, and sometimes when it was cold, wet and stormy in one part of Europe, for example, it was warm, dry and tranquil in another part. Still, over the centuries glaciers advanced and sea ice spread.  If the public has lost some faith in global warming that is because they do not understand the reality of climatic changes – largely because we as researchers have done a poor job explaining them – and that is a serious concern.

Has the pace of global warming slowed over the past decade? It depends on where you look. Globally, yes - slightly. In the poles, quite the opposite – and this is critical, because ice not only stores water but also reflects sunlight. When we lose ice, we gain water that more easily absorbs the warmth of the sun, and so polar melting results in a vicious cycle with critical consequences for global warming. As for the pace of warming slowing globally: there is no shortage of possible answers. It’s important to remember that the increasing quantity of carbon dioxide, methane and other gases pumped into the atmosphere by 7 billion humans is just one (very important) climatic stimulus among many. For example, the sun is also experiencing a historic low in sunspots, and the previous times that occurred – the Dalton Minimum, and before that the Maunder Minimum – the climate grew cooler. It’s entirely possible that when the sunspots return we’ll see a dramatic acceleration in global temperatures. The reality that the world’s climate is a complex system with many different elements doesn’t mean that human beings do not have a decisive impact. Remember that last year was still the warmest on record.

There are two points to keep in mind about science and scholarship: first, the universe is incredibly complex and we don’t fully understand it. Second, what we do think we understand rests entirely on a collection of theories that represent the cutting edge of research. The natural “laws” we take for granted – gravity, the law of conservation of mass and energy, etc. – are really nothing more than best guesses. It’s the same with global warming, and climate researchers have never stated otherwise. It’s why anyone who condemns a scientific theory – evolution, for example, or global warming – for failing to provide “certainty” is really just creating a straw man argument.

Right now, as the article reports, the vast majority of researchers in a wide range of disciplines believe global warming is an accelerating reality. The vast majority believe it is caused by human beings. These theories seem extremely sound and are backed by an enormous amount of evidence, although of course, like anything, they’re not certainties. On the other hand it’s more difficult to predict the extent of future temperature rises (and accompanying shifts in precipitation, wind directions/speeds, and storminess) because doing so with any accuracy requires more knowledge of the world’s climate than we currently possess. Just like researchers in physics or biology who push the limits of their fields, here we must proceed with much less confidance. Contrary to what this article claims, however, all indications suggest that the IPCC has been low-balling the (potential) impacts of global warming. This makes sense to me: for one, any massive institution will inevitably shift towards a certain conservatism, and secondly I study I period where temperature changes of just 1-2 degrees celsius radically influenced European environments.

As climate researchers we may not “know” the potential consequences of global warming with any certainty. However, the idea that recent articles have “refuted” (note the word choice) the possibility of dessertification or especially severe natural disasters arising from global warming is just absurd. An example: there has been some controversy over the potential link between global warming and the severe hurricanes of recent years. However, if water temperatures rise sufficiently in the coming decades we will almost certainly see far more severe storms, especially if these are accompanied by higher sea levels. J.R. McNeill’s Something New Under the Sun outlines the precarious, climatically-sensitive state of global agriculture; indeed even the relatively slight climatic shifts of the period I study influenced famines that killed millions, and potentially a revolution in European commodity prices.

As for the email controversy: this article treats the ridiculous allegations of “cherry picking,” for example, as being self-evident truths. To me it’s difficult to grasp how a cyber attack by a shady group of hackers that publicized a few emails out of thousands, out of context, could have any legitimacy at all. I won’t get into individual emails, but here’s a very good article for those interested: http://www.realclimate.org/index.php/archives/2009/11/the-cru-hack. And another: http://www.treehugger.com/files/2009/11/truth-hacked-climate-email-controversy.php. Maybe the best “unbiased” analysis, the results of the investigation by the British House of Commons Science and Technology Committee: http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/387/38702.htm

Finally, this article criticizes the supposedly radical political stances of climate scientists. Believe it or not, scientists in all disciplines have always influenced and been influenced by politics, culture, and broader society. Why exactly should climatologists alone keep their heads above the political fray when politicians ignore or reject the looming climatic crisis of this century? To do so would be the height of irresponsibility, and more importantly it would be profoundly inhuman.

For much more on the climate controversy, here are some great links:
http://www.sej.org/initiatives/climate-change/overview
http://www.sej.org/publications/climate-change/simple-introductions

This article is one of the best I know of:
Mitchell, John F. B., Jason Lowe, Richard A. Wood, and Michael Vellinga. 2006. “Extreme Events Due to Human-Induced Climate Change” in *PhilosophicalTransactions: Mathematical, Physical and Engineering Sciences*. 364 (1845).

And perhaps the finest new work about those who challenge on scientific consensus on global warming is Merchants of Doubt, published this year by Naomi Oreskes and Erik Conway.  

Sincerely,
Dagomar Degroot

Note: originally published 04/06/2010 (transferred from wordpress):

I just returned from a three-week stay in the Netherlands, where I visited three major archives and a few libraries while scheduling meetings with scholars who know a few things about my field.

This was my first major trip to any sort of physical archive. In past studies I’ve used online archives, and there are a wealth of online databases even for early modern material. My favourite quantifies almost 300,000 ship logs, though only a few of those are from the period I study. The vast majority of what I need is (fittingly) weathered, almost indecipherable, and locked up in palace-like buildings across the Netherlands.

This trip’s main purpose was to figure out what I could use to chart the influence of climate on human affairs. I wanted to figure out how to gain access to those sources, whether I could understand them, and of course what they contained. If I had time I hoped to take as many high-resolution digital photos as possible, which I could then take back to Canada and study at my leisure. Digital photography has really revolutionized archival work; while in the recent past many months, even years were required to pour through primary material in a distant archive now you just need to find what you want and put it in pixels. The hard work of deciphering the material remains the same, but my digital camera has allowed me to go on shorter trips. Europe is great, but having a home is even better.

Luckily for me I found a wealth of potentially relevant material, from ship logs (pictured above) to canal accounts, from government records to personal correspondence. I found out how to get it in my hands, and with the aid of an 18th Century dictionary I started to piece together what each source was telling me. I also took pictures: about 4000, and the resolution seems pretty great.

I spent most of my time looking through ship logs: the source I know best, with a regular pattern that renders it relatively easy to understand. Looking through logs from military vessels for the first time I noticed a lot of easterly winds in key years, and unusually frequent storminess. These are tell-tale signatures of the Little Ice Age. This summer I’ll attempt to quantify what I find in the logs to see how the climate over the Northeastern Atlantic was changing in the 17th Century.  I’ll also figure out just what sailors were thinking about the weather on which their lives often depended.

A highlight for me was seeing Michiel de Ruyter’s already-messy scrawl take a dramatic turn for the worse as he described the storm battering his ship. De Ruyter remains one of the most famous figures in Dutch history, orchestrator of perhaps the greatest defensive naval campaign ever waged. Touching his scrawl was a moment I’ll remember for a long time, a chance to really interact with the past. Later I took a trip to the North Sea and gazed over the waves, out to where he fought the battles that preserved the Republic. The wind blew from the West – atypical for the coldest decades of the Little Ice Age – but I imagine the cold, drizzly weather would have been all too familiar for de Ruyter.

As I poured through primary sources relating to inland affairs I was struck by how a temperature shift of one or two degrees Celsius over even a single season in a year could have dramatical material and social consequences. Records I examined describe how colder winters during the Little Ice Age were often accompanied by torrential flooding owing to ice dams, or catastrophic damage to dikes as a result of drifting sea ice. One reason: a temperature shift of a couple degrees Celsius may not seem like much, but it’s amazing just how much depends on those degrees. For example, a year two degrees Celsius colder than the norm will result in a growing season that’s reduced by a full two months in most of Northwestern Europe.

Temperature changes are also only a single manifestation of a fluctuating climate, which can also be expressed through unusual weather events like storms, shifting wind patterns, or changes in precipitation. Meanwhile climatic fluctuations impact different regions in different ways, altering the ways in which different environments interact. Climate is also just one expression of an environment; when it changes, even over a space of a few years, the other parts of that environment can be profoundly altered in response. Finally, human societies past and present – perhaps especially in the Netherlands – are very closely tied to their environments; far more than we often realize in our superficially insulated cities. When our climate twitches we’re easily swept away.

~Dagomar Degroot

Note: originally posted 01/05/2010 (transferred from wordpress). 

I’ve started the year by studying the mechanics of how our climate operates today, and how it comes to fluctuate. Not all of this data is new to me, but as I go through it again I’m struck by an interesting dichotomy between the simplicity of the climatic system as a whole at first glance and its almost infinite complexity at finer resolutions.

The climatic system is defined very broadly by the difference between the amount of solar heat received at the equator versus that absorbed by the poles. Air expands when heated, so the atmosphere near the meteorological equator is much wider than the atmosphere over the poles. Hence, heat moves from the meteorological equator to the poles, but that movement is broadly horizontal because of the earth’s rotation. In the air this transfer is expressed through the circumpolar vortex, winds spiralling around the poles, and it is the dominant feature of our atmosphere. Eddies, waves and troughs are formed because of differences in the pressure of the air and/or geographic features – these then cause high and low pressure systems, and by extension the world’s weather. Heat transfer in the oceans is expressed through the ocean currents; the oceans hold a far greater reserve of heat than the atmosphere but the movement of the currents is driven by the circumpolar vortex, and at higher latitudes atmospheric heat transfer grows ever more important.

That all seems quite simple, but the climatic system as a whole seems to be defined by (at least) four recurring features: first, changes in one part of the system seem to balance (and be balanced by) changes elsewhere, whether that location is geographically nearby or on the other side of the world. Second, an event – often seemingly insignificant – in one part of the system can cause cascading effects through the system and ultimately major “climatic jumps;” this is a phenomenon commonly known as the “butterfly effect,” and to a degree it holds up. Third, the effects of major climatic changes can appear similar: prolonged cold weather can expand the reach of polar ice, while prolonged warm weather melts polar ice, but both phenomena usually decrease the salinity of oceanic water at high latitudes.

Fourth, the speed and violence of climatic changes is especially remarkable to me. Recent research indicates that the great ice ages – and the warmer interglacials – emerged in the space of only a few decades. This is probably at least partially a function of climatic changes being expressed most prominently at the poles, where shifts in temperature can have runaway effects. A warming trend – as we’re experiencing right now – reduces the surface area covered by ice. Because snow and ice reflect sunlight so effectively, however, the reduction of water covered by ice actually itself contributes to the warming trend. Then again, the oceanic currents themselves, while usually a check against violent climatic oscillation, can in fact influence very rapid, dramatic climatic shifts when, for example, their salinity is altered by melting ice.
Finally, I’m struck by just how little we know about our climate, and beyond that by the rather tenuous ground on which many of our scientific breakthroughs actually stand. Systems of knowledge from palaeontology to anthropology have advanced rapidly in the twentieth century because they have attached fragmentary evidence to the assumption that things in the past in some manner resembled the present, in method if not in substance. This is where much of our understanding of dinosaur behaviour comes from, for example. Similarly, we “know” about our past climate because the simplicity of the circumpolar vortex in its broad strokes – combined with its intimate relationship to weather events – allows us to reconstruct past weather from often fragmentary evidence. It’s worth noting, however, that we fail to understand how exactly our climate works now; we don’t even know exactly how many volcanoes erupt every year, or exactly how they influence our weather systems. The ways of knowing we collectively term science and so often consider sources of unquestionable truth are, of course, really paradigms resting on changing – if informed – beliefs. This does not make them necessarily less accurate or important . . . just less certain.

Dagomar