Global carbon-dioxide emissions are rising fast, global temperatures continue to climb at a pace in line with projections, and polar regions are losing ice faster than climate models have projected.
These are some of the recent research findings highlighted by a group of 26 climate scientists in a report released Tuesday dubbed The Copenhagen Diagnosis.
The purpose of the effort, say researchers from eight countries, including the US, is to update policymakers and the public about the pulse of the planet ahead of the climate-treaty negotiations scheduled to begin in the Danish capital Dec. 7. The assessment comes amid a controversy over hacked e-mails of climate scientists – including a few who contributed to this effort – that global warming skeptics are using to question climate science.
The new report's bottom line: If the goal is to try to hold global average temperatures to an increase of 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels, global greenhouse-gas emissions need top out sometime between 2015 and 2020.
To stabilize the climate around that 2-degree goal, the global economy needs to reduce average carbon-dioxide emissions to less than 1 metric ton per person per year by 2050, the group adds. This is equivalent to cutting per capita emissions by 80 to 95 percent below 2000 levels in developed countries by 2050.
The report highlights results from some 200 recent studies in hopes of influencing upcoming climate negotiations in Copenhagen, the researchers say. The benchmarks it sets out for reaching the 2-degree neighborhood aren't significantly different from those the Intergovernmental Panel on Climate Change (IPCC) set out two years ago.
Still, "we felt that we needed to call attention of the delegates to the scientific case for urgent action," says Richard Somerville, professor emeritus at the Scripps Institution of Oceanography at the University of California, San Diego, a lead author of the IPCC's 2007 volume on climate science, and a contributor to this report. "If you want to stabilize the climate at a reasonable amount of global warming, then you cannot delay indefinitely."
The group's effort is independent of the UN-sponsored IPCC, which publishes reports on global warming roughly every five years, the last one in 2007. The Copenhagen Diagnosis aims to fill the gap on research since mid-2006 – the deadline for the 2007 IPCC report.
"There's new science and there's also three more years of data. In many instance, the observations show that climate change has accelerated," Dr. Somerville said in a briefing Tuesday on the report.
The report is being released against the backdrop of the more than 1,000 e-mails pilfered from the Climatic Research Unit of the UK's University of East Anglia. Many of the e-mails are mundane. Some, however, give the appearance of scientists – including some involved in the Copenhagen Diagnosis – introducing fudge factors in presenting results. Others scoff at their colleagues' work and at critics outside the climate community who question approaches used by the e-mails' authors to process or interpret data. And they sometimes reveal a strong undercurrent of angst over what skeptics may make of their results.
The e-mails have generated a outcry among conservative commentators over the credibility of climate science. Many climate researchers say the e-mails do nothing to undercut the science behind global warming, which has been building for more than 100 years.
What the controversy really shows is a desire on all sides to maintain a myth about how science is conducted, says Daniel Sarewitz, co-director of Arizona State University's Consortium for Science, Policy, and Outcomes.
"Both sides want to maintain this idea that science is this pure thing, this source of clarity, exactness, and truth. Of course, it isn't," he says. "It's a human endeavor, a social endeavor. The people who do it are people full of imperfections."
None of that undercuts the weight of evidence on global warming, he adds.
Among the climate-related observations the Copenhagen Diagnosis makes:
• Carbon-dioxide emissions: In 2008, emissions were almost 40 percent above 1990 levels. Even if emissions peaked today, by 2020 temperatures would stand a 25 percent chance of exceeding 2 degrees C – even if emissions fell to zero in 2030.
• Ice caps at both poles are melting faster than models have projected. Moreover, a study published this week and not part of the Copenhagen Diagnosis suggests that the loss of ice is now extending to the East Antarctic Ice Sheet, not just the west Antarctic Ice Sheet, which has long been a focus of concern. In the Arctic, the average melt-back of summer sea ice was 40 percent larger for the 2007 to 2009 period than predicted in 2007's IPCC reports.
• Rates of sea-level rise from thermal expansion and melting land-based ice – about 3.4 millimeters a year during the last 15 years – are about 80 percent above those projected in IPCC.
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