By Jeremy Lovell

LONDON, June 23 (Reuters) - The world's major cities are also among the planet's worst polluters but they have the solutions to most of their problems at their fingertips, a leading environmental consultancy said on Monday.

To make the case more compelling, consultancy McKinsey said that most of the available solutions would save more than they cost so made economic sense while the remainder still made environmental sense despite their higher cost.

"Most of this is dooable and cost effective and worth doing irrespective of climate change," director Jeremy Oppenheim told a conference in London's City Hall to present the findings of the research sponsored by German industrial giant Siemens.

The study focused on London, a leading light in the international C40 grouping of major world cities which have joined forces to cut their contribution to global warming.

The United Nations says cities already account for three-quarters of global energy consumption and produce 80 percent of greenhouse gas emissions.

It is a figure set to grow as the percentage of the world's population living in cities rises from 50 percent now to 60 percent of the total by 2025 and 70 percent by 2050.

The McKinsey study noted that London, measured against four other major cities -- New York, Rome, Stockholm and Tokyo -- on six key environmental factors, performed relatively well on most counts.

Stockholm performed best on per capita carbon emissions from buildings, industry and transport as well as municipal waste and water but was worse than everyone but New York on air pollution.

Overall New York was the worst performer in all but transport and waste where it was overtaken by Rome.

"London's score is probably six out of 10. The question is how to get all the way to the 10," said Oppenheim.

He said using available technologies, and with a bit of inducement and guidance from government locally and nationally, London with a population of some eight million people could cut its carbon dioxide emissions by 44 percent relatively easily.

And the best part was that two-thirds of the measures including better boilers, more efficient appliances, buildings insulation and low energy lighting actually paid for themselves.

This was especially true with crude oil prices having doubled in the past year and with domestic energy prices already up 15 percent this year and forecast to rise by up to 45 percent by December.

He accepted that the 44 percent cut from 1990 levels by 2025 would fall well short of the 60 percent London has set itself as a target but said it was a major step in the right direction.

But Oppenheim warned against fashionable green solutions such as hybrid cars and solar heat and power, all of which were currently expensive when costed against the carbon they cut.

"We need to be thoughtful. It is very easy to get seduced by some headline technologies," he said. "Go for the low cost things first and make this work in terms of the economics."

AlertNet news is provided by