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Twilight of the Climate Change Movement

Seems we have finally begun to move past having people scream "Climate Change is Real!". However, as we then proceed to look at the details of how much it is changing, and how much is natural versus anthropogenic, the case for taking dramatic action to cut carbon emissions looks weaker and weaker.


The public debate is dominated by simplistic claims that “climate change is man-made,” which might lead one to think that all of the current warming trend is man-made. But nearly all climate scientists accept that many factors influence temperatures, including major shifts in patterns of ocean circulation (such as the very strong El Niño, largely responsible for the warm Christmas Day 2015 temperatures in North America), variations in the earth’s orbit, variations in solar activity, and volcanic activity. The “attribution statement” in the IPCC’s latest assessment report is carefully couched: “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in GHG and other anthropogenic forces together.”

The distinction between “more than half” (the IPCC’s summary of scientific literature) and “all” or “nearly all” is crucial from the point of view of public policy. If only about half the observed warming is due to human activity, the cost-benefit analysis of currently proposed policies becomes far more dubious, and reveals another problem: As much as half the current warming trend (whatever that is) could be due to natural causes, and current policies will do nothing to address that.

To see why, it’s crucial to focus on this precise scientific question: How much do temperatures actually increase when atmospheric carbon dioxide increases? Scientists express this relationship as a measure of “equilibrium climate sensitivity,” defined as how many degrees average global temperature will increase as a result of doubling atmospheric carbon dioxide. Virtually all the climate models used in the IPCC’s worst-case predictions of dangerous global warming presume a worst-case scenario equilibrium climate sensitivity (ECS) of 3.0 to 3.5 degrees Celsius. But leading IPCC scientists have concluded that if humans were responsible for all observed warming since 1971, the ECS would be around 2.0 degrees Celsius. And if humans are only responsible for about half of the observed warming, as the IPCC itself admits is quite possible, that implies an ECS closer to 1.0 degrees Celsius.

A reliable figure for ECS continues to elude our grasp, but with an ECS of 1.0 degrees Celsius, the case for sweeping reductions in carbon emissions is greatly weakened. At that level of climate sensitivity, even if carbon dioxide emissions continue to increase unabated, temperatures would increase significantly less than the stated goal of the IPCC’s, which is warming of no more than two degrees Celsius by 2100. (This may explain why the Paris agreement moved the goalposts to a new goal of less than 1.5 degrees Celsius by 2100). But in that case, IPCC’s worst-case scenario would then be non-catastrophic by the IPCC’s own definition.

The policy implications are dramatic. Under this scenario, which lies well within the IPCC’s forecast, even dramatic reductions in carbon dioxide emissions would have no measurable impact on temperatures. And the natural factors responsible for as much as half the recently observed warming would presumably continue warming the planet, oblivious to any reduction in carbon emissions.

The key point is this: The IPCC’s latest “attribution statement” (extreme confidence that more than half the observed warming is due to humans) would be correct even if ECS is only 1.0 degrees Celsius and expected increases in carbon dioxide pose essentially no risk of catastrophic climate change.

Posted by Transcendence | Mon Apr 11, 2016, 08:10 PM (17 replies)

Return of the Pause/Slowdown/Hiatus

In June of 2015 a group of climate scientists from NOAA published a paper claiming that the "pause", "hiatus" or "slowdown" in global warming that occurred during the first 15 years of the century actually didn't happen. The paper went further to claim that the rate of warming over the period was "as fast or faster than that seen over the last half of the 20th century.” Most activists expressed great joy over the paper, glad to see the banishment of the inconvenient truth of the pause to history. More sensible people suggested waiting to see if the paper's claims would be supported by others performing similar analysis.

That time has apparently now come, and unfortunately the result is an unequivocal "no". A new paper published Nature Climate dismisses the findings of the NOAA scientists in uncharacteristically blunt terms:

It has been claimed that the early-2000s global warming slowdown or hiatus, characterized by a reduced rate of global surface warming, has been overstated, lacks sound scientific basis, or is unsupported by observations. The evidence presented here contradicts these claims.

Global warming activists seeking to discredit the paper will have their work cut out for them. Not only does the paper appear in a journal known for publishing some of the most alarming studies on climate change, one of the co-authors of the paper is none other than Michael Mann--author of the (in)famous hockey stick paper. It will be interesting to see if climate activists will be willing to turn on one of their own...
Posted by Transcendence | Wed Mar 30, 2016, 08:08 PM (39 replies)

Bernie Sanders Jesus Meme

Posted by Transcendence | Mon Mar 7, 2016, 11:30 AM (5 replies)

How much warming will we see by 2100?

How much higher do you think temperatures will be by 2100?
(relative the 1951-1980 base period as used by GISS)
Posted by Transcendence | Sat Jan 9, 2016, 12:32 AM (64 replies)

Climate Doomers Turn on Each Other

After the signing of a historic climate pact in Paris, we might now hope that the merchants of doubt – who for two decades have denied the science and dismissed the threat – are officially irrelevant.

But not so fast. There is also a new, strange form of denial that has appeared on the landscape of late, one that says that renewable sources can’t meet our energy needs.

Oddly, some of these voices include climate scientists, who insist that we must now turn to wholesale expansion of nuclear power. Just this past week, as negotiators were closing in on the Paris agreement, four climate scientists held an off-site session insisting that the only way we can solve the coupled climate/energy problem is with a massive and immediate expansion of nuclear power. More than that, they are blaming environmentalists, suggesting that the opposition to nuclear power stands between all of us and a two-degree world.

When you hear who the "four climate scientists" are, you will immediately understand why Naomi Oreskes chose not to list them. So who are these new deniers? Merely some of the top climate scientists on the planet: James Hansen, Ken Caldeira, Tom Wigley, and Kerry Emanuel.

So now that the grandfather of climate change, James Hansen, is apparently a denier, I wonder who could be next? Joe Romm? Bill McKibben? Maybe...Al Gore?

Posted by Transcendence | Wed Dec 16, 2015, 11:05 PM (4 replies)

What would it take for you to change your mind about climate change?

Any scientific theory must be falsifiable in order to be considered "scientific". If you promote a theory that cannot be proven false by empirical evidence, you are not promoting scientific theory, but religious dogma. Given this, I would ask that people on both sides of the debate to state what would have to happen for them to change their position on climate change.

Since I asked the question, I'll go first.

I would change from being a lukewarmer to a climate doomer if I saw a 30 year period with average increases in temperature in excess of 0.35° C per decade.
Posted by Transcendence | Thu Jul 16, 2015, 08:06 AM (41 replies)

A good article on adjustments to the temperature record

There have been a number of comments here in the past few weeks with regard to temperature adjustments, most of them implying that these adjustments represent some sort of conspiracy to inflate temperatures. (Confession: I myself authored one of these type of posts). I had this in mind when I came across an article at Judith Curry's blog (which is, IMHO, one of the best blog out there for climate science) that describes how these adjustments are made and what impact they have on the temperature record as a whole. Hint: it's not much.

Berkeley Earth developed a methodology for automating the adjustment process in part to answer the suspicions people had about the fairness of human aided adjustments. The particulars of the process will be covered in a separate post. For now we want to understand the magnitude of these adjustments and what they do to the relevant climate metric: the global time series. As we will see the “biggest fraud” of all time and this “criminal action” amounts to nothing.

The global time series is important, for example, if we want to make estimates of climate sensitivity or if we want to determine how much warmer it is today than in the Little Ice Age or if we want to compare today’s temperature with the temperature in the MWP or Holocene or if we want to make arguments about natural variability or anthropogenic warming.

The kicker for me was this graph, which basically shows that, at least for the most recent 40 years, the temperature adjustments hardly made any difference:

Posted by Transcendence | Tue Feb 10, 2015, 03:40 PM (10 replies)

NASA says 2014 was warmer than 1998 by 0.07 °C

1998: 14.61 °C
2014: 14.68 °C


FYI, margin of error for the measurement is ±0.05°C

Posted by Transcendence | Sat Jan 17, 2015, 03:05 AM (9 replies)
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