Let's talk about Climate Change. Who has the evidence?

Kazmarov · 1 year

Here's the summary [PDF] of the (gigantic) 2007 IPCC findings, made for politicians. It's nice because it has headlines of each section which are good summaries of the scientific consensus on various aspects of climate change.

Section 1.1 states:

"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level"

Section 2.4:

"Most of the observed increase in global average temperatures since the mid-20 th century is very likely due to the observed increase in anthropogenic GHG concentrations.

It is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent (except Antarctica)"

So the evidence for warming of the planet is as strong as scientists can possibly state. The evidence of antropogenic (human-caused) warming is not absolute because there's a lot of variables at play, but it's still pretty damn good.

dr_gonzo · 1 year

The theory that the planet is warming, and human activity is to blame, has been undergoing scientific scrutiny since the 1970s.[0] Since then, thousands of different studies and billions of observations have supported the theory of anthropological global warming. For example, recent observations of polar ice cores demonstrates that earth is undergoing traumatic and abnormal change[1], these observations support the hypothesis that humans are causing the planet to warm. We have many observations on the recent effects of climate change including the effects on plankton and glacial erosion.[2] Scientists test the theory of AGW in small steps, like positing that if the planet has been warming, plankton would be migrating. Climate science is the sum of all kinds of different observations like these.

It's often impossible for scientists to prove causation, but the scientific method allows scientists to draw causative conclusions by allowing a hypothesis to be tested repeatedly. We can't prove directly that gravity is caused by mass, but we have made enough observations on how objects with mass behave that we accept the theory of gravity, and apply it in engineering projects every day.

The same is thing is true of climate change. Scientists have spent decades generating thousands of independent studies on wildlife, our oceans, air, soil, and even snails[3], that confirm a theory that has been under evaluation for decades. Like gravity, AGW is a scientific truth.

It's linked elsewhere in the thread, but the 2007 IPCC report on climate change is a good high level summary of some of the key evidence we have. This article provides a more accesible summary of the same evidence.

Worth noting that climate skeptics often challenge IPCC reports on the grounds that because they are aimed at politicians and policy makers, they're inherently biased. It might be reasonable to reject the policy implications from IPCC, but that's no basis to object to the scientific conclusions summarized an IPCC report. In any case, the evidence that the planet is warming and humans are to blame is pretty overwhelming.

giblet_head · 1 year

http://www.youtube.com/user/potholer54?ob=0&feature=results_main#g/c/A4F0994AFB057BB8

I was a strong skeptic (not a denier, but a skeptic) prior to seeing these. Oddly enough, I think I've become a much better scientist and more rational person for having watched most of potholer's videos, so I suggest them to anyone who has the time to spare.

mind_grapes · 1 year

I'm not sure what you're asking to see here. There's a clear consensus that human activity is very likely responsible for the majority of warming since the mid-20th century. (Those are carefully chosen words).

If you're uninterested in the actual scientific debate (the "small cadre of climate scientists [who] believe it's not an issue" -- and yes there are some), and you're tired of seeing politicians misrepresent the science, then perhaps you could clarify what you'd like to see discussed.

scashman · 1 year

There are three basic questions I see as being most relevant.

Is the earth warming, and if so by how much? Are warming trends going to accelerate, decelerate, or stay constant?
How much of this warming is caused by human activity?
What effects will this warming have on human interests, and on the wider world. Will the sum of effects be a net positive or negative?

Edit:

If climate change is happening (whether caused by humans or not), and if it will have net negative effects, what can be done to slow or reverse it?

Deviator77 · 1 year

You can't blame Al Gore for not backing up his comments. He wrote a book with good, solid data. It was later politicized by opponents.

kethas · 1 year

Edit: The Economist's December 2009 special report covered climate change from numerous angles (the science, the economics of climate change mitigation, the politics and game-theory of a country setting a climate-friendly agenda unilaterally vs. worldwide consensus and enforcement). It's worth reading in its entirety:

http://www.economist.com/specialreports?year[value][year]=2009&category=76984

The Economist had a special report on climate change a few months ago that I thought was very well-written and impartial. It laid out the train of thought behind climate change decisionmaking, something like:

Has the Earth been warming in the past?
If so, was it man-made?
If so, will it continue?
If so, will future warming be a net problem for humanity?
If so, is it within our power to stop or slow future warming?
If so, are the resources required to slow or stop future warming best used to that end, instead of, for example, subsidizing rebuilding efforts farther inland, or researching more heat-resistant crops?
If so, can we trust that climate-preservation efforts on our (e.g. the U.S.) part will be reciprocated by others (e.g. China), instead of them taking our climate preservation efforts as license to continue expanding and polluting, resulting in no long-term reduction in climate change and a loss of relative industrial power on our part?
If so, can we assemble the political will to initiate, and stick to, a climate-preserving agenda?
If so, what's the best such approach?

I'll see if I can find the Economist article.

archiesteel · 1 year

Good luck keeping this politically neutral...

RAPES_GRAPES · 1 year

I think the most interesting question is cross-disciplinary with a large economic component. Namely, what is the optimal amount of resources to be allocated to reduce AGW?

Meta-complaint: Saying that "the general consensus is X" without proof is an appeal to authority, and really the writer's credibility in my eyes. When making an assertion believed to be common knowledge, please simply state it.

Kar98 · 1 year

There is a good set of videos by a BBC journalist here: http://www.youtube.com/user/potholer54?ob=4#p/c/A4F0994AFB057BB8

Will_Power · 1 year

I am a skeptic, and here's a brief list of items that summarize my position:

CO2 is a greenhouse gas. This is not disputed.
A doubling of atmospheric CO2 from preindustrial levels (i.e., from 280 ppm to 560 ppm) will increase mean global temperature by about 1°C. This is rarely disputed.
Estimates for climate sensitivity (how feedbacks from the original CO2 radiative forcing) are all over the place, but the figure one most often hears from warmists is 3°C per doubling. There is no consensus on this point.
IPCC scenarios that suggest more than 560 ppm atmospheric CO2 do not take into consideration physical limits to extraction of fossil fuels at all.

As to the original question, both sides have some things right, but grounds for alarming predictions are incredibly thin.

butch123 · 1 year

See that big ball of fire in the sky? Until recently it was denied as the main influence of climate change (over the past 100 years at least) by those who put forth the anthropogenic theory of present day climate forcing. When the Sun started a long, low intensity cycle, all of a sudden some of the AGW proponents did start to take notice...especially since the lack of warming for the past decade does conform to the decline of solar cycle 23 and the poor beginning of solar cycle 24.

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