abu afak
ALLAH SNACKBAR!
- Mar 3, 2006
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OP... Link One:
CLIMATE
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"..Here is how scientists know that the climate change we are experiencing is mainly due to human activity and not a result of natural phenomenon.
Gavin Schmidt, director of National Aeronautics and Space Administration’s Goddard Institute for Space Studies, said that scientists look at a lot of different things at once.
“We have a very, very clear understanding that the amount of heat in the ocean is increasing—the ocean heat content is going up by a lot,” said Schmidt. “That implies that there must be an external change in the radiation budget of the earth—more energy has to be going in than leaving.
“There are a number of ways that can happen, but each of them has a different fingerprint. If the sun were brighter, we would see warming all the way up through the atmosphere from the surface to the stratosphere to the mesosphere. We don’t see this. We see instead warming at the surface, cooling in the stratosphere, cooling in the mesosphere. And that’s a signature of greenhouse gas forcing, it’s not a signature of solar forcing. So we know it’s not solar.”
Moreover, according to the World Radiation Center, the sun’s radiation has not increased since at least 1978 (when satellite monitoring began) though global temperatures over the last 30 years have continued to rise.
In addition, the lower atmosphere (troposphere), which is absorbing the CO2 and expanding as it gets warmer, is pushing the boundary between the troposphere and the stratosphere upwards. If the sun’s radiation were the main factor responsible for Earth’s warming, both atmosphere layers would likely be warming and this would not occur.
Scientists also can distinguish between CO2 molecules that are emitted naturally by plants and animals and those that result from the burning of fossil fuels. Carbon molecules from different sources have different numbers of neutrons in their nuclei; these different versions of molecules are called isotopes. Carbon isotopes derived from burning fossil fuels and deforestation are lighter than those from other sources. Scientists measuring carbon in the atmosphere can see that lighter carbon molecules are increasing, corresponding to the rise in fossil fuel emissions.
Peter de Menocal, dean of science at Columbia University and founding director of Columbia’s Center for Climate and Life, studies deep-sea sediments to understand past climate change.
“Ocean sediments provide a longer term baseline [tens of millions of years] that allows you to compare the past with the present, giving you an idea of how variable ocean temperatures have been before we had thermometers,” said de Menocal. “Over the last 2,000 years, there have been natural climate variations, but they were not especially large…the Medieval Warm period around 1,000 years ago, and the little ice age which was three separate cooling periods lasting a few decades each, beginning around 1300 to around the 1850s. It’s the warming after the 1850s that’s been really remarkable and unique over the last couple of millennia—you can see that in the sediment cores.”
Photo: unlu1
Evidence from ocean sediments, ice cores, tree rings, sedimentary rocks and coral reefs show that the current warming is occurring 10 Times Faster than it did in the past when Earth emerged from the ice ages, at a rate unprecedented in the last 1,300 years.
(abu afak: IOW Ding, it is NOT "Normal Interglacial."
To understand this rapid change in climate, scientists look at data sets and climate models to try to reproduce the changes that have already been observed. When scientists input only natural phenomena such as the sun’s intensity, changes in the Earth’s orbit and ocean circulation, the models cannot reproduce the changes that have occurred so far.
“We have independent evidence that says when you put in greenhouse gases, you get the changes that we see,” said Schmidt. “If you don’t put in greenhouse gases, you don’t. And if you put in all the other things people think about—the changes in the earth’s orbit, the ocean circulation changes, El Niño, land use changes, air pollution, smog, ozone depletion—all of those things, none of them actually produce the changes that we see in multiple data sets across multiple areas of the system, all of which have been independently replicated.” In other words, only when the emissions from human activity are included, are the models and data sets able to accurately reproduce the warming in the ocean and the atmosphere that is occurring.
“Today, almost 100% [plus or minus 20%] of the unusual warmth that we’ve experienced in the last decade is due to greenhouse gas emissions,” said de Menocal.
Record shattering heat in 2015 Photo: NASA
Findings from NASA’s Goddard Institute for Space Studies show clearly how much natural and manmade factors contribute to global warming.
Climate deniers offer a variety of bases for their skepticism without providing scientific evidence. The most effective thing that the climate denier community has done, however, is to spread the notion of uncertainty about climate change, and use it as an excuse not to take any action.
“It’s been a very effective tactic,” said de Menocal, “in part because the scientific community spends a tremendous amount of effort quantifying that uncertainty. And so we make it plain as day that there are things we’re certain about, and things we’re uncertain about. There are places of debate that exist in the community. That’s the scientific process. … The deniers are not selling a new way of looking at the problem, they’re selling doubt, and it’s very easy to manufacture doubt.”
“They are in total denial of the evidence that there is,” said Schmidt. “When I challenge them to produce evidence for their attributions, all I get is crickets. There’s no actual quantitative evidence that demonstrates anything. … Show me the data, show me your analysis.”
“There are lot of things that we’re absolutely certain about,” said de Menocal. “We’re absolutely certain carbon dioxide is rising in the atmosphere. We’re absolutely certain it’s warming the planet and we’re absolutely certain that it’s acidifying the oceans.”
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CLIMATE
How We Know Today’s Climate Change Is Not Natural
APRIL 4, 2017[.......]
[.......]
"..Here is how scientists know that the climate change we are experiencing is mainly due to human activity and not a result of natural phenomenon.
Gavin Schmidt, director of National Aeronautics and Space Administration’s Goddard Institute for Space Studies, said that scientists look at a lot of different things at once.
“We have a very, very clear understanding that the amount of heat in the ocean is increasing—the ocean heat content is going up by a lot,” said Schmidt. “That implies that there must be an external change in the radiation budget of the earth—more energy has to be going in than leaving.
“There are a number of ways that can happen, but each of them has a different fingerprint. If the sun were brighter, we would see warming all the way up through the atmosphere from the surface to the stratosphere to the mesosphere. We don’t see this. We see instead warming at the surface, cooling in the stratosphere, cooling in the mesosphere. And that’s a signature of greenhouse gas forcing, it’s not a signature of solar forcing. So we know it’s not solar.”
Moreover, according to the World Radiation Center, the sun’s radiation has not increased since at least 1978 (when satellite monitoring began) though global temperatures over the last 30 years have continued to rise.
In addition, the lower atmosphere (troposphere), which is absorbing the CO2 and expanding as it gets warmer, is pushing the boundary between the troposphere and the stratosphere upwards. If the sun’s radiation were the main factor responsible for Earth’s warming, both atmosphere layers would likely be warming and this would not occur.
Scientists also can distinguish between CO2 molecules that are emitted naturally by plants and animals and those that result from the burning of fossil fuels. Carbon molecules from different sources have different numbers of neutrons in their nuclei; these different versions of molecules are called isotopes. Carbon isotopes derived from burning fossil fuels and deforestation are lighter than those from other sources. Scientists measuring carbon in the atmosphere can see that lighter carbon molecules are increasing, corresponding to the rise in fossil fuel emissions.
Peter de Menocal, dean of science at Columbia University and founding director of Columbia’s Center for Climate and Life, studies deep-sea sediments to understand past climate change.
“Ocean sediments provide a longer term baseline [tens of millions of years] that allows you to compare the past with the present, giving you an idea of how variable ocean temperatures have been before we had thermometers,” said de Menocal. “Over the last 2,000 years, there have been natural climate variations, but they were not especially large…the Medieval Warm period around 1,000 years ago, and the little ice age which was three separate cooling periods lasting a few decades each, beginning around 1300 to around the 1850s. It’s the warming after the 1850s that’s been really remarkable and unique over the last couple of millennia—you can see that in the sediment cores.”
Photo: unlu1
Evidence from ocean sediments, ice cores, tree rings, sedimentary rocks and coral reefs show that the current warming is occurring 10 Times Faster than it did in the past when Earth emerged from the ice ages, at a rate unprecedented in the last 1,300 years.
(abu afak: IOW Ding, it is NOT "Normal Interglacial."
To understand this rapid change in climate, scientists look at data sets and climate models to try to reproduce the changes that have already been observed. When scientists input only natural phenomena such as the sun’s intensity, changes in the Earth’s orbit and ocean circulation, the models cannot reproduce the changes that have occurred so far.
“We have independent evidence that says when you put in greenhouse gases, you get the changes that we see,” said Schmidt. “If you don’t put in greenhouse gases, you don’t. And if you put in all the other things people think about—the changes in the earth’s orbit, the ocean circulation changes, El Niño, land use changes, air pollution, smog, ozone depletion—all of those things, none of them actually produce the changes that we see in multiple data sets across multiple areas of the system, all of which have been independently replicated.” In other words, only when the emissions from human activity are included, are the models and data sets able to accurately reproduce the warming in the ocean and the atmosphere that is occurring.
“Today, almost 100% [plus or minus 20%] of the unusual warmth that we’ve experienced in the last decade is due to greenhouse gas emissions,” said de Menocal.
Record shattering heat in 2015 Photo: NASA
Findings from NASA’s Goddard Institute for Space Studies show clearly how much natural and manmade factors contribute to global warming.
Climate deniers offer a variety of bases for their skepticism without providing scientific evidence. The most effective thing that the climate denier community has done, however, is to spread the notion of uncertainty about climate change, and use it as an excuse not to take any action.
“It’s been a very effective tactic,” said de Menocal, “in part because the scientific community spends a tremendous amount of effort quantifying that uncertainty. And so we make it plain as day that there are things we’re certain about, and things we’re uncertain about. There are places of debate that exist in the community. That’s the scientific process. … The deniers are not selling a new way of looking at the problem, they’re selling doubt, and it’s very easy to manufacture doubt.”
“They are in total denial of the evidence that there is,” said Schmidt. “When I challenge them to produce evidence for their attributions, all I get is crickets. There’s no actual quantitative evidence that demonstrates anything. … Show me the data, show me your analysis.”
“There are lot of things that we’re absolutely certain about,” said de Menocal. “We’re absolutely certain carbon dioxide is rising in the atmosphere. We’re absolutely certain it’s warming the planet and we’re absolutely certain that it’s acidifying the oceans.”
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