HKU Climate Workshop

Back from Day 2 (of 2) of the workshop at the University of Hong Kong – and, for me, a marked improvement on yesterday afternoon, when I thought we mostly got lost in the models.

Some good info today; inc on actual impacts – such as on ecosystems; also guff from the past, and info on changing climate in Hong Kong.

Day 1 afternoon (11 December): THE SCIENCE OF CLIMATE CHANGE

Normally, I might expect an event involving words like "hot" and "models" to be highly entertaining.
But oh dearie me – too much of the first afternoon was barely preferable to being at the dentist's.

Though there was, I thought, one standout lecture – on whether there's a link between global warming and typhoon intensity (short answer: No).

I'd missed the first morning – which was mostly on political gubbins and climate change, even with suggestions HK might accept some responsibility for its role, and Pearl River Delta industries etc might clean up their acts to help the planet (and themselves). Yeah, right, and flying pigs will play a role too.

An Anomalous Lecture: Inter-decadal variability of summer precipitation in China 


by Yihui Ding, Professor, China Meteorological Administration, Beijing, China

The afternoon's first talk looked at variations in summer rains in three regions of China: south, Yangtze (middle) and northeast.

Prof Ding showed there's a trend towards wetter summers in the south, and drier summers in the northeast – where there have lately been several years of drought. They'd checked this against a few factors, found that there's correlation with snowfall in Tibetan plataau the previous winter and early spring, and low rain in northeast in summer.

Prof Ding said this is because the snow cover leading to the plateau becoming cooler, and so reducing the contrast between land heat and sea heat – which drives the monsoon; weaker monsoon barely makes it to ne China, so most rain falls in the south. When question time came, I asked (roughly), "But surely, if Tibet is colder, the contrast with the warm, tropical ocean [from which sw monsoon winds originate] will be higher, not lower?" Prof Ding said he'd explain later; and did so in coffee break.

Turned out he didn't mean difference in temperatures, but in heating – "Q1". With less snow in winter, there's more heating of Tibetan plateau, more contrast between land and sea in summer (with "memory" of the snowfall lasting 5-6 months), and so a stronger monsoon, reaching ne China.
So, I asked, what of cause of this snowfall variation? "That's another question," said the prof.
Also, I clarified something he'd mentioned during the lecture: he hadn't looked at global warming as possible reason underlying rainfall pattern changes. Hence, to me, the whole lecture was an anomaly given topic of this workshop.

He Blinded Me with Science:Impact of Climate Change on the stream flow in headwater of the Yellow River Basin

Zongxue Xu, Professor, Beijing Normal University, Beijing, China

The next lecture had a promising title. Yet, mostly focused on choosing and testing models for gauging climate change in Yellow River Basin. Lots of technical guff, like their adopting a SWAT analysis (soil, water, air, transpiration?). This befuddled me – reminding me of some of worst physical chemistry papers and talks I saw and heard during my postgrad years, when it seemed to me the more the obfuscation with jargon etc, the worse the science and the less the researchers actually understood.

Worryingly, I thought, saw forecasts from models such as, in 20 years (or whatever) temp will be 3.24C higher – such precision is ridiculous, suggesting results came from computer to presentation, without much use of brain.

We saw there was trend towards lower rainfall in river basin. Forecast of higher rain but lower flow; also higher temeratures. Someone asked why the latter: answer from Prof Xu was that may be more rain, but with temperatures higher, would also be more evaporation. A nice, simple answer: now why wasn't the lecture informative and easy to understand like this?

Maybe Warming, Maybe Not: ENSO and the South China Sea summer monsoon

Wen Zhou, City University of Hong Kong

Zhou Wen at least mentioned global warming and said she believed it's a major problem, could threaten economy. Yet in talk, it didn't feature too much. Instead, we learned that with El Nino/La Nina, and El Nino/.La Nina like phases of Pacific Decade Oscillation, get shifts in position and strength of a high pressure cell over the western Pacific. When this high is strong, and extends to S China Sea, it's harder for the westerlies (or southwesterlies?) of the summer monsoon to push to China – so, get later summer monsoon.

Has been bit of a trend towards earlier summer monsoons of late; just maybe, linked to global warming.

Sea temperature's not so crucial: Global warming and typhoon intensity

Johnny Chan, Professor, City University of Hong Kong, HKSAR

Though talks so far this aft had been dull, without too much info about global warming (err, Hello, this is a Global Warming Workshop folks!), I had some hopes for this talk: had interviewed Johnny Chan years ago re typhoons and warming; he told me that maybe not a strong connection, as can get shear that destroys typhoons. Lately, I've seen more re hurricane intensity and warming seas – with studies showing there is strong correlation; so, I was interested to see what Prof Chan would say. Proved very interesting indeed, I thought.

Prof Chan told us a little about what typhoons/hurricanes are; then briefly showed results from a couple of studies published recently, showing that numbers of strong tropical cyclones have increased as sea surface temperatures have increased. Published in Nature and Science, so seemed authoritative.

Yet, Prof Chan showed, the correlations weren't really good for typhoons. Looking at 15-year periods, there had been at least 105 Cat 4 or 5 (on Saffir-Simpson Scale) typhoons from 1960-1974, 75 from 1975-1989, and 115 from 1990-2004.

One reason extra heating of the Pacific isn't causing more typhoons is that the atmosphere is also warming: so, "no extra buoyancy" – which seems to mean no extra boost to rising air as storms form as strengthen.

But, Chan had found there were factors correlating with occurrences of major typhoons. One major change was to movements in air in upper and lower atmosphere over the Pacific: could converge, or diverge. With air converging low, and diverging high over eastern Pacific, get more strong typhoons: the converging air over the sea can rise, and helped that the upper air is diverging: plus when storms form over the east, they have more distance to strengthen as they then move westwards (further before they make landfall).

During questions, I asked if similar work done elsewhere. Prof Chan said that Atlantic is unusual, as "marginal" for hurricane formation: sea surface temps only just high enough, so a 1C rise in sea temperature there can make a big difference. In other basins where tropical cyclones form, sea temps are high, so temperature variations have low influence on numbers of strong storms.

There is, though, apparent long-term rising trend in numbers of strong typhoons (but a small rise), and may be this is due to atmospheric circulation changes linked to warming.

Those Blasted Models Again: A future climate scenario of regional changes in extreme climate events over China using PRECIS

Yong Zhang, Chinese Academy of Sciences, Beijing, China

Oh dear, oh dear; next up we  were back to the models with a vengeance. Zhang focused on choosing models for climate change modelling, presenting what seemed infinite tests of them, along with lots of jargon like "Bimodal SDII", plus RCM, GCM, PDQ and PMT (well, ok, not the latter two). I wanted to have a Brando like figure loom into the room, saying "The horror, the horror."

I'm not sure many people cared when we learned the models forecast that by late this century the temperature in northwest and northeast China could be 5C higher than at present; we didn't get any decent explanations, inc why these areas should experience such extreme changes, or S China less changed (I guess oceanic influence; already figured ne China changing pretty fast, as little influence from oceans).

Help – I can't take it!: Dynamical downscaling climate change: its necessity and challenge

Ji Chen, The University of Hong Kong, HKSAR

Perhaps the fact the title contained a hideous word – downscaling – should have given the diehard members of the audience a clue that it was time to leave before this last lecture. But, like rabbits caught in a headlight, the diehards inc me somehow sat on after the scenario of the models.
And after all, the focus was supposed to be on models re climate change in and near Hong Kong: what does the future hold in store for us? Which should be interesting, right?

But, Dr Chen again focused on darn models, showing us about modelling on scale sufficient to see Sichuan Basin in China. Showed model tested with weather results from April to July 1994.

Aaargh! – I had to go; better things to do with my life.


Day 2 of Climate Change Workshop at Hong Kong University 

12 December 2006



More than hot water: climate change and the oceans [by video-conferencing]

Lara Hansen, Senior Scientist, Climate Change, WWF USA

I arrived as this talk was underway – via the Internet: Lara Hansen's image on one screen, and slides from presentation (laptop) on main screen.

Proved very interesting – but helped set the tone for today, which gave very gloomy outlook for even next few decades. I'd known things were bad, having read lots of articles etc, but having focused day like this wasn't real cheery.

Changes are underway in the oceans: warming is a problem. Also, as more CO2 in atmosphere, more also dissolves in the oceans, making them more acidic.

WWF has some ideas for mitigation, including finding places where warming is having less impact and striving to protect these from various other problems (overfishing, pollution ….). But even with such measures, we'll see massive problems: need to slow greenhouse gas emissions.

Climate change – the Hong Kong perspective

W.M. Leung, Hong Kong Observatory, HKSAR

Next up, Mr Leung of HK Obs presented an array of information showing significant changes in Hong Kong – where, I remember, the Obs had for some time argued that rising temps were due to "heat island" effects: developing urban areas storing heat, leading to apparent rise in global temperatures. Not so any more: global warming looking well underway here.

Weather measurements here go back some 120 years. Records since then show temp rise averaging 1.2C per 100 years. But, temp rise has accelerated: 1.7C per 100yrs since 1947, and averaging 3.7C per 100 years from 1989-2005 (though a short period for calculating such an average). Of all the years with highest mean temperatures, eight were after 1990: the only other two, in 1966 and 1987, were in El Nino years.

It appears urban areas are indeed warming faster than rural – but monitoring at Tai Kwu Ling and Lau Fau Shan since 1989 also shows rise in temperatures.

Oddly, annual mean daily range of temperatures has been falling: daytime and nighttime temps are becoming more similar; around 60 years ago, difference averaging 5-6C, but now around 4C. This is evidently due to combination of increasing cloud cover, and decreasing visibility ("dust" said Leung; the rest of us normally call it smogg, aka filthy crappy air pollution). There's less solar radiation during day; at night, "refuses to cool".

Summers are getting more uncomfortable – as temps rise, also as wind speeds fall in urban areas because of buildings. Even more discomfort is forecast in summer, with significant rise in number of hot nights likely.

Rainfall has been increasing by 1% per decade. More very wet years are forecast; but also, a rise in number of very dry years.

Climatologists should work with people from other disciplines, said Mr Leung, to work on mitigation and adaptive measures, as well as warnings and protection.

Impacts of climate change on agriculture: environment and production in Japan and East Asia

Masayuki Yokozawa National Institute for Agro-Environmental Sciences, Japan

A very dull talk, I'm afraid; took a while talking about models (yes, more models! – and not a catwalk in sight). There were statistical and process based models; and in the end, forecast of higher rice yields in north Japan, lower in south, tho higher temps could be mitigated by earlier planting.

Climate change and freshwater biodiversity

David Dudgeon, Professor, The University of Hong Kong, HKSAR

Prof Dudgeon was a great contrast to the previous chap: animated and passionate; covering a wide range with some interesting and very alarming predictions. I'd been rather expecting to here about problems in our tiddly local streams: did so, but also learned of mighty rivers across Asia – including the Mekong, which holds the highest fish diversity of any river; indeed, 6 of Asia's rivers are among the world's top 10 rivers for fish species. The Pearl River ranks 31, with 106 fish species.

Already, we are seeing worrying trends in freshwater life as temperatures rise: such as extinctions of several frog species, northward movements of most UK dragonflies. There have been very few such studies in Asia – and Prof D quoted Rumsfeld about known unknowns, and unknown unknowns, and unknowns we don't even know that we don't know about that are unknown … or somesuch.

Aquatic creatures face severe problems as temperatures rise: not just as temps exceed their tolerances, or allow competitors to move in, but also as oxygen becomes less soluble. Even moving uphill – 500 metres for every 3C rise in temp – may not work, as oxygen partial pressure in the atmosphere falls with altitude.

Life in high altitude rivers, said the prof, will be the "canaries in the coal mine of freshwater biodiversity". In Hong Kong, we could lose montane species such as the Giant Spiny Frog and Hong Kong Newt.

But wait – there's more! Humans will respond to warming, including by building more dams to control water flows; these reduce river flows, and warm water before a portion is permitted to continue downriver.

There are various questions needing answering. Including to see if we can preserve biodiversity even in highly regulated rivers.

During question time, someone asked if there was any hope. "If we ignore biodiversity concerns, there probably is no hope," said Prof Dudgeon.


Climate change and corals in a marginal environment

James True, The University of Hong Kong, HKSAR

On to James True, who told us of being a new dad (all together now, aaahhh, bless  im); but I'm not sure that alone accounted for rather deadpan delivery. Not that this is the Punchline Comedy Club, as the last talk made clear.

We heard of problems with corals generally, and in Hong Kong – where weakening monsoons may reduce the currents that buffer temperatures, leading to waters becoming hotter in summer, cooler in winter.

As mentioned by Lara Hanson, increasing CO2 in oceans is increasing acidity, making it harder to form calcium skeletons. Doc True said that at during one mass extinction (Paleocene), things got so tough for corals that there is a significant gap in their fossil record.

With more rain, can get more hypoxic zones, as freshwater lenses overly saltwater, which loses oxygen: there have been a couple of such events in Hong Kong in recent years, killing corals and other marine life.

Lifting the lid on the tropics: climate change and terrestrial biodiversity in Hong Kong

Richard Corlett, The University of Hong Kong, HKSAR



Climate change and social stability during Chinese history 

David Zhang, The University of Hong Kong, HKSAR


Quaternary climate change: Lessons from the past, clues for the future

Adam Switzer, The University of Hong Kong, HKSAR


Living in a Warmer World – the workshop's page on HKU website – has links where you can download pdf files with presentations. 

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