We rely a lot on climate models. They not only help us understand our present climate, but also allow us to understand possible future conditions and how different regions of our planet are likely to be impacted by climate change.
Having access to this information is vital for the community, government and industries to make informed decisions – sectors like tourism, farming and transportation to name a few.
As useful as these tools are, the reality is that the Earth’s climate system is incredibly complicated. It is affected by an infinite number of variations in the atmosphere, land surface, oceans, ice, and biosphere. How these factors interact with one another, and our socio-economic decisions, further complicates the issue.
Two icebergs on Jokulsarlon lagoon Iceland
In the absence of a twin Earth to use as an experimental control, simulations are the only method we have to understand the future.
Using observed data, advanced algorithms and software systems, scientists have been developing and refining these valuable climate models for years. However in recent times, there has been conjecture about a key aspect of the reliability of these models; whether they are accurately predicting temperature trends?
A new study, published today in Nature Climate Change, shows that yes in fact, they are.
According to the study’s lead author Dr James Risbey, the key to evaluating decadal climate variations is recognising the difference between climate forecasts and climate projections.
He explains that climate forecasts track the detailed evolution of a range of factors, including natural variations like El Niño and La Niña (which put simply is, warm water sloshing around the ocean). This is important because in El Niño and La Niña dominated periods, temperature trends will naturally speed up and slow down.
“Climate projections, on the other hand, capture natural variations, but have no information on their sequence and timing. Since these can impact the climate on a short timescale as much as human activities, their omission from projections creates a mismatch with observed trends. In other words, comparing the two wouldn’t pass the old ‘apples with apples’ test,” he said.
For this latest study, James and his colleagues looked at a range of different climate models that were in phase with natural variability. In doing so, they were able to make meaningful comparisons between model projections and observed trends.
Their analysis showed that in these instances climate models have been very accurate in predicting trends in our climate over the past half century. In other words, climate change models are a lot more than hot air.
Fine out more about our research into climate in our recent report State of the Climate: 2014.
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