Low-carbon market to treble by 2020 -HSBC

* China forecast growth fastest, to leap-frog U.S.

* Electric vehicles strongest technology

LONDON, Sept 6 (Reuters) - The world's low-carbon energy market is likely to treble by 2020, HSBC analysts forecast on Monday, saying that rising concerns about resource scarcity would support broad consensus on the threat of climate change.

The electric vehicle market would benefit most, growing more than 20 times by 2020 to reach $473 billion, said HSBC's "Sizing the climate economy" report.

Climate policy has faced headwinds including faltering U.N. climate talks to agree a post-2012 successor to the Kyoto Protocol and repeated Senate setbacks to a U.S. climate bill.

But mounting pressure on land, water and energy as a result of growth in emerging economies and world population will add momentum towards a more efficient "climate economy", the bank said.

"A new climate is starting to emerge, driven as much by resource scarcity and industrial innovation as by the raw realities of global warming," the HSBC report said.

A market in low-carbon energy and efficiency technologies will at least double to $1.5 trillion from $740 billion now, but HSBC analysts expected that it would more likely treble to $2.2 trillion, implying global annual market growth of 7-11 percent from 2009-2020.