A climatologist’s view of climate change

This article is a bit special since I have actually been asked to write it due to my great knowledge. Admittedly, it is mostly Tove who has asked me to write it but I still feel the sweet taste of appreciation.

The background is that I am actually a climatologist. Sort of. I have a master’s degree in geography which I pursued in a way that let me choose as many courses in climatology as possible. I also wrote my thesis on climatology, more specifically on the urban heat island phenomenon.

Basically, geography is the study of everything you can place on a map. And frankly everything can be placed on a map. Therefore, geography is the study of everything. I am also of the firm belief that geographers are the best generalists. I have some scientific proof for that last statement since I have never been so thoroughly whipped while playing Trivial Pursuit as when I played it with some fellow geography students.

A geography degree is also very handy if you do not plan to ever get a real job. At least in Sweden there are only two viable career choices if you major in geography. Either you become a geography high school teacher. Or you go into research. I have never had the slightest intention of returning to high school so for me only the second alternative was available. After leaving university in 2008 I did apply for one doctorate, but I did not get it. After that I choose the third alternative: doing something completely different.

Climate change revisited

You read that last sentence correctly. I have not bothered with climatology for 15 years. If you are looking for an up-to-date report on the current state of climate change science you are in the wrong place. Even 15 years ago I would hardly have been able to give something like that. That should be the domain of doctors and professors, not former graduate students.

Nevertheless, I might be able to say something interesting about climate change. Or, maybe not on climate change itself, but rather on climatology in general. And its role in documenting climate change.

Climatologists vs. meteorologists

Being a climatologist does not mean you are the go-to person for climate related issues. At least not in Sweden where climatologists are rare birds and considered a somewhat obscure subgroup to natural geography. I am vaguely aware that this is not necessarily the case internationally where famous climatologists seem to have a background in physics (completely unrealistic in Sweden) or engineering (even more unrealistic in Sweden).

Climate scientists in Sweden, and to a lesser degree in the rest of the world, are instead meteorologists. The same people that present next day's weather on television. The reason for this seems to be that people often confuse weather (the temperature tomorrow) with climate (the temperature next year). An even bigger reason is that meteorologists actually do something useful to society which has given them quite a lot of money and also rather fancy supercomputers to simulate tomorrow’s weather. Incidentally, these supercomputers can also be used to simulate the weather next year and next decade, although with some serious limitations in accuracy.

At the geography institution where I studied meteorologists were frowned upon or even scorned. They were considered amateurs dabbling in something they did not understand. There was also a palpable feeling of jealousy at the money and honors going in the direction of meteorology and something akin to lament over the fact that the world was not more interested in the work of the climatologists.

During my years at university, in the early 2000s, almost all climatologists would have been considered climate change skeptics by today’s naming conventions. The general feeling of antipathy towards the meteorologists, who seemed to all be climate change alarmists, might have played its part. But at its root it was a question of totally different perspectives.

Choose your time frame

Meteorologists predict the weather, but even more than that they record the weather. This recording has been done meticulously and been carefully saved in gigantic meteorological databases. But it has not been done for a very long time, climatologically speaking. Continuous well-calibrated temperature recordings did not start until the middle of the 19th century. That gives us almost 200 years of very reliable climate data.

200 years might sound like a long time but when talking about climate it is not very impressive at all. In fact it is much worse than that. Climate varies for natural reasons that are still very much unknown to science. One such variation was the Little Ice Age, a period of unusually cold climate occurring between approximately 1400 and 1900 (other definitions place it between 1650 and 1850).

Chance had it that modern meteorological temperature recordings started at the very end of the coldest period since the last ice age. Looking at the world’s climate from a meteorologist’s viewpoint the world has definitely become a lot warmer. But that is only because meteorologists have very limited data to do statistics on. Climatologists study the climate thousands and tens of thousands of years back in time and have a rather different view of what is happening. Something that they like to point out to anyone who can bear to listen.

The toolbox of climatology

There is one major problem with studying the climate of the past. Neither the Romans, nor the Babylonians had any thermometers. If they had had thermometers it would not really have mattered since those thermometers would not have been calibrated to our thermometers. In short, we have no idea what the temperatures were before the 19th century. All we have is guesses and it is the job of climatologists to make as educated guesses as possible.

There are three major techniques for estimating temperatures of the past. At least I only learned of three techniques when I studied climatology. Maybe there has been major development in the last 15 years. Maybe my professors were all sworn to secrecy of some classified climatology techniques. But probably there are still only these three scientific ways of estimating the historical climate.

The first method is tree-ring analyses, also called dendroclimatology. Trees in temperate zones grow differently depending on the season, something that creates tree rings within the trunk of a tree. These tree rings can be dated very accurately and the tree rings can then be analyzed for growth. The basic principle is that a warmer climate gives more growth and vice versa. By analyzing a lot of old trees, dating them carefully and comparing them to each other climatologists can create a year-by-year climatic history going back thousands of years.

Another method of estimating past climates is looking at layered sedimentary soils. Most often this is done by drilling a cylindrical hole at a suitable location to retrieve a sedimentary core. As I remember it we often did this from the bottom of lakes, but it is also possible to take a core sample from dry locations as long as there is a layering in the soil.

The layering is created from different types of sedimentary deposition based on the seasons. From these layers it is possible to count backwards in time, sometimes to the last ice age, tens of thousands of years ago. For each layer the contents are searched for pollen which gives an indication of what type of vegetation was present at the location during different times. The vegetation then gives an indication of the climate.

The third method is oxygen isotope analysis. A rather more complex method based on the fact that two isotopes of oxygen, oxygen-18 and oxygen-16, evaporates at different speeds depending on the temperature. The oxygen being analyzed is oxygen in water molecules that have evaporated from the ocean. If there is a relatively higher amount of oxygen-18 then the ocean from which it evaporated was relatively colder and vice versa. 

Of course this only works if you have available water vapor from the time you want to study. Luckily there is an archive of precisely such water vapor, and it goes hundreds of thousands of years back in time. In the giant ice sheets of Antarctica and Greenland are trapped tiny air bubbles from the time the snow that formed the ice sheets fell. By drilling down in the ice, an ice core can be retrieved. If there are visible seasonal layers the core can be dated and different slices can be carefully melted and the air bubbles can be analyzed by spectrometer.

I cannot say that I have any personal experience of oxygen isotope analysis. Probably because my tight-fisted university would not spend money on Antarctica excursions for its graduate students. I do remember one time when we were shown an ice core from the freezer. My university did its fair share of drilling in the paltry glaciers of Sweden and it also had research projects on Greenland, so naturally there was an ice core freezer in the basement. But we were never allowed to actually do anything with this ice core, the point was probably only to put us in awe of the wonderful tools of climatology. 

Oxygen isotope analysis is great but it is not perfect. The main problem is that oxygen-18 evaporation is not only dependent on ocean temperature. It is also affected by ocean salinity, ocean currents and maybe other things as well. Still this is a very powerful tool for climatologists and it has been used successfully by for example the European Project for Ice Coring in Antarctica (EPICA).

But what about climate change

So what have the climatologists found out and does it in any way affect our understanding of climate change? That is one of those questions that is not possible to answer fully. All major climatological science is of course incorporated into the bigger climate science debate. IPCC reports and other climate scientists give at least cursory consideration to the findings of climatologists.

No one is disputing that the climate has been getting warmer since the 19th century. The question is if this is caused by human action, natural variation in climate or both. Past climate can give us an inclination of the natural variation in climate. With this information we can decide how probable we believe it is that the current global warming is man-made or of natural origin.

One problem with the climate data of prehistoric times is that it is never better than approximations. Still it seems very probable that the global climate was warmer 8000 years ago than it is today, after 200 years of global warming. This very warm period during the stone age even has a scientific name: the Holocene climatic optimum. EPICA and other ice core analyses have also disclosed that the Earth was even warmer during the last interglacial (the warm period between ice ages) 100 000 years ago.

Even if the current global warming is not yet extreme in terms of absolute temperature, surely it must be extreme in speed of change? This is not that easy to have an opinion of since we have only had decent temperature recordings since the 19th century. The indirect measurements of the climatologists are not accurate enough to give the same level of temperature detail as daily thermometer readings.

However, there is one incident in climatological history that seems to be at least as quick as the current global warming. Younger Dryas is a strange name for a thousand year long period of unusually cold climate around 12 000 years ago. It was a setback to ice age temperatures after a few thousand years of warmer climate. As far as I know there is no good explanation for the Younger Dryas, why it started and why it ended. But it ended very quickly. The graph below (borrowed from Wikipedia) based on oxygen-18 analysis from Greenlandic ice cores gives an indication of the variability of the climate at the end of the last ice age. Exact numbers are hard to pin down but I have heard scientists claim that the Younger Dryas ended with global average temperatures increasing by a full degree in the span of a decade. Much quicker than the current global warming.

Jurassic park

The period since the last ice age, about 15 000 years, is no more than the blink of an eye compared to the age of planet Earth. Climatologists generally do not venture beyond their ice cores which stretch back about a million years in time. But just as climatologists look down on meteorologists for their limited horizons there are another academic species looking down on climatologists, namely geologists. 

I have never had much interaction with geologists. At least at my university they were a completely different branch from the geographers and we hardly ever met them. When we did we did it respectfully, knowing that geologists were better people than us. This was mainly due to the fact that geologists do something useful, they find mineral ores and fossil fuels and such things that society actually needs. More relevant to graduate students was probably the fact that geology students had a well-paid job in the extraction industries waiting for them while geography students like us knew there was only a high school classroom filled with unruly teenagers at the end of our studies. 

For these reasons I know hardly anything about geology. But that is not really necessary for the argument here. Even non-geologists know that fossil fuels are organic material that has been decomposing in an oxygen-free environment for millions of years. But millions of years ago, during the mesozoic (that is a fancy geological name for the age of the dinosaurs) all of this organic material was loose in the biosphere, mainly as atmospheric carbon dioxide. 

Geologists have, through their dark and secret arts, estimated that the atmospheric carbon dioxide level was 3000 ppm during parts of the mesozoic, 8 times higher than today. Temperatures were also higher than today’s global average, by anything between 2-10 degrees (look at figure 1 which gives a number of temperature estimations from different studies and remember that global average temperature has been calculated to 14 degrees for the period 1951-1980). 

Clearly the mesozoic was warmer than today. And since carbon dioxide levels were also much higher it is an argument as good as any for anthropogenic climate change. But that is not the main point I want to make with this adventure into geology. Instead I want to point to the fact that the mesozoic, the age of the dinosaurs, was full of life, something proven beyond doubt by the fossil record. Very large terrestrial creatures, such as the largest dinosaurs, can only have existed if there was a thriving ecosystem surrounding them. Every suggestion that carbon dioxide emissions could mean an end to life on Earth are kind of silly knowing that life on Earth thrived in an environment with 8 times today’s carbon dioxide levels. 

A world full of life?

How dare you?

There are other aspects that, at least in my opinion, blunts the risks of climate change. For one the effect of global warming is not evenly spread. The actual warming is mostly taking place at higher latitudes, predominantly in the northern hemisphere. While parts of the Arctic has seen average temperatures increase by almost 5 degrees, large areas of Africa and southern Asia have experienced temperature increases of less than 1 degree. 

This does not seem like a catastrophe as much as something rather convenient. The cold parts of the globe (where, incidentally, I happen to live) get warmer while the already warm parts stay about the same. Is this not actually a good thing? 

A warmer climate is not only nice for R&R. It also leads to lower heating costs (my guess is that heating still consumes more energy than cooling globally, but I do not have the numbers to back it up). Most of all global warming is a blessing for agriculture. Not only are higher temperatures great for most plants, higher carbon dioxide levels in itself lead to quicker photosynthesis and a warmer climate also leads to more precipitation. 

That last statement might surprise someone who believes the hype around droughts caused by climate change. At some times, in some places a warmer climate might of course cause drier weather. But in general a warmer climate equals a more humid climate. This is due to the fact that higher temperatures lead to more evaporation which in its turn leads to more precipitation. One might think that the evaporation and precipitation cancel each other out. But that is not the case. Evaporation mostly takes place over the oceans, where most of the water is found, while precipitation mostly takes place over land, where most of the rain-inducing topography is located. Global warming is speeding up the water cycle meaning more water will be transported from wet seas to dry land, making the latter less dry in the process. 

I am not pretending that global warming is all fine and dandy. There are obvious risks as well. Higher temperatures will lead to rising sea levels. This does not have to be catastrophic. After all, one of the world’s richest and most successful countries, the Netherlands, is to a significant extent located below sea level. But it will require some willingness to change, which might not always be forthcoming. 

The risk-averse attitude to every type of change is conservatism. And in the case of climate change the conservative position is to limit emissions of greenhouse gasses as much as possible. When this attitude collides with economic interests we have an interesting political dilemma: keep the present environmental situation or keep the present economic situation. It is conservatism against conservatism. 

Personally I do not consume any meaningful amounts of fossil fuels. More due to economic than environmental reasons. Fossil fuels are expensive, especially in Europe, and I am poor. Personal reasons aside there is also excellent geopolitical logic in limiting fossil fuel consumption. For some reason most of the oil and gas available on world markets seem to be from less savory regimes like Russia and Saudi Arabia. Poverty aside, that is in itself a good enough reason for me to support limits on fossil fuel consumption. If it is also beneficial for the environment, so much the better. 

Actually quite true. Since Saudi Arabia is the world’s main swing producer every extra drop of oil consumed is likely to be produced by Saudi Aramco which profits go directly to the Saudi treasury which is more or less the same as the personal purse of MBS.