Another four-week break in Parliamentary sittings and some of our politicians take wing again. Kevin Rudd is off to the G20 of course, and Penny Wong is going to Ban Ki-Moon’s UN climate change summit, which is intended “to focus Heads of State and Government on the need for urgent action, and to mobilize the highest level political will needed to reach a fair, effective and scientifically ambitious global climate deal” at Copenhagen.

Good luck with that.

Malcolm Turnbull is also off, making a “private” visit to the UK for a few days to meet his Conservative counterparts, his long-ago humiliation of the Thatcher Government presumably forgotten. He is leaving Julie Bishop in charge, which could be fun, especially if acting Prime Minister Gillard decides to make trouble.

The most unexpected departure is that of Andrew Robb, whose temporary retirement to the backbench while he gets on top of a depressive illness came as a shock on the weekend.

Make no mistake, that would have been a tough call for Robb to make. He is a party man through and through, one of Turnbull’s strongest supporters (despite disappointment that he missed out on the shadow Treasurership) and has an exemplary work ethic. He has also steeped himself in the climate change issue since becoming Turnbull’s emissions trading spokesman last year. But he has made clear he thought he wasn’t able to serve his party as well as he wanted.

It was the right call both personally and professionally, as was the decision to reveal it. Recent weeks must truly have been, as he suggested to Laurie Oakes, hellish for him. The last thing you want to do in that state is constantly interact with people, which is the default setting for any politician. Even simple meetings with close colleagues can seem like nightmarish ordeals that you’ll do anything to avoid, let alone the constant cycle of media appearances and portfolio engagements required of a shadow minister.

The Liberals will miss him, badly. Robb has been the ballast of the Opposition. With Nelson and Costello leaving, Tony Abbott flapping his mouth off on most anything that takes his fancy, Julie Bishop utterly out of her depth, Joe Hockey speaking first and engaging his brain second, Barnaby Joyce becoming de facto leader of the Nationals and Malcolm Turnbull himself going off the deep end over the faked email affair, Robb has remained rock solid throughout.

Time has shown that he should have been made shadow Treasurer rather than Hockey. Instead, for months he has been trying to navigate the near impossible course of securing enough Coalition support for an ETS to get this killer issue off the political agenda as soon as possible. Unlike Greg Hunt, regarded as a bomb-throwing greenie amongst some his more conservative colleagues, Robb hails from the more sceptical end of the spectrum on climate change, meaning his endorsement of the Turnbull position on the CPRS carries weight with the flatearthers and those otherwise inclined to knock it back outright.

In his stead comes Ian Macfarlane, an outright climate sceptic, card-carrying member of the Greenhouse Mafia and former Industries and Resources Minister. Maybe, like Robb, Macfarlane understands the political need for the Opposition to simply get emissions trading off the agenda; maybe, like Robb, Macfarlane’s endorsement of a negotiating position with Labor will carry some of the more hostile backbenchers over into supporting, or at least not opposing, a deal.

One way or another, Macfarlane’s status as a former member of the “dirty dozen” will alter the dynamics of the Senate negotiations significantly.

The Liberals, and anyone who wants to see the CPRS make it into legislation this year, will fervently pray that Robb makes a speedy and complete recovery. For that matter, so will anyone who has dealt with him and knows the contribution he has made to keeping this Opposition together.