Scientists Call for 80 Percent Drop in U.S. Emissions by 2050 to Avoid Dangerous Warming
September 20, 2007
Ignoring emissions benchmark could result in dangerous climate change for plants and
By 2050, the United States must cut its emissions by at least 80 percent below those
created in the year 2000 if the world is to avoid potentially dangerous impacts of
human-induced climate change, according to a report released today by scientists at
Texas Tech University, the Union of Concerned Scientists (UCS) and Stanford University.
To avoid the most severe effects of climate change, the world must stabilize the concentration
of heat trapping gases in the atmosphere at no more than 450 parts per million, said
Katharine Hayhoe, an associate professor of geosciences at Texas Tech University who
performed the emissions-reduction calculations for the joint report.
This 450-parts-per-million limit aims to avoid a temperature increase exceeding 3.5
degrees Fahrenheit in a global average temperature above pre-industrial levels – a
temperature-change benchmark which Hayhoe and other scientists believe could wreak
increasing havoc on the environment as it is exceeded.
"The study assumes both developing and industrialized countries would have to converge
to equitable per-capita emissions to stabilize the world’s climate," she said. "However,
even with other countries taking aggressive action, since the United States is responsible
for nearly one-quarter of global emissions, it must act now to achieve the deep cuts
in its energy consumption that will be required to meet this target."
The cost of delaying U.S. emission reductions could be high, said Michael D. Mastrandrea,
a research associate at the Woods Institute for the Environment at Stanford University.
"If we wait until 2020 to start emission reductions, we’ll have to cut twice as fast
than if we start in 2010 to meet the same target," Mastrandrea said.
While an 80 percent reduction sounds daunting now, Hayhoe said that the sooner we
start, the greater our chances of successfully meeting that target.
"We’ve got 40 years to radically increase the efficiency of the way we use energy,"
she said. "It’s also time to start considering more extensive ways to harness renewable
energy sources through solar panel arrays and wind farms, for example. It’s worth
it to put in the effort now to reduce our emissions. If we don’t, there will be a
lot more work to do just to adapt to the impacts of climate change in the future."
Stabilizing above this 450-parts-per-million level would likely lead to severe risks
to both natural systems and human welfare, Hayhoe said.
"Sustained warming of this magnitude could, for example, result in the extinction
of many species and increase the threat of extensive melting of the Greenland and
West Antarctic ice sheets," she said.
Policies under consideration in the United States vary in the timing and levels of
emissions cuts they call for and many fail to achieve the minimum pollution cuts needed.
"This report makes clear that the United States must make meaningful cuts in global
warming pollution, and soon, to reduce the risk of severe climate impacts," said Alden
Meyer, director of Strategy and Policy at the Union of Concerned Scientists. "President
Bush should drop his opposition to mandatory emissions limits, and put forward a specific
proposal to aggressively reduce U.S. emissions at the meeting of major emitting countries
that he is hosting next week."
They advised that Congress must also act to help the world avoid the worst consequences
of global warming. Several pieces of legislation have been introduced that set mandatory
reductions, but only two bills would keep U.S. emissions within the overall limits
called for in the UCS study. One measure was introduced by Rep. Henry Waxman (D-Calif.),
and the other by Sens. Bernie Sanders (I-Vt.) and Barbara Boxer (D-Calif.).
To read the report, go to: http://www.ucsusa.org/emissionstarget.html.
CONTACT: Katharine Hayhoe, research associate professor, Department of Geosciences,
Texas Tech University, (806) 392-1900, or firstname.lastname@example.org.