Saturday, February 03, 2007

Global heating & IPPC 4

I’ve been trying to get my head around the Intergovernment Panel on Climate Change (IPCC) report ‘Climate Change 2007: The Physical Science Basis – Summary for Policymakers’ document. Among the better commentaries I saw were the New York Times and a good summary in The Australian. Warming is definitely occurring and, with probability = 0.9, it is anthropogenic. The warming will continue for centuries but its worst effects can be dealt with by reducing emissions – though the IPCC are not concerned here with policy.

Labor’s Kevin Rudd made yet another of his ‘fork in the road’ pronouncements and engaged in petty politics. Give us a break Kevvie. I find it hard to take the Labor Party seriously on the climate change problem given that they rule out the nuclear option. Howard returned Rudd’s fire by pointing out this obvious anomaly.

In the local blogosphere Tim Lambert at Deltoid seemed more interested in covering up a forecasting error he made than in discussing the report. John Quiggin was concerned with oil industry attempt to fund research that criticized the report. Andrew Norton makes a pretty good post on the topic – he criticizes John’s critique as ‘McCarthyism’.

But in all these commentaries there is not actually a lot on the substance of the report itself. It is an interesting document and rather complex. Some risks such as melting of the polar icecaps are downplayed. Patrick Michaels at the Cato Institute draws optimistic conclusions from the report's empirical findings. Our understanding of global warming will evolve and policy responses need to be a rolling plan.

Summary effects (based on Reuters):

1. Temperature rises. The range of possible temperature increases this century has increased to 1.1-6.4 degrees Celsius in this report from 1.8-5.4 degrees in the IPCC's previous report in 2001. Note the lower minimum anticipated increase.

The projected temperature increase to 2100 has risen because it is now considered that global warming will make nature less able to absorb carbon dioxide.

This alone could raise estimates by more than 1 degree this century.

For the first time the IPCC gives ‘best estimates’, giving greater certainty than predictions in earlier reports. The best estimates range is for a 1.8-4.0 degrees temperature rise by 2100. Only one of the six scenarios analysed generated a best estimate of less than 2 degrees warming this century (1.8 degrees).

The report does not include the possible warming impact of methane, a potent greenhouse gas, escaping from melting permafrost – there isn’t enough evidence.

It is ‘very likely’ that extremes such as heatwaves and heavy rains will become more frequent.
Warming is expected to be greatest over land and at high northern latitudes and least over the Southern Ocean and North Atlantic.

2. Sea level rises. The report cites 6 models with core projections of sea level rises ranging from 18-59 cm this century. That is a narrower and lower band than the 9-88 cm gain forecast in 2001. Note the lower anticipated maximum increase - this is the subject of Lambert dispute mentioned above.

If the Greenland ice sheet melts in the future proportionally to the temperature rises then sea levels would rise by up to 79 cm, not 59 cm, this century. Some models show an ice-free Arctic in summer by 2100 (meaning that sea ice floating in the water disappears, but not ice resting on Greenland).

If the Greenland ice sheet melted completely that would lead to a 7 metre sea level rise but this would occur only with a sustained temperature increase over 3 degrees for millennia Jurgen Willebrand, the report's author with special expertise in ocean effects, told Reuters. Thus trends are serious but somewhat less serious than earlier apocolyptic views.

3. Ocean currents. The report predicts a gradual slow-down this century in ocean currents such as the one which carries warm water to north-west Europe. Again less drama than in soime earlier forecasts.

‘It's very unlikely there will be an abrupt breakdown in ocean currents in the 21st century,’ said Willebrand.

‘Most models predict a gradual slowdown this century but you shouldn't expect a fall in temperatures (in Europe), because global warming is happening.’

4. Hurricanes. The report says it is ‘more likely than not’ that a trend of increasing intense tropical cyclones and hurricanes has a human cause. It expects such tropical cyclones to become more intense in the future’.

There may not be an increase in number, there may be a re-distribution to more intense events - which is what has been observed in the Atlantic since 1970’ lead author Stott told Reuters.

I’ll try to add further good posts if I discover them and welcome reader's advice.


conrad said...

I don't think Krudd bad, Howard good, is a fair assessment of the response. I think it should be Krudd bad, Howard bad -- Howard should be offering all potential options, not just being fixated on pushing nuclear, and Krudd shouldn't be apriori against nuclear.

Gorilla Bananas said...

If the jungle gets too hot, I'll get some baboons to fan me with palm leaves.

Anonymous said...

Harry, you can't have been looking too hard for substantive discussion of the issues if you read my post on the AEI and ignored the immediately preceding post entitled IPCC out today which focused on substantive issues raised by the IPCC report, and generated a lengthy discussion.

I've replied to Andrew Norton on his blog.


hc said...

John, I read your report on the AEI. I accept the consensus view that global warming is a significant policy issue and reject the views of the group you refer to as the 'denialists'. However I stick to the view that the latter group can legitimately contract people to present alternative viewpoints. The intellectual marketplace will sort that one out. I was aware of the AEI discussion - indeed I was an early participant.

On the earlier discussion you did indeed present some facts. I discounted it a bit since your post was made before the report was released. As you will see in my comments the report seems to me to reduce the range of possible outcomes - with respect to sea level rises in particular.

Your argument did make a good point about extreme temperature events - costs associated with these are very large and, as you correctly pointed out, these should not be ignored.

I did only do a quick flip around the blogs and was surprised that many totally ignored the report.

Fuzzflash said...

H, here's how it works: a bit bloody bleak innit?

"Published on Friday, February 2, 2007 by the Guardian / UK

Scientists Offered Cash to Dispute Climate Study
by Ian Sample

Scientists and economists have been offered $10,000 each by a lobby group funded by one of the world's largest oil companies to undermine a major climate change report due to be published today.
Letters sent by the American Enterprise Institute (AEI), an ExxonMobil-funded thinktank with close links to the Bush administration, offered the payments for articles that emphasise the shortcomings of a report from the UN's Intergovernmental Panel on Climate Change (IPCC).
Travel expenses and additional payments were also offered." cont.

Real big spenders these big carbon boys. Wonder if 10 large is sufficient to seriously tempt the average struggling economist. Apparantly the red necked crake is getting pretty thin on the wing. Have you noticed many avian extinctions since you have been twitching?

hc said...

Fuzzflash, If it was new work the payment is not large so it probably relates to representing earlier conclusions. Still then not large.

The Red-necked crake is widespread in north east Queensland and Indonesia. There has only ever been one avian extinction on continental Australia, the Paradise parrot. That's interesting info however since it conceals the fact that many species have experienced dramatic reductions in range.

Good subject for a future post.

James Dudek said...

Can someone please teach those polar bears to swim?

hc said...

James, the photo is possibly sensationalisat - but what a great photo.

James Dudek said...

Just like the WMD threat in Iraq was "possibly" sensationalized.

The oceans rise by 2 feet over decades, some species hunting areas decline causing a dip in their numbers....BFD. These types of changes have been happening for centuries with or without global warming.

The media is doing an absolute hatchet job on the truth of the consequences of global warming with these catastrophic doomsday scenarios.

What absolute nonsense.

More people have died and more species were wiped out from the Tsunami in 2004 than from global warming. And I'd bet that remains the case for the next 10 to 20 years at least.

tim said...

You accuse me of covering up a forecasting error I made. Please explain what error it is you allege I made, and why you ignored my post on the release of the new report.

Anonymous said...


59cm is not the same (or similar) to 88cm - irrespective of the tale about the new figure ignoring ice melt which IPCC found hard to pin down and quantify. Yes it could be bigger!

But more basically I am uninterested in whether you made an error or not or indeed in these types of squabbles. I was trying to understand a report that I found complex and hence searched some blogs and websites.

The long (and apparently ongoing) story about your conflict with Tim Blair et al wasn't of interest to me, I was only interested in the IPCC report.


tim said...

I did not say that 59 was the same as 88. If you were uniinterested in the dispute, why did you take a cheap shot at me and ignore my post on the new report?

Anonymous said...

Tim, My original comment was not intended to be hostile though it has evoked that response. I'm honoured you value my views so highly but assure you that you got the intent wrong.

I answered your questions re the error in forecasting and rationale for original remarks.


tim said...

Harry, you falsely accused me of dishonest conduct (covering up a forecasting error). Could you please explain how your accusation was not "hostile"

hc said...

Tim, Rather than admit you got it wrong with the forecast of sea level rise you came up with an explanation that in my view is unsound. The explanation was essentially 'It could be bigger'. I did not 'falsely accuse' you of 'dishonesty' (nor did I truthfully accuse you of dishonesty) and I was not being hostile.

Moreover, I explained this clearly in my first response to your query. I also made it clear that I thought your mistake was a non-issue that I was not interested in pursuing. I was only interested in the substance of the IPCC Report. That remains my view.

tim said...

"cover up" implies deceit. I didn't make any forecast, let alone an incorrect one. I didn't say that 59cm was the same as 88cm.

I did say the sea level rise estimates in the new report were similar to those in the old report. Kevin Trenberth, one of the lead authors of the report described them like this: "The numbers in this report are actually very similar to the previous report, however they are reported in a somewhat different way"

I guess you think he's part of the cover up conspiracy.

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