Category Archives: AGW comments

A remarkably accurate global warming prediction, made in 1972

I don’t know about my readers, but I am sick to the back teeth with uneducated idiots sitting at their computers typing bullshit feelpinions about their (I’m being generous) perception of climate science, using the argument that because the science is imprecise, nothing should be done to reduce carbon emissions.  Like other concern trolls, they try to give the impression of reasonableness, but are they? Is it reasonable to reject a consensus of 97% of experts that are 95% certain there is a serious problem, while insuring their houses and vehicles against accidents that only have a 1% or less chance of occurring, according to experts? It’s a bizarre position to take especially when the consequences of taking no action against climate change are far more serious. It’s idiotic.

But to the notion that climate systems are poorly understood and the predictions inaccurate. Dana Nuccitelli writing for the Guardian discusses a 1972 Nature paper from John Stanley Sawyer which has proven remarkably accurate.

 

John Stanley (J.S.) Sawyer was a British meteorologist born in 1916. He was elected a Fellow of the Royal Society in 1962, and was also a Fellow of the Meteorological Society and the organization’s president from 1963 to 1965.

A paper authored by Sawyer and published in the journal Nature in 1972 reveals how much climate scientists knew about the fundamental workings of the global climate over 40 years ago. For example, Sawyer predicted how much average global surface temperatures would warm by the year 2000.

The increase of 25% CO2 expected by the end of the century therefore corresponds to an increase of 0.6°C in the world temperature – an amount somewhat greater than the climatic variation of recent centuries.

Remarkably, between the years 1850 and 2000, atmospheric carbon dioxide levels did increase by very close to 25 percent, and global average surface temperatures also increased by just about 0.6°C during that time.

Sawyer also discussed several other important aspects of the Earth’s climate in his paper. For example, he addressed the myth and misunderstanding that as a trace gas in the atmosphere, it may seem natural to assume that rising levels of carbon dioxide don’t have much impact on the climate. Sawyer wrote,

Nevertheless, there are certain minor constituents of the atmosphere which have a particularly significant effect in determining the world climate. They do this by their influence on the transmission of heat through the atmosphere by radiation. Carbon dioxide, water vapour and ozone all play such a role, and the quantities of these substances are not so much greater than the products of human endeavour that the possibilities of man-made influences may be dismissed out of hand.

Sawyer referenced work by Guy Callendar in the late 1930s and early 1940s, in which Callendar estimated that the amount of carbon dioxide in the atmosphere had increased by about 10 percent over the prior 100 years (an impressively accurate measurement, as current estimates put the increase during that time at about 9 percent). Sawyer also referenced the Keeling Curve, which included continuous reliable measurements of the amount of carbon dioxide in the atmosphere beginning in 1958.

Compared to measurements of human carbon dioxide emissions from burning fossil fuels, Sawyer noted that only about half of those human emissions were remaining in the atmosphere. The other half, climate scientists had concluded, were being absorbed by the oceans and the biosphere. Sawyer wrote,

Industrial development has recently been proceeding at an increasing rate so that the output of man-made carbon dioxide has been increasing more or less exponentially. So long as the carbon dioxide output continues to increase exponentially, it is reasonable to assume that about the same proportion as at present (about half) will remain in the atmosphere and about the same amount will go into the other reservoirs.

Indeed, over the past four decades, human carbon dioxide emissions have continued to increase more or less exponentially, and about half has continued to remain in the atmosphere with the other half accumulating in natural reservoirs. The carbon dioxide being absorbed by the oceans has contributed to the problem of ocean acidification, sometimes referred to as “global warming’s evil twin.”

Climate scientists also had a good idea how quickly carbon dioxide levels in the atmosphere would continue to rise as a result of human activities.

Bolin has estimated that the concentration of carbon dioxide will be about 400 ppm by the year 2000. A recent conference put the figure somewhat lower (375 ppm).”

The latter prediction at the referenced 1971 conference on “the Study of Man’s Impact on Climate” turned out to be quite accurate. In 2000, atmospheric carbon dioxide concentrations were measured at about 370 ppm.

In his paper Sawyer discussed the predicted impacts resulting from a continued rise in atmospheric carbon dioxide. He noted that directly “it might make some vegetation grow a little faster,” which is generally true, although the situation is complicated. Sawyer noted that rising carbon dioxide levels would cause an increased greenhouse effect, and the associated warming would lead to more evaporation and more water vapor in the atmosphere. As a greenhouse gas itself, that rise in water vapor would act to further amplify human-caused global warming.

…if world temperatures rise due to an increase in carbon dioxide, it is almost certain that there will be more evaporation of water–the water vapour content of the atmosphere will also increase and will have its own effect on the radiation balance.

Sawyer referenced a 1967 paper by Manabe and Wetherald, who had calculated that a doubling of atmospheric carbon dioxide would by itself cause approximately 1.3°C global surface warming, but that warming would be amplified by a further 1.1°C due to rising water vapor concentrations if the relative humidity were to remain constant. Observations have indeed unequivocally shown that water vapor strongly amplifies human-caused global warming, for example as found in a 2009 study by Andrew Dessler and Sun Wong from Texas A&M University.

Sawyer also discussed that melting ice and snow in a warming world would act to amplify global warming, but suggested that increasing cloud cover might dampen global warming and act to regulate the global climate. However, recent research has shown that clouds may actually weakly amplify global warming as well. Sawyer also understood that significant global warming would cause changes in weather and wind patterns around the world.

All in all, Sawyer’s 1972 paper demonstrated a solid understanding of the fundamental workings of the global climate, and included a remarkably accurate prediction of global warming over the next 30 years. Sawyer’s paper was followed by similarly accurate global warming predictions by Wallace Broecker in 1975 and James Hansen in 1981.

This research illustrates that climate scientists have understood the main climate control knobs for over four decades. Perhaps it’s about time that we start listening to them.

Here’s to that. Original article here.

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Black Swan and denial

One of my favourite Youtubers is Derek with his channel Veritasium. He has a PhD in science communication and all of his videos exploit his expertise in this area. He likes to present a problem to random people and see how they solve it, usually demonstrating the weaknesses in human nature when it comes to laypeople understanding science. This next video is one of his good ones…

and that is the difference between scientists and climate change deniers. The latter tend to suffer from confirmation bias and lack the objectivity, intellect and courage to challenge their predetermined beliefs and also unlike the people in this video who eventually found the solution, refuse to accept any possibility that they are wrong.

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“an ignorant schlemiel”

I haven’t done one of these for awhile but on reading this person’s comment, I had to reproduce it and have done so below. It was made in response to a story in the Guardian where it was revealed that Tony Abbott’s visit to drought stricken farmers resulted in him further demonstrating his denial of the science underpinning anthropogenic climate change and global warming.

“The belligerent ignorance of this fool of a PM Abbott knows no bounds. Only yesterday Kerry’s choice of Indonesia, our closest neighbour, to launch a new campaign on carbon abatement from a Foreign Secretaries platform had a pointedness directed at the Abbott and co.’s attempts to dismiss the challenges of GHG and then cover himself with duplicitous attempts with a proven fraudulent and ineffectual program of Direct Action at great expense the nation’s budget.
Not only does this man, together with a small band of moronic and nescient neophytes belligerently confront the developing move to action by the major emitters, led by the US, he adds to his corrupt culpability by leading our own farmers into a calamitous and fraught future built on his illogical and damnable rejection of all the science available.
Today some of our unfortunate farmers are impacted by the unreliability’s of rain and weather in a neutral Enso. Recently members of the MET have given a 75% probability of an El Nino developing in the next six months.
Meanwhile scientist’s are identifying the impact of the degradation of the ‘dimming effect’ on our weather patterns while at the same time gather further understanding of the implications of changing patterns and velocity of equatorial trade winds. All of which offer us all a greater understanding of the perils we confront from inaction to remedy the causes.
I would recommend to any farmer to add the reading of the http. /www skepticalscience.com. to their daily MET department downloads while they prepare their budgets and projections of the future Abbott response is to embark on insulting our closest ally while committing the national budget to endless expenses and encourage the delusion that these farmers have a reliable future built on irrelevant past experiences.
The man, and many of his supporters and disciples, is an ignorant schlemiel who will cause these hard working farmers nothing but grief with his corruption of the science and his fraudulent promises.” Mike Flanagan

Mike has hit it right on the head here but as usual, the ignorant and idiotic were quick to join in the conversation. Feel free to go and check it all out. Wear headgear. I will leave you with a classic example of a positive feedback loop as described by another clever commentator.

A future with decreasing rainfall levels means there will be much more sand into which the likes of Mr Abbott can stick their heads. Redsaunas

Original article and comments here.

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Why that guy youknow hates renewable energy

pinched from Ketan Yoshi at limitednews.com.au

The carbon pricing mechanism was a funnel for vast menagerie of political discontent on display in July, 2011. Source: ABC News

Two and half years ago, I was trying to improve a sausage. I was at a barbecue, and my primary goal was finding some mustard for the tube of meat I’d just sourced from the grill. In the process, I befriended a fellow hunter/gatherer, and we chatted as I distractedly prowled for condiments.

When we reached the inevitable lull in conversation, he asked me what I do for a living. “I just started working in the wind industry”, I declared, with a smirk smattered with pride. His demeanour shifted noticeably, as if realising he’d wandered into the women’s bathroom by mistake. “Wind farms, eh. Pretty inefficient, I’ve heard” he growled, staring coldly back at me. A deer in the headlights of his unexpected disapproval, I smiled, aborted my mustard-hunt, and….

read the rest here

 

 

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Why climate change defeats our short-term thinking – On science, religion, politics and ideology | Judith Brett | The Monthly

Sometimes we come across short essays or other pieces of writing that are so well written, they present our own thoughts perfectly such that it is impossible to see any other way of saying what they have said. This is one such piece. Please share this widely.

My only criticism is that Judith Brett could have used an alternative title. My suggestion “The cognitive deficiencies of climate change deniers and why their mental disability will affect future generations.”

Why climate change defeats our short-term thinking – On science, religion, politics and ideology | Judith Brett | The Monthly.

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The Denial Beast

taming the hydra

The climate change denial machine has been described as a beast, like the mythical hydra. The following video describes the beast and how it is funded, based on a paper by Robert Brulle of Drexel University.

While this is a USA senator and the context is mostly American, it is applicable here. Just change the names of some of the players to Gina Rinehart, the IPA etc. Some of our “scientists” are however directly paid by American thinktanks and are often trotted out by deniers e.g. Bob Carter.

The charts shown by the good Senator are here. Anyone who says that ExxonMobil and Koch are no longer funding climate change denial is speaking rubbish.

sociogram

countermovement

To read the Brulle paper in full, a PDF is available here.

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Greens Senator sums up the sober reality of Australian government’s climate change denial.

Senator LUDLAM (Western Australia) (18:31): I dedicate this speech tonight on the Climate Change Authority (Abolition) Bill 2013 to all the people who were too young to cast a vote on 7 September 2013. I am proud to stand here today as a member of the Australian Greens in defence of the Climate Change Authority, an entity which most Australians could be forgiven for not even knowing existed until quite recently. The Climate Change Authority reviews Australia’s emission reduction goals and progress towards the renewable energy target every two years from 2012. It performs this essential task free from interference from the executive and the parliament. This independence is essential. It operates in the same way as the Reserve Bank sets interest rates, independently of the superficial, political churn that can so often dominate debates in here. That independence is important precisely because the role of the authority needs to be guided by science and not by politics. In setting the pace of economywide emissions reductions, powerful interests are impacted-interests with open chequebooks and strong opinions, with direct access to this morning’s cabinet meeting and tomorrow morning’s newspaper headlines.

Does anyone remember the retro sounding phrase ‘evidence based policy’? It sounds kind of quaint and naive as it rolls off the tongue, doesn’t it? So far the government have abolished more than 20 expert authorities across the board, from the High Speed Rail Advisory Group to the National Housing Supply Council. They are like a pilot punching out the dials on the instrument panel one by one, even as the engines falter and the light fades. The Climate Change Authority though is the big one. With this single act of calculated stupidity they are smashing the only legislative guidance that they have got as to the speed and the urgency of the transition that is demanded of them. If they somehow wrangle the numbers to wreck the Climate Change Authority, they really will be flying blind. They are left waving around a feeble five per cent emissions target without the faintest idea of how to get there or what on earth they plan on doing with the other 95 per cent. So much for evidence based policy! We plunge headlong into the realm of ‘making it up as you go along’ based policy, except that when they fly blind and hit the wall on climate policy, they will take everyone else down with them.

I know the Prime Minister has been told by his minders to pretend that he no longer thinks climate change is crap. The government’s tactical masterminds have settled on a rather more dishonest messaging strategy where they say: ‘Sure, we believe in climate change. We just think we can tick it off more cheaply by shovelling money into the mouths of rent seekers and LNP candidates in marginal seats and calling it direct action.’ They might as well just set fire to the money.

Yes, the climate has changed in the past. Senator Macdonald was at it again on Monday and a short while ago in this debate. I do not want to pick on my colleague from Queensland, because this attitude now corrupts the whole Liberal-National Party. It is the combination of self-confidence, stridency and breathtaking ignorance that makes it so difficult to have a sensible conversation. Yes, the climate has changed in the past. Some 240 million years ago Earth was a desert planet and 15,000 years ago Earth was in the deep winter of a planetary ice age with the sea level so low that you could walk out to Wadjemup, or Rottnest Island, which now lies 18 kilometres west of the port of Fremantle.

The climate can change profoundly and very rapidly relative to geological timescales. That is year 5 primary school science. So somewhere between year 5 and year 9 Senator Macdonald and a substantial number of his colleagues must have nodded off and missed some very important early high school science classes. Why would you want to take a system as delicately balanced as the global climate system, which you know can be thrown in a matter of centuries or millennia into quite a different regime, and put a blowtorch on it? Why would you want to take something as complex and powerful as the atmosphere itself and then dump tens of billions of tonnes of thermally opaque gases into it every single year and then when the place begins to heat up, more or less exactly as predicted, stand back and pretend that it is a total coincidence, because after all the climate has changed in the past without being shoved by fossil capitalism?

Joseph Fourier theorised about the insulating properties of the atmosphere in 1824, although the key role of carbon dioxide as a thermal blanket was not spelt out until Svante Arrhenius published his greenhouse law back in 1896. The work done by NASA, CSIRO and every single one of the world’s national science academies on climate change research still rests on evidence that was tested more than a century ago. It is actually fine for senators in the Liberal and National parties to come in here and wave their scientific illiteracy at people as though it is some sort of strange badge of honour. It is actually fine, I mean it. You should not have to be an oceanographer or an atmospheric physicist to be a good legislator but, if you do not have these qualifications yourself, the least you can do is show basic respect to those who do have those qualifications and listen to what it is they are telling you. What they are telling you is-and I will break it down into smallish words-that burning coal, oil and gas is cooking the place. We need to stop doing that.

I am sorry that it offends your donors in the coal industry. I understand that it is also quite inconvenient for your benefactors in the gas industry.

The problem is that allowing them to continue to undermine international climate agreements and poison domestic politics here, as they have done in the United States and elsewhere, is going to end up being quite inconvenient for everybody else. Let me explain what I meant by inconvenience.
In the 30-year campaign to sabotage meaningful international negotiations, your donors and your benefactors in the coal and gas industry have already committed us to dangerous global warming: the increased violence of storms as we have loaded more heat into the atmosphere and ocean; the perceptible sea level rise; the droughts; and the consequent insecurity, instability and war in places like Darfur as Lake Chad disappeared off the map. If we had followed through with the concerted efforts to front up to global warming in the 1980s and 1990s, when the issue first hit real global political prominence, we might have been able to avoid some of the storms that we are now sailing into. But instead the coal, oil and gas industries did everything they could to attack and undermine that global consensus as it was emerging. So now we live in a world in which dangerous global warming is a reality.
To get a sense of what this government is driving us into, look no further than today’s approval of the Abbot Point coal terminal. This government is pressing on regardless, flying blind-not into a world with two degrees of average warming but potentially into one with four or more. Whether it be Abbot Point, whether it be the beach at James Price Point in the West Kimberley where a huge gas proposal is afoot, whether it be the multiple gas fracking operations that are underway or planned right around this ancient continent, whether it be the predominance of freeway building over public transport or the proposal to increase logging in old-growth, high-conservation-value forests in the south-west, all around us we see the same sad expressions of business as usual. They are taking us away from a world where we could potentially survive, a world of 1½ or two degrees of global warming. That would be a very damaging and difficult place to live in, but it would be manageable, not end-of-civilisation staff. It would be something that we could deal with if we moved into it with our eyes open.

But I want to talk now about what happens if we continue with the kind of business as usual that was on display this afternoon at Abbot Point and is on display everywhere else around the country, and that is four degrees of global warming. I commend to senators a book called Four Degrees of Global Warming: Australia in a Hot World, edited by Peter Christoff. This book tells us that, according to the best models that we have-and it is like predicting the weather: it is not a precise science but it is nonetheless a science-and the best depth of expertise that we have, with a four-degree average temperature rise there will a quarter of a million coastal properties inundated by rising sea levels, at a total cost of around $63 billion; 17,200 heat related deaths a year, up from 5,800 today; snow just a distant memory in all but the very highest of alpine peaks on the east coast; a quarter of a billion people in the Asia-Pacific region displaced; and, by 2100, we will have locked in irreversible loss of the Greenland ice sheet, which effectively buys you seven or more meters of sea level rise, not in this century but in those to come.

I am glad that Senator Macdonald has joined us again. I want to tell him that I fully understand and the Greens understand that maintaining the Climate Change Authority and maintaining the carbon price and ramping it up-guiding that transition here in Australia-will not prevent those things if that is all we do. This needs to be internationally coordinated action. We need the kind of sabotage that is occurring here in Australia tonight to cease and desist in the United States, in Western Europe and in the emerging economies in India and Asia. We fully understand that this is a global problem, a global issue, and so we call on those industries in Australia-and their advocates in this very parliament-who say we should not do anything here until a global agreement has been reached, to cease and desist sabotaging those global agreements.

In a world with four degrees of global warming, our cities and entire climate systems will be basically unrecognisable. There are some various interesting studies in this book about the closest analogues of climates in future decades. Sydney, in one scenario, ends up like Rockhampton, in subtropical Queensland. Melbourne looks a bit more like Griffith, in regional New South Wales. Alice Springs mirrors the modern day Sudan, and the vast majority of the interior of Australia becomes effectively uninhabitable. The average annual temperature at Alice rises to 35½ degrees, in the hottest, driest scenario. That is the average. Darwin there is no analogue for. Darwin will be like no other city on earth. There is no climate system or climate zone on planet Earth at the moment that matches what Darwinians will be living with in in the year 2100 with four degree of global warming. Perth, my home town, will be an entirely different place-three to 4.8 degrees warmer; 50 per cent less rainfall on top of what we have already lost in the south-west; five to 16 per cent greater range of evaporation, which will exacerbate the frequency of droughts; increased heatwaves. It is effectively the depopulation of the northern wheatbelt, which destroys a $2 billion industry and wipes out communities that have existed for more than 150 years.

That is what we are buying and that is the choice that is before us. At 3½ degrees, this most recent collection of essays tells us, up to 67 per cent of frogs, 87 per cent of mammals, 64 per cent of reptiles and 72 per cent of birds are committed to extinction. Eighty-five to 90 per cent of suitable habitat is lost. So we are setting in motion mass extinction through actions like the one the government proposes to take tonight. But it is not just our action here in the Australian parliament; it is actions in the Western Australian parliament, the United States congress, the Japanese diet and the Indian parliament. All around the world, these actions collectively are committing us to a mass extinction.

I want to raise this issue tonight. This is something that has come to me from the internet. It emerged online. I do not know who invented it. It is called the extinction symbol and it is meant to stand for the species that we are thoughtlessly dispatching to the silence of geology. It also speaks to us of the choices that we have made that brought us here and the choices that we will make in votes like this tonight, and those to come, about what kind of a species extinction we lock in for those decades to come. I think it is about time that we put the extinction symbol on the Hansard record, as a reminder to all of us who make decisions in votes like this one today. I checked this with the whips a few short time ago. I seek leave to table it now.
Leave granted.

Senator LUDLAM: And, against this imperative, Prime Minister Tony Abbott posts a YouTube video on his way overseas, demanding that the Senate do the right thing.

Are you serious? Sorry, Sunshine, but the sound bites and shallow slogans that carried you through the election campaign and into the Prime Minister’s office have just hit the wall.

The ACTING DEPUTY PRESIDENT (Senator Whish-Wilson): Please refer to the Prime Minister by his title.

Senator LUDLAM: Are you saying that calling the Prime Minister ‘Sunshine’ is unparliamentary?

The ACTING DEPUTY PRESIDENT: Yes I am.

Senator LUDLAM: I will withdraw if that is the case. I could think of other things, but that felt like it would suffice.

In 2008, in the very first speech that I read in here, I told an apocryphal story that seemed appropriate at the time. It was about a group of washer women at a riverbank who noticed a child floating past on the river, in trouble. One of them wades in and rescues the child. A short while later they see another child floating past and go out and rescue that one. Then another one floats by, and another. Before long, they are overwhelmed. Then one of the women turns and makes her way up the riverbank. The other women demand: ‘Comrade, where are you going? We need you here.’ Without looking back she says, ‘I’m going to find whoever it is who’s throwing them in.’ And I feel as though I have spent with my colleagues five years in this place working my way upstream to find out who it is throwing these kids into harm’s way-who is making these repetitive, short-term decisions that set such long-term disasters into motion. And here you are; we found you.

If anything that we have said tonight reaches any members of the coalition with a flicker of conscience, join us when we put this bill to a vote, cross the floor and vote for a bill that will give us a fighting chance to meet the challenges that our country has only just begun to confront. You can join the Greens.

You can join the Labor Party. You will also be joining the solar industry-companies like SolarReserve, which just established an office in Perth and is hoping to roll out some of the projects at scale like those they do in the western part of the United States. You will be joining the wind energy developers. You will be joining the Australian Youth Climate Coalition. You will be joining campaigners and ordinary people all over the planet who are throwing everything they have at changing course while we still can. So, when we commit this bill to a vote, I know where I will be sitting. I thank the chamber.

Watch the video here

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Guess what morons?

Climate change is happening, it has always happened, and it is happening faster then it should because of we humans, and our burning fossil fuels. Now, the non-morons can relax with the realisation that I wasn’t addressing them and was directing that at anthropogenic climate change deniers. Please enjoy this video from Hank as he dismisses 10 common climate denier memes. The only criticism I have of his video is that he speaks far too quickly for morons to comprehend. However, if they can operate a mouse they should be able to pause and replay as often as they need to. For the rest of you, enjoy.

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A right wing lunatic and guess who’s following?

So, I’ve been following the #auspol #ausvotes hashtags on Twitter today to gauge the feelings in the world of Twitter about the election. Understandably, some people are upset and some people are happy. I came across one twit though that is…well…. something else.  Before reading the tweets, a language warning. It’s pretty full on.

1 2 3 4 5 6 7 8 9 10 ummm lnp prefs

So there you go. We have racism, sexism, foul language, homicidal suggestions, bizarre nationalistic xenophobia and other stuff I don’t even have a name for.  Someone probably needs to educate this person about the preferential voting system and point out that the Liberal’s only received 31% of the primary vote and the Liberal/National/LNP received less than 50% primary. In fact I might just do that. I’m all in for a bit of sport.

Now, this barrage of vitriol from someone of questionable sanity is one thing, and I’ve come to expect it, especially from the loony right, and it is bad enough, but the thing that I do find disturbing is this…

followed by tony

Yep, that’s right, our PM elect, Tony Abbott is a follower of this person. Sometimes you can really judge a person by the company they keep. Why does Tony Abbott follow this person? What insights does he expect to learn? Perhaps he thinks this person is funny? It wouldn’t surprise me. He has a disturbing, inappropriate and creepy sense of humour.

Abbott body contact

I don’t hold much hope of getting a response but I will endeavour to get one. Personally, I’d like to know why a senior politician is following somebody on Twitter who thinks Labor and Green voters should be pushed off a cliff.

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AGU make strongest statement yet.

The American Geophysical Union has updated their statement on climate change. The new statement was endorsed by a majority of members of the executive with only one person voting against it. That was Roger Pielke …. but he’s an idiot.

Here is the statement in full….

Human-induced climate change requires urgent action.

Humanity is the major influence on the global climate change observed over the past 50 years. Rapid societal responses can significantly lessen negative outcomes.“Human activities are changing Earth’s climate. At the global level, atmospheric concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8°C (1.5°F) over the past 140 years. Because natural processes cannot quickly remove some of these gases (notably carbon dioxide)from the atmosphere, our past, present, and future emissions will influence the climate system for millennia. Extensive, independent observations confirm the reality of global warming. These observations show large-scale increases in air and sea temperatures, sea level, and atmospheric water vapor; they document decreases in the extent of mountain glaciers, snow cover, permafrost, and Arctic sea ice. These changes are broadly consistent with long-understood physics and predictions of how the climate system is expected to respond to human-caused increases in greenhouse gases. The changes are inconsistent with explanations of climate change that rely on known natural influences. Climate models predict that global temperatures will continue to rise, with the amount of warming primarily determined by the level of emissions. Higher emissions of greenhouse gases will lead to larger warming, and greater risks to society and ecosystems. Some additional warming is unavoidable due to past emissions. Climate change is not expected to be uniform over space or time. Deforestation, urbanization, and particulate pollution can have complex geographical, seasonal, and longer-term effects on temperature, precipitation, and cloud properties. In addition, human-induced climate change may alter atmospheric circulation, dislocating historical patterns of natural variability and storminess. In the current climate, weather experienced at a given location or region varies from year to year; in a changing climate, both the nature of that variability and the basic patterns of weather experienced can change, sometimes in counterintuitive ways –some areas may experience cooling, for instance. This raises no challenge to the reality of human-induced climate change. Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase. Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low-latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels. While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential. Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.Actions that could diminish the threats posed by climate change to society and ecosystems include substantial emissions cuts to reduce the magnitude of climate change, as well as preparing for changes that are now unavoidable. The community of scientists has responsibilities to improve overall understanding of climate change and its impacts. Improvements will come from pursuing the research needed to understand climate change, working with stakeholders to identify relevant information, and conveying understanding clearly and accurately, both to decision makers and to the general public.”Adopted by the AmericanGeophysical UnionDecember 2003; Revised and Reaffirmed December 2007, February 2012, August 2013.
For the PDF click here.

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