"A" major cause but there are others. ENSO, the el Nino Southern Oscillation, is another. Ocean currents, ditto. These things come in waves and, like ordinary waves, when they combine they can amplify or cancel each other.
A study released today by the journal, Nature.com, says we've got at least four more years of severe and excessive heating. The title of the paper, "A novel probabilistic forecast system predicting anomalously warm 2018-2022 reinforcing the long-term global warming trend," is a bit of a plot spoiler. Anomalously warm 2018-2022.
The world is likely to see more extreme temperatures in the coming four years as natural warming reinforces manmade climate change, according to a new global forecasting system.
Following a summer of heatwaves and forest fires in the northern hemisphere, the study in the journal Nature Communications suggests there will be little respite for the planet until at least 2022, and possibly not even then.
Rising greenhouse gas emissions are steadily adding to the upward pressure on temperatures, but humans do not feel the change as a straight line because the effects are diminished or amplified by phases of natural variation.
From 1998 to 2010, global temperatures were in a “hiatus” as natural cooling (from ocean circulation and weather systems) offset anthropogenic global warming. But the planet has now entered almost the opposite phase, when natural trends are boosting man-made effects.
...Professor James Renwick of Victoria University of Wellington said the new forecasting system was clever, but its value will only be clear in the future. The broader trend, however, was clear.
“If the warming trend caused by greenhouse gas emissions continues, years like 2018 will be the norm in the 2040s, and would be classed as cold by the end of the century,” he wrote.When I read summaries of the reports that have come in over the past month, my mind goes to agriculture or, more specifically, food security. The problem isn't just the heatwaves but, of perhaps greater concern, our broken hydrologic cycle. We've lost a significant amount of surface moisture that has evaporated into water vapour, atmospheric moisture.
This warmer, wetter atmosphere fuels severe storm events of increasing frequency, duration and intensity. The recent flooding of Toronto or the inundation of Calgary in 2013 are one aspect. In many other areas it's the opposite problem - drought. This is Australia's mid-winter and yet that country is plagued with drought. Europe too, when it's not flooding. Western North America is drought-stricken resulting in record wildfires extending from Mexico to the Arctic. Sweden, yes Sweden, is on the receiving end of drought and wildfires extending well into the Arctic Circle.
Fortunately Russia is reported to be having a good year on wheat. Canada hopes to see only small declines. How will that hold up if we keep getting battered by successive record-hot summers? Well, our government should be telling us that only they're not. It's probably not the discussion you most want to have if you're planning to sell a plan to export ever more bitumen for the next 30 years.