Barack Obama: I want emissions at 1990 level

WASHINGTON — Calling climate change an urgent challenge, President-elect Barack Obama promised Tuesday that Washington would take a leading role in combating it in the United States and throughout the world.

‘‘My presidency will mark a new chapter in America’s leadership on climate change,’’ Obama said in a video message to governors and others attending a Los Angeles summit on the issue.

In the roughly four-minute message, Obama reiterated his support for a cap-and-trade system approach to cutting green house gases. He would establish annual targets to reduce emissions to their 1990 levels by 2020 and reduce them another 80 percent by 2050. Obama also promoted anew his proposal to invest $15 billion each year to support private sector efforts toward clean energy.

President Bush has been criticized for failing to do enough to combat climate change and Obama has promised quick action to address the issue. Leaders in the Democratic-controlled Congress have indicated that they aren’t likely to act until 2010 on a bill to limit the heat-trapping gases blamed for global warming. But Obama could begin to tackle global warming without Congress through administrative actions.

In his remarks, Obama criticized Washington for failing to lead on the issue in the past.

Said Obama: ‘‘I promise you this: When I am president, any governor who’s willing to promote clean energy will have a partner in the White House. Any company that’s willing to invest in clean energy will have an ally in Washington. And any nation that’s willing to join the cause of combating climate change will have an ally in the United States of America.’’

Scientists, environmentalists and government and industry officials were attending the two-day Governors’ Global Climate Summit in Los Angeles, held ahead of a U.N. gathering in Poland next month.

Obama said he won’t attend that conference but that he has asked Congress members who will to report back to him. ‘‘Once I take office, you can be sure that the United States will once again engage vigorously in these negotiations, and help lead the world toward a new era of global cooperation on climate change,’’ Obama said.