The human impact on climate proven human impact on the climate proved at the plenary session of the Working Group I of the Intergovernmental Panel on Climate Change (IPCC), which adopted the final version of the first part of the Fifth Assessment Report.
The man left footprints all over the place. (Infographics Skeptical Science.)
In the center of attention - the assertion that the IPCC is 95% sure of the nature of anthropogenic climate changes observed in the last 60 years. In the previous report, released in 2007, seems to be figured 90%. In fact this is not true.
To be totally accurate, then said the following: The greater part of the observed changes in global average temperature since the mid XX century is very likely (very likely), associated with the observed increase in anthropogenic greenhouse gas concentrations.
But the current wording, compare: It is highly likely (extremely likely), that the human influence on climate has caused more than half of the observed increase in global average surface temperature in the years 1951-2010.
See the difference? The 2007 report has focused on greenhouse gas emissions, and is now extended to all forms of human impact on the climate, including the cooling effect of aerosols (substances not only pollute the air but also scatter sunlight). Last compensates for about a third of warming caused by greenhouse gases.
But even with the cooling effects of human activities still remains the main source of global warming observed for six decades.
What is the main cause of global warming? Anthropogenic emissions of greenhouse gases, the warming observed since 1951 can be attributed to various natural and anthropogenic factors and their contribution difficult to assess. Contribution of greenhouse gases in the near-surface average world warming, probably located in the area 0,5-1,3 ° C, and the other human climatic factors, including aerosol effect - ranging from 0.6 to 0,1 ° C .
And that is not the cause of global warming? Natural external factors (for example, solar activity) and natural internal factors (such as cyclical processes in the oceans): The contribution of natural climate forcing is likely to be in the range of -0.1 to 0,1 ° C; internal variability - from 0.1 to 0,1 ° C ».
In general, over the past 60 years, global average near-surface warming was about 0,6 ° C. According to the best estimate of the IPCC, greenhouse gases have increased the temperature by about 0,9 ° C, and produced by us aerosols cool the planet somewhere at 0,3 ° C. During this period, natural external factors did not have little or no effect on global temperature. For example, solar activity since 1950 has not shown anything remarkable.
As to the natural internal variability of the climate system of the Earth, the short-term noise in the long term be reduced to zero. Warm and cold periods in the life of the ocean offset each other so that the long-term impact on global average temperature, they also do not have.
So, with 95 percent certainty the IPCC claims that the person responsible for greater rigor is often observed in 1951 near-surface warming. The most likely estimate is that we - the cause of 100% of warming.
United Nations Report Does Not Answer Pause In warming
An enormous U.N. report on the scientific data behind global warming was made available Monday, yet it offers little concrete explanation for an earthly oddity: the planet's climate has hit the pause button.
Since 1998, there has been no significant increase in global average surface temperature, and some areas -- notably the Northern Hemisphere -- have actually cooled. The 2,200-page new Technical Report attributes that to a combination of several factors, including natural variability, reduced heating from the sun and the ocean acting like a "heat sink" to suck up extra warmth in the atmosphere.
One problem with that conclusion, according to some climate scientists, is that the U.N.'s Intergovernmental Panel on Climate Change (IPCC) has limited the hiatus to 10-15 years. Anastasios Tsonis, distinguished professor at the University of Wisconsin -- Milwaukee, believes the pause will last much longer than that. He points to repeated periods of warming and cooling in the 20th century. 'I know that the models are not adequate ... they don't agree with reality.'
- Anastasios Tsonis, distinguished professor at the University of Wisconsin -- Milwaukee
"Each one of those regimes lasts about 30 years ... I would assume something like another 15 years of leveling off or cooling," he told Fox News.
That goes well beyond the window the IPCC has acknowledged, which Tsonis and other scientists believe will significantly change the predictions for temperature rise over the next century.
"I know that the models are not adequate," Tsonis told Fox News. "There are a lot of climate models out there. They don't agree with each other -- and they don't agree with reality."
In fact, the IPCC's massive, complex new report acknowledges that none of the models predicted the hiatus. The authors write that it could be due to climate models over-predicting the response to increasing greenhouse gases, or a failure to account for water vapor in the upper atmosphere.
The bottom line -- no one saw it coming.
"Almost all historical simulations do not reproduce the observed recent warming hiatus," the report states.
Tsonis was pleased that the IPCC acknowledged that natural variability may have played a part in the stall in upward temperature trends. But he said the report's authors totally ignored groundbreaking research he presented six and four years ago that fully explained such "pauses." He attributes them to an intricate interaction of oceanic and atmospheric modes which either warm or cool the planet on a time scale of decades.
Judith Curry, chair of the School of Earth And Atmospheric Sciences at Georgia Tech, says the IPCC is taking a huge credibility hit over the hiatus -- and its pronouncement that it is 95 percent certain that human activity is responsible for most global warming.
"I'm not happy with the IPCC," she told Fox News. "I think it has torqued the science in an unfortunate direction."
That torquing, she suggests, is because the money in climate science (the funding, that is) is tied to embellishing the IPCC narrative, especially the impacts of global warming. She is critical of the IPCC's leadership as well, in particular its chairman, Rajendra Pachauri.
"They have explicit policy agendas," Curry told Fox News. "Their proclamations are very alarmist and very imperative as to what we should be doing. And this does not inspire confidence in the final product."
Other scientists argue passionately against such talk.
Penn State's Michael Mann -- who authored the famous "hockey stick" graph showing a stunning rise in temperatures in the late 20th century -- believes this latest IPCC report only confirms what he has been arguing for years. That the Earth is warming, and humans are to blame.
"We cannot explain the warming through natural causes," he told Fox News. "It can only be explained by the increased greenhouse gas concentrations from human fossil fuel burning."
Mann goes so far as to say that if you remove the "noise" from the recent pause in temperature rise, human activity is to blame for 100 percent of the global warming.
Tsonis strongly disagrees. He acknowledges that human activity is likely having an impact on climate, but adds "Nobody has ever proven for 100 percent that the long-term warming is man-made. In my educated guess I will think something like less than 30 percent."
Judith Curry believes the approach the IPCC takes to climate change is fundamentally flawed. Consensus-seeking, she says, introduces bias into the science.
"They don't challenge it and say, well, how might this be wrong?" she told Fox News. "What are all the different reasons or ways this could be wrong? And once you start looking at it that way, you come up with a lot of different answers."
