While researching an item for Newsnight on climate change I've found it's been analogies between the G8 process and Iraq that pop up most often.
New research by Oxford scientists suggests global warming will stir up or "activate" African sand dunes
One prominent member of Britain's science glitterati even suggested a wild card tactic for Tony Blair, for those final hours of diplomacy at next week's Gleneagles summit: "He should threaten to pull the troops out... it's that serious."
Somehow, I think that's one ploy that's low on the list of likely exchanges between the two men.
In fact, it seems the critical conversation between the pair has already happened - over dinner in Washington at the beginning of June.
No Iraq payback?
And during that private chat, Tony Blair, it's clear now, failed to persuade the president to come up with the Iraq payback he'd expected.
What he needed, and still needs, to declare "victory" next week, is a G8 deal on climate change with three fundamental components. Without these he'll be stuck in farcical failure. It seems we're headed that way.
It's a simple list. First - the science. He must pull off an agreement that says the science is compelling. This is the cornerstone, without which the rest is meaningless.
Second - concrete moves towards cutting emissions, with a timetable. And third - recognition that urgent action is imperative.
After last-minute talks this weekend, the G8 Sherpas (the top officials charged with hammering out the closest thing to a deal in the run-up to the summit itself) were claiming some success. There was even a strong suggestion that President Bush has recognised "the science".
It seems unlikely that the "special relationship" will deliver a significant deal on climate change
But beware. Now the text heads back to the capitals where it may, or may not, be approved. Once Dick Cheney gets sight of the deal signed off in London this weekend, what comes back to Gleneagles in the president's back pocket may look radically different.
Then there's always the possibility of last-minute fireworks from the French. It would suit Chirac to paint Tony Blair as having sold out to America.
The shutters came down towards the end of last week, as the diplomats focus on the endgame. But the language from both Tony Blair and his environment secretary, Margaret Beckett, was telling.
Gone is the optimistic tone evident in January when Tony Blair wrote in a guest feature for the Economist: "Given the different positions of the G8 nations on this issue, such agreement will be a major advance. But I believe it is achievable and necessary."
Now he's lowering expectations "... we'll wait to see whether we can get an agreement or not."
The UK government seems to be suggesting we should judge the summit a success if it creates an international "dialogue" on climate change. Well, it was always supposed to be about a lot more than talk about climate change - that will be failure, indeed.
Then there's the notion - and surprisingly it is coming from some in the green groups - that Tony Blair has been brave in taking on climate change for this summit, and is genuine in his passion to achieve a real deal. The world may not doubt his passion, but it's delivery that counts.
Earlier in the month there was a suggestion that Tony Blair might do the really brave thing, and stand aside from a weak G8 statement, indicating somehow who we should all blame for failure.
Interestingly, late last week we saw the closest I think we'll get to a last minute public plea from New Labour to president Bush. It came from a bi-partisan international Task Force, put together by the left-leaning Institute for Public Policy Research, and with Stephen Byers and Republican Senator, Olympia Snowe, as its co-founders.
The group sent an open letter to the president. Byers is a well-known friend of Tony Blair, both politically and personally, and the letter speaks in plain terms about what's needed, and who's to blame if it's not achieved.
Fossil fuel burning is one of the biggest sources of CO2 emissions
The letter states: "Your administration's position is critical to the Prime Minister's aspirations for a successful G8 summit. Without your agreement, progress cannot be made on this issue at the G8 and the problem itself cannot be resolved in a timely manner.
"It is our understanding that US officials are opposing key elements of the G8 communiqué and plan of action under consideration relating to the science of climate change, targets and timetables to reduce emissions, finance for low carbon technologies, and new resources to help poor countries adapt to climate change."
It goes on to urge the president to accept that the world is warming, the cause is human and that the consequences are dangerous for all countries - with a plea for urgent action.
Perhaps the prime minister will be brave enough to test the special relationship and stand aside from a weak G8 text, for there's a question hanging in the air now. How special is a special relationship that can't come up with the goods on climate change?
My bet is that by Friday afternoon Tony Blair will still be "shoulder to shoulder" with President Bush - but perhaps at a slight, perturbed, angle.
Susan Watts is Science Editor for the BBC's Newsnight programme - broadcast every weeknight at 1030pm on BBC Two in the UK.