Shipping, airlines and road transport need to clean up their emissions and help drive governments toward policies to fight global warming, according to a top UN official.
The transport sector accounts for more than 20 per cent of mankind's carbon dioxide emissions, and further growth is likely given rising demand for cars, goods and travel in developing countries.
Transport will also be a key part of a broader UN climate pact about 190 nations will try to agree on at the end of the year during talks on a successor to the Kyoto Protocol.
"There can be no doubt that the transport sector will come under intense pressure and needs to dramatically change direction," Yvo de Boer, head of the UN Climate Change Secretariat, told a global transport ministerial gathering in Tokyo on Thursday.
"Transport industries should no longer find themselves in the position of beggars for billions of taxpayer's dollars. Instead, they need to come back into pole position of drivers of economic growth, through the production of smart and efficient cars, trains, ships and planes," he said.
"The transport sector is at a juncture," he said, adding the key question was how the industry could influence regulators to back greener policies "rather than digging itself deeper into a hole" as airlines, shippers and car makers battled shrinking revenue because of the global financial crisis.
China, believed to be now the world's top greenhouse gas polluter, pulled out at the last minute, insisting rich nations lead the charge in emissions cuts, a Japanese transport ministry official told reporters.
Mr De Boer said he expected only a broad political message to come out of the talks on how the transport sector was tackling climate change.
"It's early in the debate for a number of countries to commit to a statement," he added.
Airlines contribute about two per cent of global CO2 emissions by mankind and are expected to keep rising because of growing demand for air travel, despite aircraft becoming more efficient. Shipping's share of global emissions is about three per cent, equivalent to total industrial emissions from Germany, but the industry is trying to trim fuel use through better hull designs, cleaner fuels and simple measures such as installing more efficient lighting onboard.
In addition, separate meetings under a UN body aiming to report to the climate meeting at the end of the year in Copenhagen will look into greater fuel efficiency and emissions trading for shipping.