I have looked at Australia’s climate in 2013. Now, how did the world’s climate fare in 2013? And what does the recent “polar vortex” in the US say about climate change?
World climate 2013
2013 is estimated to have been the fourth hottest year on record – the only hotter years were 1998, 2005 and 2010. The graph shows the calculated average for the past 35 years, plotted as deviations about the mean.
Has climate changed slowed?
Some people claim that climate change has slowed, if it is even happening at all. This graph shows that the claim is very doubtful. A straight line trend over all 35 years (shown in blue) shows a significant rise. Selecting any other set of years gives a similar rate of rise (e.g. the 20 year period 1994-2013, shown in green) and even selecting the set of years that gives the lowest slope (1998-2013, shown in red) still shows about half the rate of temperature increase.
Weather can vary hugely. As well as local variations, there are the well-understood weather patterns El Niño (which produces warmer weather in the Pacific region) and La Niña (which is associated with cooler weather), variations in the sun’s energy and the effect of large volcanoes (whose ash reduces sun energy reaching the ground).
2013 was apparently the hottest La Niña year ever and solar activity was relatively low. With sun energy on the increase and a return to El Niño patterns expected, we are likely to see even hotter years soon.
Melting arctic sea ice is a major problem for the environment (just ask a polar bear), and the minimum summer extent of sea ice has been reducing for years now. 2013 was an improvement on the previous few years for both the Arctic and the less important Antarctic, though still below the 30 year average in the Arctic.
Meanwhile, weather-related losses and damage have risen from an annual average of about $50 billion in the 1980s to close to $200 billion over the last decade -confirming climate change predictions. The insurers know climate change is occurring, even if some other people don’t!
The response to the recent extreme cold weather in the US, suggesting that it shows climate change is a false idea, is an example of a silly response to weather variability. Even as the earth warms, there will still be cold weather, and even extreme cold weather – but the patterns and frequencies are changing.
The basis of climate science
Climate change science is based on more than just looking at a few graphs, but on deep understanding of the physics and verifiable computer models which fit the available data. They are not precise because (a) science is rarely precise (most scientific conclusions are known within certain statistical confidence limits), (b) climate is highly variable, (c) it is difficult to make the data representative, and (d) they cannot model small scale processes in a worldwide model.
But they are based on the best data and scientific understanding we have, and their predictions are far more likely than any other outcome. There are some genuine scientific questions to be asked of climate science, but most of the popular ‘objections’ are nonsense.
Many of the statements made in the Murdoch press, and other climate change denial sources, are misleading to the extent they suggest wilful blindness if not deliberate deception. They are generally based on a few anecdotes and random facts, and ignore the findings of thousands of reputable scientists.
Climate science predicts that variability will increase, so that overall the world will experience more variability of heat and cold, more floods and droughts, more storms. Thus, because there are significant fluctuations about the long term climate trends, looking at a few years and making derisive comments whenever a cooler event occurs is nonsense. It is the long term trends and the model outputs which count in assessing whether climate change is occurring.
Why the scepticism?
It seems as if the strongest popular critics of climate science are not scientists, but rich, powerful, elderly and conservative men who don’t want to change, and are happy to allow their grandchildren to have to pick up the pieces. The rest of us shouldn’t accept their biased viewpoint, but believe the established science, accept that even though it isn’t precise, the trends are clear.
We need our governments to start to act Real Soon Now.