1. Yes, global warming is real. I think I already covered that.
2. Yes, it is caused by human activities. On that point, you could look at the list of ten indicators of a "human fingerprint on climate change" offered up by Skeptical Science.
(Quick sidebar before someone goes off on this: The terms "global warming" and "global climate change" mean the same thing and are used interchangeably. Some prefer the former term because that is what is happening - the world as a whole, i.e., the waters, the land, and the atmosphere, is on average getting warmer - and some prefer the latter because they think it more accurate; they think the former implies everywhere will get warmer while in fact some places will get colder even as the world average temperature goes up. Both terms refer to the same set of facts and the same set of predictions.)
Getting back to the point, you could check out the fact that last March, the Met Office, the UK's national weather service, issued an analysis of 110 peer-reviewed papers on climate change that have appeared since the 2007 IPCC report and determined that the evidence for a human impact is stronger than ever.
"What this study shows is that the evidence has strengthened for human influence on climate and we know that because we've looked at evidence across the climate system and what this shows very clearly is a consistent picture of a warming world," said Dr [Peter] Stott [of the Met Office].A couple of months after that, in May, the US National Research Council, part of the National Academy of Sciences, issued a set of three reports that described the case that climate change is caused in large part by human activities as "compelling."
The core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious debate and careful evaluation of alternative explanations.Finally for the moment anyway, at the end of September the Royal Society, one of the world's leading scientific academies, issued a "Summary of the Science" of climate change. It begins by saying this:
"Climate change is occurring, is caused largely by human activities, and poses significant risks for — and in many cases is already affecting — a broad range of human and natural systems," the report concludes.
There is strong evidence that the warming of the Earth over the last half-century has been caused largely by human activity, such as the burning of fossil fuels and changes in land use, including agriculture and deforestation.Climate Progress, a leading global warming science site, trashed the report as "bland, pointless, and confused" and a waste of time because it gave some of the uncertainties in understanding climate change equal attention to the parts that are settled science - such as that yes, we are screwing with the climate, reflected in the fact that, as the document says,
each decade since the 1970s has been clearly warmer (given known uncertainties) than the one immediately preceding it.Now, it is true that some naysayer sites grabbed onto the report, citing its reference to uncertainties and claiming the Royal Society had "joined the deniers." Those naysayers, of course, were distorting the report for their own ends via cherry-picked paragraphs and edited quotes. But I still think the Climate Progress attack, which seemed mostly concerned with the opening the document provided for the naysayers, was off-base and unduly, very unduly, harsh, especially considering this was a consensus document that included two self-proclaimed skeptics among its co-authors - which means even those skeptics had to agree with the statement that it's human activity that's driving the warming.
3. No, it is not the Sun, as a lot of peer-reviewed studies have shown. For example, a 2009 study concluded that no more than roughly 14% of the currently-observed warming could be from the Sun. Another from 2009 said the Sun was responsible for no more that 6-8% of the warming over the entire 20th century and its effect was "negligible for warming since 1980." A third from 2008 put the maximum effect at around 10%.
And those are the high end. Other studies over the past few years (this is one example) suggest that over the past few decades, below-average solar irradiance may have actually generated a slight cooling trend, which would mean that instead of causing global warming, the effect of the Sun of late has actually been to conceal the true extent of human-caused warming.
As a side note, the range of possibilities in those studies, from generating a slight cooling to 14% of the warming, does not prove the models and analyses are "unreliable." It does demonstrate the great complexity involved in trying to pin down the size of various forcings and effects, which no one denies. The point, however, is that the studies agree that the Sun's effect on observed warming is small; they only disagree on just how small.
And by the way, no, it's not cosmic rays or any of the rest of that nonsense, either.
4. No, I have not been cherry-picking research papers and yes, there is a consensus not only about global warming but about our role in generating it. For one thing, the academies of science of 19 nations plus a large number of non-governmental science bodies agree with the contention of human-caused global warming.
Consider this: A 2009 survey of over 3,000 scientists in a variety of related fields that "included participants with well-documented dissenting opinions on global warming theory" found that 82% agreed that "human activity is a significant contributing factor in changing mean global temperatures." What's more,
[i]n general, as the level of active research and specialization in climate science increases, so does agreementwith that statement: Among climatologists who are "active publishers on climate change," that is, who do research on climate change and publish in peer-reviewed journals, agreement that humans are a significant contributor to global warming reached 96%. Those who insist there is a scientific "controversy" are either misinformed, uninformed, or lying.
I know that I've not even begun to exhaust the list of nanny-nanny naysayer nitpicks - Skeptical Science has a list of 130 of them (with their refutations) - but I figured that "Yes, it's real; yes, it's us; no, it's not the Sun; and yes, there is a consensus" covered the obvious ones.
Something I have noticed, though, about naysayer arguments: Like the good right-wingers most of them are, they will simply deny reality until it becomes undeniable, at which point they will start saying "Well, of course, that. We always knew that. The real issue is this over here." That is, they will airily acknowledge what they previously vociferously denied without ever admitting to the shift. (Consider it a variation on Rule #3.) So perhaps I should take some comfort in the fact that those among the nanny-nanny naysayers who actually try to argue the science have been forced to go from denying that global warming even exists to denying humans had anything to do with it to denying that humans had a lot to do with it to arguing that "it won't be so bad" to, largely, nitpicking at individual graphs and data points. Gradually, they are being brought to heel by the harsh reality of fact.
Take what comfort you can from that.
Footnote: One more tidbit for the nanny-nanny naysayers. A link to a video showing that global warming was considered a problem by at least some scientists - in 1956. (Thanks go to DD at Notes from Underground for the tip.)