Tag Archives: Climate Change

News

New study: Earth is currently in a 2000-year old cooling trend

1 Comment

Report from the UK Daily Mail.

Excerpt:

How did the Romans grow grapes in northern England? Perhaps because it was warmer than we thought.

A study suggests the Britain of 2,000 years ago experienced a lengthy period of hotter summers than today.

German researchers used data from tree rings – a key indicator of past climate – to claim the world has been on a ‘long-term cooling trend’ for two millennia until the global warming of the twentieth century.

This cooling was punctuated by a couple of warm spells.

These are the Medieval Warm Period, which is well known, but also a period during the toga-wearing Roman times when temperatures were apparently 1 deg C warmer than now.

They say the very warm period during the years 21 to 50AD has been underestimated by climate scientists.

Lead author Professor Dr Jan Esper of Johannes Gutenberg University in Mainz said: ‘We found that previous estimates of historical temperatures during the Roman era and the Middle Ages were too low.

‘This figure we calculated may not seem particularly significant, however it is not negligible when compared to global warming, which up to now has been less than 1 deg C.’

In general the scientists found a slow cooling of 0.6C over 2,000 years, which they attributed to changes in the Earth’s orbit which took it further away from the Sun.

The study is published in Nature Climate Change.

It is based on measurements stretching back to 138BC.

The finding may force scientists to rethink current theories of the impact of global warming

Professor Esper’s group at the Institute of Geography at JGU used tree-ring density measurements from sub-fossil pine trees originating from Finnish Lapland to produce a reconstruction reaching back to 138 BC.

In so doing, the researchers have been able for the first time to precisely demonstrate that the long-term trend over the past two millennia has been towards climatic cooling.

Professor Esper said: ‘Such findings are also significant with regard to climate policy, as they will influence the way today’s climate changes are seen in context of historical warm periods.’

The annual growth rings in trees are the most important witnesses over the past 1,000 to 2,000 years as they indicate how warm and cool past climate conditions were.

Researchers from Germany, Finland, Scotland, and Switzerland examined tree-ring density profiles.

The study is linked here.

News

Computer models utterly fail to predict climate changes

1 Comment

From the Financial Post, an editorial by Ross McKitrick of the University of Guelph. He is an expert reviewer for the UN’s Intergovernmental Panel on Climate Change. (H/T ECM)

Excerpt:

[I]n 2008 and 2010, a team of hydrologists at the National Technical University of Athens published a pair of studies comparing long-term (100-year) temperature and precipitation trends in a total of 55 locations around the world to model projections. The models performed quite poorly at the annual level, which was not surprising. What was more surprising was that they also did poorly even when averaged up to the 30-year scale, which is typically assumed to be the level they work best at. They also did no better over larger and larger regional scales. The authors concluded that there is no basis for the claim that climate models are well-suited for long-term predictions over large regions.

A 2011 study in the Journal of Forecasting took the same data set and compared model predictions against a “random walk” alternative, consisting simply of using the last period’s value in each location as the forecast for the next period’s value in that location. The test measures the sum of errors relative to the random walk. A perfect model gets a score of zero, meaning it made no errors. A model that does no better than a random walk gets a score of 1. A model receiving a score above 1 did worse than uninformed guesses. Simple statistical forecast models that have no climatology or physics in them typically got scores between 0.8 and 1, indicating slight improvements on the random walk, though in some cases their scores went as high as 1.8.

The climate models, by contrast, got scores ranging from 2.4 to 3.7, indicating a total failure to provide valid forecast information at the regional level, even on long time scales. The authors commented: “This implies that the current [climate] models are ill-suited to localized decadal predictions, even though they are used as inputs for policymaking.”

Indeed. Nor is the problem confined just to a few models. In a 2010 paper, a co-author and I looked at how well an average formed from all 23 climate models used for the 2007 IPCC report did at explaining the spatial pattern of temperature trends on land after 1979, compared with a rival model that all the experts keep telling me should have no explanatory power at all: the regional pattern of socioeconomic growth. Any effects from those factors, I have been told many times, are removed from the climate data before it is published. And yet I keep finding the socioeconomic patterns do a very good job of explaining the patterns of temperature trends over land. In our 2010 paper we showed that the climate models, averaged together, do very poorly, while the socioeconomic data does quite well.

The computer models have to be able to predict changes in specific regions, otherwise we have no reason to trust that they are accurate. We have to be able to evaluate whether the models work by testing them. When we can test them to predict climate change in specific regions, they fail.

News

New study: global warming skeptics know more about science than alarmists

Leave a comment

ECM posted this Fox News story on Facebook.

Excerpt:

A study published Sunday in the journal Nature Climate Change finds that people who are not that worried about the effects of global warming tend to have a slightly higher level of scientific knowledge than those who are worried, as determined by their answers to questions like:

  • “Electrons are smaller than atoms — true or false?”
  • “How long does it take the Earth to go around the Sun? One day, one month, or one year?”
  • “Lasers work by focusing sound waves — true or false?”

The quiz, containing 22 questions about both science and statistics, was given to 1,540 representative Americans. Respondents who were relatively less worried about global warming got 57 percent of them right, on average, just barely outscoring those whose who saw global warming as a bigger threat. They got 56 percent of the questions correct.

“As respondents’ science literacy scores increased, their concern with climate change decreased,” the paper, which was funded by the National Science Foundation, notes.

It reminds me of the debate between theists. On the one hand, you’ve got the theists with their Big Bang, fine-tuning and biological information. On the other hand, you’ve got the atheists with their eternally oscillating bouncy universe, their unobservable multiverse and their hypothetical aliens seeding the Earth with life. It’s science vs. religion, all right. Or perhaps I should say science vs. science fiction.