Our climate models are WRONG: Global warming has slowed – and recent changes are down to ‘natural variability’, says study
- Duke University study looked at 1,000 years of temperature records
- It compared it to the most severe emissions scenarios by the IPCC
- Found that natural variability can slow or speed the rate of warming
- These ‘climate wiggles’ were not properly accounted for in IPCC report
PUBLISHED: 15:56 EST, 23 April 2015 | UPDATED: 18:31 EST, 23 April 2015
The research claims that natural variability in surface temperatures over the course of a decade can account for increases and dips in warming rates.
But it adds that these so-called ‘climate wiggles’ could also, in the future, cause our planet to warm up much faster than anticipated.
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The study compared its results to the most severe emissions scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC). Projected temperature change from 2081-2100 by the IPCC are pictured here. The latest study, however, says this climate model may be wrong
The study compared its results to the most severe emissions scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC).
‘Based on our analysis, a middle-of-the-road warming scenario is more likely, at least for now,’ said Patrick Brown, a doctoral student in climatology at Duke University. ‘But this could change.’
The Duke-led study says that variability is caused by interactions between the ocean and atmosphere, and other natural factors.
They claim these ‘wiggles’ can slow or speed the rate of warming from decade to decade, and exaggerate or offset the effects of increases in greenhouse gas concentrations.
If not properly explained and accounted for, they may skew the reliability of climate models and lead to over-interpretation of short-term temperature trends.
Summary of projected changes in crop yields in a previous IPCC report. Because ‘climate wiggles’ were not accounted for, the Duke University researchers say the report may have been an over-interpretation of short-term temperature trends
The research, uses observed data, rather than the more commonly used climate models, to estimate decade-to-decade variability.
‘At any given time, we could start warming at a faster rate if greenhouse gas concentrations in the atmosphere increase without any offsetting changes in aerosol concentrations or natural variability,’ said Wenhong Li, assistant professor of climate at Duke, who conducted the study with Brown.
DISEASES WILL SPREAD FASTER BECAUSE OF CLIMATE CHANGE
Infectious diseases, such as Ebola and West Nile virus, will rapidly spread to new areas as a result of global warming.
This is according to zoologist, Professor Daniel Brooks, who warns humans can expect to face new illnesses as climate change brings crops, livestock, and humans into contact with pathogens.
Professor Brooks says it will be ‘the death of a thousand cuts’ with society unable to keep up with the speed of disease as it spreads around the world.
‘It’s not that there’s going to be one “Andromeda Strain” that will wipe everybody out on the planet,’ Professor Brooks said, referring to the 1971 science fiction film about a deadly pathogen.
‘There are going to be a lot of localised outbreaks that put a lot of pressure on our medical and veterinary health systems.’
In his research, Professor Brooks has focused primarily on parasites in the tropics, while his colleague, Professor Eric Hoberg, has worked in Arctic regions.
Each has observed the arrival of species that hadn’t previously lived in that area and the departure of others, said Professor Brooks, who is affiliated with the University of Nebraska-Lincoln.
The team examined whether climate models, such as those used by the IPCC, accurately account for natural chaotic variability that can occur in the rate of global warming.
To test these, created a new statistical model based on reconstructed empirical records of surface temperatures over the last 1,000 years.
‘By comparing our model against theirs, we found that climate models largely get the ‘big picture’ right but seem to underestimate the magnitude of natural decade-to-decade climate wiggles,’ Brown said.
‘Our model shows these wiggles can be big enough that they could have accounted for a reasonable portion of the accelerated warming we experienced from 1975 to 2000, as well as the reduced rate in warming that occurred from 2002 to 2013.’
‘Statistically, it’s pretty unlikely that an 11-year hiatus in warming, like the one we saw at the start of this century, would occur if the underlying human-caused warming was progressing at a rate as fast as the most severe IPCC projections,’ Brown said.
‘Hiatus periods of 11 years or longer are more likely to occur under a middle-of-the-road scenario.’
Under the IPCC’s middle-of-the-road scenario, there was a 70 per cent likelihood that at least one hiatus lasting 11 years or longer would occur between 1993 and 2050, Brown said.
‘That matches up well with what we’re seeing.’
There’s no guarantee, however, that this rate of warming will remain steady in coming years, Li stressed.
‘Our analysis clearly shows that we shouldn’t expect the observed rates of warming to be constant. They can and do change.’
The IPCC has previously warmed that global warming is impacting ‘all continents and across the oceans’. This map details some of the predicted affects of climate change in different continents. However the latest study claims that the worst-case scenario is unlikely to take place
Read more: http://www.dailymail.co.uk/sciencetech/article-3052926/Our-climate-models-WRONG-Global-warming-slowed-recent-changes-natural-variability-says-study.html#ixzz3YLwSVJUh
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