Ice and pollen

Brick and electrical metres

With good reason, ice cores have been getting a lot of attention lately. Their careful analysis gives us priceless insights into the history of Earth’s climate. Using cores from Greenland, we can go back more than 100,000 years, tracking temperature, carbon dioxide concentration, and even solar activity (using beryllium isotopes). Using cores from Antarctica, it is possible to go back about 650,000 years.

Ice cores can be even more valuable when they are matched up against records of other kinds. Living and petrified trees can be matched up, year for year, with the ice record. So can pollen deposits at the bottom of seas and lakes: arguably the richest data source of all. By looking at pollen deposits, it is possible to track the development of whole ecosystems: forests advancing and retreating with ice ages, the species mix changing in times of drought, and the unmistakable evidence of human alterations to the environment, going back tens of thousands of years.

Lake Tanganyika, in Tanzania, offers an amazing opportunity. 676km from end to end, it is the worst’s longest lake. It is also the second oldest and second deepest – after Lake Baikal in Siberia. Core samples from Tanganyika have already documented 10,000 years worth of pollen deposition. With better equipment and more funding, scientists say that it should be possible to collect data from the last five to ten million years: increasing the length of our climate records massively.

I am not sure if such an undertaking is already in the works. If not, it seems like the kind of opportunity we would be fools to pass up. If no government or scientific funding body is willing to stump up the cash, perhaps a billionaire or two can be diverted from their tinkering with rockets.

Polar opposites

By now, everybody knows that the Arctic summer sea ice is at an all-time low. What I only learned recently is that the extent of Antarctic ice is the greatest since satellite observation began in 1979. At the same time, it is undergoing “unprecedented collapses” like the much-discussed Larsen B collapse. Such realities hint at the complexities of the climate system.

Whereas the Arctic doesn’t have any effect on sea level, because it floats, the Antarctic rests on land. As such, changes in its ice mass do affect the depth of the world’s oceans. Antarctica is also the continent for which the least data is available, making it hard to incorporate into global climate models. As with all complex dynamic systems, there are non-linear effects to contend with. That makes it dangerous to extrapolate from present trends, especially when it comes to local conditions.

All this makes you appreciate why scientists frequently sound less certain about the details of climate change than politicians do. The harder you look at systems like the Earth’s climate, the more inter-relationships you discover, and the more puzzles there are to occupy your attention.

The Two Mile Time Machine

Fire hose reel

Richard Alley’s The Two Mile Time Machine: Ice Cores, Abrupt Change, and Our Future provides a good, though slightly dated, explanation of the science of ice core sampling, as a means for studying the history of Earth’s climate. Alley focuses on work conducted in Greenland prior to 2000. The book combines some surprisingly informal background sections with some rather technical passages about isotopic ratios and climatic cycles. Overall, it is a book that highlights the scientific tendency to dive right into the details of one area of inquiry, while skimming over many others that actually relate closely – especially if you are trying to use the science as the basis for sound decision-making.

This book does not really warrant inclusion in the first tier of books to read on climate change, but it certainly provides some useful background for those trying to develop a comprehensive understanding of the area. Arguably, the best contribution it makes is explaining the causes and characteristics of very long climatic cycles: those stretching over millennia or millions of years, with causes including orbital variation, continental drift, and cryosphere dynamics.

Given the amount of new data and analysis that has been undertaken since this book was published, a new edition may well be warranted. In particular, the very tenuous conclusions of Alley’s concluding chapters should either be revised, or defended in the fact of the new data.

A banking analogy for climate

[Update: 22 January 2009] Some of the information in the post below is inaccurate. Namely, it implies that some level of continuous emissions is compatible with climate stabilization. In fact, stabilizing climate required humanity to have zero net emissions in the long term. For more about this, see this post.

Every day, new announcements are made about possible emission pathways (X% reduction below year A levels by year B, and so forth). A reasonable number of people, however, seem to be confused about the relationship between emissions, greenhouse gas concentrations, and climatic change. While describing the whole system would require a huge amount of writing, there is a metaphor that seems to help clarify things a bit.

Earth’s carbon bank account

Imagine the atmosphere is a bank account, denominated in megatonnes (Mt) of carbon dioxide equivalent. I realize things are already a bit tricky, but bear with me. A megatonne is just a million tonnes, or a billion kilograms. Carbon dioxide equivalent is a way of recognizing that gasses produce different degrees of warming (by affecting how much energy from the sun is radiated by the Earth back into space). You can think of this as being like different currencies. Methane produces more warming, so it is like British Pounds compared to American dollars. CO2 equivalent is basically akin to expressing the values in the ‘currencies’ of different gasses in the form of the most important one, CO2.

Clearly, this is a bank account where more is not always better. With no greenhouse gasses (GHGs), the Earth would be far too cold to support life. Too many and all the ice melts, the forests burn, and things change profoundly. The present configuration of life on Earth depends upon the absence of radical changes in things like temperature, precipitation, air and water currents, and other climatic factors.

Assuming we want to keep the balance of the account more or less where it has been for the history of human civilization, we need to bring deposits into the account in line with withdrawals. Withdrawals occur when natural systems remove GHGs from the atmosphere. For instance, growing forests convert CO2 to wood, while single celled sea creatures turn it into pellets that sink to the bottom of the ocean. One estimate for the total amount of carbon absorbed each year by natural systems is 5,000 Mt. This is the figure cited in the Stern Review. For comparison’s sake, Canadian emissions are about 750 Mt.

Biology and physics therefore ‘set the budget’ for us. If we want a stable bank balance, all of humanity can collectively deposit 5,000 Mt a year. This implies very deep cuts. How those are split up is an important ethical, political, and economic concern. Right now, Canada represents about 2% of global emissions. If we imagine a world that has reached stabilization, one possible allotment for Canada is 2%. That is much higher than a per-capita division would produce, but it would still require us to cut our present emissions by 83%. If we only got our per-capita share (based on present Canadian and world populations), our allotment would be 24.5 Mt, about 3.2% of what we currently emit. Based on estimated Canadian and world populations in 2100, our share would be 15 Mt, or about 2% of present emissions.

Note: cutting emissions to these levels only achieves stabilization. The balance in the bank no longer changes year to year. What that balance is depends upon what happened in the years between the initial divergence between deposits and withdrawals and the time when that balance is restored. If we spend 100 years making big deposits, we are going to have a very hefty balance by the time that balance has stabilized.

Maintaining a balance similar to the one that has existed throughout the rise of human civilization seems prudent. Shifting to a balance far in excess carries with it considerable risks of massive global change, on the scale of ice ages and ice-free periods of baking heat.

On variable withdrawals

Remember the 5,000 Mt figure? That is based on the level of biological GHG withdrawal activity going on now. It is quite possible that climate change will alter the figure. For example, more CO2 in the air could make plants grow faster, increasing the amount withdrawn from the atmosphere each year. In the alternative, it is possible that a hotter world would make forests dry out, grow more slowly, and burn more. However the global rate of withdrawal changed, our rate of deposit would have to change, as well, to maintain a stable atmospheric balance.

Here’s the nightmare possibility: instead of absorbing carbon, a world full of burning forests and melting permafrost starts to release it. Now, even cutting our emissions to zero will not stop the global atmospheric balance from rising. It would be akin to being in a speeding car with no control of the steering, acceleration, or brakes. We would just carry on forward until whatever terrain in front of us stopped the motion. This could lead to a planetary equilibrium dramatically unlike anything human beings have ever inhabited. There is a reasonable chance that such runaway climate change would make civilization based on mass agriculture impossible.

An important caveat

In the above discussion, greenhouse gasses were the focus. They are actually only indirectly involved in changes in global temperature. What is really critical is the planetary energy balance. This is, quite simply, the difference between the amount of energy that the Earth absorbs (almost exclusively from the sun) and the amount the Earth emits back into space.

Greenhouse gasses alter this balance because they stop some of the radiation that hits the Earth from reflecting back into space. The more of them around, the less energy the Earth radiates, and the hotter it becomes.

They are not, however, the only factor. Other important aspects include surface albedo, which is basically a measure of how shiny the planet is. Big bright ice-fields reflect lots of energy back into space; water and dark stone reflect much less. When ice melts, as it does in response to rising global temperatures, this induces further warming. This is one example of a climatic feedback, as are the vegetation dynamics mentioned previously.

In the long run, factors other than greenhouse gasses that affect the energy balance certainly need to be considered. In the near term, as well demonstrated in the various reports of the IPCC, it is changes in atmospheric concentration that are the primary factor driving changes in the energy balance. Things that alter the Earth’s energy balance are said to have a radiative forcing effect. (See page 4 of the Summary or Policy Makers of the 4th Working Group I report of the IPCC.)

What does it mean?

To get a stable atmospheric balance, we need to cut emissions (deposits) until they match withdrawals (what the planet absorbs). To keep our balance from getting much higher than it has ever been before, we need to do this relatively quickly, and on the basis of a coordinated global effort.

The folly of Apollo redux

In an earlier post, I discussed the wastefulness of manned spaceflight. In particular, plans to return to the Moon or go to Mars cannot be justified in any sensible cost-benefit analysis. The cost is high, and the main benefit seems to be national prestige. Human spaceflight is essentially defended in a circular way: we need to undertake it so that we can learn how human beings function in space.

A post on Gristmill captures it well:

Let me be clear. There is a 0 percent chance that this Moon base or anything like it will ever be built, for the following reason: the moon missions in the ’60s and early ’70s cost something like $100 billion in today’s dollars. There is no way that setting up a semipermanent lunar base will be anything other than many times more expensive. That would put the total cost at one to a few trillion dollars.

Assuming that this taxpayer money needs to be lavished on big aerospace firms like Lockheed anyhow, it would be much better spent on satellites for the study of our planet (Some comprehensive temperature data for Antarctica, perhaps? Some RADAR analysis of the Greenland icecap? Some salaries for people studying climatic feedbacks?) or on robotic missions to objects of interest in the solar system.

New climate change site from Nature

Nature, the respected scientific journal, has a new climate change portal full of free content. A free issue in the Nature Collections series on Energy is available as a PDF.

When relatively exlusive publications try to open themselves to a more general audience, the results can be interesting. In trunks back in North Vancouver, I have hundreds of issues of The Economist where all the images are black and white, and the pages are just columns of text sometimes accented in red. In the previous span where I subscribed to Scientific American they also made a big shift towards the mainstream. I doubt that Nature will undertake such a shift. It is, after all, a peer reviewed scientific journal, but it will be interesting to see whether their attempts to promote the visibility of some scientific data and analysis will shift the overall journalistic picture of climate change at all.

Oryx and Crake

Fire truck valves

Margaret Atwood‘s novel, which was short-listed for the Booker Prize, portrays a future characterized by the massive expansion of human capabilities in genetic engineering and biotechnology. As such, it bears some resemblance to Neal Stephenson‘s The Diamond Age, which ponders what massive advances in material science could do, and posits similar stratification by class. Of course, biotechnology is an area more likely to raise ethical hackles and engage with the intuitions people have about what constitutes the ethical use of science.

Atwood does her best to provoke many such thoughts: bringing up food ethics, that of corporations, reproductive ethics, and survivor ethics (the last time period depicted is essentially post-apocalyptic). The degree to which this is brought about by a combination of simple greed, logic limited by one’s own circumstances, and unintended consequences certainly has a plausible feel to it.

The book is well constructed and compelling, obviously the work of someone who is an experienced storyteller. From a technical angle, it is also more plausible than most science fiction. It is difficult to identify any element that is highly likely to be impossible for humanity to ever do, if desired. That, of course, contributes to the chilling effect, as the consequences for some such actions unfold.

All in all, I don’t think the book has a straightforwardly anti-technological bent. It is more a cautionary tale about what can occur in the absence of moral consideration and concomitant regulation. Given how the regulation of biotechnology is such a contemporary issue (stem cells, hybrid embryos, genetic discrimination, etc), Atwood has written something that speaks to some of the more important ethical discussions occurring today.

I recommend the book without reservation, with the warning that readers may find themselves disturbed by how possible it all seems.

A storm by any other name

A couple of interesting facts relating to meteorological nomenclature:

First, a ‘cyclone’ is any “system of winds rotating around a centre of minimum barometric pressure,” according to the OED. Once those winds reach hurricane speeds (64 knots), the storm is called a ‘hurricane’ in North America; a ‘typhoon’ in the Northwest Pacific, west of the International Date Line; a ‘severe tropical cyclone’ in the Southwest Pacific, west of 160°E or the Southeast Indian Ocean east of 90°E; a ‘severe cyclonic storm’ in the North Indian Ocean; and a ‘tropical cyclone’ in the Southwest Indian Ocean.

Secondly, the American National Oceanic and Atmospheric Administration (NOAA) names cyclones in a number of different regions several years in advance. If the list of names assigned for a season runs out (there are 21 assigned names per year) subsequent storms are named after the successive letters of the Greek alphabet. Short, distinctive names are used because doing so was found to produce fewer errors than designating storms on the basis of latitude and longitude. Sometimes, a storm is “so deadly or costly” that the NOAA retires the name, for reasons of emotional sensitivity.

Pressure and the price of gas

The tendency of gasoline to increase in price during the summer is well known. Partly, this reflects increased demand (which leads to an increased quantity sold at an increased price, given a particular supply curve). Partly, this is the consequence of how summer gasoline is a different blend of hydrocarbons. The reason for this is the need to prevent too much pressure from building up inside gas tanks as more of the liquid turns to vapour in the summer heat. This is standardized in terms of Reid vapour pressure (RVP): the pressure of any particular gasoline blend at 100°F (37.8°C) expressed in kilopascals, calibrated to a standard atmospheric pressure of 101.3 kPa.

RVP is used to specify which blends of gasoline are acceptable for sale at different ambiant temperatures. Gasoline with an RVP of over 14.7 will fairly easily pressurize gas tanks and gas cans in summer heat. It will also boil if left in open containers. As such, regulations require summer gasoline to contain less butane than the winter sort. This is on account of how butane is relatively inexpensive (making companies want to include more of it), but is also the most active contributor to vapour pressure. As such, the butane content of summer gasoline must be very low – one factor behind the higher price.

I learned all this from R-Squared, an energy blog that seems to be commonly cited. The blog makes one other important point: anyone considering storing cheap winter gasoline for use in the summer should consider the dangers of having the butane therein turn to vapour and start pressurizing the container in which it has been stored.