Category: Climate science

Carbonscape and the charred potato

This column was published in the Waikato Times on 20 January

A couple of months ago a young company called Carbonscape opened a new plant in Marlborough. It makes charcoal from wood waste, hardly an exciting matter one might think. But beyond its traditional use as a fuel, charcoal may hold enormous potential for a sustainable future, for several reasons.

Soil fertility is one. Charcoal added by humans to the soil in pre-European times in the Amazon region has produced a much higher level of fertility than normal in the relatively poor soils of the region.  Modern experiments indicate that at least some soils benefit greatly from having porous charcoal added to them. Our neighbour Australia is finding this in soils which are lower in carbon content than optimal. The biochar, as it is called, seems to act as a catalyst to increase soil fertility. Less fertiliser is required. Microbial and fungal activity is increased. Water retention is improved. Leaching of nitrate and phosphate to waterways is reduced. Crop growth is greater, sometimes considerably so. And the biochar itself lasts for many centuries, being a very stable form of carbon.

Continue reading “Carbonscape and the charred potato”

Baby, it’s cold outside

Pegsnow.jpg In the make-believe world of Climate Debate Daily, where there are two sides to a great “debate” on the reality of climate change (there aren’t), a great gulf is opening between the opposing teams. Cranks are investing a great deal of (wasted) time and effort into spreading the idea that the world is cooling, while climate scientists think a new record high global temperature can’t be far away.

In The Australian today, The Great Communicator (for it is he!) runs the cooling argument for all its worth:

Thus, using several fundamentally different mathematical techniques and many different data sets, seven scientists all forecast that climatic cooling will occur during the first decades of the 21st century. Temperature records confirm that cooling is under way, the length and intensity of which remains unknown. […] Perhaps a reassessment will finally occur when two-metre thick ice develops again on Father Thames at London Bridge, or when cooling causes massive crop failure in the world’s granary belts.

Meanwhile, in an interview with Robin McKie in The Observer, Jim Hansen nails his colours to the mast:

Deniers should show caution, Hansen insisted: most of the planet was exceptionally warm last year. Only a strong La Niña – a vast cooling of the Pacific that occurs every few years – brought down the average temperature. La Niña would not persist, he said. “Before the end of Obama’s first term, we will be seeing new record temperatures. I can promise the president that.”

There’s a collision coming…

Continue reading “Baby, it’s cold outside”

The heater

global_energy_budget_in.png While some on the crank fringe fixate over a “global cooling” (that ain’t happening), the imbalance in our planet’s heat budget has inevitable — and inexorable — consequences for our climate. More heat’s coming into the system than can leave, as this excellent new article at NASA’s Earth Observatory spells out. It’s an easy to follow, but not dumbed-down explanation of how the earth and its atmosphere respond to energy arriving from the sun, with some superb illustrations — and astronaut photographs. Well worth a read, and a useful reference on the complex reality of the “greenhouse” we live in.

[Mutton Birds]

Nice weather for ducks

Duck.jpg A couple of days ago, NIWA published its climate summary for 2008 — a comprehensive overview of all the weather events that went together to make last year what it was. In general, 2008 was sunny and warm for New Zealand, but with many notable extreme weather events — a “rollercoaster” of a year, according to NIWA principal scientist Jim Renwick (who’s been a guest poster here). The Herald picked up on the rollercoaster reference, but Stuff latched on to something else Jim said:

[…] Renwick said the extremes could be a preview of how global climate change would affect New Zealand weather. “I am not saying 2008 was a result of climate change, but we should expect to see more years like that,” he said. “The idea of a sunny year, but with some pretty violent storms, is consistent with climate change. We should expect to see more of those rainfall extremes.”

The last time I looked at my weather records was last February. After musing on a heavy rain event, my comment then was “if you were to ask me what will Canterbury’s climate be like in 2030, I’d have to answer – just like this summer…” For our property in the Waipara Valley, 2007 was a dry year — only 496 mm of rain. 2008 was much wetter: 809 mm in the year, 10% over the average for the last 11 years, and the second wettest in my record. That’s been good news.

However, when I look back at the year, nearly 40% of that rain came in just three events — a big fall in February to break the dry spell, and then two big storms in late July and August, the latter severe enough to cause dramatic flooding in the region. Roughly 320 mm fell in those three events. I had to wash mud out of the garage three times, dig a drainage trench through the truffiere (truffles don’t like drowning), gullies eroded, the road slumped, and the Waipara River lowered its bed by half a metre in places.

Take away those big storms, and we had only 489 mm for the year — a dry year by my standards. Over the ten years up to 2008, we had a total of three comparable heavy rain events (Aug 2000, Jan 2002 and Sept 2003), and then like London buses, three came along at once.

What does this prove? Precisely nothing. I don’t have records going back far enough to know whether there’s any sort of statistical significance in 2008’s North Canterbury rainstorms. But… remember what Jim said earlier? The impact of global warming on the east coast of NZ is expected to increase the frequency of drought, but because warming also means more water vapour in the atmosphere — more “fuel” for weather — when rain does fall, it could come in floods. So if you were to ask me what Canterbury’s climate will be like in twenty year’s time, I’d have to answer – just like last year.

[Lemon Jelly]

Ice, Mud and Blood

Ice, Mud and Blood: Lessons from Climates Past

In the recently published Ice, Mud and Blood: Lessons from Climates Past British geologist Chris Turney describes how scientists are building up knowledge of the earth’s climate in the past and what it might mean for our future.  He describes attending a showing of The Great Warming Swindle in Australia in 2007. He remarks on the panel discussion which followed when questions were taken from the audience: “…I suddenly realised that many of my companions were either loonies or had been very badly informed. It struck home just how poor a job we’ve done as scientists in communicating our work.”

I’m not sure that the scientists are altogether to blame, but certainly his book makes amends if they are required.

He selects various periods in the past when the climate changed and reports on the current thinking about what caused those changes. Along the way he provides fascinating stories of how the jigsaws have been assembled from a great variety of pieces of scientific investigation.

His first two periods are very distant. One 55 million years ago, the drastic warming over a period of 160,000 years, known as the Peleocene-Eocene Thermal Maximum (PETM), on which Gareth had a recent post. The second from 540 million to 1000 million years ago when it appears that the globe was almost covered in ice during at least three ice ages. Acknowledging that these events happened when the patchwork of continents was different from our time he moves closer to the present in the remainder of the book. He begins a mere 2.5 million years ago when the earth became locked into the bout of ice ages and inter-glacials which continue to the present. His subsequent chapters narrow the focus to episodes within that period: a warm stretch in the last interglacial from 130,000 to 116,000 years ago; the up and down progression from then  towards the Last Glacial Maximum 21,000 years ago; the tumultuous time which marked the end of that last ice age from 21,000 to 11,700 years ago; and what it has meant to the conditions of life for humans to be in the comparatively settled, but by no means uniformly even, climate of recent millenia.

The book carries intrinsic interest in its accounts of how the changes in the past are reconstructed. The evidence gained from ice cores and ocean bed cores is always astonishing in its detail and complexity. The range of information that can be prised from the shells of foraminifera, ancient ocean-dwelling organisms, is extraordinary.  The sheer excitement of discoveries which confirm other discoveries carries a drama which the author is well capable of communicating. Clearly paleoclimate is an absorbing and rewarding area in which to work.

But Turney is much concerned with its lessons for the present. Understandably, considering the likely causes of past changes. Greenhouse gases are always an important part of his picture. For example the PETM was probably triggered by the release of a vast amount of carbon into the ocean and atmosphere over less than 2000 years, likely to have been methane from ocean sources. This was enough to drive a massive warming over 30,000 years or so.  The warm conditions persisted for another 60,000 years.It then took another 70,000 years before temperatures started to drop and return to what they were before, with the oceans playing a different part at this stage in gradually sucking greenhouse gases out of the air. The implications for us today?  If we exhaust the available fossil fuels we will release more carbon than was released at the beginning of the PETM.

Another lesson from the past is the importance of positive feedbacks in the climate system, when the changes that have occurred trigger new and greater changes than the original cause on its own would account for. There is a warning for us that a cascade of unintended consequences can follow from apparently small beginnings. “A little more greenhouse gas in the air does not cause a little change in climate.”

A further lesson is the rapidity with which changes have sometimes happened in the past as tipping points were reached. Abrupt shifts in the climate system are quite possible, as is illustrated, for example, in his account of the sudden reversals which marked the progress towards the Last Glacial Maximum.

Summaries like this unfortunately obscure the pleasure and interest of the book which lies in the wealth of detail it contains and the cheerful clarity with which it is ordered and conveyed to the reader. The underlying earnestness of the author’s concern about the direction we are headed is unmistakable but there is nothing ponderous about his narrative.

Incidentally the author has spent time in New Zealand and describes being able to correct a faulty carbon-dating of wood in the Franz Josef glacier’s Waiho Loop moraine to show that the glacier surge was 13,100 years old and thus contributory evidence of a southern hemisphere cooling at a time when the northern hemisphere was warming. This phenomenon he discusses in the context of his account of the abrupt veerings which marked the end of the last ice age.  His connection with New Zealand includes a directorship in the new young company Carbonscape which is using a world-first microwaving technology to make charcoal.  I expect to post about that soon.