Hoping to address that, the reshuffle names Malcolm Turnbull as the new minister for the renamed Department of Environment and Water Resources.
Howard told reporters in Canberra after unveiling the reshuffle: "The next election will be a very tough one for the government that is something that I have acknowledged for a long time and I acknowledge it again.
"There is no doubt that issues relating to climate change and water are going to be very important."
There was also change in the immigration portfolio – another issue likely to feature prominently in the election – with Kevin Andrews, the employment minister, replacing Senator Amanda Vanstone.
The changes come as Howard's coalition looks to take on an increasingly popular opposition Labour party, led by Kevin Rudd.
Rudd recently made changes to his own environment team, naming Peter Garrett, the former lead singer of Midnight Oil turned politician, as Labour's environment spokesman.
Tuesday's reshuffle comes as new polls show Howard's popularity slipping against the Labour leader and falling support for Australia's involvement in the Iraq war.
A random phone poll of 1,152 voters published in The Australian newspaper on Tuesday showed that Howard's approval rating had slipped to 46 per cent, while Rudd's rose to 56 per cent.
The poll also found that 62 per cent of those polled either strongly or partly opposed the prime minister's handling of Iraq.
Australia has 1,300 troops stationed in the Middle East and Howard has rejected calls to set a timetable for their withdrawal.
Tuesday's reshuffle, he suggested, did not signal any change in that policy.
"When I took the decision back in 2003 to become part of the coalition the polls were about the same,'' Howard said.
"I believed it was right then and I still believe the decision we took was right."