Is the global warming pause over? Did it ever exist?

Global warming sceptics have long relied on the “pause” in rising world temperatures to bolster their claim that it is all a myth. However, recent evidence suggests that the pause may well be over, and that it may never even have existed in the first place.

The global warming hiatus

Measurements of average global temperatures, which have become increasingly sophisticated since the advent of satellite recording to add to land and sea observations, have shown an upward rise ever since the late 19^th century.  These measurements have been incorporated in models of climate change that demonstrate worrying trends that could lead to very serious consequences for life on Earth in future generations.

However, despite the overall upward trend taken over the long term, there have been times when the steadiness of the rise has been called into question. In particular, the past 15 years appear to have demonstrated a pause or hiatus in the rise, with the overall global temperature rising very little, if at all.

Needless to say, this hiatus has provided welcome ammunition for the chorus of climate change deniers who would prefer to ignore the evidence gathered by the world’s huge army of climate scientists who are in almost universal agreement that global warming is real, is largely due to human activity, has potentially alarming consequences, and is something that the governments of the world should be taking urgent action to combat.

The deniers are concerned that action to slow down the rate of temperature rise will have severe consequences for the economies of the world’s wealthiest countries and lead to a decline in living standards. Their main weapon in furthering their claims is to try to refute the evidence produced by the climate scientists, and the “pause” is an important weapon which they have used to persuade others to their point of view.

But the pause may be over

The current evidence shows that global temperatures are once more moving upwards. Record highs have been recordeded in many parts of the world, including West Africa, South America and the Pacific Ocean. Antarctica had its warmest ever day in March 2015, with a temperature of 17.4⁰C (63.3⁰F) being recorded.

These 2015 record highs are on top of the previous records noted in 2014, thus showing that the upward spike was not a one-year blip. Ever cautious, climate scientists will not say that the evidence provides absolute certainty that the pause is over, but it very much looks as though this might be the case.

This is borne out by other evidence of continuing warming, such as there being less Arctic ice recorded than in any previous year and a rise in overall atmospheric carbon dioxide (a major driver of global warming) to more than 400 parts per million – the first time this has ever happened in human history.

Is El Nino to blame?

Climate science is extremely complex, with many factors being involved that can affect global temperatures one way or the other, and one of these is the phenomenon known as El Nino. This is a periodic warming of the waters of the Pacific Ocean that can have serious implications for weather patterns across the globe. However, the timing of the latest El Nino does not match the pattern of higher temperature recordings mentioned above. The world was already getting hotter before El Nino got going, and the expected rise due to El Nino will not be noticed until several months after it has peaked.

Is the pause a myth anyway?

However, some scientists are now claiming that there was never a global warming pause in the first place.

Scientists at the NOAA (US National Oceanic and Atmospheric Administration) have published a paper in “Science” that states that errors were made in the ocean temperature data collection methods used in past decades that led to a general underestimation of temperatures. Once these errors are accounted for, the upward trend is consistent with the earlier figures in showing a steady rise and no hiatus.

The differences come about from the change in data collection, from ships (measuring the temperature of water collected in buckets) to buoys, this change dating from the 1970s. The practice had always been to assume that the bucket-collection method produced higher temperatures, and these were accounted for in the figures used in climate models. However, these downward adjustments were still applied after buoys were used to record temperatures, despite their figures being more accurate. Once these adjustments are taken out of the reckoning, the hiatus is no longer to be seen.

In other words, the “pause” defence has ceased to be available to the climate change deniers. Whether one accepts the NOAA’s findings or not, the climate change pause is almost certainly a thing of the past.

© John Welford