Leading climate scientists on the Intergovernmental Panel on Climate Change (IPCC), a United Nations body, has confirmed its earlier conclusions that global warming is, in fact, occurring, and this time are affirming that there is over 95 percent probability that man is at fault.
The panel of experts has released a report that states: “Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes.”
The report says that it is “extremely likely” that human emissions are the “dominant cause of the observed warming since the mid-20th century.” This is a first; in earlier reports, the term “extremely likely” – which refers to a probability of over 95 percent – had never been used. In 1995, a report only suggested a correlation between rising temperatures and human activity; in 2001, that relationship was deemed “likely” – representative of a 66 percent probability – and the last report, in 2007, found a “very likely” (90 percent) probability that human activity was the main cause of the rising temperatures.
Scientists are now almost all positive that the world can expect to see hotter days and nights over the years. As the new IPCC report notes, “Each of the last three decades has been significantly warmer than all preceding decades since 1850.” Scientists are also 99 percent sure that sea-level rise has accelerated over the last two centuries, and will continue to rise in the 21st century.
Among other findings, the report describes the decade ending in 2010 as the warmest on record. IPCC co-chairman Thomas Stocker warns that heatwaves are “very likely” to occur more frequently and last longer, with the added risks of floods and droughts.
In just the past 15 years, the report finds, the planet has warmed at a rate of 0.05 degrees Celsius per decade, but the rate is significantly slower than the rate calculated since 1951, which finds a 0.12 degrees Celsius rise per decade.
The findings have heated up the already controversial debate over climate change.
Secretary of State John Kerry welcomed the report, labeling it as “yet another wakeup call.” He added that “if ever there were an issue that demanded greater cooperation, partnership, and committed diplomacy,” this would be it.
However, critics have already pointed out that the report must be closely scrutinized, after the 2007 report included an error that “exaggerated the rate of melting of Himalayan glaciers.” Skeptics also point out that the IPCC does not address in depth the slower rate of rising temperatures since 1998. The IPCC attributes the slowing rate to “substantial natural variations that masked a long-term warming trend” — an explanation that skeptics are not satisfied with.
Yet, even a slower rate of temperature rise should be cause for concern. According to The Economist, a slowing rate of warming temperatures only means that “Earth might hence have a little more time to adjust to a changing climate.”
Despite the slower rate of warmth, the report maintains that “many aspects of climate change will persist for centuries even if concentrations of greenhouse gases are stabilized. This represents a multicentury commitment created by human activities today.”
Stocker also made it clear that the effects of global warming are here to stay, adding, “As a result of our past, present, and expected future emissions of carbon dioxide, we are committed to climate change and effects will persist for many centuries even if emissions of carbon dioxide stop.”
The UN’s top climate official, Christiana Figueres, urged governments to view the report as an “alarm clock moment for the world” and “step up immediate climate action and craft an agreement in 2015 that helps to scale up and speed up the global response.” Governments have promised a UN deal meant to restrict emissions by the end of 2015.
Kerry echoed Figueres Friday morning, warning: “Those who deny the science or choose excuses over action are playing with fire.”
Photo: UNISDR Photo Gallery via Flickr.com