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A blast from the past (if we knew now what we knew then) Bryan Walker Mar 30

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Peter Sinclair’s recent Climate Denial Crock of the Week is fascinating viewing. He has unearthed a video of a talk given by climate scientist Mike McCracken thirty years ago and asks him in a recent interview what he would say differently today.

Very little has changed. The younger McCracken:

’CO2 probably has been very high in past geologic terms but certainly not in past historic times, and so we’re really doing a giant experiment and the question is what is the outcome going to be?’

The lecture was some years prior to the detailed work of Michael Mann and others on the reconstruction of past temperatures, but the reconstruction used by McCracken, taken from a 1975 report from the US National Academy of Sciences, was not far off our current understanding of recent temperature rises to a level higher than humanity has experienced in at least the last 2000 years.

On fingerprinting the comparative effects of greenhouse gases and other possible factors such as the sun or volcanoes the lecture was very much in line with current understanding. Unlike the effects of solar radiation, the CO2 fingerprint is seen in the cooling of the stratosphere at the same time as the warming of the Earth’s surface. Polar amplification is the other fingerprint the younger McCracken discusses, explaining that the polar regions were warming more rapidly than those around the equator.

On climate sensitivity the lecture spoke of an estimated temperature rise of three, plus or minus one and a half, degrees for a doubling of CO2. This compares very well with the estimate of the 2007 IPCC report as ’…likely to be in the range of 2oC to 4.5 oC with a best estimate of about 3 oC…’

Such an increase McCracken pointed out would be an unprecedented event in terms of human history.

Amplifying feedbacks were well understood. The lecture explained that increased water in the atmosphere as a result of warming will lead to more capture of solar radiation and more trapping of infrared radiation because water, like CO2, traps the outgoing radiation.  And this process will feed back on itself. McCracken also spoke of the effect of the reduction of sea ice in increasing the amount of radiation absorbed by the ocean.

Thirty years on the material presented by the younger McCracken is recognisably basic to our current understanding of climate change. And it’s not that he was advancing some individual insight. Quite the opposite. The older McCracken explains to Peter Sinclair: ’I was trying to represent the view of the broad scientific community.’

In other words the basic scientific evidence for human-caused climate change was clear thirty years ago.  And it was capable of being communicated to government agencies and lay audiences.

Sinclair to McCracken:

’So now it’s thirty years later. We haven’t done a whole lot to address this. Are you surprised?’

McCracken’s reply:

’I’m disappointed. I’m becoming very worried about how fast it’s occurring. What’s been evident in the impact of the changes is that they are occurring faster than we projected they would.  We’re seeing the sea ice disappearing in the Arctic faster than the models are projecting.’

Sinclair’s video illustrates in an arresting way that the science of climate change has been coherent and readily communicable for some decades, and that in the passing of time as research continues there is only confirmation of its basic understandings. The conservatism of its conclusions is underlined by the fact that some of the predicted impacts are occurring much more quickly than was expected. It’s a sad commentary on human society that we remain unable to fully take on board the science and its implications.

The gratification of those such as Lord Lawson who set themselves up in opposition to the science is all the more sickening when one considers how well-founded the scientific picture now is. He was self-congratulatory recently in hailing the success of his Global Warming Policy Foundation (GWPF):

’Before we came into existence there was virtually no debate about global warming policy in the UK. There is now increasingly lively debate and, within the media, only the BBC continues to regard the matter as being definitively settled and not a proper subject for debate. The GWPF has played an important part in achieving this change.”

Good on the BBC, I say, though I would have thought the Guardian would also merit his displeasure.

What to do?  Sinclair’s video ends with McCracken speaking of a colleague who went home very discouraged to his daughter, a fifteen-year-old. She listened to his discouragement and protested. ’You can’t take away my hope.’

McCracken concludes: ’I think we have an obligation to try and see if we can’t find a path…’

 

Prat Watch #3: through the looking glass Gareth Renowden Jan 15

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Sunday morning laughs: over at his Climate Conversation Club, Richard “no warming in NZ” Treadgold fulminates about about the contents1 of a stolen email:

Appalling. It’s a free world, so even the ’leaders’ in climatology are entitled to express the opinion they like. But I draw attention to those who willingly follow these atrocious examples. Such people sabotage science, ransack reason and in the end destroy democracy. Though they imagine they do these things entirely for our own good, they must feel the heat of public opprobrium before they destroy us.

Change one word in that elegant little diatribe, and I would agree one hundred percent. The word? Climatology. Strike that through, and replace it with your word of choice for those would try to persuade us to do nothing.

It really is a looking-glass world on “the other side”: a world where the direction we know as up is called down, black appears to be white, and the laws of physics are puzzling Alice2.

  1. Interestingly, his horror is at the mundane reality of an author promising to put together a first draft of a summary for policymakers, which before publication will go through numerous drafts and which will be fought over line by line by the representatives of every government participating in the IPCC process, before being explicitly approved by them all.
  2. “When I use a word,” Humpty Dumpty said in a rather a scornful tone, “it means just what I choose it to mean — neither more nor less. Source.

Stormy weather: we’re making it worse, and there’s more on the way Gareth Renowden Nov 20

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The IPCC released the summary for policymakers of its Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) in Kampala, Uganda, on Friday (SPM, SREX site, launch presentation slides). The report concludes that globally there has been a significant decrease in cold days and nights and an overall increase in warm days and nights, that it’s likely that “anthropogenic influences” have led to warming of extreme daily minimum and maximum temperatures, and that heavy rainfall events are increasing in many areas. There has also been an increase in extreme coastal high water events.

The report also projects that it is “virtually certain” that increases in the frequency and magnitude of warm daily temperature extremes will continue through this century, and that there will be corresponding decreases in cold extremes. It’s also very likely that heat waves and warm spells will become more frequent and warmer. Heavy rainfall events are also expected to increase, and the proportion of rain falling in those events is likely to increase. There are also likely to be more problems from storm surges and sea level rises, an increase in droughts, and landslides in mountainous regions.

Much of the report’s content will come as little surprise to those who have been following the subject — in common with previous IPCC reports the conclusions are conservative, couched in laboriously exact language, and exclude the most recent work1 — and for me the most interesting parts are the discussions of how extreme weather events interact with human populations to create disasters. In this respect, arguing about whether an event was “caused by” or “made worse by” warming is largely irrelevant to trying to find ways to reduce the impact of current and future extremes.

See also: Jeff Masters has an interesting post going into more detail about the report’s findings, RealClimate considers the report’s discussion of tropical cyclones, plus news reporting from the BBC, Guardian, and Reuters.

Meanwhile, the usual suspects are scrabbling around looking for ways to misrepresent the report’s findings. The most egregious to date comes from Nigel Lawson’s secretly-funded “Global Warming Policy Foundation”, who pick a paragraph out of context and pretend that it shows that…

According to a preliminary report released by the IPCC, there will be no detectable influence of mankind’s influence on the Earth’s weather systems for at least thirty years, and possibly not until the end of this century.

… which is not what the report says at all!

Finally, Green.TV and WeatherUnderground have launched a new twice monthly video on current global extreme weather events. Here’s the first episode:

Definitely one to follow with interest…

  1. Unavoidable, given the way these things are put together.

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